//
// Copyright (c) 2019-2021 Ryujinx
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//

using Ryujinx.Audio.Renderer.Dsp.State;
using Ryujinx.Audio.Renderer.Parameter.Effect;
using Ryujinx.Audio.Renderer.Server.Effect;
using System;
using System.Diagnostics;

namespace Ryujinx.Audio.Renderer.Dsp.Command
{
    public class Reverb3dCommand : ICommand
    {
        private static readonly int[] OutputEarlyIndicesTableMono = new int[20] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
        private static readonly int[] TargetEarlyDelayLineIndicesTableMono = new int[20] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 };
        private static readonly int[] TargetOutputFeedbackIndicesTableMono = new int[1] { 0 };

        private static readonly int[] OutputEarlyIndicesTableStereo = new int[20] { 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1 };
        private static readonly int[] TargetEarlyDelayLineIndicesTableStereo = new int[20] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 };
        private static readonly int[] TargetOutputFeedbackIndicesTableStereo = new int[2] { 0, 1 };

        private static readonly int[] OutputEarlyIndicesTableQuadraphonic = new int[20] { 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 0, 0, 0, 0, 3, 3, 3 };
        private static readonly int[] TargetEarlyDelayLineIndicesTableQuadraphonic = new int[20] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 };
        private static readonly int[] TargetOutputFeedbackIndicesTableQuadraphonic = new int[4] { 0, 1, 2, 3 };

        private static readonly int[] OutputEarlyIndicesTableSurround = new int[40] { 4, 5, 0, 5, 0, 5, 1, 5, 1, 5, 1, 5, 1, 5, 2, 5, 2, 5, 2, 5, 1, 5, 1, 5, 1, 5, 0, 5, 0, 5, 0, 5, 0, 5, 3, 5, 3, 5, 3, 5 };
        private static readonly int[] TargetEarlyDelayLineIndicesTableSurround = new int[40] { 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19 };
        private static readonly int[] TargetOutputFeedbackIndicesTableSurround = new int[6] { 0, 1, 2, 3, -1, 3 };

        public bool Enabled { get; set; }

        public int NodeId { get; }

        public CommandType CommandType => CommandType.Reverb3d;

        public ulong EstimatedProcessingTime { get; set; }

        public ushort InputBufferIndex { get; }
        public ushort OutputBufferIndex { get; }

        public Reverb3dParameter Parameter => _parameter;
        public Memory<Reverb3dState> State { get; }
        public ulong WorkBuffer { get; }
        public ushort[] OutputBufferIndices { get; }
        public ushort[] InputBufferIndices { get; }

        public bool IsEffectEnabled { get; }

        private Reverb3dParameter _parameter;

        public Reverb3dCommand(uint bufferOffset, Reverb3dParameter parameter, Memory<Reverb3dState> state, bool isEnabled, ulong workBuffer, int nodeId)
        {
            Enabled = true;
            IsEffectEnabled = isEnabled;
            NodeId = nodeId;
            _parameter = parameter;
            State = state;
            WorkBuffer = workBuffer;

            InputBufferIndices = new ushort[Constants.VoiceChannelCountMax];
            OutputBufferIndices = new ushort[Constants.VoiceChannelCountMax];

            for (int i = 0; i < Parameter.ChannelCount; i++)
            {
                InputBufferIndices[i] = (ushort)(bufferOffset + Parameter.Input[i]);
                OutputBufferIndices[i] = (ushort)(bufferOffset + Parameter.Output[i]);
            }
        }

        private void ProcessReverb3dMono(Memory<float>[] outputBuffers, ReadOnlyMemory<float>[] inputBuffers, uint sampleCount)
        {
            ProcessReverb3dGeneric(outputBuffers, inputBuffers, sampleCount, OutputEarlyIndicesTableMono, TargetEarlyDelayLineIndicesTableMono, TargetOutputFeedbackIndicesTableMono);
        }

        private void ProcessReverb3dStereo(Memory<float>[] outputBuffers, ReadOnlyMemory<float>[] inputBuffers, uint sampleCount)
        {
            ProcessReverb3dGeneric(outputBuffers, inputBuffers, sampleCount, OutputEarlyIndicesTableStereo, TargetEarlyDelayLineIndicesTableStereo, TargetOutputFeedbackIndicesTableStereo);
        }

        private void ProcessReverb3dQuadraphonic(Memory<float>[] outputBuffers, ReadOnlyMemory<float>[] inputBuffers, uint sampleCount)
        {
            ProcessReverb3dGeneric(outputBuffers, inputBuffers, sampleCount, OutputEarlyIndicesTableQuadraphonic, TargetEarlyDelayLineIndicesTableQuadraphonic, TargetOutputFeedbackIndicesTableQuadraphonic);
        }

        private void ProcessReverb3dSurround(Memory<float>[] outputBuffers, ReadOnlyMemory<float>[] inputBuffers, uint sampleCount)
        {
            ProcessReverb3dGeneric(outputBuffers, inputBuffers, sampleCount, OutputEarlyIndicesTableSurround, TargetEarlyDelayLineIndicesTableSurround, TargetOutputFeedbackIndicesTableSurround);
        }

        private void ProcessReverb3dGeneric(Memory<float>[] outputBuffers, ReadOnlyMemory<float>[] inputBuffers, uint sampleCount, ReadOnlySpan<int> outputEarlyIndicesTable, ReadOnlySpan<int> targetEarlyDelayLineIndicesTable, ReadOnlySpan<int> targetOutputFeedbackIndicesTable)
        {
            const int delayLineSampleIndexOffset = 1;

            ref Reverb3dState state = ref State.Span[0];

            bool isMono = Parameter.ChannelCount == 1;
            bool isSurround = Parameter.ChannelCount == 6;

            float[] outputValues = new float[Constants.ChannelCountMax];
            float[] channelInput = new float[Parameter.ChannelCount];
            float[] feedbackValues = new float[4];
            float[] feedbackOutputValues = new float[4];
            float[] values = new float[4];

            for (int sampleIndex = 0; sampleIndex < sampleCount; sampleIndex++)
            {
                outputValues.AsSpan().Fill(0);

                float tapOut = state.PreDelayLine.TapUnsafe(state.ReflectionDelayTime, delayLineSampleIndexOffset);

                for (int i = 0; i < targetEarlyDelayLineIndicesTable.Length; i++)
                {
                    int earlyDelayIndex = targetEarlyDelayLineIndicesTable[i];
                    int outputIndex = outputEarlyIndicesTable[i];

                    float tempTapOut = state.PreDelayLine.TapUnsafe(state.EarlyDelayTime[earlyDelayIndex], delayLineSampleIndexOffset);

                    outputValues[outputIndex] += tempTapOut * state.EarlyGain[earlyDelayIndex];
                }

                float targetPreDelayValue = 0;

                for (int channelIndex = 0; channelIndex < Parameter.ChannelCount; channelIndex++)
                {
                    channelInput[channelIndex] = inputBuffers[channelIndex].Span[sampleIndex];
                    targetPreDelayValue += channelInput[channelIndex];
                }

                for (int i = 0; i < Parameter.ChannelCount; i++)
                {
                    outputValues[i] *= state.EarlyReflectionsGain;
                }

                state.PreviousPreDelayValue = (targetPreDelayValue * state.TargetPreDelayGain) + (state.PreviousPreDelayValue * state.PreviousPreDelayGain);

                state.PreDelayLine.Update(state.PreviousPreDelayValue);

                for (int i = 0; i < state.FdnDelayLines.Length; i++)
                {
                    float fdnValue = state.FdnDelayLines[i].Read();

                    float feedbackOutputValue = fdnValue * state.DecayDirectFdnGain[i] + state.PreviousFeedbackOutputDecayed[i];

                    state.PreviousFeedbackOutputDecayed[i] = (fdnValue * state.DecayCurrentFdnGain[i]) + (feedbackOutputValue * state.DecayCurrentOutputGain[i]);

                    feedbackOutputValues[i] = feedbackOutputValue;
                }

                feedbackValues[0] = feedbackOutputValues[2] + feedbackOutputValues[1];
                feedbackValues[1] = -feedbackOutputValues[0] - feedbackOutputValues[3];
                feedbackValues[2] = feedbackOutputValues[0] - feedbackOutputValues[3];
                feedbackValues[3] = feedbackOutputValues[1] - feedbackOutputValues[2];

                for (int i = 0; i < state.DecayDelays1.Length; i++)
                {
                    float temp = state.DecayDelays1[i].Update(tapOut * state.LateReverbGain + feedbackValues[i]);

                    values[i] = state.DecayDelays2[i].Update(temp);

                    state.FdnDelayLines[i].Update(values[i]);
                }

                for (int channelIndex = 0; channelIndex < targetOutputFeedbackIndicesTable.Length; channelIndex++)
                {
                    int targetOutputFeedbackIndex = targetOutputFeedbackIndicesTable[channelIndex];

                    if (targetOutputFeedbackIndex >= 0)
                    {
                        outputBuffers[channelIndex].Span[sampleIndex] = (outputValues[channelIndex] + values[targetOutputFeedbackIndex] + channelInput[channelIndex] * state.DryGain);
                    }
                }

                if (isMono)
                {
                    outputBuffers[0].Span[sampleIndex] += values[1];
                }

                if (isSurround)
                {
                    outputBuffers[4].Span[sampleIndex] += (outputValues[4] + state.BackLeftDelayLine.Update((values[2] - values[3]) * 0.5f) + channelInput[4] * state.DryGain);
                }
            }
        }

        public void ProcessReverb3d(CommandList context)
        {
            Debug.Assert(Parameter.IsChannelCountValid());

            if (IsEffectEnabled && Parameter.IsChannelCountValid())
            {
                ReadOnlyMemory<float>[] inputBuffers = new ReadOnlyMemory<float>[Parameter.ChannelCount];
                Memory<float>[] outputBuffers = new Memory<float>[Parameter.ChannelCount];

                for (int i = 0; i < Parameter.ChannelCount; i++)
                {
                    inputBuffers[i] = context.GetBufferMemory(InputBufferIndices[i]);
                    outputBuffers[i] = context.GetBufferMemory(OutputBufferIndices[i]);
                }

                switch (Parameter.ChannelCount)
                {
                    case 1:
                        ProcessReverb3dMono(outputBuffers, inputBuffers, context.SampleCount);
                        break;
                    case 2:
                        ProcessReverb3dStereo(outputBuffers, inputBuffers, context.SampleCount);
                        break;
                    case 4:
                        ProcessReverb3dQuadraphonic(outputBuffers, inputBuffers, context.SampleCount);
                        break;
                    case 6:
                        ProcessReverb3dSurround(outputBuffers, inputBuffers, context.SampleCount);
                        break;
                    default:
                        throw new NotImplementedException($"{Parameter.ChannelCount}");
                }
            }
            else
            {
                for (int i = 0; i < Parameter.ChannelCount; i++)
                {
                    if (InputBufferIndices[i] != OutputBufferIndices[i])
                    {
                        context.GetBufferMemory(InputBufferIndices[i]).CopyTo(context.GetBufferMemory(OutputBufferIndices[i]));
                    }
                }
            }
        }

        public void Process(CommandList context)
        {
            ref Reverb3dState state = ref State.Span[0];

            if (IsEffectEnabled)
            {
                if (Parameter.ParameterStatus == UsageState.Invalid)
                {
                    state = new Reverb3dState(ref _parameter, WorkBuffer);
                }
                else if (Parameter.ParameterStatus == UsageState.New)
                {
                    state.UpdateParameter(ref _parameter);
                }
            }

            ProcessReverb3d(context);
        }
    }
}