/**
 * OpenAL cross platform audio library
 * Copyright (C) 2013 by Mike Gorchak
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the
 *  Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#include "config.h"

#include <math.h>
#include <stdlib.h>

#include <algorithm>
#include <functional>

#include "alMain.h"
#include "alcontext.h"
#include "alAuxEffectSlot.h"
#include "alError.h"
#include "alu.h"
#include "filters/biquad.h"
#include "vecmat.h"


namespace {

/*  The document  "Effects Extension Guide.pdf"  says that low and high  *
 *  frequencies are cutoff frequencies. This is not fully correct, they  *
 *  are corner frequencies for low and high shelf filters. If they were  *
 *  just cutoff frequencies, there would be no need in cutoff frequency  *
 *  gains, which are present.  Documentation for  "Creative Proteus X2"  *
 *  software describes  4-band equalizer functionality in a much better  *
 *  way.  This equalizer seems  to be a predecessor  of  OpenAL  4-band  *
 *  equalizer.  With low and high  shelf filters  we are able to cutoff  *
 *  frequencies below and/or above corner frequencies using attenuation  *
 *  gains (below 1.0) and amplify all low and/or high frequencies using  *
 *  gains above 1.0.                                                     *
 *                                                                       *
 *     Low-shelf       Low Mid Band      High Mid Band     High-shelf    *
 *      corner            center             center          corner      *
 *     frequency        frequency          frequency       frequency     *
 *    50Hz..800Hz     200Hz..3000Hz      1000Hz..8000Hz  4000Hz..16000Hz *
 *                                                                       *
 *          |               |                  |               |         *
 *          |               |                  |               |         *
 *   B -----+            /--+--\            /--+--\            +-----    *
 *   O      |\          |   |   |          |   |   |          /|         *
 *   O      | \        -    |    -        -    |    -        / |         *
 *   S +    |  \      |     |     |      |     |     |      /  |         *
 *   T      |   |    |      |      |    |      |      |    |   |         *
 * ---------+---------------+------------------+---------------+-------- *
 *   C      |   |    |      |      |    |      |      |    |   |         *
 *   U -    |  /      |     |     |      |     |     |      \  |         *
 *   T      | /        -    |    -        -    |    -        \ |         *
 *   O      |/          |   |   |          |   |   |          \|         *
 *   F -----+            \--+--/            \--+--/            +-----    *
 *   F      |               |                  |               |         *
 *          |               |                  |               |         *
 *                                                                       *
 * Gains vary from 0.126 up to 7.943, which means from -18dB attenuation *
 * up to +18dB amplification. Band width varies from 0.01 up to 1.0 in   *
 * octaves for two mid bands.                                            *
 *                                                                       *
 * Implementation is based on the "Cookbook formulae for audio EQ biquad *
 * filter coefficients" by Robert Bristow-Johnson                        *
 * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt                   */


struct ALequalizerState final : public EffectState {
    struct {
        /* Effect parameters */
        BiquadFilter filter[4];

        /* Effect gains for each channel */
        ALfloat CurrentGains[MAX_OUTPUT_CHANNELS]{};
        ALfloat TargetGains[MAX_OUTPUT_CHANNELS]{};
    } mChans[MAX_EFFECT_CHANNELS];

    ALfloat mSampleBuffer[BUFFERSIZE]{};


    ALboolean deviceUpdate(const ALCdevice *device) override;
    void update(const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props, const EffectTarget target) override;
    void process(ALsizei samplesToDo, const ALfloat (*RESTRICT samplesIn)[BUFFERSIZE], ALfloat (*RESTRICT samplesOut)[BUFFERSIZE], ALsizei numChannels) override;

    DEF_NEWDEL(ALequalizerState)
};

ALboolean ALequalizerState::deviceUpdate(const ALCdevice *UNUSED(device))
{
    for(auto &e : mChans)
    {
        std::for_each(std::begin(e.filter), std::end(e.filter),
                      std::mem_fn(&BiquadFilter::clear));
        std::fill(std::begin(e.CurrentGains), std::end(e.CurrentGains), 0.0f);
    }
    return AL_TRUE;
}

void ALequalizerState::update(const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props, const EffectTarget target)
{
    const ALCdevice *device = context->Device;
    ALfloat frequency = (ALfloat)device->Frequency;
    ALfloat gain, f0norm;
    ALuint i;

    /* Calculate coefficients for the each type of filter. Note that the shelf
     * filters' gain is for the reference frequency, which is the centerpoint
     * of the transition band.
     */
    gain = maxf(sqrtf(props->Equalizer.LowGain), 0.0625f); /* Limit -24dB */
    f0norm = props->Equalizer.LowCutoff/frequency;
    mChans[0].filter[0].setParams(BiquadType::LowShelf, gain, f0norm,
        calc_rcpQ_from_slope(gain, 0.75f)
    );

    gain = maxf(props->Equalizer.Mid1Gain, 0.0625f);
    f0norm = props->Equalizer.Mid1Center/frequency;
    mChans[0].filter[1].setParams(BiquadType::Peaking, gain, f0norm,
        calc_rcpQ_from_bandwidth(f0norm, props->Equalizer.Mid1Width)
    );

    gain = maxf(props->Equalizer.Mid2Gain, 0.0625f);
    f0norm = props->Equalizer.Mid2Center/frequency;
    mChans[0].filter[2].setParams(BiquadType::Peaking, gain, f0norm,
        calc_rcpQ_from_bandwidth(f0norm, props->Equalizer.Mid2Width)
    );

    gain = maxf(sqrtf(props->Equalizer.HighGain), 0.0625f);
    f0norm = props->Equalizer.HighCutoff/frequency;
    mChans[0].filter[3].setParams(BiquadType::HighShelf, gain, f0norm,
        calc_rcpQ_from_slope(gain, 0.75f)
    );

    /* Copy the filter coefficients for the other input channels. */
    for(i = 1;i < MAX_EFFECT_CHANNELS;i++)
    {
        mChans[i].filter[0].copyParamsFrom(mChans[0].filter[0]);
        mChans[i].filter[1].copyParamsFrom(mChans[0].filter[1]);
        mChans[i].filter[2].copyParamsFrom(mChans[0].filter[2]);
        mChans[i].filter[3].copyParamsFrom(mChans[0].filter[3]);
    }

    mOutBuffer = target.FOAOut->Buffer;
    mOutChannels = target.FOAOut->NumChannels;
    for(i = 0;i < MAX_EFFECT_CHANNELS;i++)
        ComputePanGains(target.FOAOut, alu::Matrix::Identity()[i].data(), slot->Params.Gain,
            mChans[i].TargetGains);
}

void ALequalizerState::process(ALsizei SamplesToDo, const ALfloat (*RESTRICT SamplesIn)[BUFFERSIZE], ALfloat (*RESTRICT SamplesOut)[BUFFERSIZE], ALsizei NumChannels)
{
    for(ALsizei c{0};c < MAX_EFFECT_CHANNELS;c++)
    {
        mChans[c].filter[0].process(mSampleBuffer, SamplesIn[c], SamplesToDo);
        mChans[c].filter[1].process(mSampleBuffer, mSampleBuffer, SamplesToDo);
        mChans[c].filter[2].process(mSampleBuffer, mSampleBuffer, SamplesToDo);
        mChans[c].filter[3].process(mSampleBuffer, mSampleBuffer, SamplesToDo);

        MixSamples(mSampleBuffer, NumChannels, SamplesOut, mChans[c].CurrentGains,
            mChans[c].TargetGains, SamplesToDo, 0, SamplesToDo);
    }
}

} // namespace

struct EqualizerStateFactory final : public EffectStateFactory {
    EffectState *create() override;
};

EffectState *EqualizerStateFactory::create()
{ return new ALequalizerState{}; }

EffectStateFactory *EqualizerStateFactory_getFactory(void)
{
    static EqualizerStateFactory EqualizerFactory{};
    return &EqualizerFactory;
}


void ALequalizer_setParami(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid equalizer integer property 0x%04x", param); }
void ALequalizer_setParamiv(ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, const ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid equalizer integer-vector property 0x%04x", param); }
void ALequalizer_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
{
    ALeffectProps *props = &effect->Props;
    switch(param)
    {
        case AL_EQUALIZER_LOW_GAIN:
            if(!(val >= AL_EQUALIZER_MIN_LOW_GAIN && val <= AL_EQUALIZER_MAX_LOW_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer low-band gain out of range");
            props->Equalizer.LowGain = val;
            break;

        case AL_EQUALIZER_LOW_CUTOFF:
            if(!(val >= AL_EQUALIZER_MIN_LOW_CUTOFF && val <= AL_EQUALIZER_MAX_LOW_CUTOFF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer low-band cutoff out of range");
            props->Equalizer.LowCutoff = val;
            break;

        case AL_EQUALIZER_MID1_GAIN:
            if(!(val >= AL_EQUALIZER_MIN_MID1_GAIN && val <= AL_EQUALIZER_MAX_MID1_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid1-band gain out of range");
            props->Equalizer.Mid1Gain = val;
            break;

        case AL_EQUALIZER_MID1_CENTER:
            if(!(val >= AL_EQUALIZER_MIN_MID1_CENTER && val <= AL_EQUALIZER_MAX_MID1_CENTER))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid1-band center out of range");
            props->Equalizer.Mid1Center = val;
            break;

        case AL_EQUALIZER_MID1_WIDTH:
            if(!(val >= AL_EQUALIZER_MIN_MID1_WIDTH && val <= AL_EQUALIZER_MAX_MID1_WIDTH))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid1-band width out of range");
            props->Equalizer.Mid1Width = val;
            break;

        case AL_EQUALIZER_MID2_GAIN:
            if(!(val >= AL_EQUALIZER_MIN_MID2_GAIN && val <= AL_EQUALIZER_MAX_MID2_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid2-band gain out of range");
            props->Equalizer.Mid2Gain = val;
            break;

        case AL_EQUALIZER_MID2_CENTER:
            if(!(val >= AL_EQUALIZER_MIN_MID2_CENTER && val <= AL_EQUALIZER_MAX_MID2_CENTER))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid2-band center out of range");
            props->Equalizer.Mid2Center = val;
            break;

        case AL_EQUALIZER_MID2_WIDTH:
            if(!(val >= AL_EQUALIZER_MIN_MID2_WIDTH && val <= AL_EQUALIZER_MAX_MID2_WIDTH))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer mid2-band width out of range");
            props->Equalizer.Mid2Width = val;
            break;

        case AL_EQUALIZER_HIGH_GAIN:
            if(!(val >= AL_EQUALIZER_MIN_HIGH_GAIN && val <= AL_EQUALIZER_MAX_HIGH_GAIN))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer high-band gain out of range");
            props->Equalizer.HighGain = val;
            break;

        case AL_EQUALIZER_HIGH_CUTOFF:
            if(!(val >= AL_EQUALIZER_MIN_HIGH_CUTOFF && val <= AL_EQUALIZER_MAX_HIGH_CUTOFF))
                SETERR_RETURN(context, AL_INVALID_VALUE,, "Equalizer high-band cutoff out of range");
            props->Equalizer.HighCutoff = val;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid equalizer float property 0x%04x", param);
    }
}
void ALequalizer_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
{ ALequalizer_setParamf(effect, context, param, vals[0]); }

void ALequalizer_getParami(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(val))
{ alSetError(context, AL_INVALID_ENUM, "Invalid equalizer integer property 0x%04x", param); }
void ALequalizer_getParamiv(const ALeffect *UNUSED(effect), ALCcontext *context, ALenum param, ALint *UNUSED(vals))
{ alSetError(context, AL_INVALID_ENUM, "Invalid equalizer integer-vector property 0x%04x", param); }
void ALequalizer_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
{
    const ALeffectProps *props = &effect->Props;
    switch(param)
    {
        case AL_EQUALIZER_LOW_GAIN:
            *val = props->Equalizer.LowGain;
            break;

        case AL_EQUALIZER_LOW_CUTOFF:
            *val = props->Equalizer.LowCutoff;
            break;

        case AL_EQUALIZER_MID1_GAIN:
            *val = props->Equalizer.Mid1Gain;
            break;

        case AL_EQUALIZER_MID1_CENTER:
            *val = props->Equalizer.Mid1Center;
            break;

        case AL_EQUALIZER_MID1_WIDTH:
            *val = props->Equalizer.Mid1Width;
            break;

        case AL_EQUALIZER_MID2_GAIN:
            *val = props->Equalizer.Mid2Gain;
            break;

        case AL_EQUALIZER_MID2_CENTER:
            *val = props->Equalizer.Mid2Center;
            break;

        case AL_EQUALIZER_MID2_WIDTH:
            *val = props->Equalizer.Mid2Width;
            break;

        case AL_EQUALIZER_HIGH_GAIN:
            *val = props->Equalizer.HighGain;
            break;

        case AL_EQUALIZER_HIGH_CUTOFF:
            *val = props->Equalizer.HighCutoff;
            break;

        default:
            alSetError(context, AL_INVALID_ENUM, "Invalid equalizer float property 0x%04x", param);
    }
}
void ALequalizer_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
{ ALequalizer_getParamf(effect, context, param, vals); }

DEFINE_ALEFFECT_VTABLE(ALequalizer);