# This file is part of photo21
# Copyright (C) 2022  Amicale des élèves de l'ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later

import hashlib

from django.core.management.base import BaseCommand, CommandError
from photologue.models import Gallery


class Command(BaseCommand):
    help = "List all duplicate for chosen galleries"

    def add_arguments(self, parser):
        parser.add_argument(
            "--slugs",
            nargs="+",
            help="Try to find duplicate in the selected galleries",
            default=[],
        )
        parser.add_argument(
            "-a",
            "--all",
            action="store_true",
            help="Try to find duplicate in all galleries, overide any slugs given",
        )
        parser.add_argument("-d", "--delete", action="store_true")

    def handle(self, *args, **options):
        # Collect all required galleries
        if options["all"]:
            galleries = Gallery.objects.all()
        else:
            galleries = []
            for slug in options["slugs"]:
                gallery_query = Gallery.objects.filter(slug=slug)
                if not gallery_query:
                    raise CommandError(
                        f"Slug {slug} does not correspond to a "
                        "gallery in the database."
                    )
                galleries += gallery_query

        # Find duplicates in all galleries
        for gallery in galleries:
            duplicates = find_duplicate(gallery)
            self.stdout.write(f"Gallery {gallery.slug}:")
            for original, copies in duplicates:
                self.stdout.write(f"  {original.slug} is duplicated:", ending="")
                for copy in copies:
                    self.stdout.write(f" {copy.slug}")

            # Delete them if --delete
            if options["delete"]:
                self.stdout.write("  Deleting duplicate in {} :".format(gallery.slug))
                for (_original, copies) in duplicates:
                    for copy in copies:
                        self.stdout.write("    Deleting {}...".format(copy.slug))
                        copy.delete()


def find_duplicate(gallery):
    # Dict of all already checked photos
    non_duplicate = {}
    # Dict of all found duplicate {h0 : (original:[duplicates])}
    duplicate = {}

    for photo in gallery.photos.all():
        with photo.image.open("rb") as f:
            h0 = hashlib.sha256(f.read()).digest()
        if h0 not in non_duplicate:
            # Photo is not a duplicate
            non_duplicate[h0] = photo
        elif h0 in duplicate:
            if len(photo.slug) > len(duplicate[h0][0].slug):
                duplicate[h0][1] += [photo]
            else:
                duplicate[h0][1] += [duplicate[h0][0]]
                duplicate[h0][0] = photo
        else:
            duplicate[h0] = [non_duplicate[h0], [photo]]
    # Return only value because hash aren't usefull
    return duplicate.values()