// @todo -- separate decl. and impl.
// inverse mode
// paint track differently left of thumb
// direct click mode (mode thumb to click pos)
// paint thumb in halo widget
#ifndef SLIDER_P_H
#define SLIDER_P_H

#include "slider.h"
#include <QPainter>
#include <QPropertyAnimation>
#include <QStateMachine>
#include <QEventTransition>
#include <QSignalTransition>
#include <QDebug>
#include "lib/style.h"

#define THUMB_OUTER_SIZE 20

class Halo : public QWidget
{
    Q_OBJECT

    Q_PROPERTY(qreal size WRITE setSize READ size)

public:
    Halo(Slider *slider)
        : QWidget(slider->parentWidget()),
          slider(slider),
          _size(0)
    {
        slider->installEventFilter(this);
        setAttribute(Qt::WA_TransparentForMouseEvents, true);

        connect(slider, SIGNAL(sliderMoved(int)), this, SLOT(update()));
        connect(slider, SIGNAL(valueChanged(int)), this, SLOT(update()));
    }

    ~Halo()
    {
    }

    inline void setSize(qreal size)
    {
        _size = size;
        update();
    }

    inline qreal size() const { return _size; }

protected:
    bool eventFilter(QObject *obj, QEvent *event)
    {
        if (QEvent::ParentChange == event->type()) {
            setParent(slider->parentWidget());
        }
        return QWidget::eventFilter(obj, event);
    }

    void paintEvent(QPaintEvent *event)
    {
        QPainter painter(this);

        QBrush brush;
        brush.setStyle(Qt::SolidPattern);
        brush.setColor(QColor(0, 0, 0, 20));
        painter.setBrush(brush);
        painter.setPen(Qt::NoPen);

        painter.setRenderHint(QPainter::Antialiasing);

        QPointF disp = Qt::Horizontal == slider->orientation()
            ? QPointF(THUMB_OUTER_SIZE/2 + slider->thumbOffset(),
                      slider->height()/2)
            : QPointF(slider->width()/2,
                      THUMB_OUTER_SIZE/2 + slider->thumbOffset());

        QRectF halo((slider->pos() - QPointF(_size, _size)/2) + disp,
                    QSize(_size, _size));

        painter.drawEllipse(halo);

#ifdef DEBUG_LAYOUT
        QPen pen;
        pen.setColor(Qt::red);
        pen.setWidth(2);
        painter.setPen(pen);
        painter.setBrush(Qt::NoBrush);

        painter.drawRect(rect().adjusted(0, 0, -2, -2));
#endif
        QWidget::paintEvent(event);
    }

private:
    const Slider *const slider;
    qreal _size;
};

class SliderPrivate
{
    Q_DISABLE_COPY(SliderPrivate)
    Q_DECLARE_PUBLIC(Slider)

public:
    SliderPrivate(Slider *parent)
        : q_ptr(parent),
          halo(new Halo(parent)),
          hoverTrack(false),
          hoverThumb(false),
          step(false),
          stepTo(0),
          oldValue(parent->value()),
          thumbSize(11),
          thumbPenWidth(0),
          thumbColor(Qt::white)
    {
        parent->setMouseTracking(true);
    }

    void init(Slider *slider)
    {
        QState *s1 = new QState(QState::ParallelStates);

        QState *s11 = new QState(s1);

        QState *inactiveState = new QState(s11);
        QState *focusState = new QState(s11);
        QState *pulseState = new QState(focusState);
        QState *pulse2State = new QState(focusState);
        QState *downState = new QState(s11);

        focusState->setInitialState(pulseState);

        inactiveState->assignProperty(halo, "size", 0);
        pulseState->assignProperty(halo, "size", 35);
        pulse2State->assignProperty(halo, "size", 28);
        downState->assignProperty(halo, "size", 0);

        inactiveState->assignProperty(slider, "thumbSize", 11);
        focusState->assignProperty(slider, "thumbSize", 11);
        downState->assignProperty(slider, "thumbSize", 17);

        machine.addState(s1);

        s11->setInitialState(inactiveState);

        //machine.addState(inactiveState);
        //machine.addState(focusState);
        //machine.addState(downState);

        //machine.setInitialState(inactiveState);

        machine.setInitialState(s1);

        QAbstractTransition *transition;
        QPropertyAnimation *animation;

        // Show halo on focus in

        transition = new QEventTransition(slider, QEvent::FocusIn);
        transition->setTargetState(focusState);

        animation = new QPropertyAnimation(halo, "size");
        transition->addAnimation(animation);
        inactiveState->addTransition(transition);

        // Hide halo on focus out

        transition = new QEventTransition(slider, QEvent::FocusOut);
        transition->setTargetState(inactiveState);

        animation = new QPropertyAnimation(halo, "size");
        transition->addAnimation(animation);
        focusState->addTransition(transition);

        // Pulse in

        transition = new QSignalTransition(pulseState, SIGNAL(propertiesAssigned()));
        transition->setTargetState(pulse2State);

        animation = new QPropertyAnimation(halo, "size");
        animation->setEasingCurve(QEasingCurve::InOutSine);
        animation->setDuration(1000);
        transition->addAnimation(animation);
        pulseState->addTransition(transition);

        // Pulse out

        transition = new QSignalTransition(pulse2State, SIGNAL(propertiesAssigned()));
        transition->setTargetState(pulseState);

        animation = new QPropertyAnimation(halo, "size");
        animation->setEasingCurve(QEasingCurve::InOutSine);
        animation->setDuration(1000);
        transition->addAnimation(animation);
        pulse2State->addTransition(transition);

        // Slider pressed

        transition = new QSignalTransition(slider, SIGNAL(sliderPressed()));
        transition->setTargetState(downState);
        transition->addAnimation(new QPropertyAnimation(slider, "thumbSize"));
        transition->addAnimation(new QPropertyAnimation(halo, "size"));
        focusState->addTransition(transition);

        // Slider released

        transition = new QSignalTransition(slider, SIGNAL(sliderReleased()));
        transition->setTargetState(focusState);
        transition->addAnimation(new QPropertyAnimation(slider, "thumbSize"));
        transition->addAnimation(new QPropertyAnimation(halo, "size"));
        downState->addTransition(transition);

        //

        QState *s12 = new QState(s1);

        QState *t1 = new QState(s12);
        QState *t2 = new QState(s12);

        t1->assignProperty(slider, "thumbColor", QColor(0, 0, 0));
        t1->assignProperty(slider, "thumbPenWidth", 0);
        t2->assignProperty(slider, "thumbColor", QColor(255, 255, 255));
        t2->assignProperty(slider, "thumbPenWidth", 1.5);

        //machine.addState(t1);
        //machine.addState(t2);

        //machine.addState(s12);

        s12->setInitialState(t1);

        transition = new QSignalTransition(slider, SIGNAL(changedToMinimum()));
        transition->setTargetState(t2);
        animation = new QPropertyAnimation(slider, "thumbColor");
        animation->setDuration(700);
        transition->addAnimation(animation);
        animation = new QPropertyAnimation(slider, "thumbPenWidth");
        animation->setDuration(700);
        transition->addAnimation(animation);
        t1->addTransition(transition);

        transition = new QSignalTransition(slider, SIGNAL(changedFromMinimum()));
        transition->setTargetState(t1);
        animation = new QPropertyAnimation(slider, "thumbColor");
        animation->setDuration(700);
        transition->addAnimation(animation);
        animation = new QPropertyAnimation(slider, "thumbPenWidth");
        animation->setDuration(700);
        transition->addAnimation(animation);
        t2->addTransition(transition);

        machine.start();
    }

    QRectF trackGeometry() const
    {
        Q_Q(const Slider);

        return Qt::Horizontal == q->orientation()
            ? QRectF(THUMB_OUTER_SIZE/2, q->rect().height()/2 - 1,
                    q->rect().width() - THUMB_OUTER_SIZE, 2)
            : QRectF(q->rect().width()/2 - 1, THUMB_OUTER_SIZE/2, 2,
                    q->rect().height() - THUMB_OUTER_SIZE);
    }

    void paintTrack(QPainter *painter)
    {
        painter->save();

        QBrush brush;
        brush.setStyle(Qt::SolidPattern);
        brush.setColor(QColor(0, 0, 0, 255));

        painter->fillRect(trackGeometry(), brush);

        painter->restore();

#ifdef DEBUG_LAYOUT
        if (hoverTrack) {
            painter->save();
            painter->setPen(Qt::red);
            painter->drawRect(trackGeometry());
            painter->restore();
        }
#endif
    }

    QRectF thumbGeometry() const
    {
        Q_Q(const Slider);

        return Qt::Horizontal == q->orientation()
            ? QRectF(q->thumbOffset(), q->rect().height()/2 - THUMB_OUTER_SIZE/2,
                     THUMB_OUTER_SIZE, THUMB_OUTER_SIZE)
            : QRectF(q->rect().width()/2 - THUMB_OUTER_SIZE/2, q->thumbOffset(),
                     THUMB_OUTER_SIZE, THUMB_OUTER_SIZE);
    }

    void paintThumb(QPainter *painter)
    {
        painter->drawRect(thumbGeometry().adjusted(0, 0, -1, -1));

        /*
        painter->save();

        QBrush brush;
        brush.setStyle(Qt::SolidPattern);
        brush.setColor(thumbColor);
        painter->setBrush(brush);

        if (thumbPenWidth) {
            QPen pen;
            pen.setWidthF(thumbPenWidth);
            painter->setPen(pen);
        } else {
            painter->setPen(Qt::NoPen);
        }

        painter->setRenderHint(QPainter::Antialiasing);

        QRectF thumb(0, 0, thumbSize, thumbSize);
        thumb.moveCenter(thumbGeometry().center());

        painter->drawEllipse(thumb);

        painter->restore();

#ifdef DEBUG_LAYOUT
        painter->drawRect(thumbGeometry());

        if (hoverThumb) {
            painter->save();
            painter->setPen(Qt::red);
            painter->drawRect(thumbGeometry());
            painter->restore();
        }
#endif
        */
    }

    int valueFromPosition(const QPoint &pos) const
    {
        Q_Q(const Slider);

        int position = Qt::Horizontal == q->orientation() ? pos.x() : pos.y();

        int span = Qt::Horizontal == q->orientation()
            ? q->rect().width() - THUMB_OUTER_SIZE
            : q->rect().height() - THUMB_OUTER_SIZE;

        return Style::sliderValueFromPosition(
                    q->minimum(),
                    q->maximum(),
                    position - THUMB_OUTER_SIZE/2,
                    span,
                    false);
    }

    Slider *const q_ptr;
    Halo   *const halo;
    QStateMachine machine;
    bool   hoverTrack;
    bool   hoverThumb;
    bool   step;
    int    stepTo;
    int    oldValue;
    qreal  thumbSize;
    qreal  thumbPenWidth;
    QColor thumbColor;
};

#endif // SLIDER_P_H