namespace Kermalis.VGMusicStudio.Core.GBA.MP2K;

public sealed partial class MP2KPlayer : Player
{
	protected override string Name => "MP2K Player";

	private readonly string?[] _voiceTypeCache;
	internal readonly MP2KConfig Config;
	internal readonly MP2KMixer MMixer;
	private MP2KLoadedSong? _loadedSong;

	public override ushort Tempo { get; set; }
	internal int TempoStack;
	private long _elapsedLoops;

	private int? _prevVoiceTableOffset;

	public override ILoadedSong? LoadedSong => _loadedSong;
	protected override Mixer Mixer => MMixer;

	internal MP2KPlayer(MP2KConfig config, MP2KMixer mixer)
		: base(GBAUtils.AGB_FPS)
	{
		Config = config;
		MMixer = mixer;

		_voiceTypeCache = new string[256];
	}

	public override void LoadSong(int index)
	{
		if (_loadedSong is not null)
		{
			_loadedSong = null;
		}

		// If there's an exception, this will remain null
		_loadedSong = new MP2KLoadedSong(this, index);
		if (_loadedSong.Events.Length == 0)
		{
			_loadedSong = null;
			return;
		}

		_loadedSong.CheckVoiceTypeCache(ref _prevVoiceTableOffset, _voiceTypeCache);
		_loadedSong.SetTicks();
	}
	public override void UpdateSongState(SongState info)
	{
		info.Tempo = Tempo;
		_loadedSong!.UpdateSongState(info, _voiceTypeCache);
	}
	internal override void InitEmulation()
	{
		Tempo = 150;
		TempoStack = 0;
		_elapsedLoops = 0;
		ElapsedTicks = 0;
		MMixer.ResetFade();
		MP2KTrack[] tracks = _loadedSong!.Tracks;
		for (int i = 0; i < tracks.Length; i++)
		{
			tracks[i].Init();
		}
	}
	protected override void SetCurTick(long ticks)
	{
		_loadedSong!.SetCurTick(ticks);
	}
	protected override void OnStopped()
	{
		MP2KTrack[] tracks = _loadedSong!.Tracks;
		for (int i = 0; i < tracks.Length; i++)
		{
			tracks[i].StopAllChannels();
		}
	}

	protected override bool Tick(bool playing, bool recording)
	{
		MP2KLoadedSong s = _loadedSong!;

		bool allDone = false;
		while (!allDone && TempoStack >= 150)
		{
			TempoStack -= 150;
			allDone = true;
			for (int i = 0; i < s.Tracks.Length; i++)
			{
				TickTrack(s, s.Tracks[i], ref allDone);
			}
			if (MMixer.IsFadeDone())
			{
				allDone = true;
			}
		}
		if (!allDone)
		{
			TempoStack += Tempo;
		}
		MMixer.Process(playing, recording);
		return allDone;
	}
	private void TickTrack(MP2KLoadedSong s, MP2KTrack track, ref bool allDone)
	{
		track.Tick();
		bool update = false;
		while (track.Rest == 0 && !track.Stopped)
		{
			s.ExecuteNext(track, ref update);
		}
		if (track.Index == s.LongestTrack)
		{
			HandleTicksAndLoop(s, track);
		}
		if (!track.Stopped)
		{
			allDone = false;
		}
		if (track.Channels.Count > 0)
		{
			allDone = false;
			if (update || track.LFODepth > 0)
			{
				track.UpdateChannels();
			}
		}
	}
	private void HandleTicksAndLoop(MP2KLoadedSong s, MP2KTrack track)
	{
		if (ElapsedTicks != s.MaxTicks)
		{
			ElapsedTicks++;
			return;
		}

		// Track reached the detected end, update loops/ticks accordingly
		if (track.Stopped)
		{
			return;
		}

		_elapsedLoops++;
		UpdateElapsedTicksAfterLoop(s.Events[track.Index], track.DataOffset, track.Rest);
		if (ShouldFadeOut && _elapsedLoops > NumLoops && !MMixer.IsFading())
		{
			MMixer.BeginFadeOut();
		}
	}

	public void SaveAsMIDI(string fileName, MIDISaveArgs args)
	{
		_loadedSong!.SaveAsMIDI(fileName, args);
	}
}