namespace StoicGoose.Core.Sound
{
	/* Channel 2, supports PCM voice */
	public sealed class SoundChannel2
	{
		const int counterReload = 2048;

		ushort counter;
		byte pointer;

		public byte OutputLeft { get; set; }
		public byte OutputRight { get; set; }

		readonly WaveTableReadDelegate waveTableReadDelegate;

		/* REG_SND_CH2_PITCH */
		public ushort Pitch { get; set; }
		/* REG_SND_CH2_VOL */
		public byte VolumeLeft { get; set; }
		public byte VolumeRight { get; set; }
		/* REG_SND_CTRL */
		public bool IsEnabled { get; set; }
		public bool IsVoiceEnabled { get; set; }

		/* REG_SND_VOICE_CTRL */
		public bool PcmRightFull { get; set; }
		public bool PcmRightHalf { get; set; }
		public bool PcmLeftFull { get; set; }
		public bool PcmLeftHalf { get; set; }

		public SoundChannel2(WaveTableReadDelegate waveTableRead) => waveTableReadDelegate = waveTableRead;

		public void Reset()
		{
			counter = counterReload;
			pointer = 0;
			OutputLeft = OutputRight = 0;

			Pitch = 0;
			VolumeLeft = VolumeRight = 0;
			IsEnabled = false;

			IsVoiceEnabled = false;

			PcmRightFull = PcmRightHalf = PcmLeftFull = PcmLeftHalf = false;
		}

		public void Step()
		{
			if (IsVoiceEnabled)
			{
				var pcm = (ushort)(VolumeLeft << 4 | VolumeRight);
				OutputLeft = (byte)(PcmLeftFull ? pcm : (PcmLeftHalf ? pcm >> 1 : 0));
				OutputRight = (byte)(PcmRightFull ? pcm : (PcmRightHalf ? pcm >> 1 : 0));
			}
			else
			{
				counter--;
				if (counter == Pitch)
				{
					var data = waveTableReadDelegate((ushort)(pointer >> 1));
					if ((pointer & 0b1) == 0b1) data >>= 4;
					data &= 0x0F;

					OutputLeft = (byte)(data * VolumeLeft);
					OutputRight = (byte)(data * VolumeRight);

					pointer++;
					pointer &= 0b11111;
					counter = counterReload;
				}
			}
		}
	}
}