using System;

using Essgee.Utilities;

namespace Essgee.Emulation.Audio
{
	public class SegaGGPSG : SegaSMSPSG
	{
		public const int PortStereoControl = 0x06;

		[StateRequired]
		readonly bool[] channel0Enable, channel1Enable, channel2Enable, channel3Enable;

		public SegaGGPSG() : base()
		{
			channel0Enable = new bool[2];
			channel1Enable = new bool[2];
			channel2Enable = new bool[2];
			channel3Enable = new bool[2];
		}

		public override void Reset()
		{
			base.Reset();

			WritePort(PortStereoControl, 0xFF);
		}

		protected override void GenerateSample()
		{
			for (int i = 0; i < numOutputChannels; i++)
			{
				/* Generate samples */
				var ch1 = (channel0Enable[i] ? (short)(volumeTable[volumeRegisters[0]] * ((toneRegisters[0] < 2 ? true : channelOutput[0]) ? 1.0 : 0.0)) : (short)0);
				var ch2 = (channel1Enable[i] ? (short)(volumeTable[volumeRegisters[1]] * ((toneRegisters[1] < 2 ? true : channelOutput[1]) ? 1.0 : 0.0)) : (short)0);
				var ch3 = (channel2Enable[i] ? (short)(volumeTable[volumeRegisters[2]] * ((toneRegisters[2] < 2 ? true : channelOutput[2]) ? 1.0 : 0.0)) : (short)0);
				var ch4 = (channel3Enable[i] ? (short)(volumeTable[volumeRegisters[3]] * (noiseLfsr & 0x1)) : (short)0);

				channelSampleBuffer[0].Add(ch1);
				channelSampleBuffer[1].Add(ch2);
				channelSampleBuffer[2].Add(ch3);
				channelSampleBuffer[3].Add(ch4);

				/* Mix samples */
				var mixed = 0;
				if (channel1ForceEnable) mixed += ch1;
				if (channel2ForceEnable) mixed += ch2;
				if (channel3ForceEnable) mixed += ch3;
				if (channel4ForceEnable) mixed += ch4;
				mixed /= numChannels;

				mixedSampleBuffer.Add((short)mixed);
			}
		}

		public override void WritePort(byte port, byte data)
		{
			if (port == PortStereoControl)
			{
				/* Stereo control */
				channel0Enable[0] = ((data & 0x10) != 0);   /* Ch1 Left */
				channel0Enable[1] = ((data & 0x01) != 0);   /* Ch1 Right */

				channel1Enable[0] = ((data & 0x20) != 0);   /* Ch2 Left */
				channel1Enable[1] = ((data & 0x02) != 0);   /* Ch2 Right */

				channel2Enable[0] = ((data & 0x40) != 0);   /* Ch3 Left */
				channel2Enable[1] = ((data & 0x04) != 0);   /* Ch3 Right */

				channel3Enable[0] = ((data & 0x80) != 0);   /* Ch4 Left */
				channel3Enable[1] = ((data & 0x08) != 0);   /* Ch4 Right */
			}
			else
				base.WritePort(port, data);
		}
	}
}