#include <QCoreApplication>
#include <QIODevice>
#include <QDebug>
/** Dont forget to set QT += core multimedia **/
#include <QtMultimedia/QAudioFormat>
#include <QtMultimedia/QAudioDeviceInfo>
#include <QtMultimedia/QAudioOutput>

/**
 * @brief Interface class for all byte beat musicals
 */
template<typename SAMPLE_TYPE, int SAMPLE_RATE, bool STEREO>
class MusicDevice : public QIODevice
{
public:
    explicit MusicDevice(QObject *parent = Q_NULLPTR) : QIODevice(parent) {}
    virtual ~MusicDevice() {}

    virtual SAMPLE_TYPE getSample() = 0;
    virtual const QAudioFormat& getFormat() const
    {
        static QAudioFormat format;
        format.setSampleRate(SAMPLE_RATE);
        format.setChannelCount(STEREO ? 2 : 1);
        format.setSampleSize(sizeof(SAMPLE_TYPE) * 8);
        format.setCodec("audio/pcm");
        format.setByteOrder(QAudioFormat::LittleEndian);
        format.setSampleType(QAudioFormat::UnSignedInt); //TODO: make this depend on SAMPLE_TYPE
        return format;
    }

    // qt specific implementation
    bool open(OpenMode mode)
    {
        auto success = mode == QIODevice::ReadOnly;
        if(success)
            setOpenMode(mode);
        else
            qWarning() << "unsupported open mode" << mode;
        return success;
    }

    void close()
    {
        setOpenMode(NotOpen);
    }

    bool isSequential() const
    {
        return true;
    }

protected:
    qint64 readData(char* data, qint64 maxSize)
    {
        for(qint64 i = 0; i < maxSize; i++)
            data[i] = getSample();
        return maxSize;
    }

    qint64 writeData(const char* data, qint64 maxSize)
    {
        Q_UNUSED(data)
        Q_UNUSED(maxSize)

        qWarning() << "read only device!";

        return -1;
    }
};

/**
 * @brief Bitshift variations by Rob Miles
 * https://www.youtube.com/watch?v=MqZgoNRERY8&t=1s
 * http://txti.es/bitshiftvariationsincminor
 */
class BitshiftVariations : public MusicDevice<quint8, 8000, false>
{
public:
    explicit BitshiftVariations(QObject *parent = Q_NULLPTR) : MusicDevice(parent) {}
    virtual ~BitshiftVariations() {}

    quint8 getSample() Q_DECL_OVERRIDE
    {
        int voice0 = g(i, 1, n = i >> 14, 12);
        int voice1 = g(i, s = i >> 17, n ^ i >> 13, 10);
        int voice2 = g(i, s / 3, n + ((i >> 11) % 3), 10);
        int voice3 = g(i, s / 5, 8 + n - ((i >> 10) % 3), 9);
        i++;

        return voice0 + voice1 + voice2 + voice3;
    }

private:
    static int g(int i, int x, int t, int o)
    {
        return ((3 & x & (i * ((3 & i >> 16 ? "BY}6YB6%" : "Qj}6jQ6%")[t % 8] + 51) >> o)) << 4);
    }

    int i, n, s;
};

/**
 * @brief Funky beat found in some forum
 */
class FunkyBeat : public MusicDevice<quint8, 8000, false>
{
public:
    explicit FunkyBeat(QObject *parent = Q_NULLPTR) : MusicDevice(parent), a(0), f(true) {}
    virtual ~FunkyBeat() {}

    quint8 getSample() Q_DECL_OVERRIDE
    {
        if(f)
        {
            b = 99;
            c = 99;
            d = 99;

            while(true)
            {
                if("+%7%+%7%5%4%2%457%0%0%754%2%+%%%5%542%457%0%0%042%2#+%!#0%+%$%%%"[a] > b)
                    d = d * 89 / 84;

                if(b-- == 0)
                    break;

                if("057+5420"[a / 8] > b)
                    c = c * 89 / 84;
            }

            s = 999 + 99 * (a & 2);

            f = false;
        }

        quint8 sample =
            s * (
                (776 - d ?
                     s * d & 32767 :
                     b
                 ) +
                (a & 2 ?
                     s * c / 2 & 32767 :
                     b
                 )
                ) / 299999;

        if(s-- == 0)
        {
            f = true;
            a++;
            a &= 63;
        }

        return sample;
    }

private:
    int a;
    int b;
    int c;
    int d;
    int s;
    bool f;
};

int main(int argc, char *argv[])
{
    QCoreApplication app(argc, argv);

    //MusicDevice<quint8, 8000, false> *source = new BitshiftVariations(&app);
    MusicDevice<quint8, 8000, false> *source = new FunkyBeat(&app);

    {
        QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
        if (!info.isFormatSupported(source->getFormat()))
        {
            qFatal("Your soundcard does not support the needed output format!");
            return -1;
        }
    }

    QAudioOutput *audioOutput = new QAudioOutput(source->getFormat(), &app);

    source->open(QIODevice::ReadOnly);
    audioOutput->start(source);

    return app.exec();
}