using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;

namespace ErsatzTV.Core.Scheduling;

/// <summary>
///     Builds the shuffle "source" for a collection key — the grouped media items fed to
///     <see cref="ShuffledMediaCollectionEnumerator" /> and the per-collection lists fed to
///     <see cref="ShuffleInOrderCollectionEnumerator" />.
///     <para>
///         Extracted from <c>PlayoutBuilder</c> (issue #380) so both the Classic builder and
///         <see cref="PlaylistEnumerator" /> share ONE stateless place to construct shuffle sources,
///         eliminating <see cref="PlaylistEnumerator" />'s cross-engine reach-in into
///         <c>PlayoutBuilder</c>'s statics. Kept as a static helper (dependencies passed as parameters)
///         to match the sibling <see cref="MultiCollectionGrouper" /> / <see cref="MultiPartEpisodeGrouper" />
///         (also <c>public static</c>) and because <see cref="PlaylistEnumerator.Create" /> is itself a
///         static factory.
///     </para>
/// </summary>
public static class ShuffleSourceBuilder
{
    public static async Task<List<GroupedMediaItem>> GetGroupedMediaItemsForShuffle(
        IMediaCollectionRepository mediaCollectionRepository,
        bool keepMultiPartEpisodesTogether,
        bool treatCollectionsAsShows,
        List<MediaItem> mediaItems,
        CollectionKey collectionKey,
        CancellationToken cancellationToken)
    {
        if (collectionKey.MultiCollectionId != null)
        {
            List<CollectionWithItems> collections = await mediaCollectionRepository
                .GetMultiCollectionCollections(collectionKey.MultiCollectionId.Value, cancellationToken);

            return MultiCollectionGrouper.GroupMediaItems(collections);
        }

        return keepMultiPartEpisodesTogether
            ? MultiPartEpisodeGrouper.GroupMediaItems(mediaItems, treatCollectionsAsShows)
            : mediaItems.Map(mi => new GroupedMediaItem(mi, null)).ToList();
    }

    public static async Task<List<CollectionWithItems>> GetCollectionItemsForShuffleInOrder(
        IMediaCollectionRepository mediaCollectionRepository,
        CollectionKey collectionKey,
        CancellationToken cancellationToken)
    {
        List<CollectionWithItems> result;

        if (collectionKey.MultiCollectionId != null)
        {
            result = await mediaCollectionRepository.GetMultiCollectionCollections(
                collectionKey.MultiCollectionId.Value,
                cancellationToken);
        }
        else
        {
            result = await mediaCollectionRepository.GetFakeMultiCollectionCollections(
                collectionKey.CollectionId,
                collectionKey.SmartCollectionId,
                cancellationToken);
        }

        return result;
    }
}