# -*- coding: utf-8 -*-
#
# diffoscope: in-depth comparison of files, archives, and directories
#
# Copyright © 2017 Chris Lamb <lamby@debian.org>
#
# diffoscope is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# diffoscope is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.

import re
import logging
import subprocess

from diffoscope.tools import tool_required
from diffoscope.config import Config
from diffoscope.difference import Difference

from .image import pixel_difference, flicker_difference, same_size
from .utils.file import File
from .utils.command import Command

logger = logging.getLogger(__name__)


class Gifbuild(Command):
    RE_FILTERS = (
        re.compile(r'^# GIF information from'),
        re.compile(r'^# End of .* dump'),
    )

    @tool_required('gifbuild')
    def cmdline(self):
        return ['gifbuild', '-d', self.path]

    def filter(self, line):
        if any(x.match(line.decode('utf-8')) for x in self.RE_FILTERS):
            return b""
        return line


@tool_required('identify')
def is_image_static(image):
    try:
        return subprocess.check_output((
            'identify',
            '-format', '%n',
            image.path,
        )) == b'1'
    except subprocess.CalledProcessError:
        return False


def can_compose_gif_images(image1, image2):
    return same_size(image1, image2) and \
        is_image_static(image1) and \
        is_image_static(image2)


class GifFile(File):
    DESCRIPTION = "GIF image files"
    FILE_TYPE_RE = re.compile(r'^GIF image data\b')

    def compare_details(self, other, source=None):
        gifbuild_diff = Difference.from_command(
            Gifbuild,
            self.path,
            other.path,
            source="gifbuild",
        )

        differences = [gifbuild_diff]

        if gifbuild_diff is not None and Config().compute_visual_diffs and \
                can_compose_gif_images(self, other):
            try:
                logger.debug(
                    "Generating visual difference for %s and %s",
                    self.path,
                    other.path,
                )
                content_diff = Difference(
                    None,
                    self.path,
                    other.path,
                    source="Image content",
                )
                content_diff.add_visuals([
                    pixel_difference(self.path, other.path),
                    flicker_difference(self.path, other.path),
                ])
                differences.append(content_diff)
            except subprocess.CalledProcessError:  # noqa
                pass

        return differences
