using ErsatzTV.Application.MediaCollections;
using ErsatzTV.Application.MediaItems;
using ErsatzTV.Core.Domain;

namespace ErsatzTV.Controllers.Api.Requests;

// A rerun collection is a tagged union: CollectionType selects which of Collection /
// MultiCollection / SmartCollection / MediaItem is populated. The Create/Update handlers
// read ONLY the `.Id` (or `.MediaItemId`) off the chosen VM — verified in
// CreateRerunCollectionHandler.Validate / UpdateRerunCollectionHandler.ApplyUpdateRequest,
// both of which do `request.Collection?.Id`, `request.MultiCollection?.Id`,
// `request.SmartCollection?.Id`, `request.MediaItem?.MediaItemId` and nothing else. So we
// construct a minimal VM carrying just the selected id (defaults elsewhere) rather than
// doing extra lookup queries. The remaining VMs are left null (the handler expects that).
internal static class RerunCollectionRequestMapping
{
    /// <summary>
    ///     The only <see cref="CollectionType" /> values valid as a rerun collection's selected
    ///     source. Excludes Playlist / RerunFirstRun / RerunRerun / SearchQuery / Fake* — those
    ///     are not media-item-backed collection types and must not be resolved via
    ///     <see cref="ResolveSelection" />. Callers (the controller) must check this first.
    /// </summary>
    public static bool IsSupportedSelectionType(CollectionType collectionType) =>
        collectionType is CollectionType.Collection
            or CollectionType.MultiCollection
            or CollectionType.SmartCollection
            or CollectionType.TelevisionShow
            or CollectionType.TelevisionSeason
            or CollectionType.Artist
            or CollectionType.Movie
            or CollectionType.Episode
            or CollectionType.MusicVideo
            or CollectionType.OtherVideo
            or CollectionType.Song
            or CollectionType.Image
            or CollectionType.RemoteStream;

    public static (MediaCollectionViewModel Collection,
        MultiCollectionViewModel MultiCollection,
        SmartCollectionViewModel SmartCollection,
        NamedMediaItemViewModel MediaItem) ResolveSelection(CollectionType collectionType, int selectedId) =>
        collectionType switch
        {
            CollectionType.Collection => (
                new MediaCollectionViewModel(
                    CollectionType.Collection,
                    selectedId,
                    string.Empty,
                    false,
                    MediaItemState.Normal),
                null,
                null,
                null),
            CollectionType.MultiCollection => (
                null,
                new MultiCollectionViewModel(selectedId, string.Empty, [], []),
                null,
                null),
            CollectionType.SmartCollection => (
                null,
                null,
                new SmartCollectionViewModel(selectedId, string.Empty, string.Empty),
                null),

            // Any media-item-backed collection type (TelevisionShow, TelevisionSeason,
            // Artist, Movie, Episode, MusicVideo, OtherVideo, Song, Image, ...) resolves to
            // the MediaItem VM keyed by media item id. The caller (RerunCollectionController)
            // has already validated CollectionType via IsSupportedSelectionType, so this
            // catch-all only ever receives a real media-item type.
            _ => (
                null,
                null,
                null,
                new NamedMediaItemViewModel(selectedId, string.Empty))
        };
}