/*
    This file is part of the KDE libraries
    SPDX-FileCopyrightText: 1997 Martin Jones <mjones@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "kselector.h"

#include <QPaintEvent>
#include <QPainter>
#include <QPixmap>
#include <QStyle>
#include <QStyleOption>

//-----------------------------------------------------------------------------
/*
 * 1D value selector with contents drawn by derived class.
 * See KColorDialog for example.
 */

#define ARROWSIZE 5

class KSelectorPrivate
{
public:
    bool m_indent = true;
    QStyle::PrimitiveElement arrowPE = QStyle::PE_IndicatorArrowLeft;
};

class KGradientSelectorPrivate
{
public:
    KGradientSelectorPrivate(KGradientSelector *qq)
        : q(qq)
    {
    }

    KGradientSelector *q;
    QLinearGradient gradient;
    QString text1;
    QString text2;
};

KSelector::KSelector(QWidget *parent)
    : QAbstractSlider(parent)
    , d(new KSelectorPrivate)
{
    setOrientation(Qt::Horizontal);
}

KSelector::KSelector(Qt::Orientation o, QWidget *parent)
    : QAbstractSlider(parent)
    , d(new KSelectorPrivate)
{
    setOrientation(o);
    if (o == Qt::Horizontal) {
        setArrowDirection(Qt::UpArrow);
    }
}

KSelector::~KSelector() = default;

void KSelector::setIndent(bool i)
{
    d->m_indent = i;
}

bool KSelector::indent() const
{
    return d->m_indent;
}

QRect KSelector::contentsRect() const
{
    int w = indent() ? style()->pixelMetric(QStyle::PM_DefaultFrameWidth) : 0;
    // TODO: is the height:width ratio of an indicator arrow always 2:1? hm.
    int iw = (w < ARROWSIZE) ? ARROWSIZE : w;

    if (orientation() == Qt::Vertical) {
        if (arrowDirection() == Qt::RightArrow) {
            return QRect(w + ARROWSIZE, //
                         iw,
                         width() - w * 2 - ARROWSIZE,
                         height() - iw * 2);
        } else {
            return QRect(w, //
                         iw,
                         width() - w * 2 - ARROWSIZE,
                         height() - iw * 2);
        }
    } else { // Qt::Horizontal
        if (arrowDirection() == Qt::UpArrow) {
            return QRect(iw, //
                         w,
                         width() - 2 * iw,
                         height() - w * 2 - ARROWSIZE);
        } else {
            return QRect(iw, //
                         w + ARROWSIZE,
                         width() - 2 * iw,
                         height() - w * 2 - ARROWSIZE);
        }
    }
}

void KSelector::paintEvent(QPaintEvent *)
{
    QPainter painter;
    int w = style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
    int iw = (w < ARROWSIZE) ? ARROWSIZE : w;

    painter.begin(this);

    if (indent()) {
        QStyleOptionFrame opt;
        opt.initFrom(this);
        opt.state = QStyle::State_Sunken;
        if (orientation() == Qt::Vertical) {
            opt.rect.adjust(0, iw - w, -5, w - iw);
        } else {
            opt.rect.adjust(iw - w, 0, w - iw, -5);
        }
        QBrush oldBrush = painter.brush();
        painter.setBrush(Qt::NoBrush);
        style()->drawPrimitive(QStyle::PE_Frame, &opt, &painter, this);
        painter.setBrush(oldBrush);
    }

    drawContents(&painter);

    QPoint pos = calcArrowPos(value());
    drawArrow(&painter, pos);

    painter.end();
}

void KSelector::mousePressEvent(QMouseEvent *e)
{
    setSliderDown(true);
    moveArrow(e->pos());
}

void KSelector::mouseMoveEvent(QMouseEvent *e)
{
    moveArrow(e->pos());
}

void KSelector::mouseReleaseEvent(QMouseEvent *e)
{
    moveArrow(e->pos());
    setSliderDown(false);
}

void KSelector::wheelEvent(QWheelEvent *e)
{
    int val = value() + e->angleDelta().y() / 120;
    setSliderDown(true);
    setValue(val);
    setSliderDown(false);
}

void KSelector::moveArrow(const QPoint &pos)
{
    int val;
    int w = style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
    int iw = (w < ARROWSIZE) ? ARROWSIZE : w;

    if (orientation() == Qt::Vertical) {
        val = (maximum() - minimum()) * (height() - pos.y() - iw) / (height() - iw * 2) + minimum();
    } else {
        val = (maximum() - minimum()) * (pos.x() - iw) / (width() - iw * 2) + minimum();
    }

    setValue(val);
    update();
}

QPoint KSelector::calcArrowPos(int val)
{
    QPoint p;
    int w = style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
    int iw = (w < ARROWSIZE) ? ARROWSIZE : w;

    if (orientation() == Qt::Vertical) {
        p.setY(height() - iw - 1 - (height() - 2 * iw - 1) * val / (maximum() - minimum()));

        if (d->arrowPE == QStyle::PE_IndicatorArrowRight) {
            p.setX(0);
        } else {
            p.setX(width() - 5);
        }
    } else {
        p.setX(iw + (width() - 2 * iw - 1) * val / (maximum() - minimum()));

        if (d->arrowPE == QStyle::PE_IndicatorArrowDown) {
            p.setY(0);
        } else {
            p.setY(height() - 5);
        }
    }

    return p;
}

void KSelector::setArrowDirection(Qt::ArrowType direction)
{
    switch (direction) {
    case Qt::UpArrow:
        if (orientation() == Qt::Horizontal) {
            d->arrowPE = QStyle::PE_IndicatorArrowUp;
        } else {
            d->arrowPE = QStyle::PE_IndicatorArrowLeft;
        }
        break;
    case Qt::DownArrow:
        if (orientation() == Qt::Horizontal) {
            d->arrowPE = QStyle::PE_IndicatorArrowDown;
        } else {
            d->arrowPE = QStyle::PE_IndicatorArrowRight;
        }
        break;
    case Qt::LeftArrow:
        if (orientation() == Qt::Vertical) {
            d->arrowPE = QStyle::PE_IndicatorArrowLeft;
        } else {
            d->arrowPE = QStyle::PE_IndicatorArrowDown;
        }
        break;
    case Qt::RightArrow:
        if (orientation() == Qt::Vertical) {
            d->arrowPE = QStyle::PE_IndicatorArrowRight;
        } else {
            d->arrowPE = QStyle::PE_IndicatorArrowUp;
        }
        break;

    case Qt::NoArrow:
        break;
    }
}

Qt::ArrowType KSelector::arrowDirection() const
{
    switch (d->arrowPE) {
    case QStyle::PE_IndicatorArrowUp:
        return Qt::UpArrow;
    case QStyle::PE_IndicatorArrowDown:
        return Qt::DownArrow;
    case QStyle::PE_IndicatorArrowRight:
        return Qt::RightArrow;
    case QStyle::PE_IndicatorArrowLeft:
    default:
        return Qt::LeftArrow;
    }
}

void KSelector::drawContents(QPainter *)
{
}

void KSelector::drawArrow(QPainter *painter, const QPoint &pos)
{
    painter->setPen(QPen());
    painter->setBrush(QBrush(palette().color(QPalette::ButtonText)));

    QStyleOption o;

    if (orientation() == Qt::Vertical) {
        o.rect = QRect(pos.x(), pos.y() - ARROWSIZE / 2, ARROWSIZE, ARROWSIZE);
    } else {
        o.rect = QRect(pos.x() - ARROWSIZE / 2, pos.y(), ARROWSIZE, ARROWSIZE);
    }
    style()->drawPrimitive(d->arrowPE, &o, painter, this);
}

//----------------------------------------------------------------------------

KGradientSelector::KGradientSelector(QWidget *parent)
    : KSelector(parent)
    , d(new KGradientSelectorPrivate(this))
{
}

KGradientSelector::KGradientSelector(Qt::Orientation o, QWidget *parent)
    : KSelector(o, parent)
    , d(new KGradientSelectorPrivate(this))
{
}

KGradientSelector::~KGradientSelector() = default;

void KGradientSelector::drawContents(QPainter *painter)
{
    d->gradient.setStart(contentsRect().topLeft());
    if (orientation() == Qt::Vertical) {
        d->gradient.setFinalStop(contentsRect().bottomLeft());
    } else {
        d->gradient.setFinalStop(contentsRect().topRight());
    }
    QBrush gradientBrush(d->gradient);

    if (!gradientBrush.isOpaque()) {
        QPixmap chessboardPattern(16, 16);
        QPainter patternPainter(&chessboardPattern);
        patternPainter.fillRect(0, 0, 8, 8, Qt::black);
        patternPainter.fillRect(8, 8, 8, 8, Qt::black);
        patternPainter.fillRect(0, 8, 8, 8, Qt::white);
        patternPainter.fillRect(8, 0, 8, 8, Qt::white);
        patternPainter.end();
        painter->fillRect(contentsRect(), QBrush(chessboardPattern));
    }
    painter->fillRect(contentsRect(), gradientBrush);

    if (orientation() == Qt::Vertical) {
        int yPos = contentsRect().top() + painter->fontMetrics().ascent() + 2;
        int xPos = contentsRect().left() + (contentsRect().width() - painter->fontMetrics().horizontalAdvance(d->text2)) / 2;
        QPen pen(qGray(firstColor().rgb()) > 180 ? Qt::black : Qt::white);
        painter->setPen(pen);
        painter->drawText(xPos, yPos, d->text2);

        yPos = contentsRect().bottom() - painter->fontMetrics().descent() - 2;
        xPos = contentsRect().left() + (contentsRect().width() - painter->fontMetrics().horizontalAdvance(d->text1)) / 2;
        pen.setColor(qGray(secondColor().rgb()) > 180 ? Qt::black : Qt::white);
        painter->setPen(pen);
        painter->drawText(xPos, yPos, d->text1);
    } else {
        int yPos = contentsRect().bottom() - painter->fontMetrics().descent() - 2;

        QPen pen(qGray(firstColor().rgb()) > 180 ? Qt::black : Qt::white);
        painter->setPen(pen);
        painter->drawText(contentsRect().left() + 2, yPos, d->text1);

        pen.setColor(qGray(secondColor().rgb()) > 180 ? Qt::black : Qt::white);
        painter->setPen(pen);
        painter->drawText(contentsRect().right() - painter->fontMetrics().horizontalAdvance(d->text2) - 2, yPos, d->text2);
    }
}

QSize KGradientSelector::minimumSize() const
{
    return sizeHint();
}

void KGradientSelector::setStops(const QGradientStops &stops)
{
    d->gradient.setStops(stops);
    update();
}

QGradientStops KGradientSelector::stops() const
{
    return d->gradient.stops();
}

void KGradientSelector::setColors(const QColor &col1, const QColor &col2)
{
    d->gradient.setColorAt(0.0, col1);
    d->gradient.setColorAt(1.0, col2);
    update();
}

void KGradientSelector::setText(const QString &t1, const QString &t2)
{
    d->text1 = t1;
    d->text2 = t2;
    update();
}

void KGradientSelector::setFirstColor(const QColor &col)
{
    d->gradient.setColorAt(0.0, col);
    update();
}

void KGradientSelector::setSecondColor(const QColor &col)
{
    d->gradient.setColorAt(1.0, col);
    update();
}

void KGradientSelector::setFirstText(const QString &t)
{
    d->text1 = t;
    update();
}

void KGradientSelector::setSecondText(const QString &t)
{
    d->text2 = t;
    update();
}

QColor KGradientSelector::firstColor() const
{
    return d->gradient.stops().first().second;
}

QColor KGradientSelector::secondColor() const
{
    return d->gradient.stops().last().second;
}

QString KGradientSelector::firstText() const
{
    return d->text1;
}

QString KGradientSelector::secondText() const
{
    return d->text2;
}
