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

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-9-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

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

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

namespace juce
{

//==============================================================================
/**
    Performs a simple reverb effect on a stream of audio data.

    This is a simple stereo reverb, based on the technique and tunings used in FreeVerb.
    Use setSampleRate() to prepare it, and then call processStereo() or processMono() to
    apply the reverb to your audio data.

    @see ReverbAudioSource

    @tags{Audio}
*/
class Reverb
{
public:
    //==============================================================================
    Reverb()
    {
        setParameters (Parameters());
        setSampleRate (44100.0);
    }

    //==============================================================================
    /** Holds the parameters being used by a Reverb object. */
    struct Parameters
    {
        float roomSize   = 0.5f;     /**< Room size, 0 to 1.0, where 1.0 is big, 0 is small. */
        float damping    = 0.5f;     /**< Damping, 0 to 1.0, where 0 is not damped, 1.0 is fully damped. */
        float wetLevel   = 0.33f;    /**< Wet level, 0 to 1.0 */
        float dryLevel   = 0.4f;     /**< Dry level, 0 to 1.0 */
        float width      = 1.0f;     /**< Reverb width, 0 to 1.0, where 1.0 is very wide. */
        float freezeMode = 0.0f;     /**< Freeze mode - values < 0.5 are "normal" mode, values > 0.5
                                          put the reverb into a continuous feedback loop. */
    };

    //==============================================================================
    /** Returns the reverb's current parameters. */
    const Parameters& getParameters() const noexcept    { return parameters; }

    /** Applies a new set of parameters to the reverb.
        Note that this doesn't attempt to lock the reverb, so if you call this in parallel with
        the process method, you may get artifacts.
    */
    void setParameters (const Parameters& newParams)
    {
        const float wetScaleFactor = 3.0f;
        const float dryScaleFactor = 2.0f;

        const float wet = newParams.wetLevel * wetScaleFactor;
        dryGain.setTargetValue (newParams.dryLevel * dryScaleFactor);
        wetGain1.setTargetValue (0.5f * wet * (1.0f + newParams.width));
        wetGain2.setTargetValue (0.5f * wet * (1.0f - newParams.width));

        gain = isFrozen (newParams.freezeMode) ? 0.0f : 0.015f;
        parameters = newParams;
        updateDamping();
    }

    //==============================================================================
    /** Sets the sample rate that will be used for the reverb.
        You must call this before the process methods, in order to tell it the correct sample rate.
    */
    void setSampleRate (const double sampleRate)
    {
        jassert (sampleRate > 0);

        static const short combTunings[] = { 1116, 1188, 1277, 1356, 1422, 1491, 1557, 1617 }; // (at 44100Hz)
        static const short allPassTunings[] = { 556, 441, 341, 225 };
        const int stereoSpread = 23;
        const int intSampleRate = (int) sampleRate;

        for (int i = 0; i < numCombs; ++i)
        {
            comb[0][i].setSize ((intSampleRate * combTunings[i]) / 44100);
            comb[1][i].setSize ((intSampleRate * (combTunings[i] + stereoSpread)) / 44100);
        }

        for (int i = 0; i < numAllPasses; ++i)
        {
            allPass[0][i].setSize ((intSampleRate * allPassTunings[i]) / 44100);
            allPass[1][i].setSize ((intSampleRate * (allPassTunings[i] + stereoSpread)) / 44100);
        }

        const double smoothTime = 0.01;
        damping .reset (sampleRate, smoothTime);
        feedback.reset (sampleRate, smoothTime);
        dryGain .reset (sampleRate, smoothTime);
        wetGain1.reset (sampleRate, smoothTime);
        wetGain2.reset (sampleRate, smoothTime);
    }

    /** Clears the reverb's buffers. */
    void reset()
    {
        for (int j = 0; j < numChannels; ++j)
        {
            for (int i = 0; i < numCombs; ++i)
                comb[j][i].clear();

            for (int i = 0; i < numAllPasses; ++i)
                allPass[j][i].clear();
        }
    }

    //==============================================================================
    /** Applies the reverb to two stereo channels of audio data. */
    void processStereo (float* const left, float* const right, const int numSamples) noexcept
    {
        JUCE_BEGIN_IGNORE_WARNINGS_MSVC (6011)
        jassert (left != nullptr && right != nullptr);

        for (int i = 0; i < numSamples; ++i)
        {
            // NOLINTNEXTLINE(clang-analyzer-core.NullDereference)
            const float input = (left[i] + right[i]) * gain;
            float outL = 0, outR = 0;

            const float damp    = damping.getNextValue();
            const float feedbck = feedback.getNextValue();

            for (int j = 0; j < numCombs; ++j)  // accumulate the comb filters in parallel
            {
                outL += comb[0][j].process (input, damp, feedbck);
                outR += comb[1][j].process (input, damp, feedbck);
            }

            for (int j = 0; j < numAllPasses; ++j)  // run the allpass filters in series
            {
                outL = allPass[0][j].process (outL);
                outR = allPass[1][j].process (outR);
            }

            const float dry  = dryGain.getNextValue();
            const float wet1 = wetGain1.getNextValue();
            const float wet2 = wetGain2.getNextValue();

            left[i]  = outL * wet1 + outR * wet2 + left[i]  * dry;
            right[i] = outR * wet1 + outL * wet2 + right[i] * dry;
        }
        JUCE_END_IGNORE_WARNINGS_MSVC
    }

    /** Applies the reverb to a single mono channel of audio data. */
    void processMono (float* const samples, const int numSamples) noexcept
    {
        JUCE_BEGIN_IGNORE_WARNINGS_MSVC (6011)
        jassert (samples != nullptr);

        for (int i = 0; i < numSamples; ++i)
        {
            const float input = samples[i] * gain;
            float output = 0;

            const float damp    = damping.getNextValue();
            const float feedbck = feedback.getNextValue();

            for (int j = 0; j < numCombs; ++j)  // accumulate the comb filters in parallel
                output += comb[0][j].process (input, damp, feedbck);

            for (int j = 0; j < numAllPasses; ++j)  // run the allpass filters in series
                output = allPass[0][j].process (output);

            const float dry  = dryGain.getNextValue();
            const float wet1 = wetGain1.getNextValue();

            samples[i] = output * wet1 + samples[i] * dry;
        }
        JUCE_END_IGNORE_WARNINGS_MSVC
    }

private:
    //==============================================================================
    static bool isFrozen (const float freezeMode) noexcept  { return freezeMode >= 0.5f; }

    void updateDamping() noexcept
    {
        const float roomScaleFactor = 0.28f;
        const float roomOffset = 0.7f;
        const float dampScaleFactor = 0.4f;

        if (isFrozen (parameters.freezeMode))
            setDamping (0.0f, 1.0f);
        else
            setDamping (parameters.damping * dampScaleFactor,
                        parameters.roomSize * roomScaleFactor + roomOffset);
    }

    void setDamping (const float dampingToUse, const float roomSizeToUse) noexcept
    {
        damping.setTargetValue (dampingToUse);
        feedback.setTargetValue (roomSizeToUse);
    }

    //==============================================================================
    class CombFilter
    {
    public:
        CombFilter() noexcept {}

        void setSize (const int size)
        {
            if (size != bufferSize)
            {
                bufferIndex = 0;
                buffer.malloc (size);
                bufferSize = size;
            }

            clear();
        }

        void clear() noexcept
        {
            last = 0;
            buffer.clear ((size_t) bufferSize);
        }

        float process (const float input, const float damp, const float feedbackLevel) noexcept
        {
            const float output = buffer[bufferIndex];
            last = (output * (1.0f - damp)) + (last * damp);
            JUCE_UNDENORMALISE (last);

            float temp = input + (last * feedbackLevel);
            JUCE_UNDENORMALISE (temp);
            buffer[bufferIndex] = temp;
            bufferIndex = (bufferIndex + 1) % bufferSize;
            return output;
        }

    private:
        HeapBlock<float> buffer;
        int bufferSize = 0, bufferIndex = 0;
        float last = 0.0f;

        JUCE_DECLARE_NON_COPYABLE (CombFilter)
    };

    //==============================================================================
    class AllPassFilter
    {
    public:
        AllPassFilter() noexcept {}

        void setSize (const int size)
        {
            if (size != bufferSize)
            {
                bufferIndex = 0;
                buffer.malloc (size);
                bufferSize = size;
            }

            clear();
        }

        void clear() noexcept
        {
            buffer.clear ((size_t) bufferSize);
        }

        float process (const float input) noexcept
        {
            const float bufferedValue = buffer [bufferIndex];
            float temp = input + (bufferedValue * 0.5f);
            JUCE_UNDENORMALISE (temp);
            buffer [bufferIndex] = temp;
            bufferIndex = (bufferIndex + 1) % bufferSize;
            return bufferedValue - input;
        }

    private:
        HeapBlock<float> buffer;
        int bufferSize = 0, bufferIndex = 0;

        JUCE_DECLARE_NON_COPYABLE (AllPassFilter)
    };

    //==============================================================================
    enum { numCombs = 8, numAllPasses = 4, numChannels = 2 };

    Parameters parameters;
    float gain;

    CombFilter comb [numChannels][numCombs];
    AllPassFilter allPass [numChannels][numAllPasses];

    SmoothedValue<float> damping, feedback, dryGain, wetGain1, wetGain2;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Reverb)
};

} // namespace juce
