/*
  ==============================================================================

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For the technical preview this file cannot be licensed commercially.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{
namespace dsp
{

//==============================================================================
template <typename SampleType>
DryWetMixer<SampleType>::DryWetMixer()
    : DryWetMixer (0)
{
}

template <typename SampleType>
DryWetMixer<SampleType>::DryWetMixer (int maximumWetLatencyInSamplesIn)
    : dryDelayLine (maximumWetLatencyInSamplesIn),
      maximumWetLatencyInSamples (maximumWetLatencyInSamplesIn)
{
    dryDelayLine.setDelay (0);

    update();
    reset();
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::setMixingRule (MixingRule newRule)
{
    currentMixingRule = newRule;
    update();
}

template <typename SampleType>
void DryWetMixer<SampleType>::setWetMixProportion (SampleType newWetMixProportion)
{
    jassert (isPositiveAndNotGreaterThan (newWetMixProportion, 1.0));

    mix = jlimit (static_cast<SampleType> (0.0), static_cast<SampleType> (1.0), newWetMixProportion);
    update();
}

template <typename SampleType>
void DryWetMixer<SampleType>::setWetLatency (SampleType wetLatencySamples)
{
    dryDelayLine.setDelay (wetLatencySamples);
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::prepare (const ProcessSpec& spec)
{
    jassert (spec.sampleRate > 0);
    jassert (spec.numChannels > 0);

    sampleRate = spec.sampleRate;

    dryDelayLine.prepare (spec);
    bufferDry.setSize ((int) spec.numChannels, (int) spec.maximumBlockSize, false, false, true);

    update();
    reset();
}

template <typename SampleType>
void DryWetMixer<SampleType>::reset()
{
    dryVolume.reset (sampleRate, 0.05);
    wetVolume.reset (sampleRate, 0.05);

    dryDelayLine.reset();

    fifo = SingleThreadedAbstractFifo (nextPowerOfTwo (bufferDry.getNumSamples()));
    bufferDry.setSize (bufferDry.getNumChannels(), fifo.getSize(), false, false, true);
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::pushDrySamples (const AudioBlock<const SampleType> drySamples)
{
    jassert (drySamples.getNumChannels() <= (size_t) bufferDry.getNumChannels());
    jassert (drySamples.getNumSamples() <= (size_t) fifo.getRemainingSpace());

    auto offset = 0;

    for (const auto& range : fifo.write ((int) drySamples.getNumSamples()))
    {
        if (range.getLength() == 0)
            continue;

        auto block = AudioBlock<SampleType> (bufferDry).getSubsetChannelBlock (0, drySamples.getNumChannels())
                                                       .getSubBlock ((size_t) range.getStart(), (size_t) range.getLength());

        auto inputBlock = drySamples.getSubBlock ((size_t) offset, (size_t) range.getLength());

        if (maximumWetLatencyInSamples == 0)
            block.copyFrom (inputBlock);
        else
            dryDelayLine.process (ProcessContextNonReplacing<SampleType> (inputBlock, block));

        offset += range.getLength();
    }
}

template <typename SampleType>
void DryWetMixer<SampleType>::mixWetSamples (AudioBlock<SampleType> inOutBlock)
{
    inOutBlock.multiplyBy (wetVolume);

    jassert (inOutBlock.getNumSamples() <= (size_t) fifo.getNumReadable());

    auto offset = 0;

    for (const auto& range : fifo.read ((int) inOutBlock.getNumSamples()))
    {
        if (range.getLength() == 0)
            continue;

        auto block = AudioBlock<SampleType> (bufferDry).getSubsetChannelBlock (0, inOutBlock.getNumChannels())
                                                       .getSubBlock ((size_t) range.getStart(), (size_t) range.getLength());
        block.multiplyBy (dryVolume);
        inOutBlock.getSubBlock ((size_t) offset).add (block);

        offset += range.getLength();
    }
}

//==============================================================================
template <typename SampleType>
void DryWetMixer<SampleType>::update()
{
    SampleType dryValue, wetValue;

    switch (currentMixingRule)
    {
        case MixingRule::balanced:
            dryValue = static_cast<SampleType> (2.0) * jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - mix);
            wetValue = static_cast<SampleType> (2.0) * jmin (static_cast<SampleType> (0.5), mix);
            break;

        case MixingRule::linear:
            dryValue = static_cast<SampleType> (1.0) - mix;
            wetValue = mix;
            break;

        case MixingRule::sin3dB:
            dryValue = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)));
            wetValue = static_cast<SampleType> (std::sin (0.5 * MathConstants<double>::pi * mix));
            break;

        case MixingRule::sin4p5dB:
            dryValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)), 1.5));
            wetValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * mix), 1.5));
            break;

        case MixingRule::sin6dB:
            dryValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * (1.0 - mix)), 2.0));
            wetValue = static_cast<SampleType> (std::pow (std::sin (0.5 * MathConstants<double>::pi * mix), 2.0));
            break;

        case MixingRule::squareRoot3dB:
            dryValue = std::sqrt (static_cast<SampleType> (1.0) - mix);
            wetValue = std::sqrt (mix);
            break;

        case MixingRule::squareRoot4p5dB:
            dryValue = static_cast<SampleType> (std::pow (std::sqrt (1.0 - mix), 1.5));
            wetValue = static_cast<SampleType> (std::pow (std::sqrt (mix), 1.5));
            break;

        default:
            dryValue = jmin (static_cast<SampleType> (0.5), static_cast<SampleType> (1.0) - mix);
            wetValue = jmin (static_cast<SampleType> (0.5), mix);
            break;
    }

    dryVolume.setTargetValue (dryValue);
    wetVolume.setTargetValue (wetValue);
}

//==============================================================================
template class DryWetMixer<float>;
template class DryWetMixer<double>;


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

struct DryWetMixerTests : public UnitTest
{
    DryWetMixerTests() : UnitTest ("DryWetMixer", UnitTestCategories::dsp) {}

    enum class Kind { down, up };

    static auto getRampBuffer (ProcessSpec spec, Kind kind)
    {
        AudioBuffer<float> buffer ((int) spec.numChannels, (int) spec.maximumBlockSize);

        for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
        {
            for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
            {
                const auto ramp = kind == Kind::up ? sample : spec.maximumBlockSize - sample;

                buffer.setSample ((int) channel,
                                  (int) sample,
                                  jmap ((float) ramp, 0.0f, (float) spec.maximumBlockSize, 0.0f, 1.0f));
            }
        }

        return buffer;
    }

    void runTest() override
    {
        constexpr ProcessSpec spec { 44100.0, 512, 2 };
        constexpr auto numBlocks = 5;

        const auto wetBuffer = getRampBuffer (spec, Kind::up);
        const auto dryBuffer = getRampBuffer (spec, Kind::down);

        for (auto maxLatency : { 0, 100, 200, 512 })
        {
            beginTest ("Mixer can push multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                        mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (sample, 1));

                    // Mix wet samples in one go
                    auto outputBlock = wetBuffer;
                    mixer.mixWetSamples ({ outputBlock });

                    // The output block should contain the wet and dry samples averaged
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, (int) sample);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can pop multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push samples in one go
                    mixer.pushDrySamples ({ dryBuffer });

                    // Process wet samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        AudioBuffer<float> outputBlock ((int) spec.numChannels, 1);
                        AudioBlock<const float> (wetBuffer).getSubBlock (sample, 1).copyTo (outputBlock);
                        mixer.mixWetSamples ({ outputBlock });

                        // The output block should contain the wet and dry samples averaged
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, 0);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can push and pop multiple small buffers");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push dry samples and process wet samples one-by-one
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (sample, 1));

                        AudioBuffer<float> outputBlock ((int) spec.numChannels, 1);
                        AudioBlock<const float> (wetBuffer).getSubBlock (sample, 1).copyTo (outputBlock);
                        mixer.mixWetSamples ({ outputBlock });

                        // The output block should contain the wet and dry samples averaged
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, 0);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }

            beginTest ("Mixer can push and pop full-sized blocks after encountering a shorter block");
            {
                DryWetMixer<float> mixer (maxLatency);
                mixer.setWetMixProportion (0.5f);
                mixer.prepare (spec);

                constexpr auto shortBlockLength = spec.maximumBlockSize / 2;
                AudioBuffer<float> shortBlock (spec.numChannels, shortBlockLength);
                mixer.pushDrySamples (AudioBlock<const float> (dryBuffer).getSubBlock (shortBlockLength));
                mixer.mixWetSamples ({ shortBlock });

                for (auto block = 0; block < numBlocks; ++block)
                {
                    // Push a full block of dry samples
                    mixer.pushDrySamples ({ dryBuffer });

                    // Mix a full block of wet samples
                    auto outputBlock = wetBuffer;
                    mixer.mixWetSamples ({ outputBlock });

                    // The output block should contain the wet and dry samples averaged
                    for (uint32_t sample = 0; sample < spec.maximumBlockSize; ++sample)
                    {
                        for (uint32_t channel = 0; channel < spec.numChannels; ++channel)
                        {
                            const auto outputValue = outputBlock.getSample ((int) channel, (int) sample);
                            expectWithinAbsoluteError (outputValue, 0.5f, 0.0001f);
                        }
                    }
                }
            }
        }
    }
};

static const DryWetMixerTests dryWetMixerTests;

#endif

} // namespace dsp
} // namespace juce