harmonia/Harmonia.Core/Playlists/Playlist.cs

using Harmonia.Core.Extensions;
using Harmonia.Core.Models;

namespace Harmonia.Core.Playlists;

public class Playlist
{
    private readonly List<PlaylistSong> _songs = [];

    public string UID { get; init; } = Guid.NewGuid().ToString();
    public string? Name { get; set; }
    public IReadOnlyList<PlaylistSong> Songs => _songs;
    public List<GroupOption> GroupOptions { get; set; } = [];
    public List<SortOption> SortOptions { get; set; } = [];
    public bool IsLocked { get; set; }

    public event EventHandler<PlaylistUpdatedEventArgs>? PlaylistUpdated;

    public void AddSong(Song song, int? index = null)
    {
        AddSongs([song], index);
    }

    public void AddSongs(Song[] songs, int? index = null)
    {
        PlaylistSong[] playlistSongs = songs.Select(song => new PlaylistSong(song)).ToArray();

        AddSongs(playlistSongs, index);
    }

    private void AddSongs(PlaylistSong[] playlistSongs, int? index = null)
    {
        if (IsLocked)
            return;

        int insertIndex = index ?? Songs.Count;

        _songs.InsertRange(insertIndex, playlistSongs);

        PlaylistUpdatedEventArgs eventArgs = new()
        {
            Action = PlaylistUpdateAction.Add,
            Index = insertIndex,
            Count = playlistSongs.Length,
            Songs = playlistSongs
        };

        PlaylistUpdated?.Invoke(this, eventArgs);
    }

    public void MoveSong(PlaylistSong playlistSong, int newIndex)
    {
        int currentIndex = _songs.IndexOf(playlistSong);

        MoveSong(currentIndex, newIndex);
    }

    public void MoveSong(int oldIndex, int newIndex)
    {
        if (IsLocked)
            return;

        if (oldIndex == newIndex)
            return;

        PlaylistSong playlistSong = Songs[oldIndex];

        _songs.Remove(playlistSong);
        _songs.Insert(newIndex, playlistSong);

        PlaylistUpdatedEventArgs eventArgs = new()
        {
            Action = PlaylistUpdateAction.Move,
            Index = oldIndex,
            Count = 1,
            Songs = [playlistSong],
            NewIndex = newIndex
        };

        PlaylistUpdated?.Invoke(this, eventArgs);
    }

    public void SortSongs(PlaylistSong[] playlistSongs, SortOption[] sortOptions)
    {
        Dictionary<int, PlaylistSong> oldPlaylistSongs = playlistSongs
            .OrderBy(_songs.IndexOf)
            .ToDictionary(_songs.IndexOf, playlistSong => playlistSong);

        Song[] songs = playlistSongs.Select(playlistSong => playlistSong.Song).ToArray();
        Song[] sortedSongs = [.. songs.SortBy(sortOptions)];

        int currentSortIndex = 0;

        foreach (int index in oldPlaylistSongs.Keys)
        {
            PlaylistSong playlistSong = oldPlaylistSongs[index];
            Song sortedSong = sortedSongs[currentSortIndex++];
            PlaylistSong newPlaylistSong = playlistSongs.First(ps => ps.Song == sortedSong);

            if (newPlaylistSong == playlistSong)
                continue;

            _songs.RemoveAt(index);
            _songs.Insert(index, newPlaylistSong);
        }

        PlaylistUpdatedEventArgs eventArgs = new()
        {
            Action = PlaylistUpdateAction.Reset,
            Index = -1,
            Count = playlistSongs.Length,
            Songs = playlistSongs
        };

        PlaylistUpdated?.Invoke(this, eventArgs);
    }

    public void RemoveSong(int index)
    {
        RemoveSongs(index, 1);
    }

    public void RemoveSongs(int index, int count)
    {
        PlaylistSong[] playlistSongs = [.. _songs.GetRange(index, count)];

        RemoveSongs(playlistSongs);
    }

    public void RemoveSong(PlaylistSong playlistSong)
    {
        RemoveSongs([playlistSong]);
    }

    public void RemoveSongs(PlaylistSong[] playlistSongs)
    {
        if (IsLocked)
            return;

        List<PlaylistSong> removedSongs = [];

        foreach (PlaylistSong playlistSong in playlistSongs)
        {
            if (_songs.Remove(playlistSong))
            {
                removedSongs.Add(playlistSong);
            }
        }

        if (removedSongs.Count == 0)
            return;

        PlaylistUpdatedEventArgs eventArgs = new()
        {
            Action = PlaylistUpdateAction.Remove,
            Index = -1,
            Count = removedSongs.Count,
            Songs = playlistSongs
        };

        PlaylistUpdated?.Invoke(this, eventArgs);
    }
}