/****************************************************************************
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** This file is part of the QtSensors module of the Qt Toolkit.
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****************************************************************************/


#include "qtwistsensorgesturerecognizer.h"

#define _USE_MATH_DEFINES
#include <QtCore/qmath.h>
#ifndef M_PI
#define M_PI 3.14159265358979323846264338327950288419717
#endif
#ifndef M_PI_2
#define M_PI_2  1.57079632679489661923
#endif

QT_BEGIN_NAMESPACE

// from qsensor2tilt
inline qreal calcPitch(double Ax, double Ay, double Az)
{
    return (float)-atan2(Ax, sqrt(Ay * Ay + Az * Az));
}

inline qreal calcRoll(double Ax, double Ay, double Az)
{
    return (float)atan2(Ay, (sqrt(Ax * Ax + Az * Az)));
}

QTwistSensorGestureRecognizer::QTwistSensorGestureRecognizer(QObject *parent) :
    QSensorGestureRecognizer(parent), detecting(0)
{
}

QTwistSensorGestureRecognizer::~QTwistSensorGestureRecognizer()
{
}

void QTwistSensorGestureRecognizer::create()
{
    accel = new QAccelerometer(this);
    accel->connectToBackend();
    timer = new QTimer(this);

    qoutputrangelist outputranges = accel->outputRanges();

    if (outputranges.count() > 0)
        accelRange = (int)(outputranges.at(0).maximum *2);
    else
        accelRange = 44; //this should never happen

    connect(timer,SIGNAL(timeout()),this,SLOT(timeout()));
    timer->setSingleShot(true);
    timer->setInterval(250);

}

QString QTwistSensorGestureRecognizer::id() const
{
    return QString("QtSensors.twist");
}

bool QTwistSensorGestureRecognizer::start()
{
    connect(accel,SIGNAL(readingChanged()),this,SLOT(accelChanged()));
    active = accel->start();
    return active;
}

bool QTwistSensorGestureRecognizer::stop()
{
    accel->stop();
    disconnect(accel,SIGNAL(readingChanged()),this,SLOT(accelChanged()));

    active = accel->isActive();
    return !active;
}

bool QTwistSensorGestureRecognizer::isActive()
{
    return active;
}

#define RESTING_VARIANCE 10

void QTwistSensorGestureRecognizer::accelChanged()
{
    qreal x = accel->reading()->x();
    qreal y = accel->reading()->y();
    qreal z = accel->reading()->z();

    pitch = calcPitch(x, y, z);
    roll = calcRoll(x, y, z);

    qreal degrees = calc(pitch);

    if (xList.count() > 4) {

        if (detecting && abs(degrees) < RESTING_VARIANCE) {
            if (lastX < 0) {
                Q_EMIT twistLeft();
                Q_EMIT detected("twistLeft");
            } else {
                Q_EMIT twistRight();
                Q_EMIT detected("twistRight");
            }
            detecting = false;
        }

        if (abs(degrees) > 60 && abs(xList.last()) < RESTING_VARIANCE) {
            detecting = true;
            timer->start();
            lastX = degrees;
        }
    }

    if (xList.count() > 5)
        xList.removeLast();
    xList.insert(0,degrees);
}

void QTwistSensorGestureRecognizer::timeout()
{
    detecting = false;
}

qreal QTwistSensorGestureRecognizer::calc(qreal yrot)
{
    qreal aG = 1 * sin(yrot);
    qreal aK = 1 * cos(yrot);

    yrot = atan2(aG, aK);
    if (yrot > M_PI_2)
        yrot = M_PI - yrot;
    else if (yrot < -M_PI_2)
        yrot = -(M_PI + yrot);

    return yrot * 180 / M_PI;
}

QT_END_NAMESPACE