# SPDX-FileCopyrightText: 2021-2023 Blender Foundation
#
# SPDX-License-Identifier: GPL-2.0-or-later

"""
Copy Global Transform

Simple add-on for copying world-space transforms.

It's called "global" to avoid confusion with the Blender World data-block.
"""

bl_info = {
    "name": "Copy Global Transform",
    "author": "Sybren A. Stüvel",
    "version": (3, 0),
    "blender": (4, 2, 0),
    "location": "N-panel in the 3D Viewport",
    "description": "Copy and paste object and bone transforms with ease",
    "category": "Animation",
    "support": 'OFFICIAL',
    "doc_url": "{BLENDER_MANUAL_URL}/addons/animation/copy_global_transform.html",
}

import ast
import abc
import contextlib
from typing import Iterable, Optional, Union, Any, TypeAlias, Iterator

import bpy
from bpy.types import Context, Object, Operator, Panel, PoseBone, UILayout, FCurve, Camera, FModifierStepped
from mathutils import Matrix


_axis_enum_items = [
    ("x", "X", "", 1),
    ("y", "Y", "", 2),
    ("z", "Z", "", 3),
]


class AutoKeying:
    """Auto-keying support.

    Based on Rigify code by Alexander Gavrilov.
    """

    # Use AutoKeying.keytype() or Authkeying.options() context to change those.
    _keytype = 'KEYFRAME'
    _force_autokey = False  # Allow use without the user activating auto-keying.
    _use_loc = True
    _use_rot = True
    _use_scale = True

    @classmethod
    @contextlib.contextmanager
    def keytype(cls, the_keytype: str) -> Iterator[None]:
        """Context manager to set the key type that's inserted."""
        default_keytype = cls._keytype
        try:
            cls._keytype = the_keytype
            yield
        finally:
            cls._keytype = default_keytype

    @classmethod
    @contextlib.contextmanager
    def options(cls, *, keytype="", use_loc=True, use_rot=True, use_scale=True, force_autokey=False) -> Iterator[None]:
        """Context manager to set various options."""
        default_keytype = cls._keytype
        default_use_loc = cls._use_loc
        default_use_rot = cls._use_rot
        default_use_scale = cls._use_scale
        default_force_autokey = cls._force_autokey
        try:
            cls._keytype = keytype
            cls._use_loc = use_loc
            cls._use_rot = use_rot
            cls._use_scale = use_scale
            cls._force_autokey = force_autokey
            yield
        finally:
            cls._keytype = default_keytype
            cls._use_loc = default_use_loc
            cls._use_rot = default_use_rot
            cls._use_scale = default_use_scale
            cls._force_autokey = default_force_autokey

    @classmethod
    def keying_options(cls, context: Context) -> set[str]:
        """Retrieve the general keyframing options from user preferences."""

        prefs = context.preferences
        ts = context.scene.tool_settings
        options = set()

        if prefs.edit.use_visual_keying:
            options.add('INSERTKEY_VISUAL')
        if prefs.edit.use_keyframe_insert_needed:
            options.add('INSERTKEY_NEEDED')
        if ts.use_keyframe_cycle_aware:
            options.add('INSERTKEY_CYCLE_AWARE')
        return options

    @classmethod
    def autokeying_options(cls, context: Context) -> Optional[set[str]]:
        """Retrieve the Auto Keyframe options, or None if disabled."""

        ts = context.scene.tool_settings

        if not (cls._force_autokey or ts.use_keyframe_insert_auto):
            return None

        if ts.use_keyframe_insert_keyingset:
            # No support for keying sets (yet).
            return None

        prefs = context.preferences
        options = cls.keying_options(context)

        if prefs.edit.use_keyframe_insert_available:
            options.add('INSERTKEY_AVAILABLE')
        if ts.auto_keying_mode == 'REPLACE_KEYS':
            options.add('INSERTKEY_REPLACE')
        return options

    @staticmethod
    def get_4d_rotlock(bone: PoseBone) -> Iterable[bool]:
        "Retrieve the lock status for 4D rotation."
        if bone.lock_rotations_4d:
            return [bone.lock_rotation_w, *bone.lock_rotation]
        else:
            return [all(bone.lock_rotation)] * 4

    @classmethod
    def keyframe_channels(
        cls,
        target: Union[Object, PoseBone],
        options: set[str],
        data_path: str,
        group: str,
        locks: Iterable[bool],
    ) -> None:
        if all(locks):
            return

        if not any(locks):
            target.keyframe_insert(data_path, group=group, options=options, keytype=cls._keytype)
            return

        for index, lock in enumerate(locks):
            if lock:
                continue
            target.keyframe_insert(data_path, index=index, group=group, options=options, keytype=cls._keytype)

    @classmethod
    def key_transformation(
        cls,
        target: Union[Object, PoseBone],
        options: set[str],
    ) -> None:
        """Keyframe transformation properties, avoiding keying locked channels."""

        is_bone = isinstance(target, PoseBone)
        if is_bone:
            group = target.name
        else:
            group = "Object Transforms"

        def keyframe(data_path: str, locks: Iterable[bool]) -> None:
            try:
                cls.keyframe_channels(target, options, data_path, group, locks)
            except RuntimeError:
                # These are expected when "Insert Available" is turned on, and
                # these curves are not available.
                pass

        if cls._use_loc and not (is_bone and target.bone.use_connect):
            keyframe("location", target.lock_location)

        if cls._use_rot:
            if target.rotation_mode == 'QUATERNION':
                keyframe("rotation_quaternion", cls.get_4d_rotlock(target))
            elif target.rotation_mode == 'AXIS_ANGLE':
                keyframe("rotation_axis_angle", cls.get_4d_rotlock(target))
            else:
                keyframe("rotation_euler", target.lock_rotation)

        if cls._use_scale:
            keyframe("scale", target.lock_scale)

    @classmethod
    def autokey_transformation(cls, context: Context, target: Union[Object, PoseBone]) -> None:
        """Auto-key transformation properties."""

        options = cls.autokeying_options(context)
        if options is None:
            return
        cls.key_transformation(target, options)


def get_matrix(context: Context) -> Matrix:
    bone = context.active_pose_bone
    if bone:
        # Convert matrix to world space
        arm = context.active_object
        mat = arm.matrix_world @ bone.matrix
    else:
        mat = context.active_object.matrix_world

    return mat


def set_matrix(context: Context, mat: Matrix) -> None:
    bone = context.active_pose_bone
    if bone:
        # Convert matrix to local space
        arm_eval = context.active_object.evaluated_get(context.view_layer.depsgraph)
        bone.matrix = arm_eval.matrix_world.inverted() @ mat
        AutoKeying.autokey_transformation(context, bone)
    else:
        context.active_object.matrix_world = mat
        AutoKeying.autokey_transformation(context, context.active_object)


def _selected_keyframes(context: Context) -> list[float]:
    """Return the list of frame numbers that have a selected key.

    Only keys on the active bone/object are considered.
    """
    bone = context.active_pose_bone
    if bone:
        return _selected_keyframes_for_bone(context.active_object, bone)
    return _selected_keyframes_for_object(context.active_object)


def _selected_keyframes_for_bone(object: Object, bone: PoseBone) -> list[float]:
    """Return the list of frame numbers that have a selected key.

    Only keys on the given pose bone are considered.
    """
    name = bpy.utils.escape_identifier(bone.name)
    return _selected_keyframes_in_action(object, f'pose.bones["{name}"].')


def _selected_keyframes_for_object(object: Object) -> list[float]:
    """Return the list of frame numbers that have a selected key.

    Only keys on the given object are considered.
    """
    return _selected_keyframes_in_action(object, "")


def _selected_keyframes_in_action(object: Object, rna_path_prefix: str) -> list[float]:
    """Return the list of frame numbers that have a selected key.

    Only keys on the given object's Action on FCurves starting with rna_path_prefix are considered.
    """

    action = object.animation_data and object.animation_data.action
    if action is None:
        return []

    keyframes = set()
    for fcurve in action.fcurves:
        if not fcurve.data_path.startswith(rna_path_prefix):
            continue

        for kp in fcurve.keyframe_points:
            if not kp.select_control_point:
                continue
            keyframes.add(kp.co.x)
    return sorted(keyframes)


def _copy_matrix_to_clipboard(window_manager: bpy.types.WindowManager, matrix: Matrix) -> None:
    rows = [f"    {tuple(row)!r}," for row in matrix]
    as_string = "\n".join(rows)
    window_manager.clipboard = f"Matrix((\n{as_string}\n))"


class OBJECT_OT_copy_global_transform(Operator):
    bl_idname = "object.copy_global_transform"
    bl_label = "Copy Global Transform"
    bl_description = (
        "Copies the matrix of the currently active object or pose bone to the clipboard. Uses world-space matrices"
    )
    # This operator cannot be un-done because it manipulates data outside Blender.
    bl_options = {'REGISTER'}

    @classmethod
    def poll(cls, context: Context) -> bool:
        return bool(context.active_pose_bone) or bool(context.active_object)

    def execute(self, context: Context) -> set[str]:
        mat = get_matrix(context)
        _copy_matrix_to_clipboard(context.window_manager, mat)
        return {'FINISHED'}


def _get_relative_ob(context: Context) -> Optional[Object]:
    """Get the 'relative' object.

    This is the object that's configured, or if that's empty, the active scene camera.
    """
    rel_ob = context.scene.addon_copy_global_transform_relative_ob
    return rel_ob or context.scene.camera


class OBJECT_OT_copy_relative_transform(Operator):
    bl_idname = "object.copy_relative_transform"
    bl_label = "Copy Relative Transform"
    bl_description = "Copies the matrix of the currently active object or pose bone to the clipboard. " \
        "Uses matrices relative to a specific object or the active scene camera"
    # This operator cannot be un-done because it manipulates data outside Blender.
    bl_options = {'REGISTER'}

    @classmethod
    def poll(cls, context: Context) -> bool:
        rel_ob = _get_relative_ob(context)
        if not rel_ob:
            return False
        return bool(context.active_pose_bone) or bool(context.active_object)

    def execute(self, context: Context) -> set[str]:
        rel_ob = _get_relative_ob(context)
        mat = rel_ob.matrix_world.inverted() @ get_matrix(context)
        _copy_matrix_to_clipboard(context.window_manager, mat)
        return {'FINISHED'}


class UnableToMirrorError(Exception):
    """Raised when mirroring is enabled but no mirror object/bone is set."""


class OBJECT_OT_paste_transform(Operator):
    bl_idname = "object.paste_transform"
    bl_label = "Paste Global Transform"
    bl_description = (
        "Pastes the matrix from the clipboard to the currently active pose bone or object. Uses world-space matrices"
    )
    bl_options = {'REGISTER', 'UNDO'}

    _method_items = [
        (
            'CURRENT',
            "Current Transform",
            "Paste onto the current values only, only manipulating the animation data if auto-keying is enabled",
        ),
        (
            'EXISTING_KEYS',
            "Selected Keys",
            "Paste onto frames that have a selected key, potentially creating new keys on those frames",
        ),
        (
            'BAKE',
            "Bake on Key Range",
            "Paste onto all frames between the first and last selected key, creating new keyframes if necessary",
        ),
    ]
    method: bpy.props.EnumProperty(  # type: ignore
        items=_method_items,
        name="Paste Method",
        description="Update the current transform, selected keyframes, or even create new keys",
    )
    bake_step: bpy.props.IntProperty(  # type: ignore
        name="Frame Step",
        description="Only used for baking. Step=1 creates a key on every frame, step=2 bakes on 2s, etc",
        min=1,
        soft_min=1,
        soft_max=5,
    )

    use_mirror: bpy.props.BoolProperty(  # type: ignore
        name="Mirror Transform",
        description="When pasting, mirror the transform relative to a specific object or bone",
        default=False,
    )

    mirror_axis_loc: bpy.props.EnumProperty(  # type: ignore
        items=_axis_enum_items,
        name="Location Axis",
        description="Coordinate axis used to mirror the location part of the transform",
        default='x',
    )
    mirror_axis_rot: bpy.props.EnumProperty(  # type: ignore
        items=_axis_enum_items,
        name="Rotation Axis",
        description="Coordinate axis used to mirror the rotation part of the transform",
        default='z',
    )

    use_relative: bpy.props.BoolProperty(  # type: ignore
        name="Use Relative Paste",
        description="When pasting, assume the pasted matrix is relative to another object (set in the user interface)",
        default=False,
    )

    @classmethod
    def poll(cls, context: Context) -> bool:
        if not context.active_pose_bone and not context.active_object:
            cls.poll_message_set("Select an object or pose bone")
            return False

        clipboard = context.window_manager.clipboard.strip()
        if not (clipboard.startswith("Matrix(") or clipboard.startswith("<Matrix 4x4")):
            cls.poll_message_set("Clipboard does not contain a valid matrix")
            return False
        return True

    @staticmethod
    def parse_print_m4(value: str) -> Optional[Matrix]:
        """Parse output from Blender's print_m4() function.

        Expects four lines of space-separated floats.
        """

        lines = value.strip().splitlines()
        if len(lines) != 4:
            return None

        floats = tuple(tuple(float(item) for item in line.split()) for line in lines)
        return Matrix(floats)

    @staticmethod
    def parse_repr_m4(value: str) -> Optional[Matrix]:
        """Four lines of (a, b, c, d) floats."""

        lines = value.strip().splitlines()
        if len(lines) != 4:
            return None

        floats = tuple(tuple(float(item.strip()) for item in line.strip()[1:-1].split(',')) for line in lines)
        return Matrix(floats)

    def execute(self, context: Context) -> set[str]:
        clipboard = context.window_manager.clipboard.strip()
        if clipboard.startswith("Matrix"):
            mat = Matrix(ast.literal_eval(clipboard[6:]))
        elif clipboard.startswith("<Matrix 4x4"):
            mat = self.parse_repr_m4(clipboard[12:-1])
        else:
            mat = self.parse_print_m4(clipboard)

        if mat is None:
            self.report({'ERROR'}, "Clipboard does not contain a valid matrix")
            return {'CANCELLED'}

        try:
            mat = self._preprocess_matrix(context, mat)
        except UnableToMirrorError:
            self.report({'ERROR'}, "Unable to mirror, no mirror object/bone configured")
            return {'CANCELLED'}

        applicator = {
            'CURRENT': self._paste_current,
            'EXISTING_KEYS': self._paste_existing_keys,
            'BAKE': self._paste_bake,
        }[self.method]
        return applicator(context, mat)

    def _preprocess_matrix(self, context: Context, matrix: Matrix) -> Matrix:
        matrix = self._relative_to_world(context, matrix)

        if self.use_mirror:
            matrix = self._mirror_matrix(context, matrix)
        return matrix

    def _relative_to_world(self, context: Context, matrix: Matrix) -> Matrix:
        if not self.use_relative:
            return matrix

        rel_ob = _get_relative_ob(context)
        if not rel_ob:
            return matrix

        rel_ob_eval = rel_ob.evaluated_get(context.view_layer.depsgraph)
        return rel_ob_eval.matrix_world @ matrix

    def _mirror_matrix(self, context: Context, matrix: Matrix) -> Matrix:
        mirror_ob = context.scene.addon_copy_global_transform_mirror_ob
        mirror_bone = context.scene.addon_copy_global_transform_mirror_bone

        # No mirror object means "current armature object".
        ctx_ob = context.object
        if not mirror_ob and mirror_bone and ctx_ob and ctx_ob.type == 'ARMATURE':
            mirror_ob = ctx_ob

        if not mirror_ob:
            raise UnableToMirrorError()

        if mirror_ob.type == 'ARMATURE' and mirror_bone:
            return self._mirror_over_bone(matrix, mirror_ob, mirror_bone)
        return self._mirror_over_ob(matrix, mirror_ob)

    def _mirror_over_ob(self, matrix: Matrix, mirror_ob: bpy.types.Object) -> Matrix:
        mirror_matrix = mirror_ob.matrix_world
        return self._mirror_over_matrix(matrix, mirror_matrix)

    def _mirror_over_bone(self, matrix: Matrix, mirror_ob: bpy.types.Object, mirror_bone_name: str) -> Matrix:
        bone = mirror_ob.pose.bones[mirror_bone_name]
        mirror_matrix = mirror_ob.matrix_world @ bone.matrix
        return self._mirror_over_matrix(matrix, mirror_matrix)

    def _mirror_over_matrix(self, matrix: Matrix, mirror_matrix: Matrix) -> Matrix:
        # Compute the matrix in the space of the mirror matrix:
        mat_local = mirror_matrix.inverted() @ matrix

        # Decompose the matrix, as we don't want to touch the scale. This
        # operator should only mirror the translation and rotation components.
        trans, rot_q, scale = mat_local.decompose()

        # Mirror the translation component:
        axis_index = ord(self.mirror_axis_loc) - ord('x')
        trans[axis_index] *= -1

        # Flip the rotation, and use a rotation order that applies the to-be-flipped axes first.
        match self.mirror_axis_rot:
            case 'x':
                rot_e = rot_q.to_euler('XYZ')
                rot_e.x *= -1  # Flip the requested rotation axis.
                rot_e.y *= -1  # Also flip the bone roll.
            case 'y':
                rot_e = rot_q.to_euler('YZX')
                rot_e.y *= -1  # Flip the requested rotation axis.
                rot_e.z *= -1  # Also flip another axis? Not sure how to handle this one.
            case 'z':
                rot_e = rot_q.to_euler('ZYX')
                rot_e.z *= -1  # Flip the requested rotation axis.
                rot_e.y *= -1  # Also flip the bone roll.

        # Recompose the local matrix:
        mat_local = Matrix.LocRotScale(trans, rot_e, scale)

        # Go back to world space:
        mirrored_world = mirror_matrix @ mat_local
        return mirrored_world

    @staticmethod
    def _paste_current(context: Context, matrix: Matrix) -> set[str]:
        set_matrix(context, matrix)
        return {'FINISHED'}

    def _paste_existing_keys(self, context: Context, matrix: Matrix) -> set[str]:
        if not context.scene.tool_settings.use_keyframe_insert_auto:
            self.report({'ERROR'}, "This mode requires auto-keying to work properly")
            return {'CANCELLED'}

        frame_numbers = _selected_keyframes(context)
        if not frame_numbers:
            self.report({'WARNING'}, "No selected frames found")
            return {'CANCELLED'}

        self._paste_on_frames(context, frame_numbers, matrix)
        return {'FINISHED'}

    def _paste_bake(self, context: Context, matrix: Matrix) -> set[str]:
        if not context.scene.tool_settings.use_keyframe_insert_auto:
            self.report({'ERROR'}, "This mode requires auto-keying to work properly")
            return {'CANCELLED'}

        bake_step = max(1, self.bake_step)
        # Put the clamped bake step back into RNA for the redo panel.
        self.bake_step = bake_step

        frame_start, frame_end = self._determine_bake_range(context)
        frame_range = range(round(frame_start), round(frame_end) + bake_step, bake_step)
        self._paste_on_frames(context, frame_range, matrix)
        return {'FINISHED'}

    def _determine_bake_range(self, context: Context) -> tuple[float, float]:
        frame_numbers = _selected_keyframes(context)
        if frame_numbers:
            # Note that these could be the same frame, if len(frame_numbers) == 1:
            return frame_numbers[0], frame_numbers[-1]

        if context.scene.use_preview_range:
            self.report({'INFO'}, "No selected keys, pasting over preview range")
            return context.scene.frame_preview_start, context.scene.frame_preview_end

        self.report({'INFO'}, "No selected keys, pasting over scene range")
        return context.scene.frame_start, context.scene.frame_end

    def _paste_on_frames(self, context: Context, frame_numbers: Iterable[float], matrix: Matrix) -> None:
        current_frame = context.scene.frame_current_final
        try:
            for frame in frame_numbers:
                context.scene.frame_set(int(frame), subframe=frame % 1.0)
                set_matrix(context, matrix)
        finally:
            context.scene.frame_set(int(current_frame), subframe=current_frame % 1.0)


# Mapping from frame number to the dominant key type.
# GENERATED is the only recessive key type, others are dominant.
KeyInfo: TypeAlias = dict[float, str]


class Transformable(metaclass=abc.ABCMeta):
    """Interface for a bone or an object."""

    def __init__(self) -> None:
        self._key_info_cache: Optional[KeyInfo] = None

    @abc.abstractmethod
    def matrix_world(self) -> Matrix:
        pass

    @abc.abstractmethod
    def set_matrix_world(self, context: Context, matrix: Matrix) -> None:
        pass

    @abc.abstractmethod
    def _my_fcurves(self) -> Iterable[bpy.types.FCurve]:
        pass

    def key_info(self) -> KeyInfo:
        if self._key_info_cache is not None:
            return self._key_info_cache

        keyinfo: KeyInfo = {}
        for fcurve in self._my_fcurves():
            for kp in fcurve.keyframe_points:
                frame = kp.co.x
                if kp.type == 'GENERATED' and frame in keyinfo:
                    # Don't bother overwriting other key types.
                    continue
                keyinfo[frame] = kp.type

        self._key_info_cache = keyinfo
        return keyinfo

    def remove_keys_of_type(self, key_type: str, *, frame_start=float("-inf"), frame_end=float("inf")) -> None:
        self._key_info_cache = None

        for fcurve in self._my_fcurves():
            to_remove = [
                kp for kp in fcurve.keyframe_points if kp.type == key_type and (frame_start <= kp.co.x <= frame_end)
            ]
            for kp in reversed(to_remove):
                fcurve.keyframe_points.remove(kp, fast=True)
            fcurve.keyframe_points.handles_recalc()


class TransformableObject(Transformable):
    object: Object

    def __init__(self, object: Object) -> None:
        super().__init__()
        self.object = object

    def matrix_world(self) -> Matrix:
        return self.object.matrix_world

    def set_matrix_world(self, context: Context, matrix: Matrix) -> None:
        self.object.matrix_world = matrix
        AutoKeying.autokey_transformation(context, self.object)

    def __hash__(self) -> int:
        return hash(self.object.as_pointer())

    def _my_fcurves(self) -> Iterable[bpy.types.FCurve]:
        action = self._action()
        if not action:
            return
        yield from action.fcurves

    def _action(self) -> Optional[bpy.types.Action]:
        adt = self.object.animation_data
        return adt and adt.action


class TransformableBone(Transformable):
    arm_object: Object
    pose_bone: PoseBone

    def __init__(self, pose_bone: PoseBone) -> None:
        super().__init__()
        self.arm_object = pose_bone.id_data
        self.pose_bone = pose_bone

    def matrix_world(self) -> Matrix:
        mat = self.arm_object.matrix_world @ self.pose_bone.matrix
        return mat

    def set_matrix_world(self, context: Context, matrix: Matrix) -> None:
        # Convert matrix to armature-local space
        arm_eval = self.arm_object.evaluated_get(context.view_layer.depsgraph)
        self.pose_bone.matrix = arm_eval.matrix_world.inverted() @ matrix
        AutoKeying.autokey_transformation(context, self.pose_bone)

    def __hash__(self) -> int:
        return hash(self.pose_bone.as_pointer())

    def _my_fcurves(self) -> Iterable[bpy.types.FCurve]:
        action = self._action()
        if not action:
            return

        rna_prefix = f"{self.pose_bone.path_from_id()}."
        for fcurve in action.fcurves:
            if fcurve.data_path.startswith(rna_prefix):
                yield fcurve

    def _action(self) -> Optional[bpy.types.Action]:
        adt = self.arm_object.animation_data
        return adt and adt.action


class FixToCameraCommon:
    """Common functionality for the Fix To Scene Camera operator + its 'delete' button."""

    keytype = 'GENERATED'

    # Operator method stubs to avoid PyLance/MyPy errors:
    @classmethod
    def poll_message_set(cls, message: str) -> None:
        raise NotImplementedError()

    def report(self, level: set[str], message: str) -> None:
        raise NotImplementedError()

    # Implement in subclass:
    def _execute(self, context: Context, transformables: list[Transformable]) -> None:
        raise NotImplementedError()

    @classmethod
    def poll(cls, context: Context) -> bool:
        if not context.active_pose_bone and not context.active_object:
            cls.poll_message_set("Select an object or pose bone")
            return False
        if context.mode not in {'POSE', 'OBJECT'}:
            cls.poll_message_set("Switch to Pose or Object mode")
            return False
        if not context.scene.camera:
            cls.poll_message_set("The Scene needs a camera")
            return False
        return True

    def execute(self, context: Context) -> set[str]:
        match context.mode:
            case 'OBJECT':
                transformables = self._transformable_objects(context)
            case 'POSE':
                transformables = self._transformable_pbones(context)
            case mode:
                self.report({'ERROR'}, 'Unsupported mode: %r' % mode)
                return {'CANCELLED'}

        restore_frame = context.scene.frame_current
        try:
            self._execute(context, transformables)
        finally:
            context.scene.frame_set(restore_frame)
        return {'FINISHED'}

    def _transformable_objects(self, context: Context) -> list[Transformable]:
        return [TransformableObject(object=ob) for ob in context.selected_editable_objects]

    def _transformable_pbones(self, context: Context) -> list[Transformable]:
        return [TransformableBone(pose_bone=bone) for bone in context.selected_pose_bones]


class OBJECT_OT_fix_to_camera(Operator, FixToCameraCommon):
    bl_idname = "object.fix_to_camera"
    bl_label = "Fix to Scene Camera"
    bl_description = "Generate new keys to fix the selected object/bone to the camera on unkeyed frames"
    bl_options = {'REGISTER', 'UNDO'}

    use_loc: bpy.props.BoolProperty(  # type: ignore
        name="Location",
        description="Create Location keys when fixing to the scene camera",
        default=True,
    )
    use_rot: bpy.props.BoolProperty(  # type: ignore
        name="Rotation",
        description="Create Rotation keys when fixing to the scene camera",
        default=True,
    )
    use_scale: bpy.props.BoolProperty(  # type: ignore
        name="Scale",
        description="Create Scale keys when fixing to the scene camera",
        default=True,
    )

    def _get_matrices(self, camera: Camera, transformables: list[Transformable]) -> dict[Transformable, Matrix]:
        camera_mat_inv = camera.matrix_world.inverted()
        return {t: camera_mat_inv @ t.matrix_world() for t in transformables}

    def _execute(self, context: Context, transformables: list[Transformable]) -> None:
        depsgraph = context.view_layer.depsgraph
        scene = context.scene

        scene.frame_set(scene.frame_start)
        camera_eval = scene.camera.evaluated_get(depsgraph)
        last_camera_name = scene.camera.name
        matrices = self._get_matrices(camera_eval, transformables)

        if scene.use_preview_range:
            frame_start = scene.frame_preview_start
            frame_end = scene.frame_preview_end
        else:
            frame_start = scene.frame_start
            frame_end = scene.frame_end

        with AutoKeying.options(
            keytype=self.keytype,
            use_loc=self.use_loc,
            use_rot=self.use_rot,
            use_scale=self.use_scale,
            force_autokey=True,
        ):
            for frame in range(frame_start, frame_end + scene.frame_step, scene.frame_step):
                scene.frame_set(frame)

                camera_eval = scene.camera.evaluated_get(depsgraph)
                cam_matrix_world = camera_eval.matrix_world
                camera_mat_inv = cam_matrix_world.inverted()

                if scene.camera.name != last_camera_name:
                    # The scene camera changed, so the previous
                    # relative-to-camera matrices can no longer be used.
                    matrices = self._get_matrices(camera_eval, transformables)
                    last_camera_name = scene.camera.name

                for t, camera_rel_matrix in matrices.items():
                    key_info = t.key_info()
                    key_type = key_info.get(frame, "")
                    if key_type not in {self.keytype, ""}:
                        # Manually set key, remember the current camera-relative matrix.
                        matrices[t] = camera_mat_inv @ t.matrix_world()
                        continue

                    # No key, or a generated one. Overwrite it with a new transform.
                    t.set_matrix_world(context, cam_matrix_world @ camera_rel_matrix)


class OBJECT_OT_delete_fix_to_camera_keys(Operator, FixToCameraCommon):
    bl_idname = "object.delete_fix_to_camera_keys"
    bl_label = "Delete Generated Keys"
    bl_description = "Delete all keys that were generated by the 'Fix to Scene Camera' operator"
    bl_options = {'REGISTER', 'UNDO'}

    def _execute(self, context: Context, transformables: list[Transformable]) -> None:
        scene = context.scene
        if scene.use_preview_range:
            frame_start = scene.frame_preview_start
            frame_end = scene.frame_preview_end
        else:
            frame_start = scene.frame_start
            frame_end = scene.frame_end

        for t in transformables:
            t.remove_keys_of_type(self.keytype, frame_start=frame_start, frame_end=frame_end)


class PanelMixin:
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = "Animation"


class VIEW3D_PT_copy_global_transform(PanelMixin, Panel):
    bl_label = "Global Transform"

    def draw(self, context: Context) -> None:
        layout = self.layout
        scene = context.scene

        # No need to put "Global Transform" in the operator text, given that it's already in the panel title.
        layout.operator("object.copy_global_transform", text="Copy", icon='COPYDOWN')

        paste_col = layout.column(align=True)

        paste_row = paste_col.row(align=True)
        paste_props = paste_row.operator("object.paste_transform", text="Paste", icon='PASTEDOWN')
        paste_props.method = 'CURRENT'
        paste_props.use_mirror = False
        paste_props = paste_row.operator("object.paste_transform", text="Mirrored", icon='PASTEFLIPDOWN')
        paste_props.method = 'CURRENT'
        paste_props.use_mirror = True

        wants_autokey_col = paste_col.column(align=False)
        has_autokey = scene.tool_settings.use_keyframe_insert_auto
        wants_autokey_col.enabled = has_autokey
        if not has_autokey:
            wants_autokey_col.label(text="These require auto-key:")

        paste_col = wants_autokey_col.column(align=True)
        paste_col.operator(
            "object.paste_transform",
            text="Paste to Selected Keys",
            icon='PASTEDOWN',
        ).method = 'EXISTING_KEYS'
        paste_col.operator(
            "object.paste_transform",
            text="Paste and Bake",
            icon='PASTEDOWN',
        ).method = 'BAKE'


class VIEW3D_PT_copy_global_transform_fix_to_camera(PanelMixin, Panel):
    bl_label = "Fix to Camera"
    bl_parent_id = "VIEW3D_PT_copy_global_transform"

    def draw(self, context: Context) -> None:
        layout = self.layout
        scene = context.scene

        # Fix to Scene Camera:
        layout.use_property_split = True
        props_box = layout.column(heading="Fix", align=True)
        props_box.prop(scene, "addon_copy_global_transform_fix_cam_use_loc", text="Location")
        props_box.prop(scene, "addon_copy_global_transform_fix_cam_use_rot", text="Rotation")
        props_box.prop(scene, "addon_copy_global_transform_fix_cam_use_scale", text="Scale")

        row = layout.row(align=True)
        props = row.operator("object.fix_to_camera")
        props.use_loc = scene.addon_copy_global_transform_fix_cam_use_loc
        props.use_rot = scene.addon_copy_global_transform_fix_cam_use_rot
        props.use_scale = scene.addon_copy_global_transform_fix_cam_use_scale
        row.operator("object.delete_fix_to_camera_keys", text="", icon='TRASH')


class VIEW3D_PT_copy_global_transform_mirror(PanelMixin, Panel):
    bl_label = "Mirror Options"
    bl_parent_id = "VIEW3D_PT_copy_global_transform"

    def draw(self, context: Context) -> None:
        layout = self.layout
        scene = context.scene
        layout.prop(scene, 'addon_copy_global_transform_mirror_ob', text="Object")

        mirror_ob = scene.addon_copy_global_transform_mirror_ob
        if mirror_ob is None:
            # No explicit mirror object means "the current armature", so then the bone name should be editable.
            if context.object and context.object.type == 'ARMATURE':
                self._bone_search(layout, scene, context.object)
            else:
                self._bone_entry(layout, scene)
        elif mirror_ob.type == 'ARMATURE':
            self._bone_search(layout, scene, mirror_ob)

    def _bone_search(self, layout: UILayout, scene: bpy.types.Scene, armature_ob: bpy.types.Object) -> None:
        """Search within the bones of the given armature."""
        assert armature_ob and armature_ob.type == 'ARMATURE'

        layout.prop_search(
            scene,
            "addon_copy_global_transform_mirror_bone",
            armature_ob.data,
            "edit_bones" if armature_ob.mode == 'EDIT' else "bones",
            text="Bone",
        )

    def _bone_entry(self, layout: UILayout, scene: bpy.types.Scene) -> None:
        """Allow manual entry of a bone name."""
        layout.prop(scene, "addon_copy_global_transform_mirror_bone", text="Bone")


class VIEW3D_PT_copy_global_transform_relative(PanelMixin, Panel):
    bl_label = "Relative"
    bl_parent_id = "VIEW3D_PT_copy_global_transform"

    def draw(self, context: Context) -> None:
        layout = self.layout
        scene = context.scene

        # Copy/Paste relative to some object:
        copy_paste_sub = layout.column(align=False)
        has_relative_ob = bool(_get_relative_ob(context))
        copy_paste_sub.label(text="Work Relative to some Object")
        copy_paste_sub.prop(scene, 'addon_copy_global_transform_relative_ob', text="Object")
        if not scene.addon_copy_global_transform_relative_ob:
            copy_paste_sub.label(text="Using Active Scene Camera")

        button_sub = copy_paste_sub.row(align=True)
        button_sub.enabled = has_relative_ob
        button_sub.operator("object.copy_relative_transform", text="Copy", icon='COPYDOWN')

        paste_props = button_sub.operator("object.paste_transform", text="Paste", icon='PASTEDOWN')
        paste_props.method = 'CURRENT'
        paste_props.use_mirror = False
        paste_props.use_relative = True

        # It is unknown whether this combination of options is in any way
        # sensible or usable, and of so, in which order the mirroring and
        # relative'ing-to should happen. That's why, for now, it's disabled.
        #
        # paste_props = paste_row.operator("object.paste_transform", text="Mirrored", icon='PASTEFLIPDOWN')
        # paste_props.method = 'CURRENT'
        # paste_props.use_mirror = True
        # paste_props.use_relative = True


# Messagebus subscription to monitor changes & refresh panels.
_msgbus_owner = object()


def _refresh_3d_panels():
    refresh_area_types = {'VIEW_3D'}
    for win in bpy.context.window_manager.windows:
        for area in win.screen.areas:
            if area.type not in refresh_area_types:
                continue
            area.tag_redraw()


classes = (
    OBJECT_OT_copy_global_transform,
    OBJECT_OT_copy_relative_transform,
    OBJECT_OT_paste_transform,
    OBJECT_OT_fix_to_camera,
    OBJECT_OT_delete_fix_to_camera_keys,
    VIEW3D_PT_copy_global_transform,
    VIEW3D_PT_copy_global_transform_mirror,
    VIEW3D_PT_copy_global_transform_fix_to_camera,
    VIEW3D_PT_copy_global_transform_relative,
)
_register, _unregister = bpy.utils.register_classes_factory(classes)


def _register_message_bus() -> None:
    bpy.msgbus.subscribe_rna(
        key=(bpy.types.ToolSettings, "use_keyframe_insert_auto"),
        owner=_msgbus_owner,
        args=(),
        notify=_refresh_3d_panels,
        options={'PERSISTENT'},
    )


def _unregister_message_bus() -> None:
    bpy.msgbus.clear_by_owner(_msgbus_owner)


@bpy.app.handlers.persistent  # type: ignore
def _on_blendfile_load_post(none: Any, other_none: Any) -> None:
    # The parameters are required, but both are None.
    _register_message_bus()


def register():
    _register()
    bpy.app.handlers.load_post.append(_on_blendfile_load_post)

    # The mirror object & bone name are stored on the scene, and not on the
    # operator. This makes it possible to set up the operator for use in a
    # certain scene, while keeping hotkey assignments working as usual.
    #
    # The goal is to allow hotkeys for "copy", "paste", and "paste mirrored",
    # while keeping the other choices in a more global place.
    bpy.types.Scene.addon_copy_global_transform_mirror_ob = bpy.props.PointerProperty(
        type=bpy.types.Object,
        name="Mirror Object",
        description="Object to mirror over. Leave empty and name a bone to always mirror "
        "over that bone of the active armature",
    )
    bpy.types.Scene.addon_copy_global_transform_mirror_bone = bpy.props.StringProperty(
        name="Mirror Bone",
        description="Bone to use for the mirroring",
    )
    bpy.types.Scene.addon_copy_global_transform_relative_ob = bpy.props.PointerProperty(
        type=bpy.types.Object,
        name="Relative Object",
        description="Object to which matrices are made relative",
    )

    bpy.types.Scene.addon_copy_global_transform_fix_cam_use_loc = bpy.props.BoolProperty(
        name="Fix Camera: Use Location",
        description="Create Location keys when fixing to the scene camera",
        default=True,
        options=set(),  # Remove ANIMATABLE default option.
    )
    bpy.types.Scene.addon_copy_global_transform_fix_cam_use_rot = bpy.props.BoolProperty(
        name="Fix Camera: Use Rotation",
        description="Create Rotation keys when fixing to the scene camera",
        default=True,
        options=set(),  # Remove ANIMATABLE default option.
    )
    bpy.types.Scene.addon_copy_global_transform_fix_cam_use_scale = bpy.props.BoolProperty(
        name="Fix Camera: Use Scale",
        description="Create Scale keys when fixing to the scene camera",
        default=True,
        options=set(),  # Remove ANIMATABLE default option.
    )


def unregister():
    _unregister()
    _unregister_message_bus()
    bpy.app.handlers.load_post.remove(_on_blendfile_load_post)

    del bpy.types.Scene.addon_copy_global_transform_mirror_ob
    del bpy.types.Scene.addon_copy_global_transform_mirror_bone
    del bpy.types.Scene.addon_copy_global_transform_relative_ob

    del bpy.types.Scene.addon_copy_global_transform_fix_cam_use_loc
    del bpy.types.Scene.addon_copy_global_transform_fix_cam_use_rot
    del bpy.types.Scene.addon_copy_global_transform_fix_cam_use_scale
