#nullable enable
using System.Collections.Generic;
using System.Linq;
using ErsatzTV.Application.MediaCollections;
using ErsatzTV.Core.Domain;

namespace ErsatzTV.Controllers.Api.Requests;

public record PlaylistItemRequest(
    int Index,
    CollectionType CollectionType,
    int? CollectionId,
    int? MultiCollectionId,
    int? SmartCollectionId,
    int? MediaItemId,
    PlaybackOrder PlaybackOrder,
    int? Count,
    bool PlayAll,
    bool IncludeInProgramGuide)
{
    public ReplacePlaylistItem ToReplaceCommand(int index) =>
        new(
            index,
            CollectionType,
            CollectionId,
            MultiCollectionId,
            SmartCollectionId,
            MediaItemId,
            PlaybackOrder,
            Count,
            PlayAll,
            IncludeInProgramGuide);

    // Mirrors ReplacePlaylistItemsHandler.CollectionTypeMustBeValid: the id required for the
    // item's collection type must be present. Kept in sync with that handler so the PUT and
    // preview endpoints enforce the same rule (the handler operates on the command type in the
    // Application layer and cannot reference this request DTO, hence the parallel logic).
    public bool HasRequiredId() =>
        CollectionType switch
        {
            CollectionType.Collection => CollectionId is not null,
            CollectionType.MultiCollection => MultiCollectionId is not null,
            CollectionType.SmartCollection => SmartCollectionId is not null,
            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 => MediaItemId is not null,
            _ => false
        };
}

public record ReplacePlaylistRequest(string? Name, List<PlaylistItemRequest>? Items)
{
    public ReplacePlaylistItems ToCommand(int id) =>
        new(id, Name ?? string.Empty, BuildItems());

    // Preview operates on the posted draft, so there is no persisted playlist id (0).
    public ReplacePlaylistItems ToReplaceCommand() =>
        new(0, Name ?? string.Empty, BuildItems());

    // Array indexes of draft items missing the id required for their collection type.
    public List<int> ItemsMissingRequiredId()
    {
        List<PlaylistItemRequest> items = Items ?? new List<PlaylistItemRequest>();
        var invalid = new List<int>();
        for (int i = 0; i < items.Count; i++)
        {
            if (!items[i].HasRequiredId())
            {
                invalid.Add(i);
            }
        }

        return invalid;
    }

    private List<ReplacePlaylistItem> BuildItems() =>
        (Items ?? new List<PlaylistItemRequest>())
        .Select((item, index) => item.ToReplaceCommand(index))
        .ToList();
}