/******************************************************************************
 * QSkinny - Copyright (C) The authors
 *           SPDX-License-Identifier: BSD-3-Clause
 *****************************************************************************/

#include "QskSlider.h"
#include "QskAnimationHint.h"
#include "QskAspect.h"
#include "QskEvent.h"

QSK_SUBCONTROL( QskSlider, Panel )
QSK_SUBCONTROL( QskSlider, Groove )
QSK_SUBCONTROL( QskSlider, Fill )
QSK_SUBCONTROL( QskSlider, Scale )
QSK_SUBCONTROL( QskSlider, Tick )
QSK_SUBCONTROL( QskSlider, Handle )

QSK_SYSTEM_STATE( QskSlider, Pressed, QskAspect::FirstSystemState << 2 )

static inline QskAspect qskAspectGraduationPolicy()
{
    return QskSlider::Tick | QskAspect::Option;
}

static QRectF qskHandleSelectionRect( const QskSlider* slider )
{
    auto rect = slider->subControlRect( QskSlider::Handle );

#if 1
    // minimum handle strut size TODO ...
    const QSizeF strutSize( 60, 60 );
    const auto w = qMax( ( strutSize.width() - rect.width() ) / 2, 0.0 );
    const auto h = qMax( ( strutSize.height() - rect.height() ) / 2, 0.0 );
#endif

    return rect.marginsAdded( { w, h, w, h } );
}

class QskSlider::PrivateData
{
  public:
    PrivateData( Qt::Orientation orientation )
        : pressedValue( 0 )
        , tracking( true )
        , orientation( orientation )
    {
    }

    QPointF pressedPos;
    qreal pressedValue;
    bool tracking : 1;
    uint orientation : 2;
};

QskSlider::QskSlider( QQuickItem* parent )
    : QskSlider( Qt::Horizontal, parent )
{
}

QskSlider::QskSlider( Qt::Orientation orientation, QQuickItem* parent )
    : Inherited( parent )
    , m_data( new PrivateData( orientation ) )
{
    setAcceptHoverEvents( true );
    setFocusPolicy( Qt::StrongFocus );

    if ( orientation == Qt::Horizontal )
        initSizePolicy( QskSizePolicy::Minimum, QskSizePolicy::Fixed );
    else
        initSizePolicy( QskSizePolicy::Fixed, QskSizePolicy::Minimum );

    connect( this, &QskSlider::boundariesChanged, this, &QskSlider::moveHandle );
    connect( this, &QskSlider::valueChanged, this, &QskSlider::moveHandle );
}

QskSlider::~QskSlider()
{
}

bool QskSlider::isPressed() const
{
    return hasSkinState( Pressed );
}

void QskSlider::setOrientation( Qt::Orientation orientation )
{
    if ( orientation != m_data->orientation )
    {
        m_data->orientation = orientation;
#if 1
        // swapping the size policy: guess this is what a user expects
        setSizePolicy( sizePolicy( Qt::Vertical ), sizePolicy( Qt::Horizontal ) );
#endif
        resetImplicitSize();
        update();

        Q_EMIT orientationChanged( this->orientation() );
    }
}

Qt::Orientation QskSlider::orientation() const
{
    return static_cast< Qt::Orientation >( m_data->orientation );
}

QskAspect::Variation QskSlider::effectiveVariation() const
{
    return static_cast< QskAspect::Variation >( m_data->orientation );
}

void QskSlider::setGraduationPolicy( Qsk::Policy policy )
{
    if ( setFlagHint( qskAspectGraduationPolicy(), policy ) )
        Q_EMIT graduationPolicyChanged( graduationPolicy() );
}

void QskSlider::resetGraduationPolicy()
{
    if ( resetSkinHint( qskAspectGraduationPolicy() ) )
        Q_EMIT graduationPolicyChanged( graduationPolicy() );
}

Qsk::Policy QskSlider::graduationPolicy() const
{
    return flagHint< Qsk::Policy >( qskAspectGraduationPolicy(), Qsk::Never );
}

void QskSlider::setTracking( bool on )
{
    if ( on != m_data->tracking )
    {
        m_data->tracking = on;
        Q_EMIT trackingChanged( on );
    }
}

bool QskSlider::isTracking() const
{
    return m_data->tracking;
}

void QskSlider::aboutToShow()
{
    setPositionHint( Handle, valueAsRatio() );
    Inherited::aboutToShow();
}

void QskSlider::mousePressEvent( QMouseEvent* event )
{
    if ( qskHandleSelectionRect( this ).contains( event->pos() ) )
    {
        // Case 1: press started in the handle, start sliding

        m_data->pressedPos = event->pos();
        m_data->pressedValue = value();
        setSkinStateFlag( Pressed );
        Q_EMIT pressedChanged( true );
    }
    else if ( pageSteps() == 0 )
    {
        // Case 2: pageSize is not used, we're done here
    }
    else
    {
        // Case 3: pressed outside of the handle, page the scroller in
        // the direction of the press requires an auto-repeat behavior
        // until the slider reaches the destination, or it simply jumps
        // there (configurable)
    }
}

void QskSlider::mouseMoveEvent( QMouseEvent* event )
{
    if ( !isPressed() )
        return;

    const auto mousePos = qskMousePosition( event );
    const auto r = subControlRect( Scale );

    qreal newValue;

    if ( m_data->orientation == Qt::Horizontal )
    {
        const auto distance = mousePos.x() - m_data->pressedPos.x();
        newValue = m_data->pressedValue + distance / r.width() * boundaryLength();
    }
    else
    {
        const auto distance = mousePos.y() - m_data->pressedPos.y();
        newValue = m_data->pressedValue - distance / r.height() * boundaryLength();
    }

    if ( m_data->tracking )
    {
        setValue( newValue );
    }
    else
    {
        moveHandleTo( newValue, QskAnimationHint() );
    }
}

void QskSlider::mouseReleaseEvent( QMouseEvent* event )
{
    if ( !isPressed() ) // Page event
    {
        const auto mousePos = qskMousePosition( event );

        const auto szHandle = qskHandleSelectionRect( this ).size();
        const auto rect = contentsRect();

        bool up;
        if ( m_data->orientation == Qt::Horizontal )
        {
            const qreal w = szHandle.width();

            const qreal x = ( mousePos.x() - rect.x() - w * 0.5 ) / ( rect.width() - w );
            up = x > valueAsRatio();
        }
        else
        {
            const qreal h = szHandle.height();

            const qreal y = ( mousePos.y() - rect.y() - h * 0.5 ) / ( rect.height() - h );
            up = y < 1.0 - valueAsRatio();
        }

        if ( up )
            pageUp();
        else
            pageDown();
    }
    else
    {
        if ( !m_data->tracking )
        {
            const auto pos = handlePosition();
            setValue( valueFromRatio( pos ) );
        }
    }

    setSkinStateFlag( Pressed, false );
    Q_EMIT pressedChanged( false );
}

qreal QskSlider::handlePosition() const
{
    return positionHint( Handle );
}

void QskSlider::moveHandle()
{
    const auto aspect = Handle | QskAspect::Metric | QskAspect::Position;
    moveHandleTo( value(), animationHint( aspect | skinStates() ) );
}

void QskSlider::moveHandleTo( qreal value, const QskAnimationHint& hint )
{
    const qreal pos = valueAsRatio( value );

    if ( hint.isValid() )
    {
        const qreal oldPos = positionHint( Handle );
        setPositionHint( Handle, pos );

        const auto aspect = Handle | QskAspect::Metric | QskAspect::Position;
        startTransition( aspect, hint, oldPos, pos );
    }
    else
    {
        setPositionHint( Handle, pos );
    }

    update();
}

#include "moc_QskSlider.cpp"