import os
from datetime import datetime, timezone as dt_timezone

from django.contrib.auth.models import User
from django.core.management.base import BaseCommand, CommandError
from django.utils.dateparse import parse_datetime

from podcasts.antennapod import AntennaPodImport, AntennaPodImportError, summary_lines


class Command(BaseCommand):
    help = (
        "Import an AntennaPod database backup (Settings > Database > Export) into one user's podcasts: "
        'subscriptions with their settings, played/new/started episodes, favourites and the queue; '
        'the episodes downloaded in AntennaPod are offered to the app for download. '
        'Feeds it creates are fetched by the next refresh; running the import once more after that '
        'also takes their older episodes that were not new in AntennaPod out of the inbox. '
        'Running it twice changes nothing more.'
    )

    def add_arguments(self, parser):
        parser.add_argument('path', help='AntennaPod backup (.db)')
        parser.add_argument('--user', required=True, help='diora username')
        parser.add_argument('--dry-run', action='store_true',
                            help='Do everything inside a transaction that is rolled back, print the summary')
        parser.add_argument('--global-auto-download', choices=('on', 'off'), default='off',
                            help="Auto-download for feeds that use AntennaPod's global setting (default off)")
        parser.add_argument('--replace', action='store_true',
                            help="A clean slate: unsubscribe podcasts the backup doesn't have, keep only "
                                 "AntennaPod's queue, AntennaPod wins over later changes in diora")
        parser.add_argument('--quiet-diora-only', action='store_true',
                            help='Podcasts only diora has (not in the backup): their episodes out before the backup '
                                 'leave the inbox (the subscriptions stay)')
        parser.add_argument('--no-downloads', action='store_true',
                            help="Don't offer AntennaPod's downloaded episodes to the app (they stay in AntennaPod)")
        parser.add_argument('--backup-date',
                            help='When the backup was made (ISO date/time, UTC if no zone); default: the file date. '
                                 'diora changes after it win over the backup.')

    def handle(self, *args, **options):
        path = options['path']
        if not os.path.isfile(path):
            raise CommandError(f'No such file: {path}')
        try:
            user = User.objects.get(username=options['user'])
        except User.DoesNotExist:
            raise CommandError(f"No such user: {options['user']}")

        if options['backup_date']:
            raw = options['backup_date']
            backup_date = parse_datetime(raw) or parse_datetime(f'{raw}T00:00')
            if backup_date is None:
                raise CommandError(f'Invalid --backup-date: {raw}')
            if backup_date.tzinfo is None:
                backup_date = backup_date.replace(tzinfo=dt_timezone.utc)
        else:
            backup_date = datetime.fromtimestamp(os.path.getmtime(path), tz=dt_timezone.utc)

        global_auto_download = options['global_auto_download'] == 'on'
        try:
            stats = AntennaPodImport(user, path, backup_date, global_auto_download,
                                     offer_downloads=not options['no_downloads'],
                                     quiet_diora_only=options['quiet_diora_only'],
                                     replace=options['replace']).run(dry_run=options['dry_run'])
        except AntennaPodImportError as e:
            raise CommandError(str(e))
        for line in summary_lines(stats, user.username, path, options['dry_run'], global_auto_download):
            self.stdout.write(line)