import os
from pathlib import Path

from django.conf import settings
from django.contrib.auth import get_user_model
from django.core.management.base import BaseCommand

from apps.library.models import MediaLocation
from apps.library.services import ALLOWED_EXTENSIONS, index_file

User = get_user_model()


class Command(BaseCommand):
    help = "Scan the watched folder and index media files into the library."

    def add_arguments(self, parser):
        parser.add_argument(
            "--prune",
            action="store_true",
            help="Remove locations whose files no longer exist on disk.",
        )
        parser.add_argument(
            "--user",
            help="Username that owns newly indexed files (default: first superuser).",
        )

    def handle(self, *args, **options):
        folder = Path(settings.WATCHED_FOLDER)
        if not folder.is_dir():
            self.stderr.write(
                self.style.ERROR(f"Watched folder does not exist: {folder}")
            )
            return

        owner = None
        if options["user"]:
            owner = User.objects.filter(username=options["user"]).first()
            if owner is None:
                self.stderr.write(
                    self.style.ERROR(f"User not found: {options['user']}")
                )
                return
        else:
            owner = User.objects.filter(is_superuser=True).order_by("id").first()
            if owner is None:
                self.stderr.write(
                    self.style.WARNING(
                        "No superuser found; scanned files will have no owner. "
                        "Use --user <name> to assign one."
                    )
                )
        if owner is not None:
            self.stdout.write(f"New files will be owned by {owner.username}.")

        self.stdout.write(f"Scanning {folder} ...")
        seen = set()
        new_items = 0
        new_locations = 0
        updated_locations = 0
        skipped = 0

        for root, dirs, files in os.walk(folder):
            dirs.sort()
            for name in sorted(files):
                if Path(name).suffix.lower() not in ALLOWED_EXTENSIONS:
                    continue
                path = Path(root) / name
                try:
                    item, created_item, _location, created_location = index_file(
                        path, folder
                    )
                except OSError as exc:
                    skipped += 1
                    self.stderr.write(f"Skipped {path}: {exc}")
                    continue
                if owner is not None and item.uploaded_by_id is None:
                    item.uploaded_by = owner
                    item.save(update_fields=["uploaded_by", "updated_at"])
                seen.add(str(path))
                new_items += int(created_item)
                if created_location:
                    new_locations += 1
                else:
                    updated_locations += 1
                processed = len(seen)
                if processed % 200 == 0:
                    self.stdout.write(f"Processed {processed} files ...")

        if options["prune"]:
            stale = MediaLocation.objects.exclude(path__in=seen)
            pruned = stale.count()
            stale.delete()
            self.stdout.write(f"Pruned {pruned} missing location(s).")

        self.stdout.write(
            self.style.SUCCESS(
                f"Done. {len(seen)} file(s) on disk, "
                f"{new_items} new item(s), "
                f"{new_locations} new location(s), "
                f"{updated_locations} refreshed, "
                f"{skipped} skipped."
            )
        )