using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Locking;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Repositories.Caching;
using ErsatzTV.Core.Interfaces.Search;
using ErsatzTV.Core.Interfaces.Trakt;
using ErsatzTV.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Application.MediaCollections;

public class DeleteTraktListHandler : TraktCommandBase, IRequestHandler<DeleteTraktList, Either<BaseError, Unit>>
{
    private readonly IDbContextFactory<TvContext> _dbContextFactory;
    private readonly IEntityLocker _entityLocker;
    private readonly IFallbackMetadataProvider _fallbackMetadataProvider;
    private readonly ISearchIndex _searchIndex;
    private readonly ICachingSearchRepository _searchRepository;

    public DeleteTraktListHandler(
        ITraktApiClient traktApiClient,
        ICachingSearchRepository searchRepository,
        ISearchIndex searchIndex,
        IFallbackMetadataProvider fallbackMetadataProvider,
        IDbContextFactory<TvContext> dbContextFactory,
        ILogger<DeleteTraktListHandler> logger,
        IEntityLocker entityLocker)
        : base(traktApiClient, searchRepository, searchIndex, fallbackMetadataProvider, logger)
    {
        _searchRepository = searchRepository;
        _searchIndex = searchIndex;
        _fallbackMetadataProvider = fallbackMetadataProvider;
        _dbContextFactory = dbContextFactory;
        _entityLocker = entityLocker;
    }

    public async Task<Either<BaseError, Unit>> Handle(
        DeleteTraktList request,
        CancellationToken cancellationToken)
    {
        try
        {
            await using TvContext dbContext = await _dbContextFactory.CreateDbContextAsync(cancellationToken);
            Validation<BaseError, TraktList> validation = await TraktListMustExist(dbContext, request.TraktListId);
            return await LanguageExtensions.Apply(validation, c => DoDeletion(dbContext, c));
        }
        finally
        {
            _entityLocker.UnlockTrakt();
        }
    }

    private async Task<Unit> DoDeletion(TvContext dbContext, TraktList traktList)
    {
        var mediaItemIds = traktList.Items.Bind(i => Optional(i.MediaItemId)).ToList();

        dbContext.TraktLists.Remove(traktList);
        if (await dbContext.SaveChangesAsync() > 0)
        {
            await _searchIndex.RebuildItems(_searchRepository, _fallbackMetadataProvider, mediaItemIds);
        }

        _searchIndex.Commit();

        return Unit.Default;
    }
}