# Copyright (C) 2009-2013  Roman Zimbelmann <hut@lavabit.com>
# This software is distributed under the terms of the GNU GPL version 3.

import re
from ranger.container.fsobject import FileSystemObject

N_FIRST_BYTES = 256
control_characters = set(chr(n) for n in
        set(range(0, 9)) | set(range(14, 32)))

# Don't even try to preview files which mach this regular expression:
PREVIEW_BLACKLIST = re.compile(r"""
        # look at the extension:
        \.(
            # one character extensions:
                [oa]
            # media formats:
                | avi | mpe?g | mp\d | og[gmv] | wm[av] | mkv | flv
                | vob | wav | mpc | flac | divx? | xcf | pdf
            # binary files:
                | torrent | class | so | img | py[co] | dmg
        )
        # ignore filetype-independent suffixes:
            (\.part|\.bak|~)?
        # ignore fully numerical file extensions:
            (\.\d+)*?
        $
""", re.VERBOSE | re.IGNORECASE)

# Preview these files (almost) always:
PREVIEW_WHITELIST = re.compile(r"""
        \.(
            txt | py | c
        )
        # ignore filetype-independent suffixes:
            (\.part|\.bak|~)?
        $
""", re.VERBOSE | re.IGNORECASE)

class File(FileSystemObject):
    is_file = True
    preview_data = None
    preview_known = False
    preview_loading = False

    @property
    def firstbytes(self):
        try:
            return self._firstbytes
        except:
            try:
                f = open(self.path, 'r')
                self._firstbytes = f.read(N_FIRST_BYTES)
                f.close()
                return self._firstbytes
            except:
                pass

    def is_binary(self):
        if self.firstbytes and control_characters & set(self.firstbytes):
            return True
        return False

    def has_preview(self):
        if not self.fm.settings.preview_files:
            return False
        if self.is_socket or self.is_fifo or self.is_device:
            return False
        if not self.accessible:
            return False
        if self.fm.settings.preview_script and \
                self.fm.settings.use_preview_script:
            return True
        if self.image and self.fm.settings.preview_images:
            return True
        if self.container:
            return False
        if PREVIEW_WHITELIST.search(self.basename):
            return True
        if PREVIEW_BLACKLIST.search(self.basename):
            return False
        if self.path == '/dev/core' or self.path == '/proc/kcore':
            return False
        if self.is_binary():
            return False
        return True

    def get_preview_source(self, width, height):
        return self.fm.get_preview(self, width, height)
