from django.core.management.base import BaseCommand
from django.db.models import Q

from apps.library.models import MediaItem
from apps.library.services import HASH_FIELDS, ensure_visual_hashes


class Command(BaseCommand):
    help = "Compute perceptual hashes for library items missing them."

    def add_arguments(self, parser):
        parser.add_argument(
            "--force",
            action="store_true",
            help="Recompute hashes even when they already exist.",
        )

    def handle(self, *args, **options):
        queryset = MediaItem.objects.prefetch_related("locations").order_by("id")
        if not options["force"]:
            missing = Q()
            for field in HASH_FIELDS:
                missing |= Q(**{field: ""})
            queryset = queryset.filter(missing)

        total = queryset.count()
        if total == 0:
            self.stdout.write(self.style.SUCCESS("All items already have hashes."))
            return

        self.stdout.write(f"Computing hashes for {total} item(s) ...")
        done = 0
        for item in queryset.iterator(chunk_size=100):
            if options["force"]:
                item.ahash = item.dhash = item.phash = item.whash = ""
            ensure_visual_hashes(item)
            done += 1
            if done % 100 == 0:
                self.stdout.write(f"Processed {done} ...")

        self.stdout.write(
            self.style.SUCCESS(f"Done. Processed {done} item(s).")
        )