/* Copyright (C) 2016
 * swift project Community / Contributors
 *
 * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
 * directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
 * including this file, may be copied, modified, propagated, or distributed except according to the terms
 * contained in the LICENSE file.
 */

#include "threadedtonepairplayer.h"
#include <QTimer>

using namespace BlackMisc;

namespace BlackSound
{

    CThreadedTonePairPlayer::CThreadedTonePairPlayer(QObject *owner, const QString &name, const QAudioDeviceInfo &device)
        : CContinuousWorker(owner, name),
          m_deviceInfo(device)
    { }

    CThreadedTonePairPlayer::~CThreadedTonePairPlayer()
    { }

    void CThreadedTonePairPlayer::play(int volume, const QList<CTonePair> &tonePairs)
    {
        QMutexLocker ml(&m_mutex);
        if (m_audioOutput->state() != QAudio::StoppedState) { return; }

        m_bufferData = getAudioByTonePairs(tonePairs);
        m_audioOutput->setVolume(static_cast<qreal>(0.01 * volume));
        QTimer::singleShot(0, this, &CThreadedTonePairPlayer::playBuffer);
    }

    void CThreadedTonePairPlayer::initialize()
    {
        m_audioFormat.setSampleRate(44100);
        m_audioFormat.setChannelCount(1);
        m_audioFormat.setSampleSize(16); // 8 or 16 works
        m_audioFormat.setCodec("audio/pcm");
        m_audioFormat.setByteOrder(QAudioFormat::LittleEndian);
        m_audioFormat.setSampleType(QAudioFormat::SignedInt);

        m_audioOutput = new QAudioOutput(m_deviceInfo, m_audioFormat, this);
        connect(m_audioOutput, &QAudioOutput::stateChanged, this, &CThreadedTonePairPlayer::handleStateChanged);
    }

    void CThreadedTonePairPlayer::handleStateChanged(QAudio::State newState)
    {
        QMutexLocker ml(&m_mutex);
        switch (newState)
        {
        case QAudio::IdleState: m_audioOutput->stop(); break;
        default: break;
        }
    }

    void CThreadedTonePairPlayer::playBuffer()
    {
        QMutexLocker ml(&m_mutex);
        if (!m_audioOutput || m_audioOutput->state() == QAudio::ActiveState) { return; }
        m_buffer.close();
        m_buffer.setBuffer(&m_bufferData);
        m_buffer.open(QIODevice::ReadOnly);
        m_audioOutput->start(&m_buffer);
    }

    QByteArray CThreadedTonePairPlayer::getAudioByTonePairs(const QList<CTonePair> &tonePairs)
    {
        Q_ASSERT(tonePairs.size() > 0);
        QByteArray finalBufferData;

        for (const auto &tonePair : as_const(tonePairs))
        {
            if (m_tonePairCache.contains(tonePair))
            {
                QByteArray bufferData;
                bufferData = m_tonePairCache.value(tonePair);
                finalBufferData.append(bufferData);
            }
            else
            {
                QByteArray bufferData;
                bufferData = generateAudioFromTonePairs(tonePair);
                m_tonePairCache.insert(tonePair, bufferData);
                finalBufferData.append(bufferData);
            }
        }
        return finalBufferData;
    }

    QByteArray CThreadedTonePairPlayer::generateAudioFromTonePairs(const CTonePair &tonePair)
    {
        const int bytesPerSample = m_audioFormat.sampleSize() / 8;
        const int bytesForAllChannels = m_audioFormat.channelCount() * bytesPerSample;

        QByteArray bufferData;
        qint64 bytesPerTonePair = m_audioFormat.sampleRate() * bytesForAllChannels * tonePair.getDurationMs() / 1000;
        bufferData.resize(bytesPerTonePair);
        unsigned char *bufferPointer = reinterpret_cast<unsigned char *>(bufferData.data());

        qint64 last0AmplitudeSample = bytesPerTonePair; // last sample when amplitude was 0
        int sampleIndexPerTonePair = 0;
        while (bytesPerTonePair)
        {
            // http://hyperphysics.phy-astr.gsu.edu/hbase/audio/sumdif.html
            // http://math.stackexchange.com/questions/164369/how-do-you-calculate-the-frequency-perceived-by-humans-of-two-sinusoidal-waves-a
            const double pseudoTime = static_cast<double>(sampleIndexPerTonePair % this->m_audioFormat.sampleRate()) / this->m_audioFormat.sampleRate();
            double amplitude = 0.0; // amplitude -1 -> +1 , 0 is silence
            if (tonePair.getFirstFrequencyHz() > 10)
            {
                // the combination of two frequencies actually would have 2*amplitude,
                // but I have to normalize with amplitude -1 -> +1
                amplitude = tonePair.getSecondFrequencyHz() == 0 ?
                            qSin(2 * M_PI * tonePair.getFirstFrequencyHz() * pseudoTime) :
                            qSin(M_PI * (tonePair.getFirstFrequencyHz() + tonePair.getSecondFrequencyHz()) * pseudoTime) *
                            qCos(M_PI * (tonePair.getFirstFrequencyHz() - tonePair.getSecondFrequencyHz()) * pseudoTime);
            }

            // avoid overflow
            Q_ASSERT(amplitude <= 1.0 && amplitude >= -1.0);
            if (amplitude < -1.0) { amplitude = -1.0; }
            else if (amplitude > 1.0) { amplitude = 1.0; }
            else if (qAbs(amplitude) < 1.0 / 65535)
            {
                amplitude = 0;
                last0AmplitudeSample = bytesPerTonePair;
            }

            // generate this for all channels, usually 1 channel
            for (int i = 0; i < this->m_audioFormat.channelCount(); ++i)
            {
                this->writeAmplitudeToBuffer(amplitude, bufferPointer);
                bufferPointer += bytesPerSample;
                bytesPerTonePair -= bytesPerSample;
            }
            ++sampleIndexPerTonePair;
        }

        // fixes the range from the last 0 pass through
        if (last0AmplitudeSample > 0)
        {
            bufferPointer -= last0AmplitudeSample;
            while (last0AmplitudeSample)
            {
                double amplitude = 0.0; // amplitude -1 -> +1 , 0 is silence

                // generate this for all channels, usually 1 channel
                for (int i = 0; i < this->m_audioFormat.channelCount(); ++i)
                {
                    this->writeAmplitudeToBuffer(amplitude, bufferPointer);
                    bufferPointer += bytesPerSample;
                    last0AmplitudeSample -= bytesPerSample;
                }
            }
        }
        return bufferData;
    }

    void CThreadedTonePairPlayer::writeAmplitudeToBuffer(double amplitude, unsigned char *bufferPointer)
    {
        Q_ASSERT(this->m_audioFormat.sampleSize() == 16);
        Q_ASSERT(this->m_audioFormat.sampleType() == QAudioFormat::SignedInt);
        Q_ASSERT(this->m_audioFormat.byteOrder() == QAudioFormat::LittleEndian);

        qint16 value = static_cast<qint16>(amplitude * 32767);
        qToLittleEndian<qint16>(value, bufferPointer);
    }
}