# 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

from django.core.management.base import BaseCommand

from photologue.models import DATE_FROM_EXIF, DATE_FROM_VIDEO, DATE_MANUAL, Photo, Video
from photologue.utils import capture_date_from_exif, capture_date_from_video


class Command(BaseCommand):
    help = (
        "Read the capture date of existing media from their metadata. Media whose "
        "date was set by hand are never touched. By default only media without a "
        "date, and media imported before dates were tracked, are read."
    )

    def add_arguments(self, parser):
        parser.add_argument(
            "--force",
            action="store_true",
            help="Re-read every media, even those with a known date source.",
        )
        parser.add_argument(
            "--dry-run",
            action="store_true",
            help="Report what would change without writing anything.",
        )

    def handle(self, *args, **options):
        for model, reader in ((Photo, self.photo_date), (Video, self.video_date)):
            queryset = model.objects.exclude(date_source=DATE_MANUAL)
            if not options["force"]:
                # An empty source means the media predates this field, and its date
                # may have been stored in the wrong time zone.
                queryset = queryset.filter(date_taken__isnull=True) | queryset.filter(date_source="")
            self.process(model, queryset.distinct(), reader, options)

    def process(self, model, queryset, reader, options):
        name = model._meta.verbose_name_plural
        found = unchanged = missing = 0
        for media in queryset.iterator():
            taken, source = reader(media)
            if taken is None:
                missing += 1
                self.stdout.write(f"  no date in {media.title}")
                continue
            if taken == media.date_taken and source == media.date_source:
                unchanged += 1
                continue
            found += 1
            self.stdout.write(f"  {media.title}: {media.date_taken} -> {taken} ({source})")
            if not options["dry_run"]:
                media.set_capture_date(taken, source)
                media.save(update_fields=["date_taken", "date_source"])
        done = "would be updated" if options["dry_run"] else "updated"
        self.stdout.write(
            self.style.SUCCESS(f"{name}: {found} {done}, {unchanged} already correct, {missing} without metadata")
        )

    @staticmethod
    def photo_date(photo):
        if not photo.image:
            return None, None
        try:
            exif_date = photo.exif(photo.image.file).get("EXIF DateTimeOriginal", None)
        except Exception:
            return None, None
        if exif_date is None:
            return None, None
        return capture_date_from_exif(exif_date.values), DATE_FROM_EXIF

    @staticmethod
    def video_date(video):
        if not video.file:
            return None, None
        return capture_date_from_video(video.file.path), DATE_FROM_VIDEO