// Copyright 2016 The OPA Authors.  All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.

package ast

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"reflect"
	"strings"
	"testing"

	"github.com/open-policy-agent/opa/v1/ast/internal/tokens"
)

const (
	testModule = `
# This policy module belongs the opa.example package.
package opa.examples

# Refer to data.servers as servers.
import data.servers
# Refer to the data.networks as networks.
import data.networks
# Refer to the data.ports as ports.
import data.ports

# A server exists in the violations set if...
violations contains server if {
    # ...the server exists
    server = servers[i]
    # ...and any of the server’s protocols is HTTP
    server.protocols[j] = "http"
    # ...and the server is public.
    public_servers[server]
}

# A server exists in the public_servers set if...
public_servers contains server if {
	# Semicolons are optional. Can group expressions onto one line.
    server = servers[i]; server.ports[j] = ports[k].id 	# ...and the server is connected to a port
    ports[k].networks[l] = networks[m].id; 				# ...and the port is connected to a network
    networks[m].public = true							# ...and the network is public.
}`
)

func TestNumberTerms(t *testing.T) {

	tests := []struct {
		input    string
		expected string
	}{
		{"0", "0"},
		{"100", "100"},
		{"-1", "-1"},
		{"1e6", "1e6"},
		{"1.1e6", "1.1e6"},
		{"-1e-6", "-1e-6"},
		{"1E6", "1E6"},
		{"0.1E6", "0.1E6"},
		{"0.1e6", "0.1e6"},
		{"0.1e-6", "0.1e-6"},
		{"0e6", "0e6"},
		{"0e-6", "0e-6"},
		{"0.1", "0.1"},
		{".1", "0.1"},
		{".0001", "0.0001"},
		{"-.1", "-0.1"},
		{"-0.0001", "-0.0001"},
		{"1e1000", "1e1000"},
		{"0e1", "0"},
		{"-0.1", "-0.1"},
	}

	for _, tc := range tests {
		t.Run(tc.input, func(t *testing.T) {
			result, err := ParseTerm(tc.input)
			if err != nil {
				t.Errorf("Unexpected error for %v: %v", tc.input, err)
			} else {
				e := NumberTerm(json.Number(tc.expected))
				if !result.Equal(e) {
					t.Errorf("Expected %v for %v but got: %v", e, tc.input, result)
				}
			}
		})
	}

	errorTests := map[string]struct {
		input         string
		expectedError string
	}{
		"leading 0": {
			input:         "03",
			expectedError: "expected number without leading zero",
		},
		"leading 0, many": {
			input:         "003",
			expectedError: "expected number without leading zero",
		},
		"leading 0, 'octal'": {
			input:         "0755",
			expectedError: "expected number without leading zero",
		},
		"leading 0, decimal": {
			input:         "03.333",
			expectedError: "expected number without leading zero",
		},
		"leading 0, negative": {
			input:         "-03",
			expectedError: "expected number without leading zero",
		},
		"leading 0, exp": {
			input:         "03e6",
			expectedError: "expected number without leading zero",
		},
		"leading 0, exp, negative": {
			input:         "-03e6",
			expectedError: "expected number without leading zero",
		},
	}

	for name, tc := range errorTests {
		t.Run(name, func(t *testing.T) {
			assertParseErrorContains(t, name, tc.input, tc.expectedError)
		})
	}
}

func TestStringTerms(t *testing.T) {
	tests := []struct {
		input    string
		expected string
	}{
		{`""`, ""},                   // empty
		{`" "`, " "},                 // whitespace
		{`"\""`, `"`},                // escaped quote
		{`"http:\/\/"`, `http://`},   // escaped solidus
		{`"\u0001"`, "\x01"},         // control code
		{`"foo\u005C"`, "foo\u005c"}, // unicode (upper hex)
		{`"foo\u005c"`, "foo\u005C"}, // unicode (lower hex)
		{`"\uD834\uDD1E"`, `𝄞`},      // g-clef
		{"`hi\\there`", `hi\there`},  // basic raw string
		{"`foo\nbar\n    baz`", `foo
bar
    baz`}, // multi-line raw string
	}

	for _, tc := range tests {
		result, err := ParseTerm(tc.input)
		if err != nil {
			t.Errorf("Unexpected error for %v: %v", tc.input, err)
		} else {
			s := StringTerm(tc.expected)
			if !result.Equal(s) {
				t.Errorf("Expected %v for %v but got: %v", s, tc.input, result)
			}
		}
	}
}

func TestScalarTerms(t *testing.T) {
	assertParseOneTerm(t, "null", "null", NullTerm())
	assertParseOneTerm(t, "true", "true", BooleanTerm(true))
	assertParseOneTerm(t, "false", "false", BooleanTerm(false))
	assertParseOneTerm(t, "integer", "53", IntNumberTerm(53))
	assertParseOneTerm(t, "integer2", "-53", IntNumberTerm(-53))
	assertParseOneTerm(t, "float", "16.7", FloatNumberTerm(16.7))
	assertParseOneTerm(t, "float2", "-16.7", FloatNumberTerm(-16.7))
	assertParseOneTerm(t, "exponent", "6e7", FloatNumberTerm(6e7))
	assertParseOneTerm(t, "string", "\"a string\"", StringTerm("a string"))
	assertParseOneTerm(t, "string", "\"a string u6abc7def8abc0def with unicode\"", StringTerm("a string u6abc7def8abc0def with unicode"))
	assertParseErrorContains(t, "hex", "6abc", "illegal number format")
	assertParseErrorContains(t, "non-terminated", "\"foo", "non-terminated string")
	assertParseErrorContains(t, "non-terminated-raw", "`foo", "non-terminated string")
	assertParseErrorContains(t, "non-string", "'a string'", "illegal token")
	assertParseErrorContains(t, "non-number", "6zxy", "illegal number format")
	assertParseErrorContains(t, "non-number2", "6d7", "illegal number format")
	assertParseErrorContains(t, "non-number3", "6\"foo\"", "expected exactly one statement") // ??
	assertParseErrorContains(t, "non-number4", "6true", "illegal number format")
	assertParseErrorContains(t, "non-number5", "6false", "illegal number format")
	assertParseErrorContains(t, "non-number6", "6[null, null]", "illegal ref (head cannot be number)") // ??
	assertParseErrorContains(t, "non-number7", "6{\"foo\": \"bar\"}", "expected exactly one statement")
	assertParseErrorContains(t, "non-number8", ".0.", "expected fraction")
	assertParseErrorContains(t, "non-number9", "0e", "expected exponent")
	assertParseErrorContains(t, "non-number10", "0e.", "expected exponent")
	assertParseErrorContains(t, "non-number11", "0F", "illegal number format")
	assertParseErrorContains(t, "non-number12", "00", "expected number")
	assertParseErrorContains(t, "non-number13", "00.1", "expected number")
	assertParseErrorContains(t, "non-number14", "-00", "expected number")
	assertParseErrorContains(t, "non-number15", "-00.1", "expected number")
	assertParseErrorContains(t, "non-number16", "-00.01", "expected number")
	assertParseErrorContains(t, "non-number17", "00e1", "expected number")
	assertParseErrorContains(t, "non-number18", "-00e1", "expected number")
	assertParseErrorContains(t, "parsing float fails", "7e3000000000", "invalid float")
	assertParseErrorContains(t, "float is +inf", "10245423601e680507880", "number too big")
	assertParseErrorContains(t, "float is -inf", "-10245423601e680507880", "number too big")

	// f := big.NewFloat(1); f.SetMantExp(f, -1e6); f.String() // => 1.010034059e-301030 (this takes ~9s)
	assertParseErrorContains(t, "float exp < -1e5", "1.010034059e-301030", "number too big")

	// g := big.NewFloat(1); g.SetMantExp(g, 1e6); g.String() // => 9.900656229e+301029
	assertParseErrorContains(t, "float exp > 1e5", "9.900656229e+301029", "number too big")
}

func TestVarTerms(t *testing.T) {
	assertParseOneTerm(t, "var", "foo", VarTerm("foo"))
	assertParseOneTerm(t, "var", "foo_bar", VarTerm("foo_bar"))
	assertParseOneTerm(t, "var", "foo0", VarTerm("foo0"))
	assertParseOneTerm(t, "import prefix", "imports", VarTerm("imports"))
	assertParseOneTerm(t, "not prefix", "not_foo", VarTerm("not_foo"))
	assertParseOneTerm(t, `package prefix`, "packages", VarTerm("packages"))
	assertParseOneTerm(t, `true prefix`, "trueish", VarTerm("trueish"))
	assertParseOneTerm(t, `false prefix`, "false_flag", VarTerm("false_flag"))
	assertParseOneTerm(t, `null prefix`, "nullable", VarTerm("nullable"))
	assertParseError(t, "illegal token", `墳`)
	assertParseError(t, "not keyword", "not")
	assertParseError(t, `package keyword`, "package")
	assertParseError(t, "import keyword", "import")
	assertParseError(t, "import invalid path", "import x.")
}

func TestRefTerms(t *testing.T) {
	assertParseOneTerm(t, "constants", "foo.bar.baz", RefTerm(VarTerm("foo"), StringTerm("bar"), StringTerm("baz")))
	assertParseOneTerm(t, "constants 2", "foo.bar[0].baz", RefTerm(VarTerm("foo"), StringTerm("bar"), IntNumberTerm(0), StringTerm("baz")))
	assertParseOneTerm(t, "variables", "foo.bar[0].baz[i]", RefTerm(VarTerm("foo"), StringTerm("bar"), IntNumberTerm(0), StringTerm("baz"), VarTerm("i")))
	assertParseOneTerm(t, "spaces", "foo[\"white space\"].bar", RefTerm(VarTerm("foo"), StringTerm("white space"), StringTerm("bar")))
	assertParseOneTerm(t, "nested", "foo[baz[1][borge[i]]].bar", RefTerm(
		VarTerm("foo"),
		RefTerm(
			VarTerm("baz"), IntNumberTerm(1), RefTerm(
				VarTerm("borge"), VarTerm("i"),
			),
		),
		StringTerm("bar"),
	))
	assertParseOneTerm(t, "composite operand 1", "foo[[1,2,3]].bar", RefTerm(VarTerm("foo"), ArrayTerm(NumberTerm("1"), NumberTerm("2"), NumberTerm("3")), StringTerm("bar")))
	assertParseOneTerm(t, "composite operand 2", `foo[{"foo": 2}].bar`, RefTerm(VarTerm("foo"), ObjectTerm(Item(StringTerm("foo"), NumberTerm("2"))), StringTerm("bar")))

	assertParseError(t, "missing component 1", "foo.")
	assertParseError(t, "missing component 2", "foo[].bar")
	assertParseError(t, "invalid composite operand", "foo[1,2]")
	assertParseError(t, "invalid call", "bar(..")
	assertParseError(t, "invalid ref", "bar[..")
	assertParseError(t, "invalid ref head type number", "0[0]")
	assertParseError(t, "invalid ref head type number (float)", "1.2[0]")
	assertParseError(t, "invalid ref head type string", `"foo"[0]`)
	assertParseError(t, "invalid ref head type string (dot)", `"foo".bar`)
}

func TestRefTermsContainingKeywords(t *testing.T) {
	for _, regoVersion := range []RegoVersion{RegoV0, RegoV1} {
		popts := ParserOptions{RegoVersion: regoVersion}

		t.Run(regoVersion.String(), func(t *testing.T) {
			for _, kw := range Keywords {
				t.Run(kw, func(t *testing.T) {
					input := "foo." + kw
					exp := RefTerm(VarTerm("foo"), StringTerm(kw))
					assertParseOneTerm(t, input, input, exp, popts)

					input = "input." + kw
					exp = RefTerm(VarTerm("input"), StringTerm(kw))
					assertParseOneTerm(t, input, input, exp, popts)

					input = "data." + kw
					exp = RefTerm(VarTerm("data"), StringTerm(kw))
					assertParseOneTerm(t, input, input, exp, popts)

					input = fmt.Sprintf("data.%s.foo", kw)
					exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)

					input = fmt.Sprintf(`data.%s["foo"]`, kw)
					exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)

					input = "data.foo." + kw
					exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
					assertParseOneTerm(t, input, input, exp, popts)

					input = `data["foo"].` + kw
					exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
					assertParseOneTerm(t, input, input, exp, popts)

					input = kw + ".foo"
					exp = RefTerm(VarTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)

					input = kw + `["foo"]`
					exp = RefTerm(VarTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)
				})
			}
		})
	}

	t.Run("v0 with future keywords", func(t *testing.T) {
		caps := CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV0))
		popts := ParserOptions{RegoVersion: RegoV0, Capabilities: caps}

		for kw := range futureKeywordsV0 {
			popts.FutureKeywords = []string{kw}

			t.Run(kw, func(t *testing.T) {
				input := "foo." + kw
				exp := RefTerm(VarTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "input." + kw
				exp = RefTerm(VarTerm("input"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "data." + kw
				exp = RefTerm(VarTerm("data"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = fmt.Sprintf("data.%s.foo", kw)
				exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = fmt.Sprintf(`data.%s["foo"]`, kw)
				exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "data.foo." + kw
				exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = `data["foo"].` + kw
				exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = kw + ".foo"
				exp = RefTerm(VarTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = kw + `["foo"]`
				exp = RefTerm(VarTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)
			})
		}
	})
}

func dropCapabilityFeature(caps *Capabilities, feature string) *Capabilities {
	feats := make([]string, 0, len(caps.Features))
	for _, f := range caps.Features {
		if f != feature {
			feats = append(feats, f)
		}
	}
	caps.Features = feats
	return caps
}

func TestRefTermsContainingKeywords_NoCapability(t *testing.T) {
	for _, regoVersion := range []RegoVersion{RegoV0, RegoV1} {
		caps := CapabilitiesForThisVersion(CapabilitiesRegoVersion(regoVersion))
		caps = dropCapabilityFeature(caps, FeatureKeywordsInRefs)
		popts := ParserOptions{RegoVersion: regoVersion, Capabilities: caps}

		t.Run(regoVersion.String(), func(t *testing.T) {
			for _, kw := range KeywordsForRegoVersion(regoVersion) {
				t.Run(kw, func(t *testing.T) {
					input := "foo." + kw
					expErr := fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	foo.%s
	    ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = "input." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	input.%s
	      ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = "data." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s
	     ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = fmt.Sprintf("data.%s.foo", kw)
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s.foo
	     ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = fmt.Sprintf(`data.%s["foo"]`, kw)
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s["foo"]
	     ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = "data.foo." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.foo.%s
	         ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = `data["foo"].` + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data["foo"].%s
	            ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					// Special cases for leading kw in ref
					// FIXME: The output from before the kw-in-ref change is preserved; but can be improved
					switch kw {
					case "null":
						input = kw + ".foo"
						expErr = fmt.Sprintf(`rego_parse_error: illegal ref (head cannot be null)
	%s.foo
	^`, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})

						input = kw + `["foo"]`
						expErr = fmt.Sprintf(`rego_parse_error: illegal ref (head cannot be null)
	%s["foo"]
	^`, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})
					case "true", "false":
						input = kw + ".foo"
						expErr = fmt.Sprintf(`rego_parse_error: illegal ref (head cannot be boolean)
	%s.foo
	^`, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})

						input = kw + `["foo"]`
						expErr = fmt.Sprintf(`rego_parse_error: illegal ref (head cannot be boolean)
	%s["foo"]
	^`, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})
					case "some":
						input = kw + ".foo"
						expErr = `rego_parse_error: unexpected . token: expected var
	some.foo
	    ^`
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})

						input = kw + `["foo"]`
						expErr = `rego_parse_error: unexpected [ token: expected var
	some["foo"]
	    ^`
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})
					case "every":
						input = kw + ".foo"
						expErr = `rego_parse_error: unexpected identifier token: expected number
	every.foo
	      ^`
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})

						input = kw + `["foo"]`
						expErr = `rego_parse_error: unexpected eof token: expected ` + "`" + `x[, y] in xs { ... }` + "`" + ` expression
	every["foo"]
	           ^`
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})
					case "contains":
						input = kw + `.foo`
						exp := RefTerm(VarTerm(kw), StringTerm("foo"))
						assertParseOneTerm(t, input, input, exp, popts)

						input = kw + `["foo"]`
						exp = RefTerm(VarTerm(kw), StringTerm("foo"))
						assertParseOneTerm(t, input, input, exp, popts)
					default:
						input = kw + ".foo"
						expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword
	%s.foo
	^`, kw, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})

						input = kw + `["foo"]`
						expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword
	%s["foo"]
	^`, kw, kw)
						t.Run(input, func(t *testing.T) {
							assertParseErrorContains(t, input, input, expErr, popts)
						})
					}
				})
			}
		})
	}

	t.Run("v0 with future keywords", func(t *testing.T) {
		caps := CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV0))
		caps = dropCapabilityFeature(caps, FeatureKeywordsInRefs)
		popts := ParserOptions{RegoVersion: RegoV0, Capabilities: caps}

		for kw := range futureKeywordsV0 {
			popts.FutureKeywords = []string{kw}

			t.Run(kw, func(t *testing.T) {
				input := "foo." + kw
				expErr := fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	foo.%s
	    ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = "input." + kw
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	input.%s
	      ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = "data." + kw
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s
	     ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = fmt.Sprintf("data.%s.foo", kw)
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s.foo
	     ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = fmt.Sprintf(`data.%s["foo"]`, kw)
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.%s["foo"]
	     ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = "data.foo." + kw
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data.foo.%s
	         ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				input = `data["foo"].` + kw
				expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected identifier
	data["foo"].%s
	            ^`, kw, kw)
				t.Run(input, func(t *testing.T) {
					assertParseErrorContains(t, input, input, expErr, popts)
				})

				switch kw {
				case "every":
					input = kw + ".foo"
					expErr = `rego_parse_error: unexpected identifier token: expected number
	every.foo
	      ^`
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = kw + `["foo"]`
					expErr = `rego_parse_error: unexpected eof token: expected ` + "`" + `x[, y] in xs { ... }` + "`" + ` expression
	every["foo"]
	           ^`
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})
				case "contains":
					input = kw + `.foo`
					exp := RefTerm(VarTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)

					input = kw + `["foo"]`
					exp = RefTerm(VarTerm(kw), StringTerm("foo"))
					assertParseOneTerm(t, input, input, exp, popts)
				default:
					input = kw + ".foo"
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword
	%s.foo
	^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = kw + `["foo"]`
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword
	%s["foo"]
	^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})
				}
			})
		}
	})
}

func TestCallRefTermsContainingKeywords(t *testing.T) {
	for _, regoVersion := range []RegoVersion{RegoV0, RegoV1} {
		popts := ParserOptions{RegoVersion: regoVersion}

		t.Run(regoVersion.String(), func(t *testing.T) {
			for _, kw := range Keywords {
				t.Run(kw, func(t *testing.T) {
					input := fmt.Sprintf("foo.%s(42)", kw)
					exp := NewExpr([]*Term{RefTerm(VarTerm("foo"), StringTerm(kw)), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf("input.%s(42)", kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("input"), StringTerm(kw)), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf("data.%s(42)", kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("data"), StringTerm(kw)), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf("data.%s.foo(42)", kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo")), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf(`data.%s["foo"](42)`, kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo")), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf("data.foo.%s(42)", kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw)), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = fmt.Sprintf(`data["foo"].%s(42)`, kw)
					exp = NewExpr([]*Term{RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw)), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = kw + ".foo(42)"
					exp = NewExpr([]*Term{RefTerm(VarTerm(kw), StringTerm("foo")), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)

					input = kw + `["foo"](42)`
					exp = NewExpr([]*Term{RefTerm(VarTerm(kw), StringTerm("foo")), NumberTerm("42")})
					assertParseOneExpr(t, input, input, exp, popts)
				})
			}
		})
	}

	t.Run("v0 with future keywords", func(t *testing.T) {
		caps := CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV0))
		popts := ParserOptions{RegoVersion: RegoV0, Capabilities: caps}

		for kw := range futureKeywordsV0 {
			popts.FutureKeywords = []string{kw}

			t.Run(kw, func(t *testing.T) {
				input := "foo." + kw
				exp := RefTerm(VarTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "input." + kw
				exp = RefTerm(VarTerm("input"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "data." + kw
				exp = RefTerm(VarTerm("data"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = fmt.Sprintf("data.%s.foo", kw)
				exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = fmt.Sprintf(`data.%s["foo"]`, kw)
				exp = RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = "data.foo." + kw
				exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = `data["foo"].` + kw
				exp = RefTerm(VarTerm("data"), StringTerm("foo"), StringTerm(kw))
				assertParseOneTerm(t, input, input, exp, popts)

				input = kw + ".foo"
				exp = RefTerm(VarTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)

				input = kw + `["foo"]`
				exp = RefTerm(VarTerm(kw), StringTerm("foo"))
				assertParseOneTerm(t, input, input, exp, popts)
			})
		}
	})
}

func TestImportContainingKeywords(t *testing.T) {
	for _, regoVersion := range []RegoVersion{RegoV0, RegoV1} {
		popts := ParserOptions{RegoVersion: regoVersion}

		t.Run(regoVersion.String(), func(t *testing.T) {
			for _, kw := range KeywordsForRegoVersion(regoVersion) {
				t.Run(kw, func(t *testing.T) {
					// Keywords are allowed mid-path in import paths.

					input := fmt.Sprintf("import data.%s.foo", kw)
					exp := &Import{Path: RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))}
					t.Run(input, func(t *testing.T) {
						assertParseImport(t, input, input, exp, popts)
					})

					input = fmt.Sprintf(`import data.%s["foo"]`, kw)
					exp = &Import{Path: RefTerm(VarTerm("data"), StringTerm(kw), StringTerm("foo"))}
					t.Run(input, func(t *testing.T) {
						assertParseImport(t, input, input, exp, popts)
					})

					// Keywords are not allowed as the first component of import paths (only 'data, 'input', 'future', and 'rego' allowed).

					input = "import " + kw
					expErr := fmt.Sprintf(`rego_parse_error: unexpected import path, must begin with one of: {data, future, input, rego}, got: %s (hint: if this is unexpected, try updating OPA)
	import %s
	       ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = fmt.Sprintf("import %s.foo", kw)
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must begin with one of: {data, future, input, rego}, got: %s (hint: if this is unexpected, try updating OPA)
	import %s.foo
	       ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = fmt.Sprintf(`import %s["foo"]`, kw)
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must begin with one of: {data, future, input, rego}, got: %s (hint: if this is unexpected, try updating OPA)
	import %s["foo"]
	       ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					// Keywords are not allowed as the last component of import paths ..

					input = "import input." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must not end with a keyword, got: %s
	import input.%s
	             ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = "import data." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must not end with a keyword, got: %s
	import data.%s
	            ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = "import data.foo." + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must not end with a keyword, got: %s
	import data.foo.%s
	                ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					input = `import data["foo"].` + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected import path, must not end with a keyword, got: %s
	import data["foo"].%s
	                   ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})

					// .. unless they have an alias.

					input = fmt.Sprintf("import data.%s as foo", kw)
					exp = &Import{Path: RefTerm(VarTerm("data"), StringTerm(kw)), Alias: "foo"}
					assertParseImport(t, input, input, exp, popts)

					input = fmt.Sprintf(`import data["%s"] as foo`, kw)
					exp = &Import{Path: RefTerm(VarTerm("data"), StringTerm(kw)), Alias: "foo"}
					assertParseImport(t, input, input, exp, popts)

					// Keywords are not allowed as import aliases

					input = "import data.foo as " + kw
					expErr = fmt.Sprintf(`rego_parse_error: unexpected %s keyword: expected var
	import data.foo as %s
	                   ^`, kw, kw)
					t.Run(input, func(t *testing.T) {
						assertParseErrorContains(t, input, input, expErr, popts)
					})
				})
			}
		})
	}
}

func TestPackageContainingKeywords(t *testing.T) {
	for _, regoVersion := range []RegoVersion{RegoV0, RegoV1} {
		popts := ParserOptions{RegoVersion: regoVersion}

		t.Run(regoVersion.String(), func(t *testing.T) {
			for _, kw := range KeywordsForRegoVersion(regoVersion) {
				t.Run(kw, func(t *testing.T) {
					// Keywords are allowed mid-path in package paths.

					input := fmt.Sprintf("package foo.%s.bar", kw)
					exp := &Package{Path: []*Term{VarTerm("data"), StringTerm("foo"), StringTerm(kw), StringTerm("bar")}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					input = fmt.Sprintf(`package foo.%s["bar"]`, kw)
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm("foo"), StringTerm(kw), StringTerm("bar")}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					// Keywords are allowed as the first component of package paths.

					input = "package " + kw
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm(kw)}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					input = fmt.Sprintf("package %s.foo", kw)
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm(kw), StringTerm("foo")}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					input = fmt.Sprintf(`package %s["foo"]`, kw)
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm(kw), StringTerm("foo")}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					// Keywords are allowed as the last component of import paths.

					input = "package foo." + kw
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm("foo"), StringTerm(kw)}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})

					input = fmt.Sprintf(`package foo["%s"]`, kw)
					exp = &Package{Path: []*Term{VarTerm("data"), StringTerm("foo"), StringTerm(kw)}}
					t.Run(input, func(t *testing.T) {
						assertParsePackage(t, input, input, exp, popts)
					})
				})
			}
		})
	}
}

func TestRuleHeadsContainingKeywords(t *testing.T) {
	for _, kw := range Keywords {
		t.Run(kw, func(t *testing.T) {
			// Complete rules

			note := "complete rule, kw name"
			input := kw + " if { true }"
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "complete rule with ref in head, kw in first term"
			input = kw + `.foo if { true }`
			exp := &Rule{
				Head: RefHead([]*Term{VarTerm(kw), StringTerm("foo")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "complete rule with ref in head, kw last term"
			input = fmt.Sprintf(`foo.%s if { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "complete rule with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`foo["%s"] if { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "complete rule with ref in head, kw middle term"
			input = fmt.Sprintf(`foo.%s.bar if { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "complete rule with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`foo["%s"].bar if { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			// Functions

			note = "function, kw name"
			input = kw + "(x, y) if { true }"
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "function with ref in head, kw in first term"
			input = kw + `.foo(x, y) if { true }`
			head := RefHead([]*Term{VarTerm(kw), StringTerm("foo")}, BooleanTerm(true))
			head.Name = Var(kw)
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw last term"
			input = fmt.Sprintf(`foo.%s(x, y) if { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true))
			head.Name = "foo"
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`foo["%s"](x, y) if { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true))
			head.Name = "foo"
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw middle term"
			input = fmt.Sprintf(`foo.%s.bar(x, y) if { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`foo["%s"].bar(x, y) if { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			// Partial set rules

			note = "partial set rule, kw name"
			input = kw + " contains { true }"
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "partial set rule with ref in head, kw in first term"
			input = kw + `.foo contains 1 if { true }`
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm(kw), StringTerm("foo")},
					Key:       NumberTerm("1"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "partial set rule with ref in head, kw last term"
			input = fmt.Sprintf(`foo.%s contains 1 if { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Key:       NumberTerm("1"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "partial set rule with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`foo["%s"] contains 1 if { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Key:       NumberTerm("1"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "partial set rule with ref in head, kw middle term"
			input = fmt.Sprintf(`foo.%s.bar contains 1 if { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Key:       NumberTerm("1"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "partial set rule with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`foo["%s"].bar contains 1 if { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Key:       NumberTerm("1"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			// Default rules

			note = "default rule, kw name"
			input = fmt.Sprintf("default %s if { true }", kw)
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "default rule with ref in head, kw in first term"
			input = fmt.Sprintf(`default %s.foo := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm(kw), StringTerm("foo")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default rule with ref in head, kw last term"
			input = fmt.Sprintf(`default foo.%s := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default rule with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"] := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default rule with ref in head, kw middle term"
			input = fmt.Sprintf(`default foo.%s.bar := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default rule with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"].bar := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			// Default functions

			note = "default function, kw name"
			input = fmt.Sprintf("default %s(_, _) if { true }", kw)
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "default function with ref in head, kw in first term"
			input = fmt.Sprintf(`default %s.foo(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm(kw), StringTerm("foo")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw last term"
			input = fmt.Sprintf(`default foo.%s(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"](_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw middle term"
			input = fmt.Sprintf(`default foo.%s.bar(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"].bar(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})
		})
	}
}

func TestRuleHeadsContainingInfixOperatorError(t *testing.T) {
	infixOperators := []struct {
		lex   string
		token tokens.Token
	}{
		{"+", tokens.Add},
		{"-", tokens.Sub},
		{"*", tokens.Mul},
		{"/", tokens.Quo},
		{"%", tokens.Rem},
		{"==", tokens.Equal},
		{"!=", tokens.Neq},
		{"<", tokens.Lt},
		{"<=", tokens.Lte},
		{">", tokens.Gt},
		{">=", tokens.Gte},
		{"&&", tokens.And},
		{"||", tokens.Or},
	}

	patterns := []string{
		"foo%[1]sbar := 1",
		"foobar%[1]s := 1",
		"fo3%[1]s4ar := 1",
		"foo%[1]sbar := 9%[1]s2",
	}

	for _, op := range infixOperators {
		t.Run(op.lex, func(t *testing.T) {
			t.Parallel()
			for _, p := range patterns {
				t.Run(p, func(t *testing.T) {
					msg := fmt.Sprintf("Expected error for pattern %q with infix operator %q", p, op.lex)
					input := fmt.Sprintf(p, op.lex)
					exp := fmt.Sprintf("rego_parse_error: unexpected %s token", op.token.String())
					assertParseErrorContains(t, msg, input, exp)
				})
			}
		})
	}
}

func TestRuleHeadsContainingKeywords_RegoV0(t *testing.T) {
	popts := ParserOptions{RegoVersion: RegoV0}

	for _, kw := range KeywordsV0 {
		t.Run(kw, func(t *testing.T) {
			// Complete rules

			note := "complete rule, kw name"
			input := kw + " { true }"
			t.Run(note, func(t *testing.T) {
				_, err := ParseRuleWithOpts(input, popts)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "complete rule with ref in head, kw in first term"
			input = kw + `.foo.bar { true }`
			exp := &Rule{
				Head: RefHead([]*Term{VarTerm(kw), StringTerm("foo"), StringTerm("bar")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "complete rule with ref in head, kw last term"
			input = fmt.Sprintf(`foo.bar.%s { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm("bar"), StringTerm(kw)}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "complete rule with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`foo.bar["%s"] { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm("bar"), StringTerm(kw)}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "complete rule with ref in head, kw middle term"
			input = fmt.Sprintf(`foo.%s.bar { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "complete rule with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`foo["%s"].bar { true }`, kw)
			exp = &Rule{
				Head: RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true)),
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			// Functions

			note = "function, kw name"
			input = kw + "(x, y) { true }"
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "function with ref in head, kw in first term"
			input = kw + `.foo(x, y) { true }`
			head := RefHead([]*Term{VarTerm(kw), StringTerm("foo")}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw last term"
			input = fmt.Sprintf(`foo.%s(x, y) { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`foo["%s"](x, y) { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw)}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw middle term"
			input = fmt.Sprintf(`foo.%s.bar(x, y) { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "function with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`foo["%s"].bar(x, y) { true }`, kw)
			head = RefHead([]*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")}, BooleanTerm(true))
			head.Args = []*Term{VarTerm("x"), VarTerm("y")}
			exp = &Rule{
				Head: head,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			// Partial set rules

			note = "partial set rule with ref in head, kw in first term (name)"
			input = kw + `.foo { true }`
			exp = &Rule{
				Head: &Head{
					Name:      Var(kw),
					Reference: []*Term{VarTerm(kw)},
					Key:       StringTerm("foo"),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "partial set rule with ref in head, kw last term (key)"
			input = fmt.Sprintf(`foo.%s { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Name:      "foo",
					Reference: []*Term{VarTerm("foo")},
					Key:       StringTerm(kw),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "partial set rule with ref in head, kw last term (key) (bracketed)"
			input = fmt.Sprintf(`foo["%s"] { true }`, kw)
			exp = &Rule{
				Head: &Head{
					Name:      "foo",
					Reference: []*Term{VarTerm("foo")},
					Key:       StringTerm(kw),
				},
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			// Default rules

			note = "default rule, kw name"
			input = fmt.Sprintf("default %s { true }", kw)
			t.Run(note, func(t *testing.T) {
				_, err := ParseRuleWithOpts(input, popts)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "default rule with ref in head, kw in first term"
			input = fmt.Sprintf(`default %s.foo := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm(kw), StringTerm("foo")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "default rule with ref in head, kw last term"
			input = fmt.Sprintf(`default foo.%s := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "default rule with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"] := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "default rule with ref in head, kw middle term"
			input = fmt.Sprintf(`default foo.%s.bar := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			note = "default rule with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"].bar := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})

			// Default functions

			note = "default function, kw name"
			input = fmt.Sprintf("default %s(_, _) if { true }", kw)
			t.Run(note, func(t *testing.T) {
				_, err := ParseRule(input)
				if err == nil {
					t.Error("Expected error, got none")
				}
			})

			note = "default function with ref in head, kw in first term"
			input = fmt.Sprintf(`default %s.foo(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm(kw), StringTerm("foo")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw last term"
			input = fmt.Sprintf(`default foo.%s(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw last term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"](_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw)},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw middle term"
			input = fmt.Sprintf(`default foo.%s.bar(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})

			note = "default function with ref in head, kw middle term (bracketed)"
			input = fmt.Sprintf(`default foo["%s"].bar(_, _) := true`, kw)
			exp = &Rule{
				Head: &Head{
					Reference: []*Term{VarTerm("foo"), StringTerm(kw), StringTerm("bar")},
					Value:     BooleanTerm(true),
					Assign:    true,
					Args:      []*Term{VarTerm("$0"), VarTerm("$1")},
				},
				Default: true,
				Body: NewBody(
					NewExpr(BooleanTerm(true)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})
		})
	}
}

func TestRefKeywordsEdgeCases(t *testing.T) {
	t.Run("'in' kw first term in ref head rule following 'contains'", func(t *testing.T) {
		input := `package test
			foo contains "a"

			in.bar contains "b" if {
			  false
			}`

		exp := &Module{
			Package: MustParsePackage("package test"),
			Rules: []*Rule{
				MustParseRule(`foo contains "a"`),
				MustParseRule(`in.bar contains "b" if { false }`),
			},
		}

		m, err := ParseModule("", input)
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}

		if !m.Equal(exp) {
			t.Fatalf("expected module:\n\n%v\n\ngot:\n\n%v", exp, m)
		}
	})
}

func TestRuleBodyContainingRefKeywords(t *testing.T) {
	for _, kw := range KeywordsForRegoVersion(RegoV1) {
		t.Run(kw, func(t *testing.T) {
			note := "rule with ref in body"
			input := fmt.Sprintf(`p if {
							%s.foo == 1
							foo.%s == 2
							foo.%s.bar == 3
						}`, kw, kw, kw)
			exp := &Rule{
				Head: NewHead("p", nil, BooleanTerm(true)),
				Body: NewBody(
					Equal.Expr(RefTerm(VarTerm(kw), StringTerm("foo")), IntNumberTerm(1)),
					Equal.Expr(RefTerm(VarTerm("foo"), StringTerm(kw)), IntNumberTerm(2)),
					Equal.Expr(RefTerm(VarTerm("foo"), StringTerm(kw), StringTerm("bar")), IntNumberTerm(3)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp)
			})
		})
	}
}

func TestRuleBodyContainingRefKeywords_RegoV0(t *testing.T) {
	popts := ParserOptions{RegoVersion: RegoV0}

	for _, kw := range KeywordsForRegoVersion(RegoV0) {
		t.Run(kw, func(t *testing.T) {
			note := "rule with ref in body"
			input := fmt.Sprintf(`p {
							%s.foo == 1
							foo.%s == 2
							foo.%s.bar == 3
						}`, kw, kw, kw)
			exp := &Rule{
				Head: NewHead("p", nil, BooleanTerm(true)),
				Body: NewBody(
					Equal.Expr(RefTerm(VarTerm(kw), StringTerm("foo")), IntNumberTerm(1)),
					Equal.Expr(RefTerm(VarTerm("foo"), StringTerm(kw)), IntNumberTerm(2)),
					Equal.Expr(RefTerm(VarTerm("foo"), StringTerm(kw), StringTerm("bar")), IntNumberTerm(3)),
				),
			}
			t.Run(note, func(t *testing.T) {
				assertParseRule(t, note, input, exp, popts)
			})
		})
	}
}

func TestObjectWithScalars(t *testing.T) {
	assertParseOneTerm(t, "number", "{\"abc\": 7, \"def\": 8}", ObjectTerm(Item(StringTerm("abc"), IntNumberTerm(7)), Item(StringTerm("def"), IntNumberTerm(8))))
	assertParseOneTerm(t, "bool", "{\"abc\": false, \"def\": true}", ObjectTerm(Item(StringTerm("abc"), BooleanTerm(false)), Item(StringTerm("def"), BooleanTerm(true))))
	assertParseOneTerm(t, "string", "{\"abc\": \"foo\", \"def\": \"bar\"}", ObjectTerm(Item(StringTerm("abc"), StringTerm("foo")), Item(StringTerm("def"), StringTerm("bar"))))
	assertParseOneTerm(t, "mixed", "{\"abc\": 7, \"def\": null}", ObjectTerm(Item(StringTerm("abc"), IntNumberTerm(7)), Item(StringTerm("def"), NullTerm())))
	assertParseOneTerm(t, "number key", "{8: 7, \"def\": null}", ObjectTerm(Item(IntNumberTerm(8), IntNumberTerm(7)), Item(StringTerm("def"), NullTerm())))
	assertParseOneTerm(t, "number key 2", "{8.5: 7, \"def\": null}", ObjectTerm(Item(FloatNumberTerm(8.5), IntNumberTerm(7)), Item(StringTerm("def"), NullTerm())))
	assertParseOneTerm(t, "bool key", "{true: false}", ObjectTerm(Item(BooleanTerm(true), BooleanTerm(false))))
	assertParseOneTerm(t, "trailing comma", `{"a": "bar", "b": 64, }`, ObjectTerm(Item(StringTerm("a"), StringTerm("bar")), Item(StringTerm("b"), IntNumberTerm(64))))
	assertParseOneTerm(t, "leading comma", `{, "a": "bar", "b": 64 }`, ObjectTerm(Item(StringTerm("a"), StringTerm("bar")), Item(StringTerm("b"), IntNumberTerm(64))))
	assertParseOneTerm(t, "leading comma not comprehension", `{, 1 | 1: "bar"}`, ObjectTerm(Item(CallTerm(RefTerm(VarTerm("or")), NumberTerm("1"), NumberTerm("1")), StringTerm("bar"))))
}

func TestObjectWithVars(t *testing.T) {
	assertParseOneTerm(t, "var keys", "{foo: \"bar\", bar: 64}", ObjectTerm(Item(VarTerm("foo"), StringTerm("bar")), Item(VarTerm("bar"), IntNumberTerm(64))))
	assertParseOneTerm(t, "nested var keys", "{baz: {foo: \"bar\", bar: qux}}", ObjectTerm(Item(VarTerm("baz"), ObjectTerm(Item(VarTerm("foo"), StringTerm("bar")), Item(VarTerm("bar"), VarTerm("qux"))))))
	assertParseOneTerm(t, "ambiguous or", `{ a: b+c | d }`, ObjectTerm(Item(VarTerm("a"), CallTerm(RefTerm(VarTerm("or")), CallTerm(RefTerm(VarTerm("plus")), VarTerm("b"), VarTerm("c")), VarTerm("d")))))
}

func TestObjectWithRelation(t *testing.T) {
	assertParseOneTerm(t, "relation term value", `{"x": 1+1}`, ObjectTerm(
		Item(StringTerm("x"), CallTerm(RefTerm(VarTerm("plus")), IntNumberTerm(1), IntNumberTerm(1))),
	))
	assertParseError(t, "invalid relation term value", `{"x": 0= }`)
}

func TestObjectFail(t *testing.T) {
	assertParseError(t, "non-terminated 1", "{foo: bar, baz: [], qux: corge")
	assertParseError(t, "non-terminated 2", "{foo: bar, baz: [], qux: ")
	assertParseError(t, "non-terminated 3", "{foo: bar, baz: [], qux ")
	assertParseError(t, "non-terminated 4", "{foo: bar, baz: [], ")
	assertParseError(t, "missing separator", "{foo: bar baz: []}")
	assertParseError(t, "missing start", "foo: bar, baz: [], qux: corge}")
	assertParseError(t, "double comma", "{a:1,,b:2}")
	assertParseError(t, "leading double comma", "{,,a:1}")
	assertParseError(t, "trailing double comma", "{a:1,,}")
}

func TestArrayWithScalars(t *testing.T) {
	assertParseOneTerm(t, "number", "[1,2,3,4.5]", ArrayTerm(IntNumberTerm(1), IntNumberTerm(2), IntNumberTerm(3), FloatNumberTerm(4.5)))
	assertParseOneTerm(t, "bool", "[true, false, true]", ArrayTerm(BooleanTerm(true), BooleanTerm(false), BooleanTerm(true)))
	assertParseOneTerm(t, "string", "[\"foo\", \"bar\"]", ArrayTerm(StringTerm("foo"), StringTerm("bar")))
	assertParseOneTerm(t, "mixed", "[null, true, 42]", ArrayTerm(NullTerm(), BooleanTerm(true), IntNumberTerm(42)))
	assertParseOneTerm(t, "trailing comma - one element", "[null, ]", ArrayTerm(NullTerm()))
	assertParseOneTerm(t, "trailing comma", "[null, true, ]", ArrayTerm(NullTerm(), BooleanTerm(true)))
	assertParseOneTerm(t, "leading comma", "[, null, true]", ArrayTerm(NullTerm(), BooleanTerm(true)))
	assertParseOneTerm(t, "leading comma not comprehension", "[, 1 | 1]", ArrayTerm(CallTerm(RefTerm(VarTerm("or")), NumberTerm("1"), NumberTerm("1"))))
	assertParseOneTerm(t, "ambiguous or", "[ 1 + 2 | 3 ]", ArrayTerm(CallTerm(RefTerm(VarTerm("or")), CallTerm(RefTerm(VarTerm("plus")), NumberTerm("1"), NumberTerm("2")), NumberTerm("3"))))
}

func TestArrayWithVars(t *testing.T) {
	assertParseOneTerm(t, "var elements", "[foo, bar, 42]", ArrayTerm(VarTerm("foo"), VarTerm("bar"), IntNumberTerm(42)))
	assertParseOneTerm(t, "nested var elements", "[[foo, true], [null, bar], 42]", ArrayTerm(ArrayTerm(VarTerm("foo"), BooleanTerm(true)), ArrayTerm(NullTerm(), VarTerm("bar")), IntNumberTerm(42)))
}

func TestArrayFail(t *testing.T) {
	assertParseError(t, "non-terminated 1", "[foo, bar")
	assertParseError(t, "non-terminated 2", "[foo, bar, ")
	assertParseError(t, "missing separator", "[foo bar]")
	assertParseError(t, "missing start", "foo, bar, baz]")
	assertParseError(t, "bad term", "[!!!]")
	assertParseError(t, "double comma", "[a,,b]")
	assertParseError(t, "leading double comma", "[,,a]")
	assertParseError(t, "trailing double comma", "[a,,]")
}

func TestSetWithScalars(t *testing.T) {
	assertParseOneTerm(t, "number", "{1,2,3,4.5}", SetTerm(IntNumberTerm(1), IntNumberTerm(2), IntNumberTerm(3), FloatNumberTerm(4.5)))
	assertParseOneTerm(t, "bool", "{true, false, true}", SetTerm(BooleanTerm(true), BooleanTerm(false), BooleanTerm(true)))
	assertParseOneTerm(t, "string", "{\"foo\", \"bar\"}", SetTerm(StringTerm("foo"), StringTerm("bar")))
	assertParseOneTerm(t, "mixed", "{null, true, 42}", SetTerm(NullTerm(), BooleanTerm(true), IntNumberTerm(42)))
	assertParseOneTerm(t, "trailing comma", "{null, true,}", SetTerm(NullTerm(), BooleanTerm(true)))
	assertParseOneTerm(t, "leading comma", "{, null, true}", SetTerm(NullTerm(), BooleanTerm(true)))
	assertParseOneTerm(t, "leading comma not comprehension", "{, 1 | 1}", SetTerm(CallTerm(RefTerm(VarTerm("or")), NumberTerm("1"), NumberTerm("1"))))
	assertParseOneTerm(t, "ambiguous or", "{ 1 + 2 | 3}", SetTerm(CallTerm(RefTerm(VarTerm("or")), CallTerm(RefTerm(VarTerm("plus")), NumberTerm("1"), NumberTerm("2")), NumberTerm("3"))))
}

func TestSetWithVars(t *testing.T) {
	assertParseOneTerm(t, "var elements", "{foo, bar, 42}", SetTerm(VarTerm("foo"), VarTerm("bar"), IntNumberTerm(42)))
	assertParseOneTerm(t, "nested var elements", "{[foo, true], {null, bar}, set()}", SetTerm(ArrayTerm(VarTerm("foo"), BooleanTerm(true)), SetTerm(NullTerm(), VarTerm("bar")), SetTerm()))
}

func TestSetFail(t *testing.T) {
	assertParseError(t, "non-terminated 1", "set(")
	assertParseError(t, "non-terminated 2", "{foo, bar")
	assertParseError(t, "non-terminated 3", "{foo, bar, ")
	assertParseError(t, "missing separator", "{foo bar}")
	assertParseError(t, "missing start", "foo, bar, baz}")
	assertParseError(t, "bad term", "{!!!}")
	assertParseError(t, "double comma", "{a,,b}")
	assertParseError(t, "leading double comma", "{,,a}")
	assertParseError(t, "trailing double comma", "{a,,}")
}

func TestEmptyComposites(t *testing.T) {
	assertParseOneTerm(t, "empty object", "{}", ObjectTerm())
	assertParseOneTerm(t, "empty array", "[]", ArrayTerm())
	assertParseOneTerm(t, "empty set", "set()", SetTerm())
}

func TestNestedComposites(t *testing.T) {
	assertParseOneTerm(t, "nested composites", "[{foo: [\"bar\", {baz}]}]", ArrayTerm(ObjectTerm(Item(VarTerm("foo"), ArrayTerm(StringTerm("bar"), SetTerm(VarTerm("baz")))))))
}

func TestCompositesWithRefs(t *testing.T) {
	ref1 := RefTerm(VarTerm("a"), VarTerm("i"), StringTerm("b"))
	ref2 := RefTerm(VarTerm("c"), IntNumberTerm(0), StringTerm("d"), StringTerm("e"), VarTerm("j"))
	assertParseOneTerm(t, "ref keys", "[{a[i].b: 8, c[0][\"d\"].e[j]: f}]", ArrayTerm(ObjectTerm(Item(ref1, IntNumberTerm(8)), Item(ref2, VarTerm("f")))))
	assertParseOneTerm(t, "ref values", "[{8: a[i].b, f: c[0][\"d\"].e[j]}]", ArrayTerm(ObjectTerm(Item(IntNumberTerm(8), ref1), Item(VarTerm("f"), ref2))))
	assertParseOneTerm(t, "ref values (sets)", `{a[i].b, {c[0]["d"].e[j]}}`, SetTerm(ref1, SetTerm(ref2)))
}

func TestArrayComprehensions(t *testing.T) {

	nestedTerm := `[{"x": [a[i] | xs = [{"a": ["baz", j]} | q[p]; p.a != "bar"; j = "foo"]; xs[j].a[k] = "foo"]}]`
	nestedExpected := ArrayTerm(
		ObjectTerm(Item(
			StringTerm("x"),
			ArrayComprehensionTerm(
				RefTerm(VarTerm("a"), VarTerm("i")),
				NewBody(
					Equality.Expr(
						VarTerm("xs"),
						ArrayComprehensionTerm(
							ObjectTerm(Item(StringTerm("a"), ArrayTerm(StringTerm("baz"), VarTerm("j")))),
							NewBody(
								NewExpr(RefTerm(VarTerm("q"), VarTerm("p"))),
								NotEqual.Expr(RefTerm(VarTerm("p"), StringTerm("a")), StringTerm("bar")),
								Equality.Expr(VarTerm("j"), StringTerm("foo")),
							),
						),
					),
					Equality.Expr(
						RefTerm(VarTerm("xs"), VarTerm("j"), StringTerm("a"), VarTerm("k")),
						StringTerm("foo"),
					),
				),
			),
		)),
	)
	assertParseOneTerm(t, "nested", nestedTerm, nestedExpected)
	assertParseOneTerm(t, "ambiguous or", "[ a | b ]", ArrayComprehensionTerm(
		VarTerm("a"),
		MustParseBody("b"),
	))
}

func TestObjectComprehensions(t *testing.T) {
	nestedTerm := `[{"x": {a[i]: b[i] | xs = {"foo":{"a": ["baz", j]} | q[p]; p.a != "bar"; j = "foo"}; xs[j].a[k] = "foo"}}]`
	nestedExpected := ArrayTerm(
		ObjectTerm(Item(
			StringTerm("x"),
			ObjectComprehensionTerm(
				RefTerm(VarTerm("a"), VarTerm("i")),
				RefTerm(VarTerm("b"), VarTerm("i")),
				NewBody(
					Equality.Expr(
						VarTerm("xs"),
						ObjectComprehensionTerm(
							StringTerm("foo"),
							ObjectTerm(Item(StringTerm("a"), ArrayTerm(StringTerm("baz"), VarTerm("j")))),
							NewBody(
								NewExpr(RefTerm(VarTerm("q"), VarTerm("p"))),
								NotEqual.Expr(RefTerm(VarTerm("p"), StringTerm("a")), StringTerm("bar")),
								Equality.Expr(VarTerm("j"), StringTerm("foo")),
							),
						),
					),
					Equality.Expr(
						RefTerm(VarTerm("xs"), VarTerm("j"), StringTerm("a"), VarTerm("k")),
						StringTerm("foo"),
					),
				),
			),
		)),
	)
	assertParseOneTerm(t, "nested", nestedTerm, nestedExpected)
	assertParseOneTerm(t, "ambiguous or", "{ 1+2: 3 | 4}", ObjectComprehensionTerm(
		CallTerm(RefTerm(VarTerm("plus")), NumberTerm("1"), NumberTerm("2")),
		NumberTerm("3"),
		MustParseBody("4"),
	))
}

func TestObjectComprehensionError(t *testing.T) {
	assertParseError(t, "bad body", "{x: y|!!!}")
}

func TestSetComprehensions(t *testing.T) {
	nestedTerm := `[{"x": {a[i] | xs = {{"a": ["baz", j]} | q[p]; p.a != "bar"; j = "foo"}; xs[j].a[k] = "foo"}}]`
	nestedExpected := ArrayTerm(
		ObjectTerm(Item(
			StringTerm("x"),
			SetComprehensionTerm(
				RefTerm(VarTerm("a"), VarTerm("i")),
				NewBody(
					Equality.Expr(
						VarTerm("xs"),
						SetComprehensionTerm(
							ObjectTerm(Item(StringTerm("a"), ArrayTerm(StringTerm("baz"), VarTerm("j")))),
							NewBody(
								NewExpr(RefTerm(VarTerm("q"), VarTerm("p"))),
								NotEqual.Expr(RefTerm(VarTerm("p"), StringTerm("a")), StringTerm("bar")),
								Equality.Expr(VarTerm("j"), StringTerm("foo")),
							),
						),
					),
					Equality.Expr(
						RefTerm(VarTerm("xs"), VarTerm("j"), StringTerm("a"), VarTerm("k")),
						StringTerm("foo"),
					),
				),
			),
		)),
	)

	assertParseOneTerm(t, "nested", nestedTerm, nestedExpected)
	assertParseOneTerm(t, "ambiguous or", "{ a | b }", SetComprehensionTerm(
		VarTerm("a"),
		MustParseBody("b"),
	))
}

func TestSetComprehensionError(t *testing.T) {
	assertParseError(t, "bad body", "{x|!!!}")
}

func TestSetComprehensionsAlone(t *testing.T) {
	input := `{k | a = [1,2,3]; a[k]}`

	expected := SetComprehensionTerm(
		VarTerm("k"),
		NewBody(
			Equality.Expr(
				VarTerm("a"),
				ArrayTerm(NumberTerm("1"), NumberTerm("2"), NumberTerm("3")),
			),
			&Expr{
				Terms: RefTerm(VarTerm("a"), VarTerm("k")),
			},
		),
	)

	assertParseOneTerm(t, "alone", input, expected)
}

func TestCalls(t *testing.T) {

	assertParseOneExpr(t, "ne", "100 != 200", NotEqual.Expr(IntNumberTerm(100), IntNumberTerm(200)))
	assertParseOneExpr(t, "gt", "17.4 > \"hello\"", GreaterThan.Expr(FloatNumberTerm(17.4), StringTerm("hello")))
	assertParseOneExpr(t, "lt", "17.4 < \"hello\"", LessThan.Expr(FloatNumberTerm(17.4), StringTerm("hello")))
	assertParseOneExpr(t, "gte", "17.4 >= \"hello\"", GreaterThanEq.Expr(FloatNumberTerm(17.4), StringTerm("hello")))
	assertParseOneExpr(t, "lte", "17.4 <= \"hello\"", LessThanEq.Expr(FloatNumberTerm(17.4), StringTerm("hello")))

	left2 := ArrayTerm(ObjectTerm(Item(FloatNumberTerm(14.2), BooleanTerm(true)), Item(StringTerm("a"), NullTerm())))
	right2 := ObjectTerm(Item(VarTerm("foo"), ObjectTerm(Item(RefTerm(VarTerm("a"), StringTerm("b"), IntNumberTerm(0)), ArrayTerm(IntNumberTerm(10))))))
	assertParseOneExpr(t, "composites", "[{14.2: true, \"a\": null}] != {foo: {a.b[0]: [10]}}", NotEqual.Expr(left2, right2))

	assertParseOneExpr(t, "plus", "1 + 2", Plus.Expr(IntNumberTerm(1), IntNumberTerm(2)))
	assertParseOneExpr(t, "minus", "1 - 2", Minus.Expr(IntNumberTerm(1), IntNumberTerm(2)))
	assertParseOneExpr(t, "mul", "1 * 2", Multiply.Expr(IntNumberTerm(1), IntNumberTerm(2)))
	assertParseOneExpr(t, "div", "1 / 2", Divide.Expr(IntNumberTerm(1), IntNumberTerm(2)))
	assertParseOneExpr(t, "rem", "3 % 2", Rem.Expr(IntNumberTerm(3), IntNumberTerm(2)))
	assertParseOneExpr(t, "and", "{1,2,3} & {2,3,4}", And.Expr(SetTerm(IntNumberTerm(1), IntNumberTerm(2), IntNumberTerm(3)), SetTerm(IntNumberTerm(2), IntNumberTerm(3), IntNumberTerm(4))))
	assertParseOneExpr(t, "or", "{1,2,3} | {3,4,5}", Or.Expr(SetTerm(IntNumberTerm(1), IntNumberTerm(2), IntNumberTerm(3)), SetTerm(IntNumberTerm(3), IntNumberTerm(4), IntNumberTerm(5))))

	assertParseOneExpr(t, "call", "count([true, false])", Count.Expr(ArrayTerm(BooleanTerm(true), BooleanTerm(false))))
	assertParseOneExpr(t, "call-ref", "foo.bar(1)", NewExpr(
		[]*Term{RefTerm(VarTerm("foo"), StringTerm("bar")),
			IntNumberTerm(1)}))
	assertParseOneExpr(t, "call-void", "foo()", NewExpr(
		[]*Term{RefTerm(VarTerm("foo"))}))

	opts := ParserOptions{FutureKeywords: []string{"in"}}
	assertParseOneExpr(t, "internal.member_2", "x in xs", Member.Expr(VarTerm("x"), VarTerm("xs")), opts)
	assertParseOneExpr(t, "internal.member_3", "x, y in xs", MemberWithKey.Expr(VarTerm("x"), VarTerm("y"), VarTerm("xs")), opts)
}

func TestInfixExpr(t *testing.T) {
	assertParseOneExpr(t, "scalars 1", "true = false", Equality.Expr(BooleanTerm(true), BooleanTerm(false)))
	assertParseOneExpr(t, "scalars 2", "3.14 = null", Equality.Expr(FloatNumberTerm(3.14), NullTerm()))
	assertParseOneExpr(t, "scalars 3", "42 = \"hello world\"", Equality.Expr(IntNumberTerm(42), StringTerm("hello world")))
	assertParseOneExpr(t, "vars 1", "hello = world", Equality.Expr(VarTerm("hello"), VarTerm("world")))
	assertParseOneExpr(t, "vars 2", "42 = hello", Equality.Expr(IntNumberTerm(42), VarTerm("hello")))

	ref1 := RefTerm(VarTerm("foo"), IntNumberTerm(0), StringTerm("bar"), VarTerm("x"))
	ref2 := RefTerm(VarTerm("baz"), BooleanTerm(false), StringTerm("qux"), StringTerm("hello"))
	assertParseOneExpr(t, "refs 1", "foo[0].bar[x] = baz[false].qux[\"hello\"]", Equality.Expr(ref1, ref2))

	left1 := ObjectTerm(Item(VarTerm("a"), ArrayTerm(ref1)))
	right1 := ArrayTerm(ObjectTerm(Item(IntNumberTerm(42), BooleanTerm(true))))
	assertParseOneExpr(t, "composites", "{a: [foo[0].bar[x]]} = [{42: true}]", Equality.Expr(left1, right1))

	assertParseOneExpr(t, "plus", "x = 1 + 2", Equality.Expr(VarTerm("x"), Plus.Call(IntNumberTerm(1), IntNumberTerm(2))))
	assertParseOneExpr(t, "plus reverse", "1 + 2 = x", Equality.Expr(Plus.Call(IntNumberTerm(1), IntNumberTerm(2)), VarTerm("x")))

	assertParseOneExpr(t, "call", "count([true, false]) = x", Equality.Expr(Count.Call(ArrayTerm(BooleanTerm(true), BooleanTerm(false))), VarTerm("x")))
	assertParseOneExpr(t, "call-reverse", "x = count([true, false])", Equality.Expr(VarTerm("x"), Count.Call(ArrayTerm(BooleanTerm(true), BooleanTerm(false)))))
}

func TestNegatedExpr(t *testing.T) {
	assertParseOneTermNegated(t, "scalars 1", "not true", BooleanTerm(true))
	assertParseOneTermNegated(t, "scalars 2", "not \"hello\"", StringTerm("hello"))
	assertParseOneTermNegated(t, "scalars 3", "not 100", IntNumberTerm(100))
	assertParseOneTermNegated(t, "scalars 4", "not null", NullTerm())
	assertParseOneTermNegated(t, "var", "not x", VarTerm("x"))
	assertParseOneTermNegated(t, "ref", "not x[y].z", RefTerm(VarTerm("x"), VarTerm("y"), StringTerm("z")))
	assertParseOneExprNegated(t, "vars", "not x = y", Equality.Expr(VarTerm("x"), VarTerm("y")))

	ref1 := RefTerm(VarTerm("x"), VarTerm("y"), StringTerm("z"), VarTerm("a"))

	assertParseOneExprNegated(t, "membership", "not x[y].z[a] = \"b\"", Equality.Expr(ref1, StringTerm("b")))
	assertParseOneExprNegated(t, "misc. builtin", "not sorted(x[y].z[a])", NewExpr([]*Term{RefTerm(VarTerm("sorted")), ref1}))
}

func TestExprWith(t *testing.T) {
	assertParseOneExpr(t, "input", "data.foo with input as baz", &Expr{
		Terms: MustParseTerm("data.foo"),
		With: []*With{
			{
				Target: NewTerm(InputRootRef),
				Value:  VarTerm("baz"),
			},
		},
	})

	assertParseOneExpr(t, "builtin/ref target/composites", `plus(data.foo, 1, x) with input.com.acmecorp.obj as {"count": [{1,2,3}]}`, &Expr{
		Terms: MustParseExpr("plus(data.foo, 1, x)").Terms,
		With: []*With{
			{
				Target: MustParseTerm("input.com.acmecorp.obj"),
				Value:  MustParseTerm(`{"count": [{1,2,3}]}`),
			},
		},
	})

	assertParseOneExpr(t, "multiple", `data.foo with input.obj as baz with input.com.acmecorp.obj as {"count": [{1,2,3}]}`, &Expr{
		Terms: MustParseTerm("data.foo"),
		With: []*With{
			{
				Target: MustParseTerm("input.obj"),
				Value:  VarTerm("baz"),
			},
			{
				Target: MustParseTerm("input.com.acmecorp.obj"),
				Value:  MustParseTerm(`{"count": [{1,2,3}]}`),
			},
		},
	})

	assertParseOneExpr(t, "variable target", "true with x as 1", &Expr{
		Terms: BooleanTerm(true),
		With: []*With{
			{
				Target: VarTerm("x"),
				Value:  IntNumberTerm(1),
			},
		},
	})
}

func TestExprWithLocation(t *testing.T) {
	cases := []struct {
		note     string
		input    string
		expected []*Location
	}{
		{
			note:  "base",
			input: "a with b as c",
			expected: []*Location{
				{
					Row:    1,
					Col:    3,
					Offset: 2,
					Text:   []byte("with b as c"),
				},
			},
		},
		{
			note:  "with line break",
			input: "a with b\nas c",
			expected: []*Location{
				{
					Row:    1,
					Col:    3,
					Offset: 2,
					Text:   []byte("with b\nas c"),
				},
			},
		},
		{
			note:  "multiple withs on single line",
			input: "a with b as c with d as e",
			expected: []*Location{
				{
					Row:    1,
					Col:    3,
					Offset: 2,
					Text:   []byte("with b as c"),
				},
				{
					Row:    1,
					Col:    15,
					Offset: 14,
					Text:   []byte("with d as e"),
				},
			},
		},
		{
			note:  "multiple withs on multiple line",
			input: "a with b as c\n\t\twith d as e",
			expected: []*Location{
				{
					Row:    1,
					Col:    3,
					Offset: 2,
					Text:   []byte("with b as c"),
				},
				{
					Row:    2,
					Col:    3,
					Offset: 16,
					Text:   []byte("with d as e"),
				},
			},
		},
	}

	for _, tc := range cases {
		t.Run(tc.note, func(t *testing.T) {
			parsed, err := ParseStatement(tc.input)
			if err != nil {
				t.Errorf("Unexpected error on %s: %s", tc.input, err)
				return
			}

			body := parsed.(Body)
			if len(body) != 1 {
				t.Errorf("Parser returned multiple expressions: %v", body)
				return
			}
			expr := body[0]
			if len(expr.With) != len(tc.expected) {
				t.Fatalf("Expected %d with statements, got %d", len(expr.With), len(tc.expected))
			}
			for i, with := range expr.With {
				if !with.Location.Equal(tc.expected[i]) {
					t.Errorf("Expected location %+v for '%v' but got %+v ", *(tc.expected[i]), with.String(), *with.Location)
				}
			}
		})
	}
}

func TestSomeDeclExpr(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"in"}}

	assertParseOneExpr(t, "one", "some x", &Expr{
		Terms: &SomeDecl{
			Symbols: []*Term{
				VarTerm("x"),
			},
		},
	})

	assertParseOneExpr(t, "internal.member_2", "some x in xs", &Expr{
		Terms: &SomeDecl{
			Symbols: []*Term{
				Member.Call(
					VarTerm("x"),
					VarTerm("xs"),
				),
			},
		},
	}, opts)

	assertParseOneExpr(t, "internal.member_3", "some x, y in xs", &Expr{
		Terms: &SomeDecl{
			Symbols: []*Term{
				MemberWithKey.Call(
					VarTerm("x"),
					VarTerm("y"),
					VarTerm("xs"),
				),
			},
		},
	}, opts)

	assertParseErrorContains(t, "not some", "not some x, y in xs",
		"unexpected some keyword: illegal negation of 'some'",
		opts)

	assertParseErrorContains(t, "some + function call", "some f(x)",
		"expected `x in xs` or `x, y in xs` expression")

	assertParseOneExpr(t, "multiple", "some x, y", &Expr{
		Terms: &SomeDecl{
			Symbols: []*Term{
				VarTerm("x"),
				VarTerm("y"),
			},
		},
	}, opts)

	assertParseOneExpr(t, "multiple split across lines", `some x, y,
		z`, &Expr{
		Terms: &SomeDecl{
			Symbols: []*Term{
				VarTerm("x"),
				VarTerm("y"),
				VarTerm("z"),
			},
		},
	})

	assertParseRule(t, "whitespace separated", `

		p[x] {
			some x
			q[x]
		}
	`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x")),
		Body: NewBody(
			NewExpr(&SomeDecl{Symbols: []*Term{VarTerm("x")}}),
			NewExpr(RefTerm(VarTerm("q"), VarTerm("x"))),
		),
	})

	// Only relevant for v0, as the 'in' keyword isn't a permitted var name in v1.
	assertParseRule(t, "whitespace separated, following `in` rule ref", `
	p[x] {
		some x
		in[x]
	}
`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x")),
		Body: NewBody(
			NewExpr(&SomeDecl{Symbols: []*Term{VarTerm("x")}}),
			NewExpr(RefTerm(VarTerm("in"), VarTerm("x"))),
		),
	}, ParserOptions{RegoVersion: RegoV0})

	// Only relevant for v0, as the 'in' keyword is included in v1.
	assertParseErrorContains(t, "some x in ... usage is hinted properly", `
	p contains x if {
		some x in {"foo": "bar"}
	}`,
		"unexpected identifier token: expected \\n or ; or } (hint: `import future.keywords.in` for `some x in xs` expressions)",
		ParserOptions{RegoVersion: RegoV0})

	// Only relevant for v0, as the 'in' keyword is included in v1.
	assertParseErrorContains(t, "some x, y in ... usage is hinted properly", `
	p[y] = x if {
		some x, y in {"foo": "bar"}
	}`,
		"unexpected identifier token: expected \\n or ; or } (hint: `import future.keywords.in` for `some x in xs` expressions)",
		ParserOptions{RegoVersion: RegoV0})

	assertNoParseError(t, `p contains x if some x in {"foo": "bar"}`, ParserOptions{RegoVersion: RegoV1})

	assertParseRule(t, "whitespace terminated", `

	p[x] {
		some x
		x
	}
`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x")),
		Body: NewBody(
			NewExpr(&SomeDecl{Symbols: []*Term{VarTerm("x")}}),
			NewExpr(VarTerm("x")),
		),
	})

	assertParseOneExpr(t, "with modifier on expr", "some x, y in input with input as []",
		&Expr{
			Terms: &SomeDecl{
				Symbols: []*Term{
					MemberWithKey.Call(
						VarTerm("x"),
						VarTerm("y"),
						NewTerm(MustParseRef("input")),
					),
				},
			},
			With: []*With{{Value: ArrayTerm(), Target: NewTerm(MustParseRef("input"))}},
		}, opts)

	assertParseErrorContains(t, "invalid domain (internal.member_2)", "some internal.member_2()", "illegal domain", opts)
	assertParseErrorContains(t, "invalid domain (internal.member_3)", "some internal.member_3()", "illegal domain", opts)

}

func TestEvery(t *testing.T) {
	opts := ParserOptions{unreleasedKeywords: true, FutureKeywords: []string{"every"}}
	assertParseOneExpr(t, "simple", "every x in xs { true }",
		&Expr{
			Terms: &Every{
				Value:  VarTerm("x"),
				Domain: VarTerm("xs"),
				Body: []*Expr{
					NewExpr(BooleanTerm(true)),
				},
			},
		},
		opts)

	assertParseOneExpr(t, "with key", "every k, v in [1,2] { true }",
		&Expr{
			Terms: &Every{
				Key:    VarTerm("k"),
				Value:  VarTerm("v"),
				Domain: ArrayTerm(IntNumberTerm(1), IntNumberTerm(2)),
				Body: []*Expr{
					NewExpr(BooleanTerm(true)),
				},
			},
		}, opts)

	assertParseErrorContains(t, "arbitrary term", "every 10", "expected `x[, y] in xs { ... }` expression", opts)
	assertParseErrorContains(t, "non-var value", "every 10 in xs { true }", "unexpected { token: expected value to be a variable", opts)
	assertParseErrorContains(t, "non-var key", "every 10, x in xs { true }", "unexpected { token: expected key to be a variable", opts)
	assertParseErrorContains(t, "arbitrary call", "every f(10)", "expected `x[, y] in xs { ... }` expression", opts)
	assertParseErrorContains(t, "no body", "every x in xs", "missing body", opts)
	assertParseErrorContains(t, "invalid body", "every x in xs { + }", "unexpected plus token", opts)
	assertParseErrorContains(t, "not every", "not every x in xs { true }", "unexpected every keyword: illegal negation of 'every'", opts)

	assertParseOneExpr(t, `"every" kw implies "in" kw`, "x in xs", Member.Expr(
		VarTerm("x"),
		VarTerm("xs"),
	), opts)

	assertParseOneExpr(t, "with modifier on expr", "every x in input { x } with input as []",
		&Expr{
			Terms: &Every{
				Value:  VarTerm("x"),
				Domain: NewTerm(MustParseRef("input")),
				Body: []*Expr{
					NewExpr(VarTerm("x")),
				},
			},
			With: []*With{{Value: ArrayTerm(), Target: NewTerm(MustParseRef("input"))}},
		}, opts)

	// Only relevant for v0, as the 'every' keyword is included in v1.
	assertParseErrorContains(t, "every x, y in ... usage is hinted properly", `
	p {
		every x, y in {"foo": "bar"} { is_string(x); is_string(y) }
	}`,
		"unexpected identifier token: expected \\n or ; or } (hint: `import future.keywords.every` for `every x in xs { ... }` expressions)",
		ParserOptions{RegoVersion: RegoV0})

	assertNoParseError(t, `p if {
		every x, y in {"foo": "bar"} { is_string(x); is_string(y) }
	}`, ParserOptions{RegoVersion: RegoV1})

	// Only relevant for v0, as the 'in' keyword is included in v1.
	assertParseErrorContains(t, "not every 'every' gets a hint", `
	p {
		every x
	}`,
		"unexpected identifier token: expected \\n or ; or }\n\tevery x\n", // this asserts that the tail of the error message doesn't contain a hint
		ParserOptions{RegoVersion: RegoV0})

	assertParseErrorContains(t, "invalid domain (internal.member_2)", "every internal.member_2()", "illegal domain", opts)
	assertParseErrorContains(t, "invalid domain (internal.member_3)", "every internal.member_3()", "illegal domain", opts)
}

func TestNestedExpressions(t *testing.T) {

	n1 := IntNumberTerm(1)
	n2 := IntNumberTerm(2)
	n3 := IntNumberTerm(3)
	n4 := IntNumberTerm(4)
	n6 := IntNumberTerm(6)
	x := VarTerm("x")
	y := VarTerm("y")
	z := VarTerm("z")
	w := VarTerm("w")
	f := RefTerm(VarTerm("f"))
	g := RefTerm(VarTerm("g"))

	tests := []struct {
		note     string
		input    string
		expected *Expr
	}{
		{"associativity", "1 + 2 * 6 / 3",
			Plus.Expr(
				n1,
				Divide.Call(
					Multiply.Call(
						n2,
						n6),
					n3))},
		{"associativity - factors", "x * y / z % w",
			Rem.Expr(Divide.Call(Multiply.Call(x, y), z), w)},
		{"associativity - factors", "w % z / x * y",
			Multiply.Expr(Divide.Call(Rem.Call(w, z), x), y)},
		{"associativity - arithetic", "x + y - z",
			Minus.Expr(Plus.Call(x, y), z)},
		{"associativity - arithmetic", "z - x + y",
			Plus.Expr(Minus.Call(z, x), y)},
		{"associativity - and", "z & x & y",
			And.Expr(And.Call(z, x), y)},
		{"associativity - or", "z | x | y",
			Or.Expr(Or.Call(z, x), y)},
		{"associativity - relations", "x == y != z",
			NotEqual.Expr(Equal.Call(x, y), z)},
		{"grouping", "(1 + 2 * 6 / 3) > 4",
			GreaterThan.Expr(
				Plus.Call(
					n1,
					Divide.Call(
						Multiply.Call(
							n2,
							n6),
						n3)),
				n4)},
		{"nested parens", "(((1 + 2) * (6 / (3))) > 4) != false",
			NotEqual.Expr(
				GreaterThan.Call(
					Multiply.Call(
						Plus.Call(
							n1,
							n2),
						Divide.Call(
							n6,
							n3)),
					n4,
				),
				BooleanTerm(false))},
		{"bitwise or", "x + 1 | 2", Or.Expr(Plus.Call(x, n1), n2)},
		{"bitwise and", "x + 1 | 2 & 3", Or.Expr(Plus.Call(x, n1), And.Call(n2, n3))},
		{"array", "[x + 1, y > 2, z]", NewExpr(ArrayTerm(Plus.Call(x, n1), GreaterThan.Call(y, n2), z))},
		{"object", "{x * 2: y < 2, z[3]: 1 + 6/2}", NewExpr(
			ObjectTerm(
				Item(Multiply.Call(x, n2), LessThan.Call(y, n2)),
				Item(RefTerm(z, n3), Plus.Call(n1, Divide.Call(n6, n2))),
			),
		)},
		{"set", "{x + 1, y + 2, set()}", NewExpr(
			SetTerm(
				Plus.Call(x, n1),
				Plus.Call(y, n2),
				SetTerm(),
			),
		)},
		{"ref", `x[1][y + z[w + 1]].b`, NewExpr(
			RefTerm(
				x,
				n1,
				Plus.Call(
					y,
					RefTerm(
						z,
						Plus.Call(w, n1))),
				StringTerm("b"),
			),
		)},
		{"call void", "f()", NewExpr([]*Term{f})},
		{"call unary", "f(x)", NewExpr([]*Term{f, x})},
		{"call binary", "f(x, y)", NewExpr([]*Term{f, x, y})},
		{"call embedded", "f([g(x), y+1])", NewExpr([]*Term{
			f,
			ArrayTerm(
				CallTerm(g, x),
				Plus.Call(y, n1))})},
		{"call fqn", "foo.bar(1)", NewExpr([]*Term{
			RefTerm(VarTerm("foo"), StringTerm("bar")),
			n1,
		})},
		{"unify", "x = 1", Equality.Expr(x, n1)},
		{"unify embedded", "1 + x = 2 - y", Equality.Expr(Plus.Call(n1, x), Minus.Call(n2, y))},
		{"not keyword", "not x = y", Equality.Expr(x, y).Complement()},
		{"with keyword", "x with p[q] as f([x+1])", NewExpr(x).IncludeWith(
			RefTerm(VarTerm("p"), VarTerm("q")),
			CallTerm(f, ArrayTerm(Plus.Call(x, n1))),
		)},
	}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			expr, err := ParseExpr(tc.input)
			if err != nil {
				t.Fatal(err)
			}
			if !expr.Equal(tc.expected) {
				t.Fatalf("Expected %v but got %v", tc.expected, expr)
			}
		})
	}
}

func TestChainedCall(t *testing.T) {
	result, err := ParseExpr("foo.bar(1)[0](1).baz")
	if err != nil {
		t.Fatal(err)
	}

	exp := NewExpr(RefTerm(
		CallTerm(
			RefTerm(
				CallTerm(
					RefTerm(VarTerm("foo"), StringTerm("bar")),
					IntNumberTerm(1)),
				IntNumberTerm(0)),
			IntNumberTerm(1)),
		StringTerm("baz")))

	if !result.Equal(exp) {
		t.Fatalf("expected %v but got: %v", exp, result)
	}
}

func TestMultiLineBody(t *testing.T) {
	tests := []struct {
		note  string
		input string
		exp   Body
	}{
		{
			note: "three definitions",
			input: `
x = 1
y = 2
z = [ i | [x,y] = arr
	arr[_] = i]
`,
			exp: MustParseBody(`x = 1; y = 2; z = [i | [x,y] = arr; arr[_] = i]`),
		},
		{
			note: "three definitions, with comments and w/o enclosing braces",
			input: `
x = 1 ; # comment after semicolon
y = 2   # comment without semicolon
z = [ i | [x,y] = arr  # comment in comprehension
	arr[_] = i]
`,
			exp: MustParseBody(`x = 1; y = 2; z = [i | [x,y] = arr; arr[_] = i]`),
		},
		{
			note:  "array following call w/ whitespace",
			input: "f(x)\n [1]",
			exp: NewBody(
				NewExpr([]*Term{RefTerm(VarTerm("f")), VarTerm("x")}),
				NewExpr(ArrayTerm(IntNumberTerm(1))),
			),
		},
		{
			note:  "set following call w/ semicolon",
			input: "f(x);{1}",
			exp: NewBody(
				NewExpr([]*Term{RefTerm(VarTerm("f")), VarTerm("x")}),
				NewExpr(SetTerm(IntNumberTerm(1))),
			),
		},
		{
			note:  "array following array w/ whitespace",
			input: "[1]\n [2]",
			exp: NewBody(
				NewExpr(ArrayTerm(IntNumberTerm(1))),
				NewExpr(ArrayTerm(IntNumberTerm(2))),
			),
		},
		{
			note:  "array following set w/ whitespace",
			input: "{1}\n [2]",
			exp: NewBody(
				NewExpr(SetTerm(IntNumberTerm(1))),
				NewExpr(ArrayTerm(IntNumberTerm(2))),
			),
		},
		{
			note:  "set following call w/ whitespace",
			input: "f(x)\n {1}",
			exp: NewBody(
				NewExpr([]*Term{RefTerm(VarTerm("f")), VarTerm("x")}),
				NewExpr(SetTerm(IntNumberTerm(1))),
			),
		},
		{
			note:  "set following ref w/ whitespace",
			input: "data.p.q\n {1}",
			exp: NewBody(
				NewExpr(&Term{Value: MustParseRef("data.p.q")}),
				NewExpr(SetTerm(IntNumberTerm(1))),
			),
		},
		{
			note:  "set following variable w/ whitespace",
			input: "input\n {1}",
			exp: NewBody(
				NewExpr(&Term{Value: MustParseRef("input")}),
				NewExpr(SetTerm(IntNumberTerm(1))),
			),
		},
		{
			note:  "set following equality w/ whitespace",
			input: "input = 2 \n {1}",
			exp: NewBody(
				Equality.Expr(&Term{Value: MustParseRef("input")}, IntNumberTerm(2)),
				NewExpr(SetTerm(IntNumberTerm(1))),
			),
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			assertParseOneBody(t, tc.note, tc.input, tc.exp)
		})
	}
}

func TestBitwiseOrVsComprehension(t *testing.T) {

	x := VarTerm("x")
	y := VarTerm("y")
	z := VarTerm("z")
	a := VarTerm("a")
	b := VarTerm("b")

	tests := []struct {
		note  string
		input string
		exp   *Term
	}{
		{
			note:  "array containing bitwise or",
			input: "[x|y,z]",
			exp:   ArrayTerm(Or.Call(x, y), z),
		},
		{
			note:  "array containing bitwise or - last element",
			input: "[z,x|y]",
			exp:   ArrayTerm(z, Or.Call(x, y)),
		},
		{
			note:  "array containing bitwise or - middle",
			input: "[z,x|y,a]",
			exp:   ArrayTerm(z, Or.Call(x, y), a),
		},
		{
			note:  "array containing single bitwise or",
			input: "[x|y,]",
			exp:   ArrayTerm(Or.Call(x, y)),
		},
		{
			note:  "set containing bitwise or",
			input: "{x|y,z}",
			exp:   SetTerm(Or.Call(x, y), z),
		},
		{
			note:  "set containing bitwise or - last element",
			input: "{z,x|y}",
			exp:   SetTerm(z, Or.Call(x, y)),
		},
		{
			note:  "set containing bitwise or - middle",
			input: "{z,x|y,a}",
			exp:   SetTerm(z, Or.Call(x, y), a),
		},
		{
			note:  "set containing single bitwise or",
			input: "{x|y,}",
			exp:   SetTerm(Or.Call(x, y)),
		},
		{
			note:  "object containing bitwise or",
			input: "{x:y|z,a:b}",
			exp:   ObjectTerm([2]*Term{x, Or.Call(y, z)}, [2]*Term{a, b}),
		},
		{
			note:  "object containing single bitwise or",
			input: "{x:y|z,}",
			exp:   ObjectTerm([2]*Term{x, Or.Call(y, z)}),
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {

			term, err := ParseTerm(tc.input)
			if err != nil {
				t.Fatal(err)
			}

			if !term.Equal(tc.exp) {
				t.Fatalf("Expected %v but got %v", tc.exp, term)
			}
		})
	}

}

func TestPackage(t *testing.T) {
	ref1 := RefTerm(DefaultRootDocument, StringTerm("foo"))
	assertParsePackage(t, "single", `package foo`, &Package{Path: ref1.Value.(Ref)})
	ref2 := RefTerm(DefaultRootDocument, StringTerm("f00"), StringTerm("bar_baz"), StringTerm("qux"))
	assertParsePackage(t, "multiple", `package f00.bar_baz.qux`, &Package{Path: ref2.Value.(Ref)})
	ref3 := RefTerm(DefaultRootDocument, StringTerm("foo"), StringTerm("bar baz"))
	assertParsePackage(t, "space", `package foo["bar baz"]`, &Package{Path: ref3.Value.(Ref)})
	assertParseError(t, "non-ground ref", "package foo[x]")
	assertParseError(t, "non-string value", "package foo.bar[42].baz")
	assertParseError(t, "invalid term", "package 42")
	assertParseError(t, "scanner error", "package foo.")
	assertParseError(t, "non-string first value", "package e().s")
}

func TestImport(t *testing.T) {
	foo := RefTerm(VarTerm("input"), StringTerm("foo"))
	foobarbaz := RefTerm(VarTerm("input"), StringTerm("foo"), StringTerm("bar"), StringTerm("baz"))
	whitespace := RefTerm(VarTerm("input"), StringTerm("foo"), StringTerm("bar"), StringTerm("white space"))
	assertParseImport(t, "single-input", "import input", &Import{Path: RefTerm(InputRootDocument)})
	assertParseImport(t, "single-data", "import data", &Import{Path: RefTerm(DefaultRootDocument)})
	assertParseImport(t, "multiple", "import input.foo.bar.baz", &Import{Path: foobarbaz})
	assertParseImport(t, "single alias", "import input.foo as bar", &Import{Path: foo, Alias: Var("bar")})
	assertParseImport(t, "multiple alias", "import input.foo.bar.baz as qux", &Import{Path: foobarbaz, Alias: Var("qux")})
	assertParseImport(t, "white space", "import input.foo.bar[\"white space\"]", &Import{Path: whitespace})
	assertParseErrorContains(t, "non-ground ref", "import data.foo[x]", "rego_parse_error: unexpected var token: expecting string")
	assertParseErrorContains(t, "non-string", "import input.foo[0]", "rego_parse_error: unexpected number token: expecting string")
	assertParseErrorContains(t, "unknown root", "import foo.bar", "rego_parse_error: unexpected import path, must begin with one of: {data, future, input, rego}, got: foo")
	assertParseErrorContains(t, "bad variable term", "import input as A(", "rego_parse_error: unexpected eof token: expected var")

	_, _, err := ParseStatements("", "package foo\nimport bar.data\ndefault foo=1")
	if err == nil {
		t.Fatalf("Expected error, but got nil")
	}
	if len(err.(Errors)) > 1 {
		t.Fatalf("Expected a single error, got %s", err)
	}
	txt := err.(Errors)[0].Details.Lines()[0]
	expected := "import bar.data"
	if txt != expected {
		t.Fatalf("Expected error detail text '%s' but got '%s'", expected, txt)
	}
}

func TestFutureImports(t *testing.T) {
	assertParseErrorContains(t, "future", "import future", "invalid import, must be `future.keywords`")
	assertParseErrorContains(t, "future.a", "import future.a", "invalid import, must be `future.keywords`")
	assertParseErrorContains(t, "unknown keyword", "import future.keywords.xyz", "unexpected keyword, must be one of [contains every if in]")
	assertParseErrorContains(t, "all keyword import + alias", "import future.keywords as xyz", "`future` imports cannot be aliased")
	assertParseErrorContains(t, "keyword import + alias", "import future.keywords.in as xyz", "`future` imports cannot be aliased")

	assertParseImport(t, "import kw with kw in options",
		"import future.keywords.in", &Import{Path: RefTerm(VarTerm("future"), InternedTerm("keywords"), StringTerm("in"))},
		ParserOptions{FutureKeywords: []string{"in"}})
	assertParseImport(t, "import kw with all kw in options",
		"import future.keywords.in", &Import{Path: RefTerm(VarTerm("future"), InternedTerm("keywords"), StringTerm("in"))},
		ParserOptions{AllFutureKeywords: true})

	mod := `
		package p
		import future.keywords
		import future.keywords.in
	`
	parsed := Module{
		Package: MustParseStatement(`package p`).(*Package),
		Imports: []*Import{
			MustParseStatement("import future.keywords").(*Import),
			MustParseStatement("import future.keywords.in").(*Import),
		},
	}
	assertParseModule(t, "multiple imports, all kw in options", mod, &parsed, ParserOptions{AllFutureKeywords: true})
	assertParseModule(t, "multiple imports, single in options", mod, &parsed, ParserOptions{FutureKeywords: []string{"in"}})
}

func TestFutureAndRegoV1ImportsExtraction(t *testing.T) {
	// These tests assert that "import future..." and "import rego.v1" statements in policies cause
	// the proper keywords to be added to the parser's list of known keywords.
	tests := []struct {
		note, imp string
		exp       map[string]tokens.Token
	}{
		{
			note: "simple import",
			imp:  "import future.keywords.in",
			exp:  map[string]tokens.Token{"in": tokens.In},
		},
		{
			note: "all keywords imported",
			imp:  "import future.keywords",
			exp: map[string]tokens.Token{
				"in":       tokens.In,
				"every":    tokens.Every,
				"contains": tokens.Contains,
				"if":       tokens.If,
			},
		},
		{
			note: "all keywords + single keyword imported",
			imp: `
				import future.keywords
				import future.keywords.in`,
			exp: map[string]tokens.Token{
				"in":       tokens.In,
				"every":    tokens.Every,
				"contains": tokens.Contains,
				"if":       tokens.If,
			},
		},
		{
			note: "rego.v1 imported",
			imp:  "import rego.v1",
			exp: map[string]tokens.Token{
				"in":       tokens.In,
				"every":    tokens.Every,
				"contains": tokens.Contains,
				"if":       tokens.If,
			},
		},
	}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			parser := NewParser().WithFilename("").WithReader(bytes.NewBufferString(tc.imp))
			_, _, errs := parser.Parse()
			if exp, act := 0, len(errs); exp != act {
				t.Fatalf("expected %d errors, got %d: %v", exp, act, errs)
			}
			for kw, exp := range tc.exp {
				act := parser.s.s.Keyword(kw)
				if act != exp {
					t.Errorf("expected keyword %q to yield token %v, got %v", kw, exp, act)
				}
			}
		})
	}
}

func TestHintsOnUnknownImport(t *testing.T) {
	assertParseErrorContains(t, "unknown", "import unknown",
		"unexpected import path, must begin with one of: {data, future, input, rego}, got: unknown (hint: if this is unexpected, try updating OPA)")
}

func TestRegoV1Import(t *testing.T) {
	// These tests assert that the 'rego.v1' import is correctly handled in v0.
	popts := ParserOptions{RegoVersion: RegoV0}

	assertParseErrorContains(t, "rego", "import rego", "invalid import `rego`, must be `rego.v1`", popts)
	assertParseErrorContains(t, "rego.foo", "import rego.foo", "invalid import `rego.foo`, must be `rego.v1`", popts)
	assertParseErrorContains(t, "rego.foo.bar", "import rego.foo.bar", "invalid import `rego.foo.bar`, must be `rego.v1`", popts)
	assertParseErrorContains(t, "rego.v1.bar", "import rego.v1.bar", "invalid import `rego.v1.bar`, must be `rego.v1`", popts)
	assertParseErrorContains(t, "rego.v1 + alias", "import rego.v1 as xyz", "`rego` imports cannot be aliased", popts)

	assertParseImport(t, "import rego.v1",
		"import rego.v1", &Import{Path: RefTerm(VarTerm("rego"), StringTerm("v1"))},
		ParserOptions{})

	tests := []struct {
		note           string
		module         string
		expectedErrors []string
	}{
		{
			note: "only rego.v1 imported",
			module: `package test
import rego.v1
p contains 1 if 1 == 1`,
		},
		{
			note: "rego.v1 and future.keywords imported",
			module: `package test
import rego.v1
import future.keywords
p contains 1 if {
	input.x == 1
}`,
		},
		{
			note: "`if` keyword used on rule",
			module: `package test
import rego.v1
p if {
	input.x == 1
}`,
		},
		{
			note: "`if` keyword not used on rule",
			module: `package test
import rego.v1
p {
	input.x == 1
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
		},
		{
			note: "constant definition",
			module: `package test
import rego.v1
p := 1`,
		},
		{
			note: "`if` keyword used before else body",
			module: `package test
import rego.v1
p if {
	input.x == 1
} else if {
	input.x == 2
}`,
		},
		{
			note: "`if` keyword used before else body (value assignment)",
			module: `package test
import rego.v1
p := "foo" if {
	input.x == 1
} else := "bar" if {
	input.x == 2
} else := "baz" if input.x == 3
else := "qux"`,
		},
		{
			note: "no else body (value assignment, but not on primary head) (regression test for #6364)",
			module: `package test
import rego.v1
p if {
	input.x == 1
} else := "baz" if input.x == 3
else := "qux"`,
		},
		{
			note: "`if` keyword used before else body (value assignment, but not on primary head) (regression test for #6364)",
			module: `package test
import rego.v1
p if {
	input.x == 1
} else := "bar" if {
	input.x == 2
} else := "baz" if input.x == 3
else := "qux"`,
		},
		{
			note: "`if` keyword not used before else body",
			module: `package test
import rego.v1
p if {
	input.x == 1
} else {
	input.x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
		},
		{
			note: "`if` keyword not used before else body (value assignment)",
			module: `package test
import rego.v1
p := "foo" if {
	input.x == 1
} else := "bar" {
	input.x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
		},
		{
			note: "`contains` keyword used on partial set rule (const key)",
			module: `package test
import rego.v1
p contains "q"`,
		},
		{
			note: "`contains` keyword used on partial set rule (ref-head, const key)",
			module: `package test
import rego.v1
p.q contains "r"`,
		},
		{
			note: "`contains` keyword not used on partial set rule (const key)",
			module: `package test
import rego.v1
p.q`,
			expectedErrors: []string{"rego_parse_error: `contains` keyword is required for partial set rules"},
		},
		{
			note: "object definition (naked ref-head with implicit `true` value)",
			module: `package test
import rego.v1
p.q.r`,
			expectedErrors: []string{"rego_parse_error: rule must have value assignment and/or body declaration"},
		},
		{
			note: "`contains` keyword used on partial set rule (var key, no body)",
			module: `package test
import rego.v1
p contains input.x`,
		},
		{
			note: "`contains` keyword not used on partial set rule (var key, no body)",
			module: `package test
import rego.v1
p[input.x]`,
			expectedErrors: []string{"rego_parse_error: `contains` keyword is required for partial set rules"},
		},
		{
			note: "`if` keyword not used on partial object rule (ref-head, var key, implicit `true` value, no body)",
			module: `package test
import rego.v1
p.q[input.x]`,
			expectedErrors: []string{"rego_parse_error: rule must have value assignment and/or body declaration"},
		},
		{
			note: "`contains` keyword used on partial set rule (var key)",
			module: `package test
import rego.v1
p contains x if { x = input.x}`,
		},
		{
			note: "`if` keyword used on partial map rule (would be multi-value without `if`)",
			module: `package test
import rego.v1
p[x] if { x = input.x}`,
		},
		{
			note: "`contains` and `if` keyword not used on partial rule",
			module: `package test
import rego.v1
p[x] { x = input.x}`,
			// The developer likely intended a partial set.
			expectedErrors: []string{
				"rego_parse_error: `contains` keyword is required for partial set rules",
				"rego_parse_error: `if` keyword is required before rule body",
			},
		},
		{
			note: "`if` keyword not used on partial object rule (ref-head)",
			module: `package test
import rego.v1
p.q[x] { x = input.x}`,
			expectedErrors: []string{
				"rego_parse_error: `if` keyword is required before rule body",
			},
		},
		{
			note: "`if` keyword not used on default rule",
			module: `package test
import rego.v1
default allow := false`,
		},
		{
			note: "function, value assignment, no body",
			module: `package test
import rego.v1
f(x) := x`,
		},
		{
			note: "function, value assignment, body, with if",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
}`,
		},
		{
			note: "function, value assignment, body, no if",
			module: `package test
import rego.v1
f(x) := x {
	x == 1
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, no value assignment, body, with if",
			module: `package test
import rego.v1
f(x) if {
	x == 1
}`,
		},
		{
			note: "function, no value assignment, body, no if",
			module: `package test
import rego.v1
f(x) {
	x == 1
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, else without body, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 42`,
		},
		{
			note: "function, else without body, value assignment only on else (regression test for #6364)",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else := 42`,
		},
		{
			note: "function, else with body and if, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 42 if {
	x == 2
}`,
		},
		{
			note: "function, else with body and if, no value assignment",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else if {
	x == 2
}`,
		},
		{
			note: "function, else with body and no if, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, else with body and no if, no value assignment",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, else with body and no if, value assignment on primary head",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, else with body and no if, value assignment on else",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on last else, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 1 if {
	x == 2
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on last else, value assignment on primary head",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else if {
	x == 2
} else {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on last else, value assignment on first else",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else := 1 if {
	x == 2
} else {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on last else, value assignment on last else",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else if {
	x == 2
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on first else, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 1 {
	x == 2
} else := 42 if {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on first else, value assignment on primary head",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else {
	x == 2
} else if {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on first else, value assignment on first else",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else := 1 {
	x == 2
} else if {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on first else, value assignment on last else",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} else {
	x == 2
} else := 42 if {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if on any else, value assignment",
			module: `package test
import rego.v1
f(x) := x if {
	x == 1
} else := 1 {
	x == 2
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function, multiple else with body, no if, value assignment",
			module: `package test
import rego.v1
f(x) := x {
	x == 1
} else := 1 {
	x == 2
} else := 42 {
	x == 2
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "rule with chained bodies, no `if`",
			module: `package test
import rego.v1
p {
	input.x == 1
} {
	input.x == 2
} {
	input.x == 3
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
		},
		{
			note: "rule with chained bodies, `if` on first body",
			module: `package test
import rego.v1
p if {
	input.x == 1
} {
	input.x == 2
} {
	input.x == 3
}`,
		},
		{
			note: "rule with chained bodies, `if` on second body",
			module: `package test
import rego.v1
p if {
	input.x == 1
} if {
	input.x == 2
} {
	input.x == 3
}`,
			expectedErrors: []string{`5:3: rego_parse_error: unexpected if keyword
	} if {
	  ^`},
		},
		{
			note: "rule with chained bodies, `if` on third/last body",
			module: `package test
import rego.v1
p if {
	input.x == 1
} {
	input.x == 2
} if {
	input.x == 3
}`,
			expectedErrors: []string{`7:3: rego_parse_error: unexpected if keyword
	} if {
	  ^`},
		},
		{
			note: "rule with chained bodies, `if` and `contains` on first body",
			module: `package test
import rego.v1
p contains x if {
	x == 1
} {
	x == 2
} {
	x == 3
}`,
		},
		{
			note: "function with chained bodies, no `if`",
			module: `package test
import rego.v1
f(x) {
	x == 1
} {
	x == 2
} {
	x == 3
}`,
			expectedErrors: []string{"rego_parse_error: `if` keyword is required before function body"},
		},
		{
			note: "function with chained bodies, `if` on first body",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} {
	x == 2
} {
	x == 3
}`,
		},
		{
			note: "function with chained bodies, `if` on other than first body",
			module: `package test
import rego.v1
f(x) if {
	x == 1
} if {
	x == 2
} {
	x == 3
}`,
			expectedErrors: []string{`5:3: rego_parse_error: unexpected if keyword
	} if {
	  ^`},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, errs := ParseModuleWithOpts("", tc.module, popts)

			if len(tc.expectedErrors) == 0 && errs != nil {
				t.Fatalf("expected no errors, got:\n\n%v", errs)
			}

			actual := ""
			if errs != nil {
				actual = errs.Error()
			}

			for _, expected := range tc.expectedErrors {
				if !strings.Contains(actual, expected) {
					t.Errorf("expected error:\n\n%q\n\ngot:\n\n%v", expected, actual)
				}
			}
		})
	}
}

func TestIsValidImportPath(t *testing.T) {
	tests := []struct {
		path     string
		expected error
	}{
		{"[1,2,3]", errors.New("invalid path [1, 2, 3]: path must be ref or var")},
	}

	for _, tc := range tests {
		path := MustParseTerm(tc.path).Value
		result := IsValidImportPath(path)
		if tc.expected == nil && result != nil {
			t.Errorf("Unexpected error for %v: %v", path, result)
		} else if tc.expected.Error() != result.Error() {
			t.Errorf("For %v expected %v but got: %v", path, tc.expected, result)
		}
	}

}

func TestRule(t *testing.T) {

	assertParseRule(t, "constant", `p = true { true }`, &Rule{
		Head: NewHead(Var("p"), nil, BooleanTerm(true)),
		Body: NewBody(
			&Expr{Terms: BooleanTerm(true)},
		),
	})

	assertParseRule(t, "set", `p[x] { x = 42 }`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x")),
		Body: NewBody(
			Equality.Expr(VarTerm("x"), IntNumberTerm(42)),
		),
	})

	assertParseRule(t, "object", `p[x] = y { x = 42; y = "hello" }`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x"), VarTerm("y")),
		Body: NewBody(
			Equality.Expr(VarTerm("x"), IntNumberTerm(42)),
			Equality.Expr(VarTerm("y"), StringTerm("hello")),
		),
	})

	assertParseRule(t, "constant composite", `p = [{"foo": [1, 2, 3, 4]}] { true }`, &Rule{
		Head: NewHead(Var("p"), nil, ArrayTerm(
			ObjectTerm(Item(StringTerm("foo"), ArrayTerm(IntNumberTerm(1), IntNumberTerm(2), IntNumberTerm(3), IntNumberTerm(4)))))),
		Body: NewBody(
			&Expr{Terms: BooleanTerm(true)},
		),
	})

	assertParseRule(t, "true", `p = true { true }`, &Rule{
		Head: NewHead(Var("p"), nil, BooleanTerm(true)),
		Body: NewBody(
			&Expr{Terms: BooleanTerm(true)},
		),
	})

	assertParseRule(t, "composites in head", `p[[{"x": [a, b]}]] { a = 1; b = 2 }`, &Rule{
		Head: NewHead(Var("p"), ArrayTerm(
			ObjectTerm(
				Item(StringTerm("x"), ArrayTerm(VarTerm("a"), VarTerm("b"))),
			),
		)),
		Body: NewBody(
			Equality.Expr(VarTerm("a"), IntNumberTerm(1)),
			Equality.Expr(VarTerm("b"), IntNumberTerm(2)),
		),
	})

	assertParseRule(t, "refs in head", `p = data.foo[x] { x = 1 }`, &Rule{
		Head: NewHead(Var("p"), nil, &Term{
			Value: MustParseRef("data.foo[x]"),
		}),
		Body: MustParseBody("x = 1"),
	})

	assertParseRule(t, "refs in head", `p[data.foo[x]] { true }`, &Rule{
		Head: NewHead(Var("p"), &Term{
			Value: MustParseRef("data.foo[x]"),
		}),
		Body: MustParseBody("true"),
	})

	assertParseRule(t, "refs in head", `p[data.foo[x]] = data.bar[y] { true }`, &Rule{
		Head: NewHead(Var("p"), &Term{
			Value: MustParseRef("data.foo[x]"),
		}, &Term{
			Value: MustParseRef("data.bar[y]"),
		}),
		Body: MustParseBody("true"),
	})

	assertParseRule(t, "data", `data = true { true }`, &Rule{
		Head: NewHead(Var("data"), nil, MustParseTerm("true")),
		Body: MustParseBody("true"),
	})

	assertParseRule(t, "input", `input = true { true }`, &Rule{
		Head: NewHead(Var("input"), nil, MustParseTerm("true")),
		Body: MustParseBody("true"),
	})

	assertParseRule(t, "default", `default allow = false`, &Rule{
		Default: true,
		Head:    NewHead(Var("allow"), nil, MustParseTerm("false")),
		Body:    NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "default w/ assignment", `default allow := false`, &Rule{
		Default: true,
		Head: &Head{
			Name:      "allow",
			Reference: Ref{VarTerm("allow")},
			Value:     BooleanTerm(false),
			Assign:    true,
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "default w/ comprehension", `default widgets = [x | x = data.fooz[_]]`, &Rule{
		Default: true,
		Head:    NewHead(Var("widgets"), nil, MustParseTerm(`[x | x = data.fooz[_]]`)),
		Body:    NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "one line with braces", `p[x] { x = data.a[_]; count(x, 3) }`, &Rule{
		Head: NewHead(Var("p"), VarTerm("x")),
		Body: MustParseBody(`x = data.a[_]; count(x, 3)`),
	})

	assertParseRule(t, "multiple lines with braces", `p[[x, y]] { [data.a[0]] = [{"x": x}]; count(x, 3); sum(x, y); y > 100 }`,

		&Rule{
			Head: NewHead(Var("p"), MustParseTerm("[x, y]")),
			Body: MustParseBody(`[data.a[0]] = [{"x": x}]; count(x, 3); sum(x, y); y > 100`),
		})

	fxy := &Head{
		Name:      Var("f"),
		Reference: Ref{VarTerm("f")},
		Args:      Args{VarTerm("x")},
		Value:     VarTerm("y"),
	}

	assertParseRule(t, "identity", `f(x) = y { y = x }`, &Rule{
		Head: fxy,
		Body: NewBody(
			Equality.Expr(VarTerm("y"), VarTerm("x")),
		),
	})

	assertParseRule(t, "composite arg", `f([x, y]) = z { split(x, y, z) }`, &Rule{
		Head: &Head{
			Name:      Var("f"),
			Reference: Ref{VarTerm("f")},
			Args:      Args{ArrayTerm(VarTerm("x"), VarTerm("y"))},
			Value:     VarTerm("z"),
		},
		Body: NewBody(
			Split.Expr(VarTerm("x"), VarTerm("y"), VarTerm("z")),
		),
	})

	assertParseRule(t, "composite result", `f(1) = [x, y] { split("foo.bar", x, y) }`, &Rule{
		Head: &Head{
			Name:      Var("f"),
			Reference: Ref{VarTerm("f")},
			Args:      Args{IntNumberTerm(1)},
			Value:     ArrayTerm(VarTerm("x"), VarTerm("y")),
		},
		Body: NewBody(
			Split.Expr(StringTerm("foo.bar"), VarTerm("x"), VarTerm("y")),
		),
	})

	assertParseRule(t, "expr terms: key", `p[f(x) + g(x)] { true }`, &Rule{
		Head: &Head{
			Name:      Var("p"),
			Reference: Ref{VarTerm("p")},
			Key: Plus.Call(
				CallTerm(RefTerm(VarTerm("f")), VarTerm("x")),
				CallTerm(RefTerm(VarTerm("g")), VarTerm("x")),
			),
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "expr terms: value", `p = f(x) + g(x) { true }`, &Rule{
		Head: &Head{
			Name:      Var("p"),
			Reference: Ref{VarTerm("p")},
			Value: Plus.Call(
				CallTerm(RefTerm(VarTerm("f")), VarTerm("x")),
				CallTerm(RefTerm(VarTerm("g")), VarTerm("x")),
			),
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "expr terms: args", `p(f(x) + g(x)) { true }`, &Rule{
		Head: &Head{
			Name:      Var("p"),
			Reference: Ref{VarTerm("p")},
			Args: Args{
				Plus.Call(
					CallTerm(RefTerm(VarTerm("f")), VarTerm("x")),
					CallTerm(RefTerm(VarTerm("g")), VarTerm("x")),
				),
			},
			Value: BooleanTerm(true),
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "assignment operator", `x := 1 { true }`, &Rule{
		Head: &Head{
			Name:      Var("x"),
			Reference: Ref{VarTerm("x")},
			Value:     IntNumberTerm(1),
			Assign:    true,
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "else assignment", `x := 1 { false } else := 2`, &Rule{
		Head: &Head{
			Name:      "x", // ha! clever!
			Reference: Ref{VarTerm("x")},
			Value:     IntNumberTerm(1),
			Assign:    true,
		},
		Body: NewBody(NewExpr(BooleanTerm(false))),
		Else: &Rule{
			Head: &Head{
				Name:      "x",
				Reference: Ref{VarTerm("x")},
				Value:     IntNumberTerm(2),
				Assign:    true,
			},
			Body: NewBody(NewExpr(BooleanTerm(true))),
		},
	})

	assertParseRule(t, "partial assignment", `p[x] := y { true }`, &Rule{
		Head: &Head{
			Name:      "p",
			Reference: MustParseRef("p[x]"),
			Value:     VarTerm("y"),
			Key:       VarTerm("x"),
			Assign:    true,
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	assertParseRule(t, "function assignment", `f(x) := y { true }`, &Rule{
		Head: &Head{
			Name:      "f",
			Reference: Ref{VarTerm("f")},
			Value:     VarTerm("y"),
			Args: Args{
				VarTerm("x"),
			},
			Assign: true,
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})

	// TODO: expect expressions instead?
	assertParseErrorContains(t, "empty body", `f(_) = y {}`, "rego_parse_error: found empty body")
	assertParseErrorContains(t, "empty rule body", "p {}", "rego_parse_error: found empty body")
	assertParseErrorContains(t, "unmatched braces", `f(x) = y { trim(x, ".", y) `, `rego_parse_error: unexpected eof token: expected \n or ; or }
	f(x) = y { trim(x, ".", y) 
	                         ^`)

	assertParseErrorContains(t, "no output", `f(_) = { "foo" = "bar" }`, "rego_parse_error: unexpected eq token: expected rule value term")

	assertParseErrorContains(t, "no output", `f(_) := { "foo" = "bar" }`, `rego_parse_error: unexpected eq token: non-terminated set
	f(_) := { "foo" = "bar" }
	                ^
1:17: rego_parse_error: unexpected eq token: expected function value term (e.g., f(...) := <VALUE> { ... })
	f(_) := { "foo" = "bar" }
	                ^`)

	assertParseErrorContains(t, "no output", `f := { "foo" = "bar" }`, `rego_parse_error: unexpected eq token: non-terminated set
	f := { "foo" = "bar" }
	             ^
1:14: rego_parse_error: unexpected eq token: expected rule value term (e.g., f := <VALUE> { ... })
	f := { "foo" = "bar" }
	             ^`)
	assertParseErrorContains(t, "no output", `f[_] := { "foo" = "bar" }`, `rego_parse_error: unexpected eq token: non-terminated set
	f[_] := { "foo" = "bar" }
	                ^
1:17: rego_parse_error: unexpected eq token: expected rule value term (e.g., f[_] := <VALUE> { ... })
	f[_] := { "foo" = "bar" }
	                ^`)
	assertParseErrorContains(t, "no output", `default f :=`, `rego_parse_error: unexpected eof token
	default f :=
	           ^
1:12: rego_parse_error: unexpected eof token: expected default rule value term (e.g., default f := <VALUE>)
	default f :=
	           ^`)

	// TODO(tsandall): improve error checking here. This is a common mistake
	// and the current error message is not very good. Need to investigate if the
	// parser can be improved.
	assertParseError(t, "dangling semicolon", "p { true; false; }")

	assertParseErrorContains(t, "default invalid rule name", `default 0[0`, "unexpected default keyword")
	assertParseErrorContains(t, "default invalid rule value", `default a[0]`, "illegal default rule (must have a value)")
	assertParseRule(t, "default missing value", `default a`, &Rule{
		Default: true,
		Head: &Head{
			Name:      Var("a"),
			Reference: Ref{VarTerm("a")},
			Value:     BooleanTerm(true),
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})
	assertParseRule(t, "empty arguments", `f() { x := 1 }`, &Rule{
		Head: &Head{
			Name:      "f",
			Reference: Ref{VarTerm("f")},
			Value:     BooleanTerm(true),
		},
		Body: MustParseBody(`x := 1`),
	})

	assertParseErrorContains(t, "default invalid rule head ref", `default a = b.c.d`, "illegal default rule (value cannot contain ref)")
	assertParseErrorContains(t, "default invalid rule head call", `default a = g(x)`, "illegal default rule (value cannot contain call)")
	assertParseErrorContains(t, "default invalid rule head builtin call", `default a = upper("foo")`, "illegal default rule (value cannot contain call)")
	assertParseErrorContains(t, "default invalid rule head call", `default a = b`, "illegal default rule (value cannot contain var)")

	assertParseErrorContains(t, "default invalid function head ref", `default f(x) = b.c.d`, "illegal default rule (value cannot contain ref)")
	assertParseErrorContains(t, "default invalid function head call", `default f(x) = g(x)`, "illegal default rule (value cannot contain call)")
	assertParseErrorContains(t, "default invalid function head builtin call", `default f(x) = upper("foo")`, "illegal default rule (value cannot contain call)")
	assertParseErrorContains(t, "default invalid function head call", `default f(x) = b`, "illegal default rule (value cannot contain var)")
	assertParseErrorContains(t, "default invalid function composite argument", `default f([x]) = 1`, "illegal default rule (arguments cannot contain array)")
	assertParseErrorContains(t, "default invalid function number argument", `default f(1) = 1`, "illegal default rule (arguments cannot contain number)")
	assertParseErrorContains(t, "default invalid function repeated vars", `default f(x, x) = 1`, "illegal default rule (arguments cannot be repeated x)")

	assertParseError(t, "extra braces", `{ a := 1 }`)
	assertParseError(t, "invalid rule name hyphen", `a-b = x { x := 1 }`)

	assertParseRule(t, "wildcard name", `_ { x == 1 }`, &Rule{
		Head: &Head{
			Name:      "$0",
			Reference: Ref{VarTerm("$0")},
			Value:     BooleanTerm(true),
		},
		Body: MustParseBody(`x == 1`),
	})

	assertParseRule(t, "partial object array key", `p[[a, 1, 2]] = x { a := 1; x := "foo" }`, &Rule{
		Head: &Head{
			Name:      "p",
			Reference: MustParseRef("p[[a,1,2]]"),
			Key:       ArrayTerm(VarTerm("a"), NumberTerm("1"), NumberTerm("2")),
			Value:     VarTerm("x"),
		},
		Body: MustParseBody(`a := 1; x := "foo"`),
	})
	assertParseError(t, "invalid rule body no separator", `p { a = "foo"bar }`)
	assertParseError(t, "invalid rule body no newline", `p { a b c }`)

	assertParseRule(t, "wildcard in else args", `f(_) { true } else := false`, &Rule{
		Head: &Head{
			Name:      "f",
			Reference: Ref{VarTerm("f")},
			Args: Args{
				VarTerm("$0"),
			},
			Value: BooleanTerm(true),
		},
		Body: MustParseBody(`true`),
		Else: &Rule{
			Head: &Head{
				Name:      "f",
				Assign:    true,
				Reference: Ref{VarTerm("f")},
				Args: Args{
					VarTerm("$1"),
				},
				Value: BooleanTerm(false),
			},
			Body: MustParseBody(`true`),
		},
	})

	name := Var("f")
	ref := Ref{VarTerm("f")}
	tr := BooleanTerm(true)
	head := func(v string) *Head { return &Head{Name: name, Reference: ref, Value: tr, Args: []*Term{VarTerm(v)}} }
	assertParseModule(t, "wildcard in chained function heads", `package test
	f(_) if { true } { true }
`, &Module{
		Package: MustParsePackage(`package test`),
		Rules: []*Rule{
			{
				Head: head("$0"),
				Body: MustParseBody("true"),
			},
			{
				Head: head("$1"),
				Body: MustParseBody("true"),
			},
		},
	},
		ParserOptions{AllFutureKeywords: true})
}

func TestRuleContains(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"contains", "if"}}

	tests := []struct {
		note string
		rule string
		exp  *Rule
	}{
		{
			note: "simple",
			rule: `p contains "x" { true }`,
			exp: &Rule{
				Head: NewHead(Var("p"), StringTerm("x")),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "no body",
			rule: `p contains "x"`,
			exp: &Rule{
				Head: NewHead(Var("p"), StringTerm("x")),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "ref head, no body",
			rule: `p.q contains "x"`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q"),
					Key:       StringTerm("x"),
				},
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "ref head",
			rule: `p.q contains "x" { true }`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q"),
					Key:       StringTerm("x"),
				},
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "set with var element",
			rule: `deny contains msg { msg := "nonono" }`,
			exp: &Rule{
				Head: NewHead(Var("deny"), VarTerm("msg")),
				Body: MustParseBody(`msg := "nonono"`),
			},
		},
		{
			note: "set with object elem",
			rule: `deny contains {"allow": false, "msg": msg} { msg := "nonono" }`,
			exp: &Rule{
				Head: NewHead(Var("deny"), MustParseTerm(`{"allow": false, "msg": msg}`)),
				Body: MustParseBody(`msg := "nonono"`),
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			assertParseRule(t, tc.note, tc.rule, tc.exp, opts)
		})
	}
}

func TestRuleContainsFail(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"contains", "if", "every"}}

	tests := []struct {
		note     string
		rule     string
		expected string
	}{
		{
			note:     "contains used with a 1+ argument function",
			rule:     "p(a) contains x { x := a }",
			expected: "the contains keyword can only be used with multi-value rule definitions (e.g., p contains <VALUE> { ... })",
		},
		{
			note:     "contains used with a 0 argument function",
			rule:     "p() contains x { x := 1 }",
			expected: "the contains keyword can only be used with multi-value rule definitions (e.g., p contains <VALUE> { ... })",
		},
	}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			assertParseErrorContains(t, tc.note, tc.rule, tc.expected, opts)
		})
	}
}

func TestRuleIf(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"contains", "if", "every"}}

	tests := []struct {
		note string
		rule string
		exp  *Rule
	}{
		{
			note: "complete",
			rule: `p if { true }`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "else",
			rule: `p if { true } else if { true }`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: NewBody(NewExpr(BooleanTerm(true))),
				Else: &Rule{
					Head: NewHead(Var("p"), nil, BooleanTerm(true)),
					Body: NewBody(NewExpr(BooleanTerm(true))),
				},
			},
		},
		{
			note: "ref head, complete",
			rule: `p.q if { true }`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q"),
					Value:     BooleanTerm(true),
				},
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "complete, normal body",
			rule: `p if { x := 10; x > y }`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: MustParseBody(`x := 10; x > y`),
			},
		},
		{
			note: "complete+else, normal bodies, assign",
			rule: `p := "yes" if { 10 > y } else := "no" { 10 <= y }`,
			exp: &Rule{
				Head: &Head{
					Reference: Ref{VarTerm("p")},
					Name:      Var("p"),
					Value:     StringTerm("yes"),
					Assign:    true,
				},
				Body: MustParseBody(`10 > y`),
				Else: &Rule{
					Head: &Head{
						Reference: Ref{VarTerm("p")},
						Name:      Var("p"),
						Value:     StringTerm("no"),
						Assign:    true,
					},
					Body: MustParseBody(`10 <= y`),
				},
			},
		},
		{
			note: "complete+else, normal bodies, assign; if",
			rule: `p := "yes" if { 10 > y } else := "no" if { 10 <= y }`,
			exp: &Rule{
				Head: &Head{
					Reference: Ref{VarTerm("p")},
					Name:      Var("p"),
					Value:     StringTerm("yes"),
					Assign:    true,
				},
				Body: MustParseBody(`10 > y`),
				Else: &Rule{
					Head: &Head{
						Reference: Ref{VarTerm("p")},
						Name:      Var("p"),
						Value:     StringTerm("no"),
						Assign:    true,
					},
					Body: MustParseBody(`10 <= y`),
				},
			},
		},
		{
			note: "complete, shorthand",
			rule: `p if true`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "complete, else, shorthand",
			rule: `p if true else if true`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: NewBody(NewExpr(BooleanTerm(true))),
				Else: &Rule{
					Head: NewHead(Var("p"), nil, BooleanTerm(true)),
					Body: NewBody(NewExpr(BooleanTerm(true))),
				},
			},
		},
		{
			note: "complete, else, assignment+shorthand",
			rule: `p if true else := 3 if 2 < 1`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: NewBody(NewExpr(BooleanTerm(true))),
				Else: &Rule{
					Head: &Head{
						Reference: Ref{VarTerm("p")},
						Name:      Var("p"),
						Value:     NumberTerm("3"),
						Assign:    true,
					},
					Body: NewBody(LessThan.Expr(IntNumberTerm(2), IntNumberTerm(1))),
				},
			},
		},
		{
			note: "complete+not, shorthand",
			rule: `p if not q`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: MustParseBody(`not q`),
			},
		},
		{
			note: "complete+else, shorthand",
			rule: `p if 1 > 2 else = 42 { 2 > 1 }`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: MustParseBody(`1 > 2`),
				Else: &Rule{
					Head: &Head{
						Reference: Ref{VarTerm("p")},
						Name:      Var("p"),
						Value:     NumberTerm("42"),
					},
					Body: MustParseBody(`2 > 1`),
				},
			},
		},
		{
			note: "complete+call, shorthand",
			rule: `p if count(q) > 0`,
			exp: &Rule{
				Head: NewHead(Var("p"), nil, BooleanTerm(true)),
				Body: MustParseBody(`count(q) > 0`),
			},
		},
		{
			note: "function, shorthand",
			rule: `f(x) = y if y := x + 1`,
			exp: &Rule{
				Head: &Head{
					Reference: Ref{VarTerm("f")},
					Name:      Var("f"),
					Args:      []*Term{VarTerm("x")},
					Value:     VarTerm("y"),
				},
				Body: MustParseBody(`y := x + 1`),
			},
		},
		{
			note: "function+every, shorthand",
			rule: `f(xs) if every x in xs { x != 0 }`,
			exp: &Rule{
				Head: &Head{
					Reference: Ref{VarTerm("f")},
					Name:      Var("f"),
					Args:      []*Term{VarTerm("xs")},
					Value:     BooleanTerm(true),
				},
				Body: MustParseBodyWithOpts(`every x in xs { x != 0 }`, opts),
			},
		},
		{
			note: "object",
			rule: `p["foo"] = "bar" if { true }`,
			exp: &Rule{
				Head: &Head{
					Name:      Var("p"),
					Reference: MustParseRef("p.foo"),
					Value:     StringTerm("bar"),
				},
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "object, shorthand",
			rule: `p["foo"] = "bar" if true`,
			exp: &Rule{
				Head: &Head{
					Name:      Var("p"),
					Reference: MustParseRef("p.foo"),
					Value:     StringTerm("bar"),
				},
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "object with vars",
			rule: `p[x] = y if {
				x := "foo"
				y := "bar"
			}`,
			exp: &Rule{
				Head: &Head{
					Name:      Var("p"),
					Reference: MustParseRef("p[x]"),
					Key:       VarTerm("x"),
					Value:     VarTerm("y"),
				},
				Body: MustParseBody(`x := "foo"; y := "bar"`),
			},
		},
		{
			note: "set",
			rule: `p contains "foo" if { true }`,
			exp: &Rule{
				Head: NewHead(Var("p"), StringTerm("foo")),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "set, shorthand",
			rule: `p contains "foo" if true`,
			exp: &Rule{
				Head: NewHead(Var("p"), StringTerm("foo")),
				Body: NewBody(NewExpr(BooleanTerm(true))),
			},
		},
		{
			note: "set+var+shorthand",
			rule: `p contains x if { x := "foo" }`,
			exp: &Rule{
				Head: NewHead(Var("p"), VarTerm("x")),
				Body: MustParseBody(`x := "foo"`),
			},
		},
		{
			note: "partial set+if, shorthand", // these are now Head.Ref rules, previously forbidden
			rule: `p[x] if x := 1`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p[x]"),
					Key:       VarTerm("x"),
					Value:     BooleanTerm(true),
				},
				Body: MustParseBody(`x := 1`),
			},
		},
		{
			note: "partial set+if", // these are now Head.Ref rules, previously forbidden
			rule: `p[x] if { x := 1 }`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p[x]"),
					Key:       VarTerm("x"),
					Value:     BooleanTerm(true),
				},
				Body: MustParseBody(`x := 1`),
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			assertParseRule(t, tc.note, tc.rule, tc.exp, opts)
		})
	}
}

func TestRuleRefHeads(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"contains", "if", "every"}}
	trueBody := NewBody(NewExpr(BooleanTerm(true)))

	tests := []struct {
		note string
		rule string
		exp  *Rule
	}{
		{
			note: "single-value rule",
			rule: "p.q.r = 1 if true",
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.r"),
					Value:     IntNumberTerm(1),
				},
				Body: trueBody,
			},
		},
		{
			note: "single-value with brackets, string key",
			rule: `p.q["r"] = 1 if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.r"),
					Value:     IntNumberTerm(1),
				},
				Body: trueBody,
			},
		},
		{
			note: "single-value with brackets, number key",
			rule: `p.q[2] = 1 if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q[2]"),
					Value:     IntNumberTerm(1),
				},
				Body: trueBody,
			},
		},
		{
			note: "single-value with brackets, no value",
			rule: `p.q[2] if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q[2]"),
					Value:     BooleanTerm(true),
				},
				Body: trueBody,
			},
		},
		{
			note: "single-value with brackets, var key",
			rule: `p.q[x] = 1 if x := 2`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q[x]"),
					Value:     IntNumberTerm(1),
				},
				Body: MustParseBody("x := 2"),
			},
		},
		{
			note: "single-value with brackets, var key, no dot",
			rule: `p[x] = 1 if x := 2`,
			exp: &Rule{
				Head: &Head{
					Name:      Var("p"),
					Reference: MustParseRef("p[x]"),
					Key:       VarTerm("x"),
					Value:     IntNumberTerm(1),
				},
				Body: MustParseBody("x := 2"),
			},
		},
		{
			note: "multi-value, simple",
			rule: `p.q.r contains x if x := 2`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.r"),
					Key:       VarTerm("x"),
				},
				Body: MustParseBody("x := 2"),
			},
		},
		{
			note: "backcompat: multi-value, no dot",
			rule: `p[x] { x := 2 }`, // no "if", which triggers ref-interpretation
			exp: &Rule{
				Head: &Head{
					Name:      "p",
					Reference: Ref{VarTerm("p")}, // we're defining p as multi-val rule
					Key:       VarTerm("x"),
				},
				Body: MustParseBody("x := 2"),
			},
		},
		{
			note: "backcompat: single-value, no dot",
			rule: `p[x] = 3 { x := 2 }`,
			exp: &Rule{
				Head: &Head{
					Name:      "p",
					Reference: MustParseRef("p[x]"),
					Key:       VarTerm("x"), // not used
					Value:     IntNumberTerm(3),
				},
				Body: MustParseBody("x := 2"),
			},
		},
		{
			note: "backcompat: single-value, no dot, complex object",
			rule: `partialobj[x] = {"foo": y} { y = "bar"; x = y }`,
			exp: &Rule{
				Head: &Head{
					Name:      "partialobj",
					Reference: MustParseRef("partialobj[x]"),
					Key:       VarTerm("x"), // not used
					Value:     MustParseTerm(`{"foo": y}`),
				},
				Body: MustParseBody(`y = "bar"; x = y`),
			},
		},
		{
			note: "function, simple",
			rule: `p.q.f(x) = 1 if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.f"),
					Args:      Args([]*Term{VarTerm("x")}),
					Value:     IntNumberTerm(1),
				},
				Body: trueBody,
			},
		},
		{
			note: "function, no value",
			rule: `p.q.f(x) if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.f"),
					Args:      Args([]*Term{VarTerm("x")}),
					Value:     BooleanTerm(true),
				},
				Body: trueBody,
			},
		},
		{
			note: "function, with value",
			rule: `p.q.f(x) = x + 1 if true`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("p.q.f"),
					Args:      Args([]*Term{VarTerm("x")}),
					Value:     Plus.Call(VarTerm("x"), IntNumberTerm(1)),
				},
				Body: trueBody,
			},
		},
	}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			assertParseRule(t, tc.note, tc.rule, tc.exp, opts)
		})
	}

	assertParseErrorContains(t, "first ref head term is call", `package p
q(0).r(0) { true }`,
		"unexpected { token: rule head ref q(0).r invalid", opts)
}

func TestRuleElseKeyword(t *testing.T) {
	mod := `package test

	p if {
		"p0"
	}

	p if {
		"p1"
	} else if {
		"p1_e1"
	} else = [null] if {
		"p1_e2"
	} else = x if {
		x = "p1_e3"
	}

	p if {
		"p2"
	}

	f(x) if {
		x < 100
	} else = false if {
		x > 200
	} else if {
		x != 150
	}

	_ if {
		x > 0
	} else if {
	    x == -1
	} else if {
		x > -100
	}

	nobody = 1 if {
		false
	} else = 7

	nobody_f(x) = 1 if {
		false
	} else = 7
	`

	parsed, err := ParseModuleWithOpts("", mod, ParserOptions{AllFutureKeywords: true})
	if err != nil {
		t.Fatalf("Unexpected parse error: %v", err)
	}

	name := Var("p")
	ref := Ref{VarTerm("p")}
	tr := BooleanTerm(true)
	head := &Head{Name: name, Reference: ref, Value: tr}

	expected := &Module{
		Package: MustParsePackage(`package test`),
		Rules: []*Rule{
			{
				Head: head,
				Body: MustParseBody(`"p0"`),
			},
			{
				Head: head,
				Body: MustParseBody(`"p1"`),
				Else: &Rule{
					Head: head,
					Body: MustParseBody(`"p1_e1"`),
					Else: &Rule{
						Head: &Head{
							Name:      name,
							Reference: ref,
							Value:     ArrayTerm(NullTerm()),
						},
						Body: MustParseBody(`"p1_e2"`),
						Else: &Rule{
							Head: &Head{
								Name:      name,
								Reference: ref,
								Value:     VarTerm("x"),
							},
							Body: MustParseBody(`x = "p1_e3"`),
						},
					},
				},
			},
			{
				Head: head,
				Body: MustParseBody(`"p2"`),
			},
			{
				Head: &Head{
					Name:      Var("f"),
					Reference: Ref{VarTerm("f")},
					Args:      Args{VarTerm("x")},
					Value:     BooleanTerm(true),
				},
				Body: MustParseBody(`x < 100`),
				Else: &Rule{
					Head: &Head{
						Name:      Var("f"),
						Reference: Ref{VarTerm("f")},
						Args:      Args{VarTerm("x")},
						Value:     BooleanTerm(false),
					},
					Body: MustParseBody(`x > 200`),
					Else: &Rule{
						Head: &Head{
							Name:      Var("f"),
							Reference: Ref{VarTerm("f")},
							Args:      Args{VarTerm("x")},
							Value:     BooleanTerm(true),
						},
						Body: MustParseBody(`x != 150`),
					},
				},
			},

			{
				Head: &Head{
					Name:      Var("$0"),
					Reference: Ref{VarTerm("$0")},
					Value:     BooleanTerm(true),
				},
				Body: MustParseBody(`x > 0`),
				Else: &Rule{
					Head: &Head{
						Name:      Var("$0"),
						Reference: Ref{VarTerm("$0")},
						Value:     BooleanTerm(true),
					},
					Body: MustParseBody(`x == -1`),
					Else: &Rule{
						Head: &Head{
							Name:      Var("$0"),
							Reference: Ref{VarTerm("$0")},
							Value:     BooleanTerm(true),
						},
						Body: MustParseBody(`x > -100`),
					},
				},
			},
			{
				Head: &Head{
					Name:      Var("nobody"),
					Reference: Ref{VarTerm("nobody")},
					Value:     IntNumberTerm(1),
				},
				Body: MustParseBody("false"),
				Else: &Rule{
					Head: &Head{
						Name:      Var("nobody"),
						Reference: Ref{VarTerm("nobody")},
						Value:     IntNumberTerm(7),
					},
					Body: MustParseBody("true"),
				},
			},
			{
				Head: &Head{
					Name:      Var("nobody_f"),
					Reference: Ref{VarTerm("nobody_f")},
					Args:      Args{VarTerm("x")},
					Value:     IntNumberTerm(1),
				},
				Body: MustParseBody("false"),
				Else: &Rule{
					Head: &Head{
						Name:      Var("nobody_f"),
						Reference: Ref{VarTerm("nobody_f")},
						Args:      Args{VarTerm("x")},
						Value:     IntNumberTerm(7),
					},
					Body: MustParseBody("true"),
				},
			},
		},
	}

	if parsed.Compare(expected) != 0 {
		t.Fatalf("Expected:\n%v\n\nGot:\n%v", expected, parsed)
	}

	notExpected := &Module{
		Package: MustParsePackage(`package test`),
		Rules: []*Rule{
			{
				Head: head,
				Body: MustParseBody(`"p0"`),
			},
			{
				Head: head,
				Body: MustParseBody(`"p1"`),
				Else: &Rule{
					Head: head,
					Body: MustParseBody(`"p1_e1"`),
					Else: &Rule{
						Head: &Head{
							Name:      Var("p"),
							Reference: Ref{VarTerm("p")},
							Value:     ArrayTerm(NullTerm()),
						},
						Body: MustParseBody(`"p1_e2"`),
						Else: &Rule{
							Head: &Head{
								Name:      name,
								Reference: ref,
								Value:     VarTerm("x"),
							},
							Body: MustParseBody(`x = "p1_e4"`),
						},
					},
				},
			},
			{
				Head: head,
				Body: MustParseBody(`"p2"`),
			},
		},
	}

	if parsed.Compare(notExpected) != -1 {
		t.Fatalf("Expected not equal:\n%v\n\nGot:\n%v", parsed, notExpected)
	}

	_, err = ParseModule("", `
	package test
	p[1] { false } else { true }
	`)

	if err == nil || !strings.Contains(err.Error(), "else keyword cannot be used on multi-value rules") {
		t.Fatalf("Expected parse error but got: %v", err)
	}

	_, err = ParseModule("", `
	package test
	p { false } { false } else { true }
	`)

	if err == nil || !strings.Contains(err.Error(), "unexpected else keyword") {
		t.Fatalf("Expected parse error but got: %v", err)
	}

	_, err = ParseModule("", `
	package test
	p { false } else { false } { true }
	`)

	if err == nil || !strings.Contains(err.Error(), "expected else keyword") {
		t.Fatalf("Expected parse error but got: %v", err)
	}

}

func TestRuleElseRefHeads(t *testing.T) {
	tests := []struct {
		note string
		rule string
		exp  *Rule
		err  string
	}{
		{
			note: "simple ref head",
			rule: `
a.b.c := 1 if false
else := 2
`,
			exp: &Rule{
				Head: &Head{
					Reference: MustParseRef("a.b.c"),
					Value:     NumberTerm("1"),
					Assign:    true,
				},
				Body: MustParseBody("false"),
				Else: &Rule{
					Head: &Head{
						Reference: MustParseRef("a.b.c"),
						Value:     NumberTerm("2"),
						Assign:    true,
					},
					Body: MustParseBody("true"),
				},
			},
		},
		{
			note: "multi-value ref head",
			rule: `
a.b.c contains 1 if false
else := 2
`,
			err: "else keyword cannot be used on multi-value rules",
		},
		{
			note: "single-value ref head with var",
			rule: `
a.b[x] := 1 if false
else := 2
`,
			err: "else keyword cannot be used on rules with variables in head",
		},
		{
			note: "single-value general ref head with var",
			rule: `
a.b[x].c := 1 if false
else := 2
`,
			err: "else keyword cannot be used on rules with variables in head",
		},
		{
			note: "single-value ref head with length 1 (last is var)",
			rule: `
a := 1 if false
else := 2
`,
			exp: &Rule{
				Head: &Head{
					Reference: Ref{VarTerm("a")},
					Name:      Var("a"),
					Value:     NumberTerm("1"),
					Assign:    true,
				},
				Body: MustParseBody("false"),
				Else: &Rule{
					Head: &Head{
						Reference: Ref{VarTerm("a")},
						Name:      Var("a"),
						Value:     NumberTerm("2"),
						Assign:    true,
					},
					Body: MustParseBody("true"),
				},
			},
		},
	}

	opts := ParserOptions{FutureKeywords: []string{"if", "contains"}}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			if tc.err != "" {
				assertParseErrorContains(t, tc.note, tc.rule, tc.err, opts)
				return
			}
			if tc.exp != nil {
				testModule := "package test\n" + tc.rule
				assertParseModule(t, tc.note, testModule, &Module{
					Package: MustParseStatement(`package test`).(*Package),
					Rules:   []*Rule{tc.exp},
				}, opts)
			}
		})
	}
}

func TestMultipleEnclosedBodies(t *testing.T) {

	result := module(`package ex

p[x] = y if {
	x = "a"
	y = 1
} {
	x = "b"
	y = 2
}

q = 1

f(x) if {
	x < 10
} {
	x > 1000
}
`)

	expected := module(`package ex

p[x] = y if { x = "a"; y = 1 }
p[x] = y if { x = "b"; y = 2 }
q = 1 if { true }
f(x) if { x < 10 }
f(x) if { x > 1000 }`,
	)

	if !expected.Equal(result) {
		t.Fatal("Expected modules to be equal but got:\n\n", result, "\n\nExpected:\n\n", expected)
	}
}

func TestEmptyModule(t *testing.T) {
	r, err := ParseModule("", "    ")
	if err == nil {
		t.Error("Expected error for empty module")
		return
	}
	if r != nil {
		t.Errorf("Expected nil for empty module: %v", r)
	}
}

func TestComments(t *testing.T) {
	testModule := `package a.b.c

    import input.e.f as g  # end of line
    import input.h

    # by itself

    p[x] = y if { y = "foo";
        # inside a rule
        x = "bar";
        x != y;
        q[x]
	}

    import input.xyz.abc

    q # interrupting

	contains a  # the head of a rule

	if { m = [1,2,
    3, ];
    a = m[i]

	}

	r contains x if { x = [ a | # inside comprehension
					  a = z[i]
	                  b[i].a = a ]

		y = { a | # inside set comprehension
				a = z[i]
			b[i].a = a}

		z = {a: i | # inside object comprehension
				a = z[i]
			b[i].a = a}
					  }`

	popts := ParserOptions{AllFutureKeywords: true}

	assertParseModule(t, "module comments", testModule, &Module{
		Package: MustParseStatement(`package a.b.c`).(*Package),
		Imports: []*Import{
			MustParseStatement("import input.e.f as g").(*Import),
			MustParseStatement("import input.h").(*Import),
			MustParseStatement("import input.xyz.abc").(*Import),
		},
		Rules: []*Rule{
			MustParseStatementWithOpts(`p[x] = y if { y = "foo"; x = "bar"; x != y; q[x] }`, popts).(*Rule),
			MustParseStatementWithOpts(`q contains a if { m = [1, 2, 3]; a = m[i] }`, popts).(*Rule),
			MustParseStatementWithOpts(`r contains x if { x = [a | a = z[i]; b[i].a = a]; y = {a |  a = z[i]; b[i].a = a}; z = {a: i | a = z[i]; b[i].a = a} }`, popts).(*Rule),
		},
	}, popts)

	module, err := ParseModuleWithOpts("test.rego", testModule, popts)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}

	exp := []struct {
		text string
		row  int
		col  int
	}{
		{text: "end of line", row: 3, col: 28},
		{text: "by itself", row: 6, col: 5},
		{text: "inside a rule", row: 9, col: 9},
		{text: "interrupting", row: 17, col: 7},
		{text: "the head of a rule", row: 19, col: 14},
		{text: "inside comprehension", row: 27, col: 30},
		{text: "inside set comprehension", row: 31, col: 13},
		{text: "inside object comprehension", row: 35, col: 15},
	}

	if len(module.Comments) != len(exp) {
		t.Fatalf("Expected %v comments but got %v", len(exp), len(module.Comments))
	}

	for i := range exp {

		expc := &Comment{
			Text: []byte(" " + exp[i].text),
			Location: &Location{
				File: "test.rego",
				Text: []byte("# " + exp[i].text),
				Row:  exp[i].row,
				Col:  exp[i].col,
			},
		}

		if !expc.Equal(module.Comments[i]) {
			comment := module.Comments[i]
			fmt.Printf("comment: %v %v %v %v\n", comment.Location.File, comment.Location.Text, comment.Location.Col, comment.Location.Row)
			fmt.Printf("expcomm: %v %v %v %v\n", expc.Location.File, expc.Location.Text, expc.Location.Col, expc.Location.Row)
			t.Errorf("Expected %q but got: %q (want: %d:%d, got: %d:%d)", expc, comment, exp[i].row, exp[i].col, comment.Location.Row, comment.Location.Col)
		}
	}
}

func TestCommentsV0(t *testing.T) {
	testModule := `package a.b.c

    import input.e.f as g  # end of line
    import input.h

    # by itself

    p[x] = y { y = "foo";
        # inside a rule
        x = "bar";
        x != y;
        q[x]
	}

    import input.xyz.abc

    q # interrupting

	[a] # the head of a rule

	{ m = [1,2,
    3, ];
    a = m[i]

	}

	r[x] { x = [ a | # inside comprehension
					  a = z[i]
	                  b[i].a = a ]

		y = { a | # inside set comprehension
				a = z[i]
			b[i].a = a}

		z = {a: i | # inside object comprehension
				a = z[i]
			b[i].a = a}
					  }`

	popts := ParserOptions{RegoVersion: RegoV0}

	assertParseModule(t, "module comments", testModule, &Module{
		Package: MustParseStatement(`package a.b.c`).(*Package),
		Imports: []*Import{
			MustParseStatement("import input.e.f as g").(*Import),
			MustParseStatement("import input.h").(*Import),
			MustParseStatement("import input.xyz.abc").(*Import),
		},
		Rules: []*Rule{
			MustParseStatementWithOpts(`p[x] = y { y = "foo"; x = "bar"; x != y; q[x] }`, popts).(*Rule),
			MustParseStatementWithOpts(`q[a] { m = [1, 2, 3]; a = m[i] }`, popts).(*Rule),
			MustParseStatementWithOpts(`r[x] { x = [a | a = z[i]; b[i].a = a]; y = {a |  a = z[i]; b[i].a = a}; z = {a: i | a = z[i]; b[i].a = a} }`, popts).(*Rule),
		},
	}, popts)

	module, err := ParseModuleWithOpts("test.rego", testModule, popts)
	if err != nil {
		t.Fatal("Unexpected error:", err)
	}

	exp := []struct {
		text string
		row  int
		col  int
	}{
		{text: "end of line", row: 3, col: 28},
		{text: "by itself", row: 6, col: 5},
		{text: "inside a rule", row: 9, col: 9},
		{text: "interrupting", row: 17, col: 7},
		{text: "the head of a rule", row: 19, col: 6},
		{text: "inside comprehension", row: 27, col: 19},
		{text: "inside set comprehension", row: 31, col: 13},
		{text: "inside object comprehension", row: 35, col: 15},
	}

	if len(module.Comments) != len(exp) {
		t.Fatalf("Expected %v comments but got %v", len(exp), len(module.Comments))
	}

	for i := range exp {

		expc := &Comment{
			Text: []byte(" " + exp[i].text),
			Location: &Location{
				File: "test.rego",
				Text: []byte("# " + exp[i].text),
				Row:  exp[i].row,
				Col:  exp[i].col,
			},
		}

		if !expc.Equal(module.Comments[i]) {
			comment := module.Comments[i]
			fmt.Printf("comment: %v %v %v %v\n", comment.Location.File, comment.Location.Text, comment.Location.Col, comment.Location.Row)
			fmt.Printf("expcomm: %v %v %v %v\n", expc.Location.File, expc.Location.Text, expc.Location.Col, expc.Location.Row)
			t.Errorf("Expected %q but got: %q (want: %d:%d, got: %d:%d)", expc, comment, exp[i].row, exp[i].col, comment.Location.Row, comment.Location.Col)
		}
	}
}

func TestCommentsWhitespace(t *testing.T) {
	cases := []struct {
		note     string
		module   string
		expected []string
	}{
		{
			note:     "trailing spaces",
			module:   "# a comment    \t   \n",
			expected: []string{" a comment    \t   "},
		},
		{
			note:     "trailing carriage return",
			module:   "# a comment\r\n",
			expected: []string{" a comment"},
		},
		{
			note:     "trailing carriage return double newline",
			module:   "# a comment\r\n\n",
			expected: []string{" a comment"},
		},
		{
			note:     "double trailing carriage return newline",
			module:   "#\r\r\n",
			expected: []string{"\r"},
		},
		{
			note:     "double trailing carriage return",
			module:   "#\r\r",
			expected: []string{"\r"},
		},
		{
			note:     "carriage return",
			module:   "#\r",
			expected: []string{""},
		},
		{
			note:     "carriage return in comment",
			module:   "# abc\rdef\r\n",
			expected: []string{" abc\rdef"},
		},
	}

	for _, tc := range cases {
		t.Run(tc.note, func(t *testing.T) {
			_, comments, err := ParseStatements("", tc.module)
			if err != nil {
				t.Fatalf("Unexpected parse error: %s", err)
			}

			for i, exp := range tc.expected {
				actual := string(comments[i].Text)
				if exp != actual {
					t.Errorf("Expected comment text (len %d):\n\n\t%q\n\nbut got (len %d):\n\n\t%q\n\n", len(exp), exp, len(actual), actual)
				}
			}
		})
	}
}

func TestExample(t *testing.T) {
	popts := ParserOptions{AllFutureKeywords: true}

	assertParseModule(t, "example module", testModule, &Module{
		Package: MustParseStatement(`package opa.examples`).(*Package),
		Imports: []*Import{
			MustParseStatement("import data.servers").(*Import),
			MustParseStatement("import data.networks").(*Import),
			MustParseStatement("import data.ports").(*Import),
		},
		Rules: []*Rule{
			MustParseStatementWithOpts(`violations contains server if { server = servers[i]; server.protocols[j] = "http"; public_servers[server] }`, popts).(*Rule),
			MustParseStatementWithOpts(`public_servers contains server if { server = servers[i]; server.ports[j] = ports[k].id; ports[k].networks[l] = networks[m].id; networks[m].public = true }`, popts).(*Rule),
		},
	}, popts)
}

func TestModuleParseErrors(t *testing.T) {
	input := `
	x = 1			# expect package
	package a  		# unexpected package
	1 = 2			# non-var head
	1 != 2			# non-equality expr
	x = y; x = 1    # multiple exprs
	`

	mod, err := ParseModule("test.rego", input)
	if err == nil {
		t.Fatalf("Expected error but got: %v", mod)
	}

	errs, ok := err.(Errors)
	if !ok {
		panic("unexpected error value")
	}

	if len(errs) != 5 {
		t.Fatalf("Expected exactly 5 errors but got: %v", err)
	}
}

func TestLocation(t *testing.T) {
	mod, err := ParseModuleWithOpts("test", testModule, ParserOptions{AllFutureKeywords: true})
	if err != nil {
		t.Errorf("Unexpected error while parsing test module: %v", err)
		return
	}
	expr := mod.Rules[0].Body[0]
	if expr.Location.Col != 5 {
		t.Errorf("Expected column of %v to be 5 but got: %v", expr, expr.Location.Col)
	}
	if expr.Location.Row != 15 {
		t.Errorf("Expected row of %v to be 8 but got: %v", expr, expr.Location.Row)
	}
	if expr.Location.File != "test" {
		t.Errorf("Expected file of %v to be test but got: %v", expr, expr.Location.File)
	}
}

func TestRuleFromBodyRefs(t *testing.T) {
	opts := ParserOptions{FutureKeywords: []string{"if", "contains"}}

	// NOTE(sr): These tests assert that the other code path, parsing a module, and
	// then interpreting naked expressions into (shortcut) rule definitions, works
	// the same as parsing the string as a Rule directly. Without also passing
	// TestRuleRefHeads, these tests are not to be trusted -- if changing something,
	// start with getting TestRuleRefHeads to PASS.
	//
	// NOTE: Some of these test cases are invalid v1 Rego, and are locked to v0.
	tests := []struct {
		note        string
		regoVersion RegoVersion
		rule        string
		exp         string
	}{
		{
			note:        "no dots: single-value rule (complete doc)",
			regoVersion: RegoV0,
			rule:        `foo["bar"] = 12`,
			exp:         `foo["bar"] = 12 { true }`,
		},
		{
			note:        "no dots: partial set of numbers",
			regoVersion: RegoV0,
			rule:        `foo[1]`,
			exp:         `foo[1] { true }`,
		},
		{
			note:        "no dots: shorthand set of strings", // back compat
			regoVersion: RegoV0,
			rule:        `foo.one`,
			exp:         `foo["one"] { true }`,
		},
		{
			note:        "no dots: partial set",
			regoVersion: RegoV0,
			rule:        `foo[x] { x = 1 }`,
			exp:         `foo[x] { x = 1 }`,
		},
		{
			note: "no dots + contains + if: partial set",
			rule: `foo contains x if { x = 1 }`,
			exp:  `foo contains x if { x = 1 }`,
		},
		{
			note: "no dots + if: complete doc",
			rule: `foo[x] if x := 1`,
			exp:  `foo[x] if x := 1`,
		},
		{
			note: "no dots: function",
			rule: `foo(x)`,
			exp:  `foo(x) { true }`,
		},
		{
			note: "no dots: function with value",
			rule: `foo(x) = y`,
			exp:  `foo(x) = y { true }`,
		},
		{
			note:        "no dots: partial set, ref element",
			regoVersion: RegoV0,
			rule:        `test[arr[0]]`,
			exp:         `test[arr[0]] { true }`,
		},
		{
			note: "no dots + contains: partial set, ref element",
			rule: `test contains arr[0]`,
			exp:  `test contains arr[0] if { true }`,
		},
		{
			note: "one dot: complete rule shorthand",
			rule: `foo.bar = "buz"`,
			exp:  `foo.bar = "buz" { true }`,
		},
		{
			note: "one dot, bracket with var: partial object",
			rule: `foo.bar[x] = "buz"`,
			exp:  `foo.bar[x] = "buz" { true }`,
		},
		{
			note:        "one dot, bracket with var: partial set",
			regoVersion: RegoV0,
			rule:        `foo.bar[x] { x = 1 }`,
			exp:         `foo.bar[x] { x = 1 }`,
		},
		{
			note: "one dot, contains with var: partial set",
			rule: `foo.bar contains x if { x = 1 }`,
			exp:  `foo.bar contains x if { x = 1 }`,
		},
		{
			note: "one dot, bracket with string: complete doc",
			rule: `foo.bar["baz"] = "buz"`,
			exp:  `foo.bar.baz = "buz" { true }`,
		},
		{
			note: "one dot, bracket with var, rule body: partial object",
			rule: `foo.bar[x] = "buz" if { x = 1 }`,
			exp:  `foo.bar[x] = "buz" if { x = 1 }`,
		},
		{
			note: "one dot: function",
			rule: `foo.bar(x)`,
			exp:  `foo.bar(x) { true }`,
		},
		{
			note: "one dot: function with value",
			rule: `foo.bar(x) = y`,
			exp:  `foo.bar(x) = y { true }`,
		},
		{
			note: "two dots, bracket with var: partial object",
			rule: `foo.bar.baz[x] = "buz" if { x = 1 }`,
			exp:  `foo.bar.baz[x] = "buz" if { x = 1 }`,
		},
		{
			note:        "two dots, bracket with var: partial set",
			regoVersion: RegoV0,
			rule:        `foo.bar.baz[x] { x = 1 }`,
			exp:         `foo.bar.baz[x] { x = 1 }`,
		},
		{
			note: "two dots, contains with var: partial set",
			rule: `foo.bar.baz contains x if { x = 1 }`,
			exp:  `foo.bar.baz contains x if { x = 1 }`,
		},
		{
			note:        "one dot, bracket with string, no key: complete doc",
			regoVersion: RegoV0,
			rule:        `foo.bar["baz"]`,
			exp:         `foo.bar.baz { true }`,
		},
		{
			note: "one dot, bracket with string, no key, value: complete doc",
			rule: `foo.bar["baz"] := true`,
			exp:  `foo.bar.baz := true if { true }`,
		},
		{
			note: "two dots: function",
			rule: `foo.bar("baz")`,
			exp:  `foo.bar("baz") { true }`,
		},
		{
			note: "two dots: function with value",
			rule: `foo.bar("baz") = y`,
			exp:  `foo.bar("baz") = y { true }`,
		},
		{
			note: "non-ground ref: complete doc",
			rule: `foo.bar[i].baz if { i := 1 }`,
			exp:  `foo.bar[i].baz if { i := 1 }`,
		},
		{
			note:        "non-ground ref, bracket-key: partial set",
			regoVersion: RegoV0,
			rule:        `foo.bar[i].baz[x] { i := 1; x := 2 }`,
			exp:         `foo.bar[i].baz[x] { i := 1; x := 2 }`,
		},
		{
			note: "non-ground ref, contains-key: partial set",
			rule: `foo.bar[i].baz contains x if { i := 1; x := 2 }`,
			exp:  `foo.bar[i].baz contains x if { i := 1; x := 2 }`,
		},
		{
			note: "non-ground ref: partial object",
			rule: `foo.bar[i].baz[x] = 3 if { i := 1; x := 2 }`,
			exp:  `foo.bar[i].baz[x] = 3 if { i := 1; x := 2 }`,
		},
		{
			note: "non-ground ref: function",
			rule: `foo.bar[i].baz(x) = 3 if { i := 1 }`,
			exp:  `foo.bar[i].baz(x) = 3 if { i := 1 }`,
		},
		{
			note:        "last term is number: partial set",
			regoVersion: RegoV0,
			rule:        `foo.bar.baz[3] { true }`,
			exp:         `foo.bar.baz[3] { true }`,
		},
		{
			note: "contains with number: partial set",
			rule: `foo.bar.baz contains 3 if { true }`,
			exp:  `foo.bar.baz contains 3 if { true }`,
		},
	}
	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			opts.RegoVersion = tc.regoVersion

			r, err := ParseRuleWithOpts(tc.exp, opts)
			if err != nil {
				t.Fatal(err)
			}

			testModule := "package a.b.c\n" + tc.rule
			m, err := ParseModuleWithOpts("", testModule, opts)
			if err != nil {
				t.Fatal(err)
			}
			mr := m.Rules[0]

			if r.Head.Name.Compare(mr.Head.Name) != 0 {
				t.Errorf("rule.Head.Name differs:\n exp = %#v\nrule = %#v", r.Head.Name, mr.Head.Name)
			}
			if r.Head.Ref().Compare(mr.Head.Ref()) != 0 {
				t.Errorf("rule.Head.Ref() differs:\n exp = %v\nrule = %v", r.Head.Ref(), mr.Head.Ref())
			}
			exp, err := ParseRuleWithOpts(tc.exp, opts)
			if err != nil {
				t.Fatal(err)
			}
			assertParseModule(t, tc.note, testModule, &Module{
				Package: MustParseStatement(`package a.b.c`).(*Package),
				Rules:   []*Rule{exp},
			}, opts)
		})
	}

	// edge cases
	t.Run("errors", func(t *testing.T) {
		t.Run("naked 'data' ref", func(t *testing.T) {
			_, err := ParseModuleWithOpts("", "package a.b.c\ndata", opts)
			assertErrorWithMessage(t, err, "refs cannot be used for rule head")
		})
		t.Run("naked 'input' ref", func(t *testing.T) {
			_, err := ParseModuleWithOpts("", "package a.b.c\ninput", opts)
			assertErrorWithMessage(t, err, "refs cannot be used for rule head")
		})
	})
}

func assertErrorWithMessage(t *testing.T, err error, msg string) {
	t.Helper()
	var errs Errors
	if !errors.As(err, &errs) {
		t.Fatalf("expected Errors, got %v %[1]T", err)
	}
	if exp, act := 1, len(errs); exp != act {
		t.Fatalf("expected %d errors, got %d", exp, act)
	}
	e := errs[0]
	if exp, act := msg, e.Message; exp != act {
		t.Fatalf("expected error message %q, got %q", exp, act)
	}
}

func TestRuleFromBody(t *testing.T) {
	popts := ParserOptions{RegoVersion: RegoV0}

	tests := []struct {
		input string
		exp   string
	}{
		{`pi = 3.14159`, `pi = 3.14159 { true }`},
		{`p[x] { x = 1 }`, `p[x] { x = 1 }`},
		{`greeting = "hello"`, `greeting = "hello" { true }`},
		{`cores = [{0: 1}, {1: 2}]`, `cores = [{0: 1}, {1: 2}] { true }`},
		{`wrapper = cores[0][1]`, `wrapper = cores[0][1] { true }`},
		{`pi = [3, 1, 4, x, y, z]`, `pi = [3, 1, 4, x, y, z] { true }`},
		{`foo["bar"] = "buz"`, `foo["bar"] = "buz" { true }`},
		{`foo["9"] = "10"`, `foo["9"] = "10" { true }`},
		{`foo.buz = "bar"`, `foo["buz"] = "bar" { true }`},
		{`bar[1]`, `bar[1] { true }`},
		{`bar[[{"foo":"baz"}]]`, `bar[[{"foo":"baz"}]] { true }`},
		{`bar.qux`, `bar["qux"] { true }`},
		{`input = 1`, `input = 1 { true }`},
		{`data = 2`, `data = 2 { true }`},
		{`f(1) = 2`, `f(1) = 2 { true }`},
		{`f(1)`, `f(1) = true { true }`},
		{`d1 := 1234`, "d1 := 1234 { true }"},
	}

	for _, tc := range tests {
		t.Run(tc.input, func(t *testing.T) {
			testModule := "package a.b.c\n" + tc.input
			assertParseModule(t, tc.input, testModule, &Module{
				Package: MustParseStatement(`package a.b.c`).(*Package),
				Rules: []*Rule{
					MustParseRule(tc.exp),
				},
			}, popts)
		})
	}

	// Verify the rule and rule and rule head col/loc values
	testModule := "package a.b.c\n\n"
	for _, tc := range tests {
		//nolint:perfsprint
		testModule += tc.input + "\n"
	}
	module, err := ParseModuleWithOpts("test.rego", testModule, popts)
	if err != nil {
		t.Fatal(err)
	}

	for i := range module.Rules {
		col := module.Rules[i].Location.Col
		if col != 1 {
			t.Errorf("expected rule %v column to be 1 but got %v", module.Rules[i].Head.Name, col)
		}
		row := module.Rules[i].Location.Row
		if row != 3+i { // 'pi' rule starts on row 3
			t.Errorf("expected rule %v row to be %v but got %v", module.Rules[i].Head.Name, 3+i, row)
		}
		col = module.Rules[i].Head.Location.Col
		if col != 1 {
			t.Errorf("expected rule head %v column to be 1 but got %v", module.Rules[i].Head.Name, col)
		}
		row = module.Rules[i].Head.Location.Row
		if row != 3+i { // 'pi' rule starts on row 3
			t.Errorf("expected rule head %v row to be %v but got %v", module.Rules[i].Head.Name, 3+i, row)
		}
	}

	mockModule := `package ex

input = {"foo": 1}
data = {"bar": 2}`

	assertParseModule(t, "rule name: input/data", mockModule, &Module{
		Package: MustParsePackage(`package ex`),
		Rules: []*Rule{
			MustParseRule(`input = {"foo": 1} { true }`),
			MustParseRule(`data = {"bar": 2} { true }`),
		},
	})

	multipleExprs := `
    package a.b.c

    pi = 3.14159; pi > 3
    `

	nonEquality := `
    package a.b.c

    pi > 3
    `

	nonVarName := `
    package a.b.c

    "pi" = 3
    `

	withExpr := `
	package a.b.c

	foo = input with input as 1
	`

	negated := `
	package a.b.c

	not p = 1`

	nonRefTerm := `
	package a.b.c

	p`

	zeroArgs := `
	package a.b.c

	p()`

	assignToTerm := `
	package a.b.c

	"foo" := 1`

	someDecl := `
	package a

	some x`

	arrayTerm := `
	package a
	[][0]
	`

	callWithRuleKeyPartialSet := `
	package a
	f(x)[x] { true }`

	callWithRuleKeyPartialObject := `
	package a
	f(x)[x] = x { true }`

	assignNoOperands := `
	package a
	assign()`

	assignOneOperand := `
	package a
	assign(x)`

	eqNoOperands := `
	package a
	eq()`

	eqOneOperand := `
	package a
	eq(x)`

	assertParseModuleError(t, "multiple expressions", multipleExprs)
	assertParseModuleError(t, "non-equality", nonEquality)
	assertParseModuleError(t, "non-var name", nonVarName)
	assertParseModuleError(t, "with expr", withExpr)
	assertParseModuleError(t, "negated", negated)
	assertParseModuleError(t, "non ref term", nonRefTerm)
	assertParseModuleError(t, "zero args", zeroArgs)
	assertParseModuleError(t, "assign to term", assignToTerm)
	assertParseModuleError(t, "some decl", someDecl)
	assertParseModuleError(t, "array term", arrayTerm)
	assertParseModuleError(t, "call in ref partial set", "package test\nf().x {}")
	assertParseModuleError(t, "call in ref partial object", "package test\nf().x = y {}")
	assertParseModuleError(t, "number in ref", "package a\n12[3]()=4")
	assertParseModuleError(t, "rule with args and key", callWithRuleKeyPartialObject)
	assertParseModuleError(t, "rule with args and key", callWithRuleKeyPartialSet)
	assertParseModuleError(t, "assign without operands", assignNoOperands)
	assertParseModuleError(t, "assign with only one operand", assignOneOperand)
	assertParseModuleError(t, "eq without operands", eqNoOperands)
	assertParseModuleError(t, "eq with only one operand", eqOneOperand)

	if _, err := ParseRuleFromExpr(&Module{}, &Expr{
		Terms: struct{}{},
	}); err == nil {
		t.Fatal("expected error for unknown expression term type")
	}
}

func TestWildcards(t *testing.T) {

	assertParseOneTerm(t, "ref", "a.b[_].c[_]", RefTerm(
		VarTerm("a"),
		StringTerm("b"),
		VarTerm("$0"),
		StringTerm("c"),
		VarTerm("$1"),
	))

	assertParseOneTerm(t, "nested", `[{"a": a[_]}, _, {"b": _}]`, ArrayTerm(
		ObjectTerm(
			Item(StringTerm("a"), RefTerm(VarTerm("a"), VarTerm("$0"))),
		),
		VarTerm("$1"),
		ObjectTerm(
			Item(StringTerm("b"), VarTerm("$2")),
		),
	))

	assertParseOneExpr(t, "expr", `_ = [a[_]]`, Equality.Expr(
		VarTerm("$0"),
		ArrayTerm(
			RefTerm(VarTerm("a"), VarTerm("$1")),
		)))

	assertParseOneExpr(t, "comprehension", `_ = [x | a = a[_]]`, Equality.Expr(
		VarTerm("$0"),
		ArrayComprehensionTerm(
			VarTerm("x"),
			NewBody(
				Equality.Expr(
					VarTerm("a"),
					RefTerm(VarTerm("a"), VarTerm("$1")),
				),
			),
		)))

	assertParseRule(t, "functions", `f(_) = y { true }`, &Rule{
		Head: &Head{
			Name:      Var("f"),
			Reference: Ref{VarTerm("f")},
			Args: Args{
				VarTerm("$0"),
			},
			Value: VarTerm("y"),
		},
		Body: NewBody(NewExpr(BooleanTerm(true))),
	})
}

// https://github.com/open-policy-agent/opa/issues/7128
func TestParseMultiValueRuleGeneratedBodyLocationText(t *testing.T) {
	t.Parallel()

	mod := `package test

	import rego.v1

	foo contains "bar"
	`

	parsed, err := ParseModule("test.rego", mod)
	if err != nil {
		t.Fatal(err)
	}

	text := string(parsed.Rules[0].Location.Text)

	if text != `foo contains "bar"` {
		t.Errorf("Expected rule location text to be %q but got %q", `foo contains "bar"`, text)
	}
}

func TestRuleModulePtr(t *testing.T) {
	mod := `package test

	p if { true }
	p if { true }
	q if { true }
	r = 1
	default s = 2
	`

	parsed, err := ParseModuleWithOpts("", mod, ParserOptions{AllFutureKeywords: true})
	if err != nil {
		t.Fatalf("Unexpected parse error: %v", err)
	}

	for _, rule := range parsed.Rules {
		if rule.Module != parsed {
			t.Fatalf("Expected module ptr to be %p but got %p", parsed, rule.Module)
		}
	}
}

func TestNoMatchError(t *testing.T) {
	mod := `package test

	p if { true;
		 1 != 0; # <-- parse error: no match
	}`

	_, err := ParseModule("foo.rego", mod)

	expected := "1 error occurred: foo.rego:5: rego_parse_error: unexpected } token"

	if !strings.HasPrefix(err.Error(), expected) {
		t.Fatalf("Bad parse error, expected %v but got: %v", expected, err)
	}

	mod = `package test

	p if { true // <-- parse error: no match`

	_, err = ParseModuleWithOpts("foo.rego", mod, ParserOptions{AllFutureKeywords: true})

	loc := NewLocation([]byte{'/'}, "foo.rego", 3, 15)

	if !loc.Equal(err.(Errors)[0].Location) {
		t.Fatalf("Expected %v but got: %v", loc, err)
	}
}

func TestBraceBracketParenMatchingErrors(t *testing.T) {
	// Checks to prevent regression on issue #4672.
	// Error location is important here, which is why we check
	// the error strings directly.
	tests := []struct {
		note  string
		err   string
		input string
	}{
		{
			note: "Unmatched ')' case",
			err: `1 error occurred: test.rego:4: rego_parse_error: unexpected , token: expected \n or ; or }
	y := contains("a"), "b")
	                  ^`,
			input: `package test
p {
	x := 5
	y := contains("a"), "b")
}`,
		},
		{
			note: "Unmatched '}' case",
			err: `1 error occurred: test.rego:4: rego_parse_error: unexpected , token: expected \n or ; or }
	y := {"a", "b", "c"}, "a"}
	                    ^`,
			input: `package test
p {
	x := 5
	y := {"a", "b", "c"}, "a"}
}`,
		},
		{
			note: "Unmatched ']' case",
			err: `1 error occurred: test.rego:4: rego_parse_error: unexpected , token: expected \n or ; or }
	y := ["a", "b", "c"], "a"]
	                    ^`,
			input: `package test
p {
	x := 5
	y := ["a", "b", "c"], "a"]
}`,
		},
		{
			note: "Unmatched '(' case",
			err: `1 error occurred: test.rego:5: rego_parse_error: unexpected } token: expected "," or ")"
	}
	^`,
			input: `package test
p {
	x := 5
	y := contains("a", "b"
}`,
		},
		{
			note: "Unmatched '{' case",

			err: `1 error occurred: test.rego:5: rego_parse_error: unexpected eof token: expected \n or ; or }
	}
	^`,
			input: `package test
p {
	x := 5
	y := {{"a", "b", "c"}, "a"
}`,
		},
		{
			note: "Unmatched '[' case",
			err: `1 error occurred: test.rego:5: rego_parse_error: unexpected } token: expected "," or "]"
	}
	^`,
			input: `package test
p {
	x := 5
	y := [["a", "b", "c"], "a"
}`,
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, err := ParseModule("test.rego", tc.input)
			if err == nil {
				t.Fatal("Expected error")
			}
			if tc.err != "" && tc.err != err.Error() {
				t.Fatalf("Expected error string %q but got: %q", tc.err, err.Error())
			}
		})
	}
}

func TestParseErrorDetails(t *testing.T) {

	tests := []struct {
		note  string
		exp   *ParserErrorDetail
		err   string
		input string
	}{
		{
			note: "no match: bad rule name",
			exp: &ParserErrorDetail{
				Line: ".",
				Idx:  0,
			},
			input: `
package test
.`,
		},
		{
			note: "no match: bad termination for comprehension",
			exp: &ParserErrorDetail{
				Line: "p = [true | true}",
				Idx:  16,
			},
			input: `
package test
p = [true | true}`},
		{
			note: "no match: non-terminated comprehension",
			exp: &ParserErrorDetail{
				Line: "p = [true | true",
				Idx:  15,
			},
			input: `
package test
p = [true | true`},
		{
			note: "no match: expected expression",
			exp: &ParserErrorDetail{
				Line: "p { true; }",
				Idx:  10,
			},
			input: `
package test
p { true; }`},
		{
			note: "empty body",
			exp: &ParserErrorDetail{
				Line: "p { }",
				Idx:  4,
			},
			input: `
package test
p { }`},
		{
			note: "non-terminated string",
			exp: &ParserErrorDetail{
				Line: `p = "foo`,
				Idx:  4,
			},
			input: `
package test
p = "foo`},
		{
			note: "rule with error begins with one tab",
			exp: &ParserErrorDetail{
				Line: "\tas",
				Idx:  1,
			},
			input: `
package test
	as`,
			err: `1 error occurred: test.rego:3: rego_parse_error: unexpected as keyword
	as
	^`},
		{
			note: "rule term with error begins with two tabs",
			exp: &ParserErrorDetail{
				Line: "\t\tas",
				Idx:  2,
			},
			input: `
package test
p = true {
		as
}`,
			err: `1 error occurred: test.rego:4: rego_parse_error: unexpected as keyword
	as
	^`},
		{
			note: "input is tab and space tokens only",
			exp: &ParserErrorDetail{
				Line: "\t\v\f ",
				Idx:  0,
			},
			input: "\t\v\f ",
			// NOTE(sr): With the unprintable control characters, the output is pretty
			// useless. But it's also quite an edge case.
			err: "1 error occurred: test.rego:1: rego_parse_error: illegal token\n\t\v\f \n\t^",
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, err := ParseModule("test.rego", tc.input)
			if err == nil {
				t.Fatal("Expected error")
			}
			detail := err.(Errors)[0].Details
			if !reflect.DeepEqual(detail, tc.exp) {
				t.Errorf("Expected %v but got: %v", tc.exp, detail)
			}
			if tc.err != "" && tc.err != err.Error() {
				t.Fatalf("Expected error string %q but got: %q", tc.err, err.Error())
			}
		})
	}
}

func TestNamespacedBuiltins(t *testing.T) {

	tests := []struct {
		expr     string
		expected *Term
		wantErr  bool
	}{
		{`foo.bar.baz(1, 2)`, MustParseTerm("foo.bar.baz"), false},
		{`foo.(1,2)`, nil, true},
		{`foo.#.bar(1,2)`, nil, true},
	}

	for _, tc := range tests {
		expr, err := ParseExpr(tc.expr)
		if !tc.wantErr {
			if err != nil {
				t.Fatalf("Unexpected parse error: %v", err)
			}
			terms, ok := expr.Terms.([]*Term)
			if !ok {
				t.Fatalf("Expected terms not: %T", expr.Terms)
			}
			if !terms[0].Equal(tc.expected) {
				t.Fatalf("Expected builtin-name to equal %v but got: %v", tc.expected, terms)
			}
		} else if err == nil {
			t.Fatalf("Expected error from %v but got: %v", tc.expr, expr)
		}
	}
}

func TestRuleHeadLocation(t *testing.T) {

	const input = `package pkg

p contains x if {
	x = "hi"
} {
	x = "bye"
}

f(x) if {
	false
} else = false if {
	true
}
`

	module := module(input)

	for _, tc := range []struct {
		note         string
		location     *Location
		expectedRow  int
		expectedText string
	}{
		{
			note:        "partial rule",
			location:    module.Rules[0].Location,
			expectedRow: 3,
			expectedText: `
p contains x if {
	x = "hi"
}
			`,
		},
		{
			note:         "partial rule head",
			location:     module.Rules[0].Head.Location,
			expectedRow:  3,
			expectedText: `p contains x`,
		},
		{
			note:         "partial rule head key",
			location:     module.Rules[0].Head.Key.Location,
			expectedRow:  3,
			expectedText: `x`,
		},
		{
			note:        "chained rule",
			location:    module.Rules[1].Location,
			expectedRow: 5,
			expectedText: `
{
	x = "bye"
}
			`,
		},
		{
			note:        "chained rule head",
			location:    module.Rules[1].Head.Location,
			expectedRow: 5,
			expectedText: `
{
	x = "bye"
}
			`,
		},
		{
			note:        "chained rule head key",
			location:    module.Rules[1].Head.Key.Location,
			expectedRow: 5,
			expectedText: `
{
	x = "bye"
}
			`,
		},
		{
			note:        "rule with args",
			location:    module.Rules[2].Location,
			expectedRow: 9,
			expectedText: `
f(x) if {
	false
} else = false if {
	true
}
			`,
		},
		{
			note:         "rule with args head",
			location:     module.Rules[2].Head.Location,
			expectedRow:  9,
			expectedText: `f(x)`,
		},
		{
			note:         "rule with args head arg 0",
			location:     module.Rules[2].Head.Args[0].Location,
			expectedRow:  9,
			expectedText: `x`,
		},
		{
			note:        "else with args",
			location:    module.Rules[2].Else.Location,
			expectedRow: 11,
			expectedText: `
else = false if {
	true
}
			`,
		},
		{
			note:         "else with args head",
			location:     module.Rules[2].Else.Head.Location,
			expectedRow:  11,
			expectedText: `else = false`,
		},
		{
			note:         "else with args head arg 0",
			location:     module.Rules[2].Else.Head.Args[0].Location,
			expectedRow:  9,
			expectedText: `x`,
		},
	} {
		t.Run(tc.note, func(t *testing.T) {
			if tc.location.Row != tc.expectedRow {
				t.Errorf("Expected %d but got %d", tc.expectedRow, tc.location.Row)
			}
			exp := strings.TrimSpace(tc.expectedText)
			if string(tc.location.Text) != exp {
				t.Errorf("Expected text:\n%s\n\ngot:\n%s\n\n", exp, tc.location.Text)
			}
		})
	}
}

func TestParserText(t *testing.T) {

	tests := []struct {
		note  string
		input string
		want  string
	}{
		{
			note:  "relational term",
			input: `(1 == (2 > 3))`,
		},
		{
			note:  "array - empty",
			input: `[ ]`,
		},
		{
			note:  "array - one element",
			input: `[ 1 ]`,
		},
		{
			note:  "array - multiple elements",
			input: `[1 , 2 , 3]`,
		},
		{
			note:  "object - empty",
			input: `{ }`,
		},
		{
			note:  "object - one element",
			input: `{ "foo": 1 }`,
		},
		{
			note:  "object - multiple elements",
			input: `{"foo": 1, "bar": 2}`,
		},
		{
			note:  "set - one element",
			input: `{ 1 }`,
		},
		{
			note:  "set - multiple elements",
			input: `{1 , 2 , 3}`,
		},
		{
			note:  "idents",
			input: "foo",
		},
		{
			note:  "ref",
			input: `data.foo[x].bar`,
		},
		{
			note:  "call",
			input: `data.foo.bar(x)`,
		},
		{
			note:  "ref and call",
			input: `data.foo[1](x).bar(y)[z]`,
		},
		{
			note:  "infix",
			input: "input = 1",
		},
		{
			note:  "negated",
			input: "not x = 1",
		},
		{
			note:  "expr with statements",
			input: "x = 1 with input as 2 with input as 3",
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			for _, suffix := range []string{"", "\t\n "} {
				input := tc.input + suffix

				stmts, _, err := ParseStatements("test.rego", input)
				if err != nil {
					t.Fatal(err)
				}

				if len(stmts) != 1 {
					t.Fatal("expected exactly one statement but got:", stmts)
				}

				result := string(stmts[0].Loc().Text)

				if result != tc.input {
					t.Fatalf("expected %q but got: %q", tc.input, result)
				}
			}
		})
	}
}

func TestRuleText(t *testing.T) {
	input := ` package test

r[x] = y if {
	x = input.a
	x = "foo"
} {
	x = input.b
	x = "bar"
} {
	x = input.c
	x = "baz"
}

r[x] = y if {
	x = input.d
	x = "qux"
}
`

	mod := module(input)
	rules := mod.Rules

	if len(rules) != 4 {
		t.Fatalf("Expected 4 rules, got %d", len(rules))
	}

	expectedRuleText := []string{
		`
r[x] = y if {
	x = input.a
	x = "foo"
}
		`,
		`
{
	x = input.b
	x = "bar"
}
		`,
		`
{
	x = input.c
	x = "baz"
}
		`,
		`
r[x] = y if {
	x = input.d
	x = "qux"
}
		`,
	}

	assertLocationText(t, strings.TrimSpace(expectedRuleText[0]), rules[0].Location)
	assertLocationText(t, "r[x] = y", rules[0].Head.Location)
	assertLocationText(t, "y", rules[0].Head.Value.Location)

	// Chained rules recursively set text on heads to be the full rule
	for i := 1; i < len(expectedRuleText)-1; i++ {
		text := strings.TrimSpace(expectedRuleText[i])
		assertLocationText(t, text, rules[i].Location)
		assertLocationText(t, text, rules[i].Head.Location)
		assertLocationText(t, text, rules[i].Head.Value.Location)
	}

	assertLocationText(t, strings.TrimSpace(expectedRuleText[3]), rules[3].Location)
	assertLocationText(t, "r[x] = y", rules[3].Head.Location)
	assertLocationText(t, "y", rules[3].Head.Value.Location)
}

func TestRuleElseText(t *testing.T) {
	input := `
r1 = x {
	a == "foo"
} else = y {
	b == "bar"
}

else {
	c == "baz"
}

else = {
	"k1": 1,
	"k2": 2
} {
	true
}
`

	rule := MustParseRule(input)
	assertLocationText(t, strings.TrimSpace(input), rule.Location)
	assertLocationText(t, "r1 = x", rule.Head.Location)
	assertLocationText(t, "x", rule.Head.Value.Location)

	curElse := rule.Else
	if curElse == nil {
		t.Fatalf("Expected an else block, got nil")
	}
	assertLocationText(t, strings.TrimSpace(`
else = y {
	b == "bar"
}

else {
	c == "baz"
}

else = {
	"k1": 1,
	"k2": 2
} {
	true
}
	`), curElse.Location)
	assertLocationText(t, "else = y", curElse.Head.Location)
	assertLocationText(t, "y", curElse.Head.Value.Location)

	curElse = curElse.Else
	if curElse == nil {
		t.Fatalf("Expected an else block, got nil")
	}
	assertLocationText(t, strings.TrimSpace(`
else {
	c == "baz"
}

else = {
	"k1": 1,
	"k2": 2
} {
	true
}
	`), curElse.Location)
	assertLocationText(t, "else", curElse.Head.Location)
	if curElse.Head.Value.Location != nil {
		t.Errorf("Expected a nil location")
	}

	curElse = curElse.Else
	if curElse == nil {
		t.Fatalf("Expected an else block, got nil")
	}
	assertLocationText(t, strings.TrimSpace(`
else = {
	"k1": 1,
	"k2": 2
} {
	true
}
	`), curElse.Location)
	assertLocationText(t, strings.TrimSpace(`
else = {
	"k1": 1,
	"k2": 2
}
	`), curElse.Head.Location)
	assertLocationText(t, strings.TrimSpace(`
{
	"k1": 1,
	"k2": 2
}
	`), curElse.Head.Value.Location)
}

func TestNestedCallText(t *testing.T) {
	cases := []struct {
		note     string
		input    string
		expected *Location
	}{
		{
			note:  "Nested call",
			input: "foo(bar(1))",
			expected: &Location{
				Row:    1,
				Col:    5,
				Offset: 4,
				Text:   []byte("bar(1)"),
			},
		},
		{
			note:  "Inner set term",
			input: "foo(set())",
			expected: &Location{
				Row:    1,
				Col:    5,
				Offset: 4,
				Text:   []byte("set()"),
			},
		},
	}

	for _, tc := range cases {
		t.Run(tc.note, func(t *testing.T) {
			parsed, err := ParseExpr(tc.input)
			if err != nil {
				t.Errorf("Unexpected error on %s: %s", tc.input, err)
				return
			}

			innerCall := parsed.Operand(0)
			if !innerCall.Location.Equal(tc.expected) {
				t.Errorf("Expected location %+v for '%v' but got %+v ", *(tc.expected), innerCall.String(), *innerCall.Location)
			}
		})
	}
}

func TestAnnotations(t *testing.T) {

	dataServers := MustParseRef("data.servers")
	dataNetworks := MustParseRef("data.networks")
	dataPorts := MustParseRef("data.ports")

	schemaServers := MustParseRef("schema.servers")
	schemaNetworks := MustParseRef("schema.networks")
	schemaPorts := MustParseRef("schema.ports")

	stringSchemaAsMap := map[string]any{
		"type": "string",
	}
	var stringSchema any = stringSchemaAsMap

	tests := []struct {
		note           string
		module         string
		expNumComments int
		expAnnotations []*Annotations
		expError       string
		expErrorRow    int
	}{
		{
			note: "Single valid annotation",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
public_servers contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 4,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Multiple annotations on multiple lines",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports
public_servers contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 6,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
						{Path: dataNetworks, Schema: schemaNetworks},
						{Path: dataPorts, Schema: schemaPorts},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Comment in between metadata and rule (valid)",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports

# This is a comment after the metadata YAML
public_servers contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 7,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
						{Path: dataNetworks, Schema: schemaNetworks},
						{Path: dataPorts, Schema: schemaPorts},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Empty comment line in between metadata and rule (valid)",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports
#
public_servers contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 7,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
						{Path: dataNetworks, Schema: schemaNetworks},
						{Path: dataPorts, Schema: schemaPorts},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Ill-structured (invalid) metadata start",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports
# METADATA
public_servers[server] {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expError: "test.rego:14: rego_parse_error: yaml: line 6: could not find expected ':'",
		},
		{
			note: "Ill-structured (invalid) annotation document path",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data/servers: schema.servers
public_servers[server] {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 4,
			expError:       "rego_parse_error: invalid document reference",
		},
		{
			note: "Ill-structured (invalid) annotation schema path",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema/servers
public_servers[server] {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 4,
			expError:       "rego_parse_error: invalid schema reference",
		},
		{
			note: "Ill-structured (invalid) annotation",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers= schema
public_servers[server] {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 5,
			expError:       "rego_parse_error: yaml: unmarshal errors:\n  line 3: cannot unmarshal !!str",
			expErrorRow:    11,
		},
		{
			note: "Ill-structured (invalid) annotation with control character (vertical tab)",
			module: "# METADATA\n" +
				"# title: foo\vbar\n" +
				"package opa.examples\n",
			expError: "rego_parse_error: yaml: control characters are not allowed",
		},
		{
			note: "Indentation error in yaml",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
# - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports
public_servers[server] {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 6,
			expError:       "rego_parse_error: yaml: line 2: did not find expected key",
		},
		{
			note: "Multiple rules with and without metadata",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
#   - data.networks: schema.networks
#   - data.ports: schema.ports
public_servers contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}

public_servers_1 contains server if {
	server = servers[i]; server.ports[j] = ports[k].id
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
	server.typo  # won't catch this type error since rule has no schema metadata
}`,
			expNumComments: 7,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
						{Path: dataNetworks, Schema: schemaNetworks},
						{Path: dataPorts, Schema: schemaPorts},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Multiple rules with metadata",
			module: `
package opa.examples

import data.servers
import data.networks
import data.ports

# METADATA
# scope: rule
# schemas:
#   - data.servers: schema.servers
public_servers contains server if {
	server = servers[i]
}

# METADATA
# scope: rule
# schemas:
#   - data.networks: schema.networks
#   - data.ports: schema.ports
public_servers_1 contains server if {
	ports[k].networks[l] = networks[m].id;
	networks[m].public = true
}`,
			expNumComments: 9,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: dataServers, Schema: schemaServers},
					},
					Scope: annotationScopeRule,
					node:  MustParseRule(`public_servers[server] { server = servers[i] }`),
				},
				{
					Schemas: []*SchemaAnnotation{

						{Path: dataNetworks, Schema: schemaNetworks},
						{Path: dataPorts, Schema: schemaPorts},
					},
					Scope: annotationScopeRule,
					node:  MustParseRule(`public_servers_1[server] { ports[k].networks[l] = networks[m].id; networks[m].public = true }`),
				},
			},
		},
		{
			note: "multiple metadata blocks on a single rule",
			module: `package test

# METADATA
# title: My rule

# METADATA
# title: My rule 2
p if { input = "str" }`,
			expNumComments: 4,
			expAnnotations: []*Annotations{
				{
					Scope: annotationScopeRule,
					Title: "My rule",
				},
				{
					Scope: annotationScopeRule,
					Title: "My rule 2",
				},
			},
		},
		{
			note: "Empty annotation error due to whitespace following METADATA hint",
			module: `package test

# METADATA

# scope: rule
p if { input.x > 7 }`,
			expError: "test.rego:3: rego_parse_error: expected METADATA block, found whitespace",
		},
		{
			note: "Annotation on constant",
			module: `
package test

# METADATA
# scope: rule
p := 7`,
			expNumComments: 2,
			expAnnotations: []*Annotations{
				{Scope: annotationScopeRule},
			},
		},
		{
			note: "annotation on package",
			module: `# METADATA
# title: My package
package test

p if { input = "str" }`,
			expNumComments: 2,
			expAnnotations: []*Annotations{
				{
					Scope: annotationScopePackage,
					Title: "My package",
				},
			},
		},
		{
			note: "annotation on import",
			module: `package test

# METADATA
# title: My import
import input.foo

p if { input = "str" }`,
			expNumComments: 2,
			expError:       "1 error occurred: test.rego:3: rego_parse_error: invalid annotation scope 'import'",
		},
		{
			note: "Default rule scope",
			module: `
package test

# METADATA
# {}
p := 7`,
			expNumComments: 2,
			expAnnotations: []*Annotations{
				{Scope: annotationScopeRule},
			},
		},
		{
			note: "Unknown scope",
			module: `
package test

# METADATA
# scope: deadbeef
p := 7`,
			expNumComments: 2,
			expError:       "invalid annotation scope 'deadbeef'",
		},
		{
			note: "Invalid rule scope/attachment",
			module: `
# METADATA
# scope: rule
package test

p := 7`,
			expNumComments: 2,
			expError:       "test.rego:2: rego_parse_error: annotation scope 'rule' must be applied to rule (have package)",
		},
		{
			note: "Scope attachment error: document on import",
			module: `package test
# METADATA
# scope: document
import data.foo.bar`,
			expError: "test.rego:2: rego_parse_error: annotation scope 'document' must be applied to rule (have import)",
		},
		{
			note: "Scope attachment error: unattached",
			module: `package test

# METADATA
# scope: package`,
			expError: "test.rego:3: rego_parse_error: annotation scope 'package' must be applied to package",
		},
		{
			note: "Scope attachment error: package on non-package",
			module: `package test
# METADATA
# scope: package
import data.foo`,
			expError: "test.rego:2: rego_parse_error: annotation scope 'package' must be applied to package (have import)",
		},
		{
			note: "Inline schema definition",
			module: `package test

# METADATA
# schemas:
# - input: {"type": "string"}
p if { input = "str" }`,
			expNumComments: 3,
			expAnnotations: []*Annotations{
				{
					Schemas: []*SchemaAnnotation{
						{Path: InputRootRef, Definition: &stringSchema},
					},
					Scope: annotationScopeRule,
				},
			},
		},
		{
			note: "Rich meta",
			module: `package test

# METADATA
# title: My rule
# description: |
#  My rule has a
#  multiline description.
# organizations:
# - Acme Corp.
# - Soylent Corp.
# - Tyrell Corp.
# related_resources:
# - https://example.com
# -
#  ref: http://john:123@do.re/mi?foo=bar#baz
#  description: foo bar
# authors:
# - John Doe <john@example.com>
# - name: Jane Doe
#   email: jane@example.com
# custom:
#  list:
#   - a
#   - b
#  map:
#   a: 1
#   b: 2.2
#   c:
#    "3": d
#    "4": e
#  number: 42
#  string: foo bar baz
#  flag:
p if { input = "str" }`,
			expNumComments: 31,
			expAnnotations: []*Annotations{
				{
					Scope:         annotationScopeRule,
					Title:         "My rule",
					Description:   "My rule has a\nmultiline description.\n",
					Organizations: []string{"Acme Corp.", "Soylent Corp.", "Tyrell Corp."},
					RelatedResources: []*RelatedResourceAnnotation{
						{
							Ref: mustParseURL("https://example.com"),
						},
						{
							Ref:         mustParseURL("http://john:123@do.re/mi?foo=bar#baz"),
							Description: "foo bar",
						},
					},
					Authors: []*AuthorAnnotation{
						{
							Name:  "John Doe",
							Email: "john@example.com",
						},
						{
							Name:  "Jane Doe",
							Email: "jane@example.com",
						},
					},
					Custom: map[string]any{
						"list": []any{
							"a", "b",
						},
						"map": map[string]any{
							"a": 1,
							"b": 2.2,
							"c": map[string]any{
								"3": "d",
								"4": "e",
							},
						},
						"number": 42,
						"string": "foo bar baz",
						"flag":   nil,
					},
				},
			},
		},
		{
			note: "compile annotation, short mask_rule",
			module: `
package opa.examples

# METADATA
# scope: document
# compile:
#   unknowns:
#   - input.fruits
#   mask_rule: mask
include if input.fruits.name == "banana"
mask.fruits.owner.replace.value := "___"
`,
			expNumComments: 6,
			expAnnotations: []*Annotations{
				{
					Scope: annotationScopeDocument,
					Compile: &CompileAnnotation{
						Unknowns: []Ref{MustParseRef("input.fruits")},
						MaskRule: EmptyRef().Append(VarTerm("mask")),
					},
				},
			},
		},
		{
			note: "compile annotation, full mask_rule",
			module: `
package opa.examples

# METADATA
# scope: document
# compile:
#   unknowns:
#   - input.fruits
#   mask_rule: data.filtering.mask
include if input.fruits.name == "banana"
mask.fruits.owner.replace.value := "___"
`,
			expNumComments: 6,
			expAnnotations: []*Annotations{
				{
					Scope: annotationScopeDocument,
					Compile: &CompileAnnotation{
						Unknowns: []Ref{MustParseRef("input.fruits")},
						MaskRule: MustParseRef("data.filtering.mask"),
					},
				},
			},
		},
		{
			note: "compile annotation, no mask_rule",
			module: `
package opa.examples

# METADATA
# scope: document
# compile:
#   unknowns:
#   - input.fruits
include if input.fruits.name == "banana"
`,
			expNumComments: 5,
			expAnnotations: []*Annotations{
				{
					Scope: annotationScopeDocument,
					Compile: &CompileAnnotation{
						Unknowns: []Ref{MustParseRef("input.fruits")},
					},
				},
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			mod, err := ParseModuleWithOpts("test.rego", tc.module, ParserOptions{
				ProcessAnnotation: true,
				AllFutureKeywords: true,
			})
			if err != nil {
				if tc.expError == "" || !strings.Contains(err.Error(), tc.expError) {
					t.Fatalf("Unexpected parse error when getting annotations: %v", err)
				}
				if tc.expErrorRow != 0 {
					if errs, ok := err.(Errors); !ok {
						t.Fatalf("expected ast.Errors, got %v", err)
					} else if len(errs) != 1 {
						t.Fatalf("expected exactly one ast.Error, got %v: %v", len(errs), errs)
					} else if loc := errs[0].Location; tc.expErrorRow != loc.Row {
						t.Fatalf("expected error location row %v, got %v", tc.expErrorRow, loc.Row)
					}
				}
				return
			} else if tc.expError != "" {
				t.Fatalf("Expected err: %v but no error from parse module", tc.expError)
			}

			if len(mod.Comments) != tc.expNumComments {
				t.Fatalf("Expected %v comments but got %v", tc.expNumComments, len(mod.Comments))
			}

			if annotationsCompare(tc.expAnnotations, mod.Annotations) != 0 {
				t.Fatalf("expected %v but got %v", tc.expAnnotations, mod.Annotations)
			}
		})
	}
}

func TestAnnotationsAttachedToRule(t *testing.T) {

	tests := []struct {
		note           string
		module         string
		expAnnotations map[int][]*Annotations
	}{
		{
			note: "single metadata block for rule (implied rule scope)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# title: p
# description: p
p := 1`,
			expAnnotations: map[int][]*Annotations{9: {{
				Description: "p",
				Scope:       "rule",
				Title:       "p",
			}}},
		},
		{
			note: "single metadata block for rule (explicit rule scope)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# title: p
# description: p
# scope: rule
p := 1`,
			expAnnotations: map[int][]*Annotations{10: {{
				Description: "p",
				Scope:       "rule",
				Title:       "p",
			}}},
		},
		{
			note: "multiple metadata blocks for single rule",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# title: One

# METADATA
# title: Two

# METADATA
# title: Three

# METADATA
# title: Four
p := 1`,
			expAnnotations: map[int][]*Annotations{17: {
				{
					Scope: "rule",
					Title: "One",
				},
				{
					Scope: "rule",
					Title: "Two",
				}, {
					Scope: "rule",
					Title: "Three",
				},
				{
					Scope: "rule",
					Title: "Four",
				},
			}},
		},
		{
			note: "document scope",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# scope: document
# title: doc
# description: doc

p := 1`,
			expAnnotations: map[int][]*Annotations{11: {{
				Description: "doc",
				Scope:       "document",
				Title:       "doc",
			}}},
		},
		{
			note: "document and rule scope (single rule)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# scope: document
# title: doc
# description: doc

# METADATA
# title: p
# description: p
p := 1`,
			expAnnotations: map[int][]*Annotations{14: {
				{
					Description: "doc",
					Scope:       "document",
					Title:       "doc",
				},
				{
					Description: "p",
					Scope:       "rule",
					Title:       "p",
				},
			}},
		},
		{
			note: "document and rule scope (multiple rules)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# scope: document
# title: doc
# description: doc

# METADATA
# title: p
# description: p
p := 1

# METADATA
# title: q
# description: q
q := 1`,
			expAnnotations: map[int][]*Annotations{
				14: {
					{
						Description: "doc",
						Scope:       "document",
						Title:       "doc",
					},
					{
						Description: "p",
						Scope:       "rule",
						Title:       "p",
					},
				},
				19: {
					{
						Description: "q",
						Scope:       "rule",
						Title:       "q",
					},
				},
			},
		},
		{
			note: "document and rule scope (unordered annotations, multiple rules)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# scope: document
# title: p-rules

# METADATA
# title: p-1
# description: p-1
p contains 1

# METADATA
# title: p-2
# description: p-2
p contains 2

# METADATA
# title: q
# description: q
q := 1`,
			expAnnotations: map[int][]*Annotations{
				13: {
					{
						Scope: "document",
						Title: "p-rules",
					},
					{
						Description: "p-1",
						Scope:       "rule",
						Title:       "p-1",
					},
				},
				18: {
					{
						Scope: "document",
						Title: "p-rules",
					},
					{
						Description: "p-2",
						Scope:       "rule",
						Title:       "p-2",
					},
				},
				23: {
					{
						Description: "q",
						Scope:       "rule",
						Title:       "q",
					},
				},
			},
		},
		{
			note: "document and rule scope (unordered annotations, multiple unordered rules)",
			module: `# METADATA
# title: pkg
# description: pkg
package test

# METADATA
# scope: document
# title: p-rules

# METADATA
# title: p-1
# description: p-1
p contains 1

# METADATA
# title: q
# description: q
q := 1

# METADATA
# title: p-2
# description: p-2
p contains 2
`,
			expAnnotations: map[int][]*Annotations{
				13: {
					{
						Scope: "document",
						Title: "p-rules",
					},
					{
						Description: "p-1",
						Scope:       "rule",
						Title:       "p-1",
					},
				},
				18: {
					{
						Description: "q",
						Scope:       "rule",
						Title:       "q",
					},
				},
				23: {
					{
						Scope: "document",
						Title: "p-rules",
					},
					{
						Description: "p-2",
						Scope:       "rule",
						Title:       "p-2",
					},
				},
			},
		},
		{
			note: "rule with variable in ref head",
			module: `package test

# METADATA
# title: foo
rule[x] := true if x := 1
			`,
			expAnnotations: map[int][]*Annotations{
				5: {
					{
						Scope: "rule",
						Title: "foo",
					},
				},
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {

			pm, err := ParseModuleWithOpts("test.rego", tc.module, ParserOptions{
				ProcessAnnotation: true,
				AllFutureKeywords: true,
			})
			if err != nil {
				t.Fatal(err)
			}

			for _, rule := range pm.Rules {
				annotations, ok := tc.expAnnotations[rule.Location.Row]
				if !ok {
					t.Fatalf("No annotations for rule on row %v", rule.Location.Row)
				}

				if annotationsCompare(annotations, rule.Annotations) != 0 {
					t.Fatalf("expected rule on row %d to have annotations:\n\n%v\n\nbut got:\n\n%v",
						rule.Location.Row, annotations, rule.Annotations)
				}
			}
		})
	}
}

func TestAnnotationsAttachedToRuleMixScope(t *testing.T) {

	module := `# METADATA
# title: pkg
# description: pkg
package test

import rego.v1

# METADATA
# scope: document
# title: doc
# description: doc

# METADATA
# title: p1
# description: p1
p contains x if {
	input.x == 1
	x := "hello"
}

# METADATA
# title: p2
# description: p2
p contains x if {
	input.x == 2
	x := "world"
}

# METADATA
# title: q
# description: q
q := 1`

	pm, err := ParseModuleWithOpts("test.rego", module, ParserOptions{ProcessAnnotation: true})
	if err != nil {
		t.Fatal(err)
	}

	a1 := []*Annotations{
		{
			Description: "doc",
			Scope:       "document",
			Title:       "doc",
		},
		{
			Description: "p1",
			Scope:       "rule",
			Title:       "p1",
		},
	}

	a2 := []*Annotations{
		{
			Description: "doc",
			Scope:       "document",
			Title:       "doc",
		},
		{
			Description: "p2",
			Scope:       "rule",
			Title:       "p2",
		},
	}

	a3 := []*Annotations{
		{
			Description: "q",
			Scope:       "rule",
			Title:       "q",
		},
	}

	expAnnotations := [][]*Annotations{a1, a2, a3}

	for i, rule := range pm.Rules {
		if annotationsCompare(expAnnotations[i], rule.Annotations) != 0 {
			t.Fatalf("expected %v but got %v", expAnnotations[i], rule.Annotations)
		}
	}
}

func TestAnnotationsAttachedToRuleDocScopeBeforeRule(t *testing.T) {

	module := `# METADATA
# title: pkg
# description: pkg
package test

import rego.v1

# METADATA
# title: p1
# description: p1

# METADATA
# scope: document
# title: doc
# description: doc

p contains x if {
	input.x == 1
	x := "hello"
}

# METADATA
# title: p2
# description: p2
p contains x if {
	input.x == 2
	x := "world"
}

# METADATA
# title: q
# description: q
q := 1`

	pm, err := ParseModuleWithOpts("test.rego", module, ParserOptions{ProcessAnnotation: true})
	if err != nil {
		t.Fatal(err)
	}

	a1 := []*Annotations{
		{
			Description: "p1",
			Scope:       "rule",
			Title:       "p1",
		},
		{
			Description: "doc",
			Scope:       "document",
			Title:       "doc",
		},
	}

	a2 := []*Annotations{
		{
			Description: "doc",
			Scope:       "document",
			Title:       "doc",
		},
		{
			Description: "p2",
			Scope:       "rule",
			Title:       "p2",
		},
	}

	a3 := []*Annotations{
		{
			Description: "q",
			Scope:       "rule",
			Title:       "q",
		},
	}

	expAnnotations := [][]*Annotations{a1, a2, a3}

	for i, rule := range pm.Rules {
		if annotationsCompare(expAnnotations[i], rule.Annotations) != 0 {
			t.Fatalf("expected %v but got %v", expAnnotations[i], rule.Annotations)
		}
	}
}

func TestAnnotationsAugmentedError(t *testing.T) {
	tests := []struct {
		note           string
		module         string
		expAnnotations []*Annotations
		expErrorHint   string
		expErrorRow    int
	}{
		{
			note: "no whitespace after key/value separator",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# description:p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['p'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  4,
		},
		{
			note: "non-breaking whitespace (\\u00A0) after key/value separator",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# description:\u00A0p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['\\u00a0'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  4,
		},
		{
			note: "non-breaking whitespace (\\u00A0) after key/value separator (different line)",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# title: P\n" +
				"# description:\u00A0p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 5, symbol(s) ['\\u00a0'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  5,
		},
		{
			note: "non-breaking whitespace (\\u00A0) after key/value separator (different line)",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# title:\n" +
				"#   P\n" +
				"# description:\u00A0p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 6, symbol(s) ['\\u00a0'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  6,
		},
		{
			note: "non-breaking whitespace (\\u00A0) after key/value separator (different line)",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# title:\u00A0P\n" +
				"# description: p is true\n" +
				"# scope: rule\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['\\u00a0'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  6, // Should be 5 really, and yaml.v2 reported the error as on line 1, but v3 on line 3..
		},
		{
			note: "thin whitespace (\\u2009) after key/value separator",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# description:\u2009p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['\\u2009'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  4,
		},
		{
			note: "ideographic whitespace (\\u3000) after key/value separator",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# description:\u3000p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['\\u3000'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  4,
		},
		{
			note: "several offending runes after key/value separator on single line",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# descr:iption:\u3000p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['i' '\\u3000'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow:  4,
		},
		{
			note: "several offending runes after key/value separator on single line",
			module: "package opa.examples\n" +
				"\n" +
				"# METADATA\n" +
				"# title:\u3000p\n" +
				"# scope: rule\n" +
				"# description:\u2009p is true\n" +
				"p := true\n",
			expErrorHint: "Hint: on line 4, symbol(s) ['\\u3000'] immediately following a key/value separator ':' is not a legal yaml space character\n" +
				"  Hint: on line 6, symbol(s) ['\\u2009'] immediately following a key/value separator ':' is not a legal yaml space character",
			expErrorRow: 6,
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, err := ParseModuleWithOpts("test.rego", tc.module, ParserOptions{
				ProcessAnnotation: true,
			})

			if err == nil {
				t.Fatalf("Expected err with hint: %v but no error from parse module", tc.expErrorHint)
			}

			if !strings.Contains(err.Error(), tc.expErrorHint) {
				t.Fatalf("Unexpected parse error when getting annotations: %v", err)
			}

			if errs, ok := err.(Errors); !ok {
				t.Fatalf("expected ast.Errors, got %v", err)
			} else if len(errs) != 1 {
				t.Fatalf("expected exactly one ast.Error, got %v: %v", len(errs), errs)
			} else if loc := errs[0].Location; tc.expErrorRow != loc.Row {
				t.Fatalf("expected error location row %v, got %v", tc.expErrorRow, loc.Row)
			}
		})
	}
}

func TestAnnotationsAreParsedAsYamlv1_2(t *testing.T) {
	policy := `package p

# METADATA
# custom:
#   string: yes
is_string := rego.metadata.rule().custom.string == "yes"
`
	mod := MustParseModuleWithOpts(policy, ParserOptions{ProcessAnnotation: true})

	if len(mod.Annotations) != 1 {
		t.Fatalf("Expected exactly one annotation but got %v", len(mod.Annotations))
	}

	anno := mod.Annotations[0]
	if value, ok := anno.Custom["string"].(string); !ok || value != "yes" {
		t.Fatalf("Expected custom.string to be 'yes' but got %v", value)
	}
}

// https://github.com/open-policy-agent/opa/issues/6587
func TestAnnotationsParseErrorOnFirstRowGetsCorrectLocation(t *testing.T) {
	module := `# METADATA
# description: ` + "`foo` bars" + `
# title: foo
package foo`

	_, err := ParseModuleWithOpts("test.rego", module, ParserOptions{ProcessAnnotation: true})
	if err == nil {
		t.Fatalf("Expected error but got none")
	}

	if len(err.(Errors)) != 1 {
		t.Fatalf("Expected exactly one error but got %v", err)
	}

	if err.(Errors)[0].Location.Row != 2 {
		t.Errorf("Expected error on row 2 but got error on row %d", err.(Errors)[0].Location.Row)
	}
}

func TestAuthorAnnotation(t *testing.T) {
	tests := []struct {
		note     string
		raw      any
		expected any
	}{
		{
			note:     "no name",
			raw:      "",
			expected: errors.New("author is an empty string"),
		},
		{
			note:     "only whitespaces",
			raw:      " \t",
			expected: errors.New("author is an empty string"),
		},
		{
			note:     "one name only",
			raw:      "John",
			expected: AuthorAnnotation{Name: "John"},
		},
		{
			note:     "multiple names",
			raw:      "John Jr.\tDoe",
			expected: AuthorAnnotation{Name: "John Jr. Doe"},
		},
		{
			note:     "email only",
			raw:      "<john@example.com>",
			expected: AuthorAnnotation{Email: "john@example.com"},
		},
		{
			note:     "name and email",
			raw:      "John Doe <john@example.com>",
			expected: AuthorAnnotation{Name: "John Doe", Email: "john@example.com"},
		},
		{
			note:     "empty email",
			raw:      "John Doe <>",
			expected: AuthorAnnotation{Name: "John Doe"},
		},
		{
			note:     "name with reserved characters",
			raw:      "John Doe < >",
			expected: AuthorAnnotation{Name: "John Doe < >"},
		},
		{
			note:     "name with reserved characters (email with space)",
			raw:      "<john@ example.com>",
			expected: AuthorAnnotation{Name: "<john@ example.com>"},
		},
		{
			note: "map with name",
			raw: map[string]any{
				"name": "John Doe",
			},
			expected: AuthorAnnotation{Name: "John Doe"},
		},
		{
			note: "map with email",
			raw: map[string]any{
				"email": "john@example.com",
			},
			expected: AuthorAnnotation{Email: "john@example.com"},
		},
		{
			note: "map with name and email",
			raw: map[string]any{
				"name":  "John Doe",
				"email": "john@example.com",
			},
			expected: AuthorAnnotation{Name: "John Doe", Email: "john@example.com"},
		},
		{
			note: "map with extra entry",
			raw: map[string]any{
				"name":  "John Doe",
				"email": "john@example.com",
				"foo":   "bar",
			},
			expected: AuthorAnnotation{Name: "John Doe", Email: "john@example.com"},
		},
		{
			note:     "empty map",
			raw:      map[string]any{},
			expected: errors.New("'name' and/or 'email' values required in object"),
		},
		{
			note: "map with empty name",
			raw: map[string]any{
				"name": "",
			},
			expected: errors.New("'name' and/or 'email' values required in object"),
		},
		{
			note: "map with email and empty name",
			raw: map[string]any{
				"name":  "",
				"email": "john@example.com",
			},
			expected: AuthorAnnotation{Email: "john@example.com"},
		},
		{
			note: "map with empty email",
			raw: map[string]any{
				"email": "",
			},
			expected: errors.New("'name' and/or 'email' values required in object"),
		},
		{
			note: "map with name and empty email",
			raw: map[string]any{
				"name":  "John Doe",
				"email": "",
			},
			expected: AuthorAnnotation{Name: "John Doe"},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			parsed, err := parseAuthor(tc.raw)

			switch expected := tc.expected.(type) {
			case AuthorAnnotation:
				if err != nil {
					t.Fatal(err)
				}

				if parsed.Compare(&expected) != 0 {
					t.Fatalf("expected %v but got %v", tc.expected, parsed)
				}
			case error:
				if err == nil {
					t.Fatalf("expected '%v' error but got %v", tc.expected, parsed)
				}

				if strings.Compare(expected.Error(), err.Error()) != 0 {
					t.Fatalf("expected %v but got %v", tc.expected, err)
				}
			default:
				t.Fatalf("Unexpected result type: %T", expected)
			}
		})
	}
}

func TestRelatedResourceAnnotation(t *testing.T) {
	tests := []struct {
		note     string
		raw      any
		expected any
	}{
		{
			note:     "empty ref URL",
			raw:      "",
			expected: errors.New("ref URL may not be empty string"),
		},
		{
			note:     "only whitespaces in ref URL",
			raw:      " \t",
			expected: errors.New("parse \" \\t\": net/url: invalid control character in URL"),
		},
		{
			note:     "invalid ref URL",
			raw:      "https://foo:bar",
			expected: errors.New("parse \"https://foo:bar\": invalid port \":bar\" after host"),
		},
		{
			note:     "ref URL as string",
			raw:      "https://example.com/foo?bar#baz",
			expected: RelatedResourceAnnotation{Ref: mustParseURL("https://example.com/foo?bar#baz")},
		},
		{
			note: "map with only ref",
			raw: map[string]any{
				"ref": "https://example.com/foo?bar#baz",
			},
			expected: RelatedResourceAnnotation{Ref: mustParseURL("https://example.com/foo?bar#baz")},
		},
		{
			note: "map with only description",
			raw: map[string]any{
				"description": "foo bar",
			},
			expected: errors.New("'ref' value required in object"),
		},
		{
			note: "map with ref and description",
			raw: map[string]any{
				"ref":         "https://example.com/foo?bar#baz",
				"description": "foo bar",
			},
			expected: RelatedResourceAnnotation{
				Ref:         mustParseURL("https://example.com/foo?bar#baz"),
				Description: "foo bar",
			},
		},
		{
			note: "map with ref and description",
			raw: map[string]any{
				"ref":         "https://example.com/foo?bar#baz",
				"description": "foo bar",
				"foo":         "bar",
			},
			expected: RelatedResourceAnnotation{
				Ref:         mustParseURL("https://example.com/foo?bar#baz"),
				Description: "foo bar",
			},
		},
		{
			note:     "empty map",
			raw:      map[string]any{},
			expected: errors.New("'ref' value required in object"),
		},
		{
			note: "map with empty ref",
			raw: map[string]any{
				"ref": "",
			},
			expected: errors.New("'ref' value required in object"),
		},
		{
			note: "map with only whitespace in ref",
			raw: map[string]any{
				"ref": " \t",
			},
			expected: errors.New("'ref' value required in object"),
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			parsed, err := parseRelatedResource(tc.raw)

			switch expected := tc.expected.(type) {
			case RelatedResourceAnnotation:
				if err != nil {
					t.Fatal(err)
				}

				if parsed.Compare(&expected) != 0 {
					t.Fatalf("expected %v but got %v", tc.expected, parsed)
				}
			case error:
				if err == nil {
					t.Fatalf("expected '%v' error but got %v", tc.expected, parsed)
				}

				if strings.Compare(expected.Error(), err.Error()) != 0 {
					t.Fatalf("expected %v but got %v", tc.expected, err)
				}
			default:
				t.Fatalf("Unexpected result type: %T", expected)
			}
		})
	}
}

func TestAnnotationsLocationText(t *testing.T) {
	module := `# METADATA
# title: pkg
# description: a package
package pkg

import rego.v1

# METADATA
# title: rule
allow if {
	true
}
`

	m, err := ParseModuleWithOpts("test.rego", module, ParserOptions{ProcessAnnotation: true})
	if err != nil {
		t.Fatal(err)
	}

	assertLocationText(t, "# METADATA\n# title: pkg\n# description: a package", m.Annotations[0].Location)
	assertLocationText(t, "# METADATA\n# title: rule", m.Annotations[1].Location)

	assertLocationText(t, "# METADATA\n# title: rule", m.Rules[0].Annotations[0].Location)
}

func TestMaxParsingRecursionDepth(t *testing.T) {
	tests := []struct {
		name        string
		input       string
		depthLimit  int
		expectError bool
	}{
		{
			name:        "deeply nested array exceeds default limit",
			input:       generateDeeplyNestedArray(DefaultMaxParsingRecursionDepth + 1),
			expectError: true,
		},
		{
			name:        "deeply nested array exceeds limit",
			input:       generateDeeplyNestedArray(1000),
			depthLimit:  500,
			expectError: true,
		},
		{
			name:        "deeply nested array within limit",
			input:       generateDeeplyNestedArray(100),
			depthLimit:  500,
			expectError: false,
		},
		{
			name:        "deeply nested object exceeds limit",
			input:       generateDeeplyNestedObject(1000),
			depthLimit:  500,
			expectError: true,
		},
		{
			name:        "deeply nested object within limit",
			input:       generateDeeplyNestedObject(100),
			depthLimit:  500,
			expectError: false,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			// Create module code
			moduleCode := "package test\n\nvalue = " + tc.input

			// Parse module
			parser := NewParser().
				WithFilename("test.rego").
				WithReader(strings.NewReader(moduleCode))

			if tc.depthLimit != 0 {
				parser = parser.WithMaxRecursionDepth(tc.depthLimit)
			}

			_, _, errs := parser.Parse()

			hasErr := len(errs) > 0
			if hasErr != tc.expectError {
				t.Errorf("Test %q: expected error: %v, got error: %v, error detail: %v", tc.name, tc.expectError, hasErr, errs)
			}

			if tc.expectError && hasErr {
				// Verify the error contains our expected error
				errFound := false
				for _, e := range errs {
					if strings.Contains(e.Message, ErrMaxParsingRecursionDepthExceeded.Error()) {
						errFound = true
						break
					}
				}
				if !errFound {
					t.Errorf("Expected error to contain %q, but got: %v",
						ErrMaxParsingRecursionDepthExceeded.Error(), errs)
				}
			}
		})
	}
}

// generateDeeplyNestedArray creates a deeply nested array as a string
// with the specified depth.
func generateDeeplyNestedArray(depth int) string {
	return strings.Repeat("[", depth) + "1" + strings.Repeat("]", depth)
}

// generateDeeplyNestedObject creates a deeply nested object as a string
// with the specified depth.
func generateDeeplyNestedObject(depth int) string {
	var sb strings.Builder
	for i := range depth {
		sb.WriteString(fmt.Sprintf(`{"key%d": `, i))
	}
	sb.WriteString("1")
	for range depth {
		sb.WriteString("}")
	}

	return sb.String()
}

func assertLocationText(t *testing.T, expected string, actual *Location) {
	t.Helper()
	if actual == nil || actual.Text == nil {
		t.Errorf("Expected a non nil location and text")
		return
	}
	if string(actual.Text) != expected {
		t.Errorf("Unexpected Location text, got:\n%s\n\nExpected:\n%s\n\n", actual.Text, expected)
	}
}

func assertParseError(t *testing.T, msg string, input string, opts ...ParserOptions) {
	t.Helper()
	t.Run(msg, func(t *testing.T) {
		assertParseErrorFunc(t, msg, input, func(string) {}, opts...)
	})
}

func assertNoParseError(t *testing.T, input string, opts ...ParserOptions) {
	t.Helper()
	assertParseErrorFunc(t, "", input, func(result string) {
		t.Helper()
		t.Fatalf("expected no parser error, got %s", result)
	}, opts...)
}

func assertParseErrorContains(t *testing.T, msg string, input string, expected string, opts ...ParserOptions) {
	t.Helper()
	assertParseErrorFunc(t, msg, input, func(result string) {
		t.Helper()
		if !strings.Contains(result, expected) {
			t.Errorf("Error on test \"%s\": expected parse error to contain:\n\n%v\n\nbut got:\n\n%v", msg, expected, result)
		}
	}, opts...)
}

func assertParseErrorFunc(t *testing.T, msg string, input string, f func(string), opts ...ParserOptions) {
	t.Helper()
	opt := ParserOptions{}
	if len(opts) == 1 {
		opt = opts[0]
	}
	stmts, _, err := ParseStatementsWithOpts("", input, opt)
	if err == nil && len(stmts) != 1 {
		err = errors.New("expected exactly one statement")
	}
	if err == nil {
		if msg == "" {
			return
		}
		t.Errorf("Error on test \"%s\": expected parse error on %s: expected no statements, got %d: %v", msg, input, len(stmts), stmts)
		return
	}
	result := err.Error()
	// error occurred: <line>:<col>: <message>
	parts := strings.SplitN(result, ":", 4)
	result = strings.TrimSpace(parts[len(parts)-1])
	f(result)
}

func assertParseImport(t *testing.T, msg string, input string, correct *Import, opts ...ParserOptions) {
	t.Helper()
	assertParseOne(t, msg, input, func(parsed any) {
		t.Helper()
		imp := parsed.(*Import)
		if !imp.Equal(correct) {
			t.Errorf("Error on test \"%s\": imports not equal: %v (parsed), %v (correct)", msg, imp, correct)
		}
	}, opts...)
}

func assertParseModule(t *testing.T, msg string, input string, correct *Module, opts ...ParserOptions) {
	t.Helper()

	opt := ParserOptions{}
	if len(opts) == 1 {
		opt = opts[0]
	}
	m, err := ParseModuleWithOpts("", input, opt)
	if err != nil {
		t.Errorf("Error on test \"%s\": parse error on %s: %s", msg, input, err)
		return
	}

	if !m.Equal(correct) {
		t.Errorf("Error on test %s: modules not equal: %v (parsed), %v (correct)", msg, m, correct)
	}

}

func assertParseModuleError(t *testing.T, msg, input string) {
	m, err := ParseModule("", input)
	if err == nil {
		t.Errorf("Error on test \"%s\": expected parse error: %v (parsed)", msg, m)
	}
}

func assertParsePackage(t *testing.T, msg string, input string, correct *Package, opts ...ParserOptions) {
	assertParseOne(t, msg, input, func(parsed any) {
		pkg := parsed.(*Package)
		if !pkg.Equal(correct) {
			t.Errorf("Error on test \"%s\": packages not equal: %v (parsed), %v (correct)", msg, pkg, correct)
		}
	}, opts...)
}

func assertParseOne(t *testing.T, msg string, input string, correct func(any), opts ...ParserOptions) {
	t.Helper()
	opt := ParserOptions{}
	if len(opts) == 1 {
		opt = opts[0]
	}
	stmts, _, err := ParseStatementsWithOpts("", input, opt)
	if err != nil {
		t.Errorf("Error on test \"%s\": parse error on %s: %s", msg, input, err)
		return
	}
	if len(stmts) != 1 {
		t.Errorf("Error on test \"%s\": parse error on %s: expected exactly one statement, got %d: %v", msg, input, len(stmts), stmts)
		return
	}
	correct(stmts[0])
}

func assertParseOneBody(t *testing.T, msg string, input string, correct Body) {
	t.Helper()
	body, err := ParseBody(input)
	if err != nil {
		t.Fatal(err)
	}
	if !body.Equal(correct) {
		t.Fatalf("Error on test \"%s\": bodies not equal:\n%v (parsed)\n%v (correct)", msg, body, correct)
	}
}

func assertParseOneExpr(t *testing.T, msg string, input string, correct *Expr, opts ...ParserOptions) {
	t.Helper()
	assertParseOne(t, msg, input, func(parsed any) {
		t.Helper()
		body := parsed.(Body)
		if len(body) != 1 {
			t.Errorf("Error on test \"%s\": parser returned multiple expressions: %v", msg, body)
			return
		}
		expr := body[0]
		if !expr.Equal(correct) {
			t.Errorf("Error on test \"%s\": expressions not equal:\n%v (parsed)\n%v (correct)", msg, expr, correct)
		}
	}, opts...)
}

func assertParseOneExprNegated(t *testing.T, msg string, input string, correct *Expr) {
	correct.Negated = true
	assertParseOneExpr(t, msg, input, correct)
}

func assertParseOneTerm(t *testing.T, msg string, input string, correct *Term, opts ...ParserOptions) {
	t.Helper()
	t.Run(msg, func(t *testing.T) {
		assertParseOneExpr(t, msg, input, &Expr{Terms: correct}, opts...)
	})
}

func assertParseOneTermNegated(t *testing.T, msg string, input string, correct *Term) {
	t.Helper()
	assertParseOneExprNegated(t, msg, input, &Expr{Terms: correct})
}

func assertParseRule(t *testing.T, msg string, input string, correct *Rule, opts ...ParserOptions) {
	t.Helper()
	assertParseOne(t, msg, input, func(parsed any) {
		t.Helper()
		rule := parsed.(*Rule)
		if rule.Head.Name != correct.Head.Name {
			t.Errorf("Error on test \"%s\": rule heads not equal: name = %v (parsed), name = %v (correct)", msg, rule.Head.Name, correct.Head.Name)
		}
		if !rule.Head.Ref().Equal(correct.Head.Ref()) {
			t.Errorf("Error on test \"%s\": rule heads not equal: ref = %v (parsed), ref = %v (correct)", msg, rule.Head.Ref(), correct.Head.Ref())
		}
		if !rule.Head.Equal(correct.Head) {
			t.Errorf("Error on test \"%s\": rule heads not equal: %v (parsed), %v (correct)", msg, rule.Head, correct.Head)
		}
		if !rule.Equal(correct) {
			t.Errorf("Error on test \"%s\": rules not equal: %v (parsed), %v (correct)", msg, rule, correct)
		}
	},
		opts...)
}

func TestTemplateString(t *testing.T) {
	tests := []struct {
		note string
		expr string
		exp  *Expr
	}{
		{
			note: "simple template string",
			expr: `$"foo"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false, StringTerm("foo")),
			},
		},
		{
			note: "with template expression",
			expr: `$"foo {x}"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("foo "),
					&Expr{
						Terms: VarTerm("x"),
					},
				),
			},
		},
		{
			note: "escapes",
			expr: `$"\t\n\"\{"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("\t\n\"{"),
				),
			},
		},
		{
			note: "JSON-specific escapes",
			expr: `$"\/\uD834\uDD1E"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("/𝄞"),
				),
			},
		},
		{
			note: "escapes, multi-line",
			expr: "$`\\{`",
			exp: &Expr{
				Terms: TemplateStringTerm(true,
					StringTerm(`{`),
				),
			},
		},

		{
			note: "with modifier, global",
			expr: `$"foo {input}" with input as 42`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("foo "),
					&Expr{
						Terms: RefTerm(VarTerm("input")),
					},
				),
				With: []*With{
					{
						Target: RefTerm(VarTerm("input")),
						Value:  NumberTerm("42"),
					},
				},
			},
		},
		{
			note: "with modifier, global, multiple",
			expr: `$"foo {input} {x}" with input as 42 with x as "bar"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("foo "),
					&Expr{
						Terms: RefTerm(VarTerm("input")),
					},
					StringTerm(" "),
					&Expr{
						Terms: VarTerm("x"),
					},
				),
				With: []*With{
					{
						Target: RefTerm(VarTerm("input")),
						Value:  NumberTerm("42"),
					},
					{
						Target: VarTerm("x"),
						Value:  StringTerm("bar"),
					},
				},
			},
		},
		{
			note: "with modifier, inside template expression",
			expr: `$"foo {x with input as 42}"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					StringTerm("foo "),
					&Expr{
						Terms: VarTerm("x"),
						With: []*With{
							{
								Target: RefTerm(VarTerm("input")),
								Value:  NumberTerm("42"),
							},
						},
					},
				),
			},
		},
		{
			note: "template-string inside with value",
			expr: `allow with input.x as $"<{x}>"`,
			exp: &Expr{
				Terms: VarTerm("allow"),
				With: []*With{
					{
						Target: RefTerm(VarTerm("input"), StringTerm("x")),
						Value: TemplateStringTerm(false,
							StringTerm("<"),
							&Expr{
								Terms: VarTerm("x"),
							},
							StringTerm(">"),
						),
					},
				},
			},
		},

		{
			note: "template-string inside some symbols",
			expr: `some $"user_{id}" in users`,
			exp: &Expr{
				Terms: &SomeDecl{
					Symbols: []*Term{
						Member.Call(
							TemplateStringTerm(false,
								StringTerm("user_"),
								&Expr{
									Terms: VarTerm("id"),
								},
							),
							VarTerm("users"),
						),
					},
				},
			},
		},

		{
			note: "multi-line expression in single-line template-string",
			expr: `$"{[x |
					x := 42]}"`,
			exp: &Expr{
				Terms: TemplateStringTerm(false,
					&Expr{
						Terms: &Term{
							Value: &ArrayComprehension{
								Term: VarTerm("x"),
								Body: NewBody(
									&Expr{
										Terms: []*Term{RefTerm(VarTerm("assign")), VarTerm("x"), NumberTerm("42")},
									},
								),
							},
						},
					},
				),
			},
		},

		{
			note: "multi-line template string",
			expr: "$`<foo>\n" +
				"  <bar>{x}</bar>\n" +
				"  <baz>{y}</baz>\n" +
				"</foo>`",
			exp: &Expr{
				Terms: TemplateStringTerm(true,
					StringTerm("<foo>\n  <bar>"),
					&Expr{
						Terms: VarTerm("x"),
					},
					StringTerm("</bar>\n  <baz>"),
					&Expr{
						Terms: VarTerm("y"),
					},
					StringTerm("</baz>\n</foo>"),
				),
			},
		},
		{
			note: "multi-line template string, nested single-line template string",
			expr: "$`<foo>\n" +
				"  <bar>{$\"a {x} b\"}</bar>\n" +
				"</foo>`",
			exp: &Expr{
				Terms: TemplateStringTerm(true,
					StringTerm("<foo>\n  <bar>"),
					&Expr{
						Terms: TemplateStringTerm(false,
							StringTerm("a "),
							&Expr{
								Terms: VarTerm("x"),
							},
							StringTerm(" b"),
						),
					},
					StringTerm("</bar>\n</foo>"),
				),
			},
		},
		{
			note: "multi-line template string, nested multi-line template string",
			expr: "$`<foo>\n" +
				"  <bar>{$`a {x} b`}</bar>\n" +
				"</foo>`",
			exp: &Expr{
				Terms: TemplateStringTerm(true,
					StringTerm("<foo>\n  <bar>"),
					&Expr{
						Terms: TemplateStringTerm(true,
							StringTerm("a "),
							&Expr{
								Terms: VarTerm("x"),
							},
							StringTerm(" b"),
						),
					},
					StringTerm("</bar>\n</foo>"),
				),
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			stmts, _, err := ParseStatements("", tc.expr)

			if err != nil {
				t.Fatalf("Unexpected error: %v", err)
			}

			if len(stmts) != 1 {
				t.Fatalf("Expected exactly one statement, got %d: %v", len(stmts), stmts)
			}

			body, ok := stmts[0].(Body)
			if !ok {
				t.Fatalf("Expected body, got %T", stmts[0])
			}

			if len(body) != 1 {
				t.Fatalf("Expected exactly one expression, got %d: %v", len(body), body)
			}

			if !tc.exp.Equal(body[0]) {
				t.Errorf("Expressions not equal:\n%v (parsed)\n%v (correct)", body[0], tc.exp)
			}
		})
	}
}

func TestTemplateStringLocation(t *testing.T) {
	tests := []struct {
		note string
		expr string
		exp  Location
	}{
		{
			note: "empty template-string",
			expr: `$""`,
			exp: Location{
				Text: []byte(`$""`),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "empty template-string, multi-line",
			expr: "$``",
			exp: Location{
				Text: []byte("$``"),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "no template-expressions",
			expr: `$"foo bar"`,
			exp: Location{
				Text: []byte(`$"foo bar"`),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "no template-expressions, multi-line",
			expr: "$`foo\n" +
				"bar`",
			exp: Location{
				Text: []byte("$`foo\nbar`"),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "template-expressions, expr tail",
			expr: `$"foo {42} bar {x}"`,
			exp: Location{
				Text: []byte(`$"foo {42} bar {x}"`),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "template-expressions, expr tail, multi-line",
			expr: "$`foo\n{42}\nbar\n{x}`",
			exp: Location{
				Text: []byte("$`foo\n{42}\nbar\n{x}`"),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "template-expressions, string tail",
			expr: `$"foo {42} bar {x} baz"`,
			exp: Location{
				Text: []byte(`$"foo {42} bar {x} baz"`),
				Row:  1,
				Col:  1,
			},
		},
		{
			note: "template-expressions, string tail, multi-line",
			expr: "$`foo\n{42}\nbar\n{x}\nbaz`",
			exp: Location{
				Text: []byte("$`foo\n{42}\nbar\n{x}\nbaz`"),
				Row:  1,
				Col:  1,
			},
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			stmts, _, err := ParseStatements("", tc.expr)

			if err != nil {
				t.Fatalf("Unexpected error: %v", err)
			}

			if len(stmts) != 1 {
				t.Fatalf("Expected exactly one statement, got %d: %v", len(stmts), stmts)
			}

			body, ok := stmts[0].(Body)
			if !ok {
				t.Fatalf("Expected body, got %T", stmts[0])
			}

			if len(body) != 1 {
				t.Fatalf("Expected exactly one expression, got %d: %v", len(body), body)
			}

			trm, ok := body[0].Terms.(*Term)
			if !ok {
				t.Fatalf("Expected term, got %T", stmts[0])
			}

			_, ok = trm.Value.(*TemplateString)
			if !ok {
				t.Fatalf("Expected template-string, got %T", stmts[0])
			}

			loc := trm.Loc()
			if !tc.exp.Equal(loc) {
				t.Errorf("Locations not equal:\n%v (parsed)\n%v (correct)", *loc, tc.exp)
			}
		})
	}
}

func TestTemplateStringError(t *testing.T) {
	tests := []struct {
		note     string
		expr     string
		expError string
	}{
		{
			note:     "empty template expression",
			expr:     `$"{}"`,
			expError: "rego_parse_error: invalid template-string expression",
		},
		{
			note:     "unification in template expression",
			expr:     `$"{x = 1}"`,
			expError: "rego_parse_error: unexpected unification ('=') in template-string expression",
		},
		{
			note:     "assignment in template expression",
			expr:     `$"{x := 1}"`,
			expError: "rego_parse_error: unexpected assignment (':=') in template-string expression",
		},
		{
			note:     "not in template expression",
			expr:     `$"{not false}"`,
			expError: "rego_parse_error: unexpected negation ('not') in template-string expression",
		},
		{
			note:     "some in template expression",
			expr:     `$"{some 2 in [1, 2]}"`,
			expError: "rego_parse_error: unexpected 'some' in template-string expression",
		},
		{
			note:     "every in template expression",
			expr:     `$"{every x in [1, 2] {x > 0}}"`,
			expError: "rego_parse_error: unexpected 'every' in template-string expression",
		},
		{
			note:     "multiple expressions in template expression",
			expr:     `$"{true; false}"`,
			expError: "rego_parse_error: expected } to end template string expression",
		},

		{
			note:     "single-line start terminator, multi-line end terminator",
			expr:     "$\"{x}`",
			expError: "rego_parse_error: non-terminated string",
		},
		{
			note:     "multi-line start terminator, single-line end terminator",
			expr:     "$`{x}\"",
			expError: "rego_parse_error: non-terminated string",
		},
	}

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, _, err := ParseStatements("", tc.expr)
			if err == nil {
				t.Fatalf("Expected error, got nil")
			}

			if !strings.Contains(err.Error(), tc.expError) {
				t.Fatalf("Expected error to contain %q, but got: %v", tc.expError, err)
			}
		})
	}
}

func TestTemplateStringCapabilities(t *testing.T) {
	tests := []struct {
		note   string
		caps   *Capabilities
		expErr string
	}{
		{
			note: "default capabilities",
		},
		{
			note:   "v0 capabilities",
			caps:   CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV0)),
			expErr: `rego_parse_error: template strings are not supported by current capabilities`,
		},
		{
			note: "v1 capabilities",
			caps: CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV1)),
		},
		{
			note:   "v1 capabilities, missing feature",
			caps:   removeCapabilityFeature(CapabilitiesForThisVersion(CapabilitiesRegoVersion(RegoV1)), FeatureTemplateStrings),
			expErr: `rego_parse_error: template strings are not supported by current capabilities`,
		},
	}

	expr := `$"foo {bar} baz"`

	for _, tc := range tests {
		t.Run(tc.note, func(t *testing.T) {
			_, _, err := ParseStatementsWithOpts("", expr, ParserOptions{Capabilities: tc.caps})

			if tc.expErr != "" {
				if err == nil {
					t.Fatalf("Expected error, got nil")
				}

				if !strings.Contains(err.Error(), tc.expErr) {
					t.Fatalf("Expected error to contain %q, but got: %v", tc.expErr, err)
				}
			} else if err != nil {
				t.Fatalf("Unexpected error: %v", err)
			}
		})
	}
}

func removeCapabilityFeature(caps *Capabilities, feat string) *Capabilities {
	feats := make([]string, 0, len(caps.Features)-1)
	for _, f := range caps.Features {
		if feat != f {
			feats = append(feats, f)
		}
	}
	caps.Features = feats
	return caps
}
