using System;
using System.Runtime.InteropServices;

namespace Nerfed.Runtime.Audio;

/// <summary>
/// Use this in conjunction with SourceVoice.SetReverbEffectChain to add reverb to a voice.
/// </summary>
public unsafe class ReverbEffect : SubmixVoice
{
	// Defaults based on FAUDIOFX_I3DL2_PRESET_GENERIC
	public static FAudio.FAudioFXReverbParameters DefaultParams = new FAudio.FAudioFXReverbParameters
	{
		WetDryMix = 100.0f,
		ReflectionsDelay = 7,
		ReverbDelay = 11,
		RearDelay = FAudio.FAUDIOFX_REVERB_DEFAULT_REAR_DELAY,
		PositionLeft = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION,
		PositionRight = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION,
		PositionMatrixLeft = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX,
		PositionMatrixRight = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX,
		EarlyDiffusion = 15,
		LateDiffusion = 15,
		LowEQGain = 8,
		LowEQCutoff = 4,
		HighEQGain = 8,
		HighEQCutoff = 6,
		RoomFilterFreq = 5000f,
		RoomFilterMain = -10f,
		RoomFilterHF = -1f,
		ReflectionsGain = -26.0200005f,
		ReverbGain = 10.0f,
		DecayTime = 1.49000001f,
		Density = 100.0f,
		RoomSize = FAudio.FAUDIOFX_REVERB_DEFAULT_ROOM_SIZE
	};

	public FAudio.FAudioFXReverbParameters Params { get; private set; }

	public ReverbEffect(AudioDevice audioDevice, uint processingStage) : base(audioDevice, 1, audioDevice.DeviceDetails.OutputFormat.Format.nSamplesPerSec, processingStage)
	{
		/* Init reverb */
		IntPtr reverb;
		FAudio.FAudioCreateReverb(out reverb, 0);

		FAudio.FAudioEffectChain chain = new FAudio.FAudioEffectChain();
		FAudio.FAudioEffectDescriptor descriptor = new FAudio.FAudioEffectDescriptor
		{
			InitialState = 1,
			OutputChannels = 1,
			pEffect = reverb
		};

		chain.EffectCount = 1;
		chain.pEffectDescriptors = (nint) (&descriptor);

		FAudio.FAudioVoice_SetEffectChain(
			Handle,
			ref chain
		);

		FAudio.FAPOBase_Release(reverb);

		SetParams(DefaultParams);
	}

	public void SetParams(in FAudio.FAudioFXReverbParameters reverbParams)
	{
		Params = reverbParams;

		fixed (FAudio.FAudioFXReverbParameters* reverbParamsPtr = &reverbParams)
		{
			FAudio.FAudioVoice_SetEffectParameters(
				Handle,
				0,
				(nint) reverbParamsPtr,
				(uint) Marshal.SizeOf<FAudio.FAudioFXReverbParameters>(),
				0
			);
		}
	}
}