/*
 * Copyright (C) 2001-2015 Klaralvdalens Datakonsult AB.  All rights reserved.
 *
 * This file is part of the KD Chart library.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "KChartLegend.h"
#include "KChartLegend_p.h"
#include <KChartTextAttributes.h>
#include <KChartMarkerAttributes.h>
#include <KChartPalette.h>
#include <KChartAbstractDiagram.h>
#include "KTextDocument.h"
#include <KChartDiagramObserver.h>
#include "KChartLayoutItems.h"
#include "KChartPrintingParameters.h"

#include <QFont>
#include <QGridLayout>
#include <QPainter>
#include <QTextTableCell>
#include <QTextCursor>
#include <QTextCharFormat>
#include <QTextDocumentFragment>
#include <QTimer>
#include <QAbstractTextDocumentLayout>
#include <QtDebug>
#include <QLabel>

using namespace KChart;

Legend::Private::Private() :
    referenceArea( nullptr ),
    position( Position::East ),
    alignment( Qt::AlignCenter ),
    textAlignment( Qt::AlignCenter ),
    relativePosition( RelativePosition() ),
    orientation( Qt::Vertical ),
    order( Qt::AscendingOrder ),
    showLines( false ),
    titleText( QObject::tr( "Legend" ) ),
    spacing( 1 ),
    useAutomaticMarkerSize( true ),
    legendStyle( MarkersOnly )
{
    // By default we specify a simple, hard point as the 'relative' position's ref. point,
    // since we can not be sure that there will be any parent specified for the legend.
    relativePosition.setReferencePoints( PositionPoints( QPointF( 0.0, 0.0 ) ) );
    relativePosition.setReferencePosition( Position::NorthWest );
    relativePosition.setAlignment( Qt::AlignTop | Qt::AlignLeft );
    relativePosition.setHorizontalPadding( Measure( 4.0, KChartEnums::MeasureCalculationModeAbsolute ) );
    relativePosition.setVerticalPadding( Measure( 4.0, KChartEnums::MeasureCalculationModeAbsolute ) );
}

Legend::Private::~Private()
{
    // this bloc left empty intentionally
}


#define d d_func()


Legend::Legend( QWidget* parent ) :
    AbstractAreaWidget( new Private(), parent )
{
    d->referenceArea = parent;
    init();
}

Legend::Legend( AbstractDiagram* diagram, QWidget* parent ) :
    AbstractAreaWidget( new Private(), parent )
{
    d->referenceArea = parent;
    init();
    setDiagram( diagram );
}

Legend::~Legend()
{
    Q_EMIT destroyedLegend( this );
}

void Legend::init()
{
    setSizePolicy( QSizePolicy::Fixed, QSizePolicy::Fixed );

    d->layout = new QGridLayout( this );
    d->layout->setContentsMargins( 2, 2, 2, 2 );
    d->layout->setSpacing( d->spacing );

    const Measure normalFontSizeTitle( 12, KChartEnums::MeasureCalculationModeAbsolute );
    const Measure normalFontSizeLabels( 10, KChartEnums::MeasureCalculationModeAbsolute );
    const Measure minimalFontSize( 4, KChartEnums::MeasureCalculationModeAbsolute );

    TextAttributes textAttrs;
    textAttrs.setPen( QPen( Qt::black ) );
    textAttrs.setFont( QFont( QLatin1String( "helvetica" ), 10, QFont::Normal, false ) );
    textAttrs.setFontSize( normalFontSizeLabels );
    textAttrs.setMinimalFontSize( minimalFontSize );
    setTextAttributes( textAttrs );

    TextAttributes titleTextAttrs;
    titleTextAttrs.setPen( QPen( Qt::black ) );
    titleTextAttrs.setFont( QFont( QLatin1String( "helvetica" ), 12, QFont::Bold, false ) );
    titleTextAttrs.setFontSize( normalFontSizeTitle );
    titleTextAttrs.setMinimalFontSize( minimalFontSize );
    setTitleTextAttributes( titleTextAttrs );

    FrameAttributes frameAttrs;
    frameAttrs.setVisible( true );
    frameAttrs.setPen( QPen( Qt::black ) );
    frameAttrs.setPadding( 1 );
    setFrameAttributes( frameAttrs );

    d->position = Position::NorthEast;
    d->alignment = Qt::AlignCenter;
}


QSize Legend::minimumSizeHint() const
{
    return sizeHint();
}

//#define DEBUG_LEGEND_PAINT

QSize Legend::sizeHint() const
{
#ifdef DEBUG_LEGEND_PAINT
    qDebug()  << "Legend::sizeHint() started";
#endif
    Q_FOREACH( AbstractLayoutItem* paintItem, d->paintItems ) {
        paintItem->sizeHint();
    }
    return AbstractAreaWidget::sizeHint();
}

void Legend::needSizeHint()
{
    buildLegend();
}

void Legend::resizeLayout( const QSize& size )
{
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "Legend::resizeLayout started";
#endif
    if ( d->layout ) {
        d->reflowHDatasetItems( this );
        d->layout->setGeometry( QRect(QPoint( 0,0 ), size) );
        activateTheLayout();
    }
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "Legend::resizeLayout done";
#endif
}

void Legend::activateTheLayout()
{
    if ( d->layout && d->layout->parent() ) {
        d->layout->activate();
    }
}

void Legend::setLegendStyle( LegendStyle style )
{
    if ( d->legendStyle == style ) {
        return;
    }
    d->legendStyle = style;
    setNeedRebuild();
}

Legend::LegendStyle Legend::legendStyle() const
{
    return d->legendStyle;
}

Legend* Legend::clone() const
{
    Legend* legend = new Legend( new Private( *d ), nullptr );
    legend->setTextAttributes( textAttributes() );
    legend->setTitleTextAttributes( titleTextAttributes() );
    legend->setFrameAttributes( frameAttributes() );
    legend->setUseAutomaticMarkerSize( useAutomaticMarkerSize() );
    legend->setPosition( position() );
    legend->setAlignment( alignment() );
    legend->setTextAlignment( textAlignment() );
    legend->setLegendStyle( legendStyle() );
    return legend;
}


bool Legend::compare( const Legend* other ) const
{
    if ( other == this ) {
        return true;
    }
    if ( !other ) {
        return false;
    }

    return  ( AbstractAreaBase::compare( other ) ) &&
            (isVisible()              == other->isVisible()) &&
            (position()               == other->position()) &&
            (alignment()              == other->alignment())&&
            (textAlignment()          == other->textAlignment())&&
            (floatingPosition()       == other->floatingPosition()) &&
            (orientation()            == other->orientation())&&
            (showLines()              == other->showLines())&&
            (texts()                  == other->texts())&&
            (brushes()                == other->brushes())&&
            (pens()                   == other->pens())&&
            (markerAttributes()       == other->markerAttributes())&&
            (useAutomaticMarkerSize() == other->useAutomaticMarkerSize()) &&
            (textAttributes()         == other->textAttributes()) &&
            (titleText()              == other->titleText())&&
            (titleTextAttributes()    == other->titleTextAttributes()) &&
            (spacing()                == other->spacing()) &&
            (legendStyle()            == other->legendStyle());
}


void Legend::paint( QPainter* painter )
{
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "entering Legend::paint( QPainter* painter )";
#endif
    if ( !diagram() ) {
        return;
    }

    activateTheLayout();

    Q_FOREACH( AbstractLayoutItem* paintItem, d->paintItems ) {
        paintItem->paint( painter );
    }

#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "leaving Legend::paint( QPainter* painter )";
#endif
}

void Legend::paint( QPainter *painter, const QRect& rect )
{
    if ( rect.isEmpty() ) {
        return;
    }
    // set up the contents of the widget so we get a useful geometry
    QPaintDevice* prevDevice = GlobalMeasureScaling::paintDevice();
    GlobalMeasureScaling::setPaintDevice( painter->device() );

    const QRect oldGeometry(geometry() );
    const QRect newGeo( QPoint(0,0), rect.size() );
    if (oldGeometry != newGeo) {
        setGeometry(newGeo);
        needSizeHint();
    }
    painter->translate( rect.left(), rect.top() );
    paintAll( *painter );
    painter->translate( -rect.left(), -rect.top() );

    if (oldGeometry != newGeo) {
        setGeometry(oldGeometry);
    }
    GlobalMeasureScaling::setPaintDevice( prevDevice );
}

uint Legend::datasetCount() const
{
    int modelLabelsCount = 0;
    Q_FOREACH ( DiagramObserver* observer, d->observers ) {
        AbstractDiagram* diagram = observer->diagram();
        Q_ASSERT( diagram->datasetLabels().count() == diagram->datasetBrushes().count() );
        modelLabelsCount += diagram->datasetLabels().count();
    }
    return modelLabelsCount;
}


void Legend::setReferenceArea( const QWidget* area )
{
    if ( area == d->referenceArea ) {
        return;
    }
    d->referenceArea = area;
    setNeedRebuild();
}

const QWidget* Legend::referenceArea() const
{
    return d->referenceArea ? d->referenceArea : qobject_cast< const QWidget* >( parent() );
}


AbstractDiagram* Legend::diagram() const
{
    if ( d->observers.isEmpty() ) {
        return nullptr;
    }
    return d->observers.first()->diagram();
}

DiagramList Legend::diagrams() const
{
    DiagramList list;
    for ( int i = 0; i < d->observers.size(); ++i ) {
        list << d->observers.at(i)->diagram();
    }
    return list;
}

ConstDiagramList Legend::constDiagrams() const
{
    ConstDiagramList list;
    for ( int i = 0; i < d->observers.size(); ++i ) {
        list << d->observers.at(i)->diagram();
    }
    return list;
}

void Legend::addDiagram( AbstractDiagram* newDiagram )
{
    if ( newDiagram ) {
        DiagramObserver* observer = new DiagramObserver( newDiagram, this );

        DiagramObserver* oldObs = d->findObserverForDiagram( newDiagram );
        if ( oldObs ) {
            delete oldObs;
            d->observers[ d->observers.indexOf( oldObs ) ] = observer;
        } else {
            d->observers.append( observer );
        }
        connect( observer, SIGNAL(diagramAboutToBeDestroyed(AbstractDiagram*)),
                 SLOT(resetDiagram(AbstractDiagram*)));
        connect( observer, SIGNAL(diagramDataChanged(AbstractDiagram*)),
                 SLOT(setNeedRebuild()));
        connect( observer, SIGNAL(diagramDataHidden(AbstractDiagram*)),
                 SLOT(setNeedRebuild()));
        connect( observer, SIGNAL(diagramAttributesChanged(AbstractDiagram*)),
                 SLOT(setNeedRebuild()));
        setNeedRebuild();
    }
}

void Legend::removeDiagram( AbstractDiagram* oldDiagram )
{
    int datasetBrushOffset = 0;
    QList< AbstractDiagram * > diagrams = this->diagrams();
    for ( int i = 0; i <diagrams.count(); i++ ) {
        if ( diagrams.at( i ) == oldDiagram ) {
            for ( int i = 0; i < oldDiagram->datasetBrushes().count(); i++ ) {
                d->brushes.remove(datasetBrushOffset + i);
                d->texts.remove(datasetBrushOffset + i);
            }
            for ( int i = 0; i < oldDiagram->datasetPens().count(); i++ ) {
                d->pens.remove(datasetBrushOffset + i);
            }
            break;
        }
        datasetBrushOffset += diagrams.at(i)->datasetBrushes().count();
    }

    if ( oldDiagram ) {
        DiagramObserver *oldObs = d->findObserverForDiagram( oldDiagram );
        if ( oldObs ) {
            delete oldObs;
            d->observers.removeAt( d->observers.indexOf( oldObs ) );
        }
        setNeedRebuild();
    }
}

void Legend::removeDiagrams()
{
    // removeDiagram() may change the d->observers list. So, build up the list of
    // diagrams to remove first and then remove them one by one.
    QList< AbstractDiagram * > diagrams;
    for ( int i = 0; i < d->observers.size(); ++i ) {
        diagrams.append( d->observers.at( i )->diagram() );
    }
    for ( int i = 0; i < diagrams.count(); ++i ) {
        removeDiagram( diagrams[ i ] );
    }
}

void Legend::replaceDiagram( AbstractDiagram* newDiagram,
                             AbstractDiagram* oldDiagram )
{
    AbstractDiagram* old = oldDiagram;
    if ( !d->observers.isEmpty() && !old ) {
        old = d->observers.first()->diagram();
        if ( !old ) {
            d->observers.removeFirst(); // first entry had a 0 diagram
        }
    }
    if ( old ) {
        removeDiagram( old );
    }
    if ( newDiagram ) {
        addDiagram( newDiagram );
    }
}

uint Legend::dataSetOffset( AbstractDiagram* diagram )
{
    uint offset = 0;

    for ( int i = 0; i < d->observers.count(); ++i ) {
        if ( d->observers.at(i)->diagram() == diagram ) {
            return offset;
        }
        AbstractDiagram* diagram = d->observers.at(i)->diagram();
        if ( !diagram->model() ) {
            continue;
        }
        offset = offset + diagram->model()->columnCount();
    }

    return offset;
}

void Legend::setDiagram( AbstractDiagram* newDiagram )
{
    replaceDiagram( newDiagram );
}

void Legend::resetDiagram( AbstractDiagram* oldDiagram )
{
    removeDiagram( oldDiagram );
}

void Legend::setVisible( bool visible )
{
    // do NOT bail out if visible == isVisible(), because the return value of isVisible() also depends
    // on the visibility of the parent.
    QWidget::setVisible( visible );
    emitPositionChanged();
}

void Legend::setNeedRebuild()
{
    buildLegend();
    sizeHint();
}

void Legend::setPosition( Position position )
{
    if ( d->position == position ) {
        return;
    }
    d->position = position;
    emitPositionChanged();
}

void Legend::emitPositionChanged()
{
    Q_EMIT positionChanged( this );
    Q_EMIT propertiesChanged();
}


Position Legend::position() const
{
    return d->position;
}

void Legend::setAlignment( Qt::Alignment alignment )
{
    if ( d->alignment == alignment ) {
        return;
    }
    d->alignment = alignment;
    emitPositionChanged();
}

Qt::Alignment Legend::alignment() const
{
    return d->alignment;
}

void Legend::setTextAlignment( Qt::Alignment alignment )
{
    if ( d->textAlignment == alignment ) {
        return;
    }
    d->textAlignment = alignment;
    emitPositionChanged();
}

Qt::Alignment Legend::textAlignment() const
{
    return d->textAlignment;
}

void Legend::setLegendSymbolAlignment( Qt::Alignment alignment )
{
    if ( d->legendLineSymbolAlignment == alignment ) {
        return;
    }
    d->legendLineSymbolAlignment = alignment;
    emitPositionChanged();
}

Qt::Alignment Legend::legendSymbolAlignment() const
{
    return d->legendLineSymbolAlignment ;
}

void Legend::setFloatingPosition( const RelativePosition& relativePosition )
{
    d->position = Position::Floating;
    if ( d->relativePosition != relativePosition ) {
        d->relativePosition  = relativePosition;
        emitPositionChanged();
    }
}

const RelativePosition Legend::floatingPosition() const
{
    return d->relativePosition;
}

void Legend::setOrientation( Qt::Orientation orientation )
{
    if ( d->orientation == orientation ) {
        return;
    }
    d->orientation = orientation;
    setNeedRebuild();
    emitPositionChanged();
}

Qt::Orientation Legend::orientation() const
{
    return d->orientation;
}

void Legend::setSortOrder( Qt::SortOrder order )
{
    if ( d->order == order ) {
        return;
    }
    d->order = order;
    setNeedRebuild();
    emitPositionChanged();
}

Qt::SortOrder Legend::sortOrder() const
{
    return d->order;
}

void Legend::setShowLines( bool legendShowLines )
{
    if ( d->showLines == legendShowLines ) {
        return;
    }
    d->showLines = legendShowLines;
    setNeedRebuild();
    emitPositionChanged();
}

bool Legend::showLines() const
{
    return d->showLines;
}

void Legend::setUseAutomaticMarkerSize( bool useAutomaticMarkerSize )
{
    d->useAutomaticMarkerSize = useAutomaticMarkerSize;
    setNeedRebuild();
    emitPositionChanged();
}

bool Legend::useAutomaticMarkerSize() const
{
    return d->useAutomaticMarkerSize;
}

void Legend::resetTexts()
{
    if ( !d->texts.count() ) {
        return;
    }
    d->texts.clear();
    setNeedRebuild();
}

void Legend::setText( uint dataset, const QString& text )
{
    if ( d->texts[ dataset ] == text ) {
        return;
    }
    d->texts[ dataset ] = text;
    setNeedRebuild();
}

QString Legend::text( uint dataset ) const
{
    if ( d->texts.find( dataset ) != d->texts.end() ) {
        return d->texts[ dataset ];
    } else {
        return d->modelLabels[ dataset ];
    }
}

const QMap<uint,QString> Legend::texts() const
{
    return d->texts;
}

void Legend::setColor( uint dataset, const QColor& color )
{
    if ( d->brushes[ dataset ] != color ) {
        d->brushes[ dataset ] = color;
        setNeedRebuild();
        update();
    }
}

void Legend::setBrush( uint dataset, const QBrush& brush )
{
    if ( d->brushes[ dataset ] != brush ) {
        d->brushes[ dataset ] = brush;
        setNeedRebuild();
        update();
    }
}

QBrush Legend::brush( uint dataset ) const
{
    if ( d->brushes.contains( dataset ) ) {
        return d->brushes[ dataset ];
    } else {
        return d->modelBrushes[ dataset ];
    }
}

const QMap<uint,QBrush> Legend::brushes() const
{
    return d->brushes;
}


void Legend::setBrushesFromDiagram( AbstractDiagram* diagram )
{
    bool changed = false;
    QList<QBrush> datasetBrushes = diagram->datasetBrushes();
    for ( int i = 0; i < datasetBrushes.count(); i++ ) {
        if ( d->brushes[ i ] != datasetBrushes[ i ] ) {
            d->brushes[ i ]  = datasetBrushes[ i ];
            changed = true;
        }
    }
    if ( changed ) {
        setNeedRebuild();
        update();
    }
}


void Legend::setPen( uint dataset, const QPen& pen )
{
    if ( d->pens[dataset] == pen ) {
        return;
    }
    d->pens[dataset] = pen;
    setNeedRebuild();
    update();
}

QPen Legend::pen( uint dataset ) const
{
    if ( d->pens.find( dataset ) != d->pens.end() ) {
        return d->pens[ dataset ];
    } else {
        return d->modelPens[ dataset ];
    }
}

const QMap<uint,QPen> Legend::pens() const
{
    return d->pens;
}


void Legend::setMarkerAttributes( uint dataset, const MarkerAttributes& markerAttributes )
{
    if ( d->markerAttributes[dataset] == markerAttributes ) {
        return;
    }
    d->markerAttributes[ dataset ] = markerAttributes;
    setNeedRebuild();
    update();
}

MarkerAttributes Legend::markerAttributes( uint dataset ) const
{
    if ( d->markerAttributes.find( dataset ) != d->markerAttributes.end() ) {
        return d->markerAttributes[ dataset ];
    } else if ( static_cast<uint>( d->modelMarkers.count() ) > dataset ) {
        return d->modelMarkers[ dataset ];
    } else {
        return MarkerAttributes();
    }
}

const QMap<uint, MarkerAttributes> Legend::markerAttributes() const
{
    return d->markerAttributes;
}


void Legend::setTextAttributes( const TextAttributes &a )
{
    if ( d->textAttributes == a ) {
        return;
    }
    d->textAttributes = a;
    setNeedRebuild();
}

TextAttributes Legend::textAttributes() const
{
    return d->textAttributes;
}

void Legend::setTitleText( const QString& text )
{
    if ( d->titleText == text ) {
        return;
    }
    d->titleText = text;
    setNeedRebuild();
}

QString Legend::titleText() const
{
    return d->titleText;
}

void Legend::setTitleTextAttributes( const TextAttributes &a )
{
    if ( d->titleTextAttributes == a ) {
        return;
    }
    d->titleTextAttributes = a;
    setNeedRebuild();
}

TextAttributes Legend::titleTextAttributes() const
{
    return d->titleTextAttributes;
}

void Legend::forceRebuild()
{
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "entering Legend::forceRebuild()";
#endif
    buildLegend();
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "leaving Legend::forceRebuild()";
#endif
}

void Legend::setSpacing( uint space )
{
    if ( d->spacing == space && d->layout->spacing() == int( space ) ) {
        return;
    }
    d->spacing = space;
    d->layout->setSpacing( space );
    setNeedRebuild();
}

uint Legend::spacing() const
{
    return d->spacing;
}

void Legend::setDefaultColors()
{
    Palette pal = Palette::defaultPalette();
    for ( int i = 0; i < pal.size(); i++ ) {
        setBrush( i, pal.getBrush( i ) );
    }
}

void Legend::setRainbowColors()
{
    Palette pal = Palette::rainbowPalette();
    for ( int i = 0; i < pal.size(); i++ ) {
        setBrush( i, pal.getBrush( i ) );
    }
}

void Legend::setSubduedColors( bool ordered )
{
    Palette pal = Palette::subduedPalette();
    if ( ordered ) {
        for ( int i = 0; i < pal.size(); i++ ) {
            setBrush( i, pal.getBrush( i ) );
        }
    } else {
        static const int s_subduedColorsCount = 18;
        Q_ASSERT( pal.size() >= s_subduedColorsCount );
        static const int order[ s_subduedColorsCount ] = {
            0, 5, 10, 15, 2, 7, 12, 17, 4,
            9, 14, 1, 6, 11, 16, 3, 8, 13
        };
        for ( int i = 0; i < s_subduedColorsCount; i++ ) {
            setBrush( i, pal.getBrush( order[i] ) );
        }
    }
}

void Legend::resizeEvent( QResizeEvent * event )
{
    Q_UNUSED( event );
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "Legend::resizeEvent() called";
#endif
    forceRebuild();
    sizeHint();
    QTimer::singleShot( 0, this, SLOT(emitPositionChanged()) );
}

void Legend::Private::fetchPaintOptions( Legend *q )
{
    modelLabels.clear();
    modelBrushes.clear();
    modelPens.clear();
    modelMarkers.clear();
    // retrieve the diagrams' settings for all non-hidden datasets
    for ( int i = 0; i < observers.size(); ++i ) {
        const AbstractDiagram* diagram = observers.at( i )->diagram();
        if ( !diagram ) {
            continue;
        }
        const QStringList diagramLabels = diagram->datasetLabels();
        const QList<QBrush> diagramBrushes = diagram->datasetBrushes();
        const QList<QPen> diagramPens = diagram->datasetPens();
        const QList<MarkerAttributes> diagramMarkers = diagram->datasetMarkers();

        const bool ascend = q->sortOrder() == Qt::AscendingOrder;
        int dataset = ascend ? 0 : diagramLabels.count() - 1;
        const int end = ascend ? diagramLabels.count() : -1;
        for ( ; dataset != end; dataset += ascend ? 1 : -1 ) {
            if ( diagram->isHidden( dataset ) || q->datasetIsHidden( dataset ) ) {
                continue;
            }
            modelLabels += diagramLabels[ dataset ];
            modelBrushes += diagramBrushes[ dataset ];
            modelPens += diagramPens[ dataset ];
            modelMarkers += diagramMarkers[ dataset ];
        }
    }

    Q_ASSERT( modelLabels.count() == modelBrushes.count() );
}

QSizeF Legend::Private::markerSize( Legend *q, int dataset, qreal fontHeight ) const
{
    QSizeF suppliedSize = q->markerAttributes( dataset ).markerSize();
    if ( q->useAutomaticMarkerSize() || !suppliedSize.isValid() ) {
        return QSizeF( fontHeight, fontHeight );
    } else {
        return suppliedSize;
    }
}

QSizeF Legend::Private::maxMarkerSize( Legend *q, qreal fontHeight ) const
{
    QSizeF ret( 1.0, 1.0 );
    if ( q->legendStyle() != LinesOnly ) {
        for ( int dataset = 0; dataset < modelLabels.count(); ++dataset ) {
            ret = ret.expandedTo( markerSize( q, dataset, fontHeight ) );
        }
    }
    return ret;
}

HDatasetItem::HDatasetItem()
   : markerLine(nullptr),
     label(nullptr),
     separatorLine(nullptr),
     spacer(nullptr)
{}

static void updateToplevelLayout(QWidget *w)
{
    while ( w ) {
        if ( w->isTopLevel() ) {
            // The null check has proved necessary during destruction of the Legend / Chart
            if ( w->layout() ) {
                w->layout()->update();
            }
            break;
        } else {
            w = qobject_cast< QWidget * >( w->parent() );
            Q_ASSERT( w );
        }
    }
}

void Legend::buildLegend()
{
    /* Grid layout partitioning (horizontal orientation): row zero is the title, row one the divider
       line between title and dataset items, row two for each item: line, marker, text label and separator
       line in that order.
       In a vertically oriented legend, row pairs (2, 3), ... contain a possible separator line (first row)
       and (second row) line, marker, text label each. */
    d->destroyOldLayout();

    if ( orientation() == Qt::Vertical ) {
        d->layout->setColumnStretch( 6, 1 );
    } else {
        d->layout->setColumnStretch( 6, 0 );
    }

    d->fetchPaintOptions( this );

    const KChartEnums::MeasureOrientation measureOrientation =
        orientation() == Qt::Vertical ? KChartEnums::MeasureOrientationMinimum
                                      : KChartEnums::MeasureOrientationHorizontal;

    // legend caption
    if ( !titleText().isEmpty() && titleTextAttributes().isVisible() ) {
        TextLayoutItem* titleItem =
            new TextLayoutItem( titleText(), titleTextAttributes(), referenceArea(),
                                         measureOrientation, d->textAlignment );
        titleItem->setParentWidget( this );

        d->paintItems << titleItem;
        d->layout->addItem( titleItem, 0, 0, 1, 5, Qt::AlignCenter );

        // The line between the title and the legend items, if any.
        if ( showLines() && d->modelLabels.count() ) {
            HorizontalLineLayoutItem* lineItem = new HorizontalLineLayoutItem;
            d->paintItems << lineItem;
            d->layout->addItem( lineItem, 1, 0, 1, 5, Qt::AlignCenter );
        }
    }

    qreal fontHeight = textAttributes().calculatedFontSize( referenceArea(), measureOrientation );
    {
        QFont tmpFont = textAttributes().font();
        tmpFont.setPointSizeF( fontHeight );
        if ( GlobalMeasureScaling::paintDevice() ) {
            fontHeight = QFontMetricsF( tmpFont, GlobalMeasureScaling::paintDevice() ).height();
        } else {
            fontHeight = QFontMetricsF( tmpFont ).height();
        }
    }

    const QSizeF maxMarkerSize = d->maxMarkerSize( this, fontHeight );

    // If we show a marker on a line, we paint it after 8 pixels
    // of the line have been painted. This allows to see the line style
    // at the right side of the marker without the line needing to
    // be too long.
    // (having the marker in the middle of the line would require longer lines)
    const int lineLengthLeftOfMarker = 8;

    int maxLineLength = 18;
    {
        bool hasComplexPenStyle = false;
        for ( int dataset = 0; dataset < d->modelLabels.count(); ++dataset ) {
            const QPen pn = pen( dataset );
            const Qt::PenStyle ps = pn.style();
            if ( ps != Qt::NoPen ) {
                maxLineLength = qMin( pn.width() * 18, maxLineLength );
                if ( ps != Qt::SolidLine ) {
                    hasComplexPenStyle = true;
                }
            }
        }
        if ( legendStyle() != LinesOnly ) {
            if ( hasComplexPenStyle )
              maxLineLength += lineLengthLeftOfMarker;
            maxLineLength += int( maxMarkerSize.width() );
        }
    }

    // for all datasets: add (line)marker items and text items to the layout;
    // actual layout happens in flowHDatasetItems() for horizontal layout, here for vertical
    for ( int dataset = 0; dataset < d->modelLabels.count(); ++dataset ) {
        const int vLayoutRow = 2 + dataset * 2;
        HDatasetItem dsItem;

        // It is possible to set the marker brush through markerAttributes as well as
        // the dataset brush set in the diagram - the markerAttributes have higher precedence.
        MarkerAttributes markerAttrs = markerAttributes( dataset );
        markerAttrs.setMarkerSize( d->markerSize( this, dataset, fontHeight ) );
        const QBrush markerBrush = markerAttrs.markerColor().isValid() ?
                                   QBrush( markerAttrs.markerColor() ) : brush( dataset );

        switch ( legendStyle() ) {
        case MarkersOnly:
            dsItem.markerLine = new MarkerLayoutItem( diagram(), markerAttrs, markerBrush,
                                                      markerAttrs.pen(), Qt::AlignLeft | Qt::AlignVCenter );
            break;
        case LinesOnly:
            dsItem.markerLine = new LineLayoutItem( diagram(), maxLineLength, pen( dataset ),
                                                    d->legendLineSymbolAlignment, Qt::AlignCenter );
            break;
        case MarkersAndLines:
            dsItem.markerLine = new LineWithMarkerLayoutItem(
                diagram(), maxLineLength, pen( dataset ), lineLengthLeftOfMarker, markerAttrs,
                markerBrush, markerAttrs.pen(), Qt::AlignCenter );
            break;
        default:
            Q_ASSERT( false );
        }

        dsItem.label = new TextLayoutItem( text( dataset ), textAttributes(), referenceArea(),
                                           measureOrientation, d->textAlignment );
        dsItem.label->setParentWidget( this );

        // horizontal layout is deferred to flowDatasetItems()

        if ( orientation() == Qt::Horizontal ) {
            d->hLayoutDatasets << dsItem;
            continue;
        }

        // (actual) vertical layout here
        if ( dsItem.markerLine ) {
            d->layout->addItem( dsItem.markerLine, vLayoutRow, 1, 1, 1, Qt::AlignCenter );
            d->paintItems << dsItem.markerLine;
        }
        d->layout->addItem( dsItem.label, vLayoutRow, 3, 1, 1, Qt::AlignLeft | Qt::AlignVCenter );
        d->paintItems << dsItem.label;

        // horizontal separator line, only between items
        if ( showLines() && dataset != d->modelLabels.count() - 1 ) {
            HorizontalLineLayoutItem* lineItem = new HorizontalLineLayoutItem;
            d->layout->addItem( lineItem, vLayoutRow + 1, 0, 1, 5, Qt::AlignCenter );
            d->paintItems << lineItem;
        }
    }

    if ( orientation() == Qt::Horizontal ) {
        d->flowHDatasetItems( this );
    }

    // vertical line (only in vertical mode)
    if ( orientation() == Qt::Vertical && showLines() && d->modelLabels.count() ) {
        VerticalLineLayoutItem* lineItem = new VerticalLineLayoutItem;
        d->paintItems << lineItem;
        d->layout->addItem( lineItem, 2, 2, d->modelLabels.count() * 2, 1 );
    }

    updateToplevelLayout( this );

    Q_EMIT propertiesChanged();
#ifdef DEBUG_LEGEND_PAINT
    qDebug() << "leaving Legend::buildLegend()";
#endif
}

int HDatasetItem::height() const
{
    return qMax( markerLine->sizeHint().height(), label->sizeHint().height() );
}

void Legend::Private::reflowHDatasetItems( Legend *q )
{
    if (hLayoutDatasets.isEmpty()) {
        return;
    }

    paintItems.clear();
    // Dissolve exactly the QHBoxLayout(s) created as "currentLine" in flowHDatasetItems - don't remove the
    // caption and line under the caption! Those are easily identified because they aren't QLayouts.
    for ( int i = layout->count() - 1; i >= 0; i-- ) {
        QLayoutItem *const item = layout->itemAt( i );
        QLayout *const hbox = item->layout();
        if ( !hbox ) {
            AbstractLayoutItem *alItem = dynamic_cast< AbstractLayoutItem * >( item );
            Q_ASSERT( alItem );
            paintItems << alItem;
            continue;
        }
        Q_ASSERT( dynamic_cast< QHBoxLayout * >( hbox ) );
        layout->takeAt( i );
        // detach children so they aren't deleted with the parent
        for ( int j = hbox->count() - 1; j >= 0; j-- ) {
            hbox->takeAt( j );
        }
        delete hbox;
    }

    flowHDatasetItems( q );
}

// this works pretty much like flow layout for text, and it is only applicable to dataset items
// laid out horizontally
void Legend::Private::flowHDatasetItems( Legend *q )
{
    const int separatorLineWidth = 3; // hardcoded in VerticalLineLayoutItem::sizeHint()

    const int allowedWidth = q->areaGeometry().width();
    QHBoxLayout *currentLine = new QHBoxLayout;
    int columnSpan = 5;
    int mainLayoutColumn = 0;
    int row = 0;
    if ( !titleText.isEmpty() && titleTextAttributes.isVisible() ) {
        ++row;
        if (q->showLines()){
            ++row;
        }
    }
    layout->addItem( currentLine, row, mainLayoutColumn,
                     /*rowSpan*/1 , columnSpan, Qt::AlignLeft | Qt::AlignVCenter );
    mainLayoutColumn += columnSpan;

    for ( int dataset = 0; dataset < hLayoutDatasets.size(); dataset++ ) {
        HDatasetItem *hdsItem = &hLayoutDatasets[ dataset ];

        bool spacerUsed = false;
        bool separatorUsed = false;
        if ( !currentLine->isEmpty() ) {
            const int separatorWidth = ( q->showLines() ? separatorLineWidth : 0 ) + q->spacing();
            const int payloadWidth = hdsItem->markerLine->sizeHint().width() +
                                     hdsItem->label->sizeHint().width();
            if ( currentLine->sizeHint().width() + separatorWidth + payloadWidth > allowedWidth ) {
                // too wide, "line break"
#ifdef DEBUG_LEGEND_PAINT
                qDebug() << Q_FUNC_INFO << "break" << mainLayoutColumn
                         << currentLine->sizeHint().width()
                         << currentLine->sizeHint().width() + separatorWidth + payloadWidth
                         << allowedWidth;
#endif
                currentLine = new QHBoxLayout;
                layout->addItem( currentLine, row, mainLayoutColumn,
                                 /*rowSpan*/1 , columnSpan, Qt::AlignLeft | Qt::AlignVCenter );
                mainLayoutColumn += columnSpan;
            } else {
                // > 1 dataset item in line, put spacing and maybe a separator between them
                if ( !hdsItem->spacer ) {
                    hdsItem->spacer = new QSpacerItem( q->spacing(), 1 );
                }
                currentLine->addItem( hdsItem->spacer );
                spacerUsed = true;

                if ( q->showLines() ) {
                    if ( !hdsItem->separatorLine ) {
                        hdsItem->separatorLine = new VerticalLineLayoutItem;
                    }
                    paintItems << hdsItem->separatorLine;
                    currentLine->addItem( hdsItem->separatorLine );
                    separatorUsed = true;
                }
            }
        }
        // those have no parents in the current layout, so they wouldn't get cleaned up otherwise
        if ( !spacerUsed ) {
            delete hdsItem->spacer;
            hdsItem->spacer = nullptr;
        }
        if ( !separatorUsed ) {
            delete hdsItem->separatorLine;
            hdsItem->separatorLine = nullptr;
        }

        currentLine->addItem( hdsItem->markerLine );
        paintItems << hdsItem->markerLine;
        currentLine->addItem( hdsItem->label );
        paintItems << hdsItem->label;
    }
}

bool Legend::hasHeightForWidth() const
{
    // this is better than using orientation() because, for layout purposes, we're not height-for-width
    // *yet* before buildLegend() has been called, and the layout logic might get upset if we say
    // something that will only be true in the future
    return !d->hLayoutDatasets.isEmpty();
}

int Legend::heightForWidth( int width ) const
{
    if ( d->hLayoutDatasets.isEmpty() ) {
        return -1;
    }

    int ret = 0;
    // space for caption and line under caption (if any)
    for (int i = 0; i < 2; i++) {
        if ( QLayoutItem *item = d->layout->itemAtPosition( i, 0 ) ) {
            ret += item->sizeHint().height();
        }
    }
    const int separatorLineWidth = 3; // ### hardcoded in VerticalLineLayoutItem::sizeHint()

    int currentLineWidth = 0;
    int currentLineHeight = 0;
    Q_FOREACH( const HDatasetItem &hdsItem, d->hLayoutDatasets ) {
        const int payloadWidth = hdsItem.markerLine->sizeHint().width() +
                                 hdsItem.label->sizeHint().width();
        if ( !currentLineWidth ) {
            // first iteration
            currentLineWidth = payloadWidth;
        } else {
            const int separatorWidth = ( showLines() ? separatorLineWidth : 0 ) + spacing();
            currentLineWidth += separatorWidth + payloadWidth;
            if ( currentLineWidth > width ) {
                // too wide, "line break"
#ifdef DEBUG_LEGEND_PAINT
                qDebug() << Q_FUNC_INFO << "heightForWidth break" << currentLineWidth
                         << currentLineWidth + separatorWidth + payloadWidth
                         << width;
#endif
                ret += currentLineHeight + spacing();
                currentLineWidth = payloadWidth;
                currentLineHeight = 0;
            }
        }
        currentLineHeight = qMax( currentLineHeight, hdsItem.height() );
    }
    ret += currentLineHeight; // one less spacings than lines
    return ret;
}

void Legend::Private::destroyOldLayout()
{
    // in the horizontal layout case, the QHBoxLayout destructor also deletes child layout items
    // (it isn't documented that QLayoutItems delete their children)
    for ( int i = layout->count() - 1; i >= 0; i-- ) {
        delete layout->takeAt( i );
    }
    Q_ASSERT( !layout->count() );
    hLayoutDatasets.clear();
    paintItems.clear();
}

void Legend::setHiddenDatasets( const QList<uint> hiddenDatasets )
{
    d->hiddenDatasets = hiddenDatasets;
}

const QList<uint> Legend::hiddenDatasets() const
{
    return d->hiddenDatasets;
}

void Legend::setDatasetHidden( uint dataset, bool hidden )
{
    if ( hidden && !d->hiddenDatasets.contains( dataset ) ) {
        d->hiddenDatasets.append( dataset );
    } else if ( !hidden && d->hiddenDatasets.contains( dataset ) ) {
        d->hiddenDatasets.removeAll( dataset );
    }
}

bool Legend::datasetIsHidden( uint dataset ) const
{
    return d->hiddenDatasets.contains( dataset );
}
