/*
 * Copyright (C) 2001-2015 Klaralvdalens Datakonsult AB.  All rights reserved.
 *
 * This file is part of the KGantt 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 "kganttgraphicsitem.h"
#include "kganttgraphicsscene.h"
#include "kganttgraphicsview.h"
#include "kganttitemdelegate.h"
#include "kganttconstraintgraphicsitem.h"
#include "kganttconstraintmodel.h"
#include "kganttconstraint.h"
#include "kganttabstractgrid.h"
#include "kganttabstractrowcontroller.h"

#include <cassert>
#include <cmath>
#include <algorithm>
#include <iterator>

#include <QPainter>
#include <QAbstractItemModel>
#include <QAbstractProxyModel>
#include <QGraphicsSceneMouseEvent>
#include <QGraphicsLineItem>
#include <QApplication>

#include <QDebug>



using namespace KGantt;

typedef QGraphicsItem BASE;

namespace {
    class Updater {
        bool *u_ptr;
        bool oldval;
    public:
        Updater( bool* u ) : u_ptr( u ), oldval( *u ) {
            *u=true;
        }
        ~Updater() {
            *u_ptr = oldval;
        }
    };
}

GraphicsItem::GraphicsItem( QGraphicsItem* parent, GraphicsScene* scene )
    : BASE( parent ),  m_isupdating( false )
{
  if ( scene )
    scene->addItem( this );
  init();
}

GraphicsItem::GraphicsItem( const QModelIndex& idx, QGraphicsItem* parent,
                                            GraphicsScene* scene )
    : BASE( parent ),  m_index( idx ), m_isupdating( false )
{
  init();
  if ( scene )
    scene->addItem( this );
}

GraphicsItem::~GraphicsItem()
{
}

void GraphicsItem::init()
{
    setCacheMode( QGraphicsItem::DeviceCoordinateCache );
    setFlags( ItemIsMovable|ItemIsSelectable|ItemIsFocusable );
    setAcceptHoverEvents( true );
    setHandlesChildEvents( true );
    setZValue( 100. );
    m_dragline = nullptr;
}

int GraphicsItem::type() const
{
    return Type;
}

StyleOptionGanttItem GraphicsItem::getStyleOption() const
{
    StyleOptionGanttItem opt;
    if (!m_index.isValid()) {
        // TODO: find out why we get invalid indexes
        //qDebug()<<"GraphicsItem::getStyleOption: Invalid index";
        return opt;
    }
    opt.palette = QApplication::palette();
    opt.itemRect = rect();
    opt.boundingRect = boundingRect();
    QVariant tp = m_index.model()->data( m_index, TextPositionRole );
    if (tp.isValid()) {
        opt.displayPosition = static_cast<StyleOptionGanttItem::Position>(tp.toInt());
    } else {
#if 0
        qDebug() << "Item" << m_index.model()->data( m_index, Qt::DisplayRole ).toString()
                 << ", ends="<<m_endConstraints.size() << ", starts="<<m_startConstraints.size();
#endif
        opt.displayPosition = m_endConstraints.size()<m_startConstraints.size()?StyleOptionGanttItem::Left:StyleOptionGanttItem::Right;
#if 0
        qDebug() << "choosing" << opt.displayPosition;
#endif
    }
    QVariant da = m_index.model()->data( m_index, Qt::TextAlignmentRole );
    if ( da.isValid() ) {
        opt.displayAlignment = static_cast< Qt::Alignment >( da.toInt() );
    } else {
        switch ( opt.displayPosition ) {
        case StyleOptionGanttItem::Left: opt.displayAlignment = Qt::AlignLeft|Qt::AlignVCenter; break;
        case StyleOptionGanttItem::Right: opt.displayAlignment = Qt::AlignRight|Qt::AlignVCenter; break;
        case StyleOptionGanttItem::Hidden: // fall through
        case StyleOptionGanttItem::Center: opt.displayAlignment = Qt::AlignCenter; break;
        }
    }
    opt.grid = const_cast<AbstractGrid*>(scene()->getGrid());
    opt.text = m_index.model()->data( m_index, Qt::DisplayRole ).toString();
    if ( isEnabled() ) opt.state  |= QStyle::State_Enabled;
    if ( isSelected() ) opt.state |= QStyle::State_Selected;
    if ( hasFocus() ) opt.state   |= QStyle::State_HasFocus;
    return opt;
}

GraphicsScene* GraphicsItem::scene() const
{
    return qobject_cast<GraphicsScene*>( QGraphicsItem::scene() );
}

void GraphicsItem::setRect( const QRectF& r )
{
#if 0
    qDebug() << "GraphicsItem::setRect("<<r<<"), txt="<<m_index.model()->data( m_index, Qt::DisplayRole ).toString();
    if ( m_index.model()->data( m_index, Qt::DisplayRole ).toString() == QLatin1String("Code Freeze" ) ) {
        qDebug() << "gotcha";
    }
#endif

    prepareGeometryChange();
    m_rect = r;
    updateConstraintItems();
    update();
}

void GraphicsItem::setBoundingRect( const QRectF& r )
{
    prepareGeometryChange();
    m_boundingrect = r;
    update();
}

bool GraphicsItem::isEditable() const
{
    return !scene()->isReadOnly() && m_index.isValid() && m_index.model()->flags( m_index ) & Qt::ItemIsEditable;
}

void GraphicsItem::paint( QPainter* painter, const QStyleOptionGraphicsItem* option,
                                  QWidget* widget )
{
    Q_UNUSED( widget );
    if ( boundingRect().isValid() && scene() ) {
        StyleOptionGanttItem opt = getStyleOption();
        *static_cast<QStyleOption*>(&opt) = *static_cast<const QStyleOption*>( option );
        //opt.fontMetrics = painter->fontMetrics();
        if (widget) {
            opt.palette = widget->palette();
        } else {
            opt.palette = QApplication::palette();
        }
        scene()->itemDelegate()->paintGanttItem( painter, opt, index() );
    }
}

void GraphicsItem::setIndex( const QPersistentModelIndex& idx )
{
    m_index=idx;
    update();
}

QString GraphicsItem::ganttToolTip() const
{
    return scene()->itemDelegate()->toolTip( index() );
}

QRectF GraphicsItem::boundingRect() const
{
    return m_boundingrect;
}

QPointF GraphicsItem::startConnector( int relationType ) const
{
    switch ( relationType ) {
        case Constraint::StartStart:
        case Constraint::StartFinish:
            return mapToScene( m_rect.left(), m_rect.top()+m_rect.height()/2. );
        default:
            break;
    }
    return mapToScene( m_rect.right(), m_rect.top()+m_rect.height()/2. );
}

QPointF GraphicsItem::endConnector( int relationType ) const
{
    switch ( relationType ) {
        case Constraint::FinishFinish:
        case Constraint::StartFinish:
            return mapToScene( m_rect.right(), m_rect.top()+m_rect.height()/2. );
        default:
            break;
    }
    return mapToScene( m_rect.left(), m_rect.top()+m_rect.height()/2. );
}


void GraphicsItem::constraintsChanged()
{
    if ( !scene() || !scene()->itemDelegate() ) return;
    const Span bs = scene()->itemDelegate()->itemBoundingSpan( getStyleOption(), index() );
    const QRectF br = boundingRect();
    setBoundingRect( QRectF( bs.start(), 0., bs.length(), br.height() ) );
}

void GraphicsItem::addStartConstraint( ConstraintGraphicsItem* item )
{
    assert( item );
    m_startConstraints << item;
    item->setStart( startConnector( item->constraint().relationType() ) );
    constraintsChanged();
}

void GraphicsItem::addEndConstraint( ConstraintGraphicsItem* item )
{
    assert( item );
    m_endConstraints << item;
    item->setEnd( endConnector( item->constraint().relationType() ) );
    constraintsChanged();
}

void GraphicsItem::removeStartConstraint( ConstraintGraphicsItem* item )
{
    assert( item );
    m_startConstraints.removeAll( item );
    constraintsChanged();
}

void GraphicsItem::removeEndConstraint( ConstraintGraphicsItem* item )
{
    assert( item );
    m_endConstraints.removeAll( item );
    constraintsChanged();
}

void GraphicsItem::updateConstraintItems()
{
    { // Workaround for multiple definition error with MSVC6
    Q_FOREACH( ConstraintGraphicsItem* item, m_startConstraints ) {
        QPointF s = startConnector( item->constraint().relationType() );
        item->setStart( s );
    }}
    {// Workaround for multiple definition error with MSVC6
    Q_FOREACH( ConstraintGraphicsItem* item, m_endConstraints ) {
        QPointF e = endConnector( item->constraint().relationType() );
        item->setEnd( e );
    }}
}

void GraphicsItem::updateItem( const Span& rowGeometry, const QPersistentModelIndex& idx )
{
    //qDebug() << "GraphicsItem::updateItem("<<rowGeometry<<idx<<")";
    Updater updater( &m_isupdating );
    if ( !idx.isValid() || idx.data( ItemTypeRole )==TypeMulti ) {
        setRect( QRectF() );
        hide();
        return;
    }

    const Span s = scene()->getGrid()->mapToChart( static_cast<const QModelIndex&>(idx) );
    setPos( QPointF( s.start(), rowGeometry.start() ) );
    setRect( QRectF( 0., 0., s.length(), rowGeometry.length() ) );
    setIndex( idx );
    const Span bs = scene()->itemDelegate()->itemBoundingSpan( getStyleOption(), index() );
    //qDebug() << "boundingSpan for" << getStyleOption().text << rect() << "is" << bs;
    setBoundingRect( QRectF( bs.start(), 0., bs.length(), rowGeometry.length() ) );
    const int maxh = scene()->rowController()->maximumItemHeight();
    if ( maxh < rowGeometry.length() ) {
        QRectF r = rect();
        const Qt::Alignment align = getStyleOption().displayAlignment;
        if ( align & Qt::AlignTop ) {
            // Do nothing
        } else if ( align & Qt::AlignBottom ) {
            r.setY( rowGeometry.length()-maxh );
        } else {
            // Center
            r.setY( ( rowGeometry.length()-maxh ) / 2. );
        }
        r.setHeight( maxh );
        setRect( r );
    }

    //scene()->setSceneRect( scene()->sceneRect().united( mapToScene( boundingRect() ).boundingRect() ) );
    //updateConstraintItems();
}

QVariant GraphicsItem::itemChange( GraphicsItemChange change, const QVariant& value )
{
    if ( !isUpdating() && change==ItemPositionChange && scene() ) {
        QPointF newPos=value.toPointF();
        if ( isEditable() ) {
            newPos.setY( pos().y() );
            return newPos;
        } else {
            return pos();
        }
    } else if ( change==QGraphicsItem::ItemSelectedChange ) {
        if ( index().isValid() && !( index().model()->flags( index() ) & Qt::ItemIsSelectable ) ) {
            // Reject selection attempt
            return QVariant::fromValue( false );
        }
    }

    return QGraphicsItem::itemChange( change, value );
}

void GraphicsItem::focusInEvent( QFocusEvent* event )
{
    Q_UNUSED( event );
}

void GraphicsItem::updateModel()
{
    //qDebug() << "GraphicsItem::updateModel()";
    if ( isEditable() ) {
        QAbstractItemModel* model = const_cast<QAbstractItemModel*>( index().model() );
#if !defined(NDEBUG)
        ConstraintModel* cmodel = scene()->constraintModel();
#endif
        assert( model );
        assert( cmodel );
        if ( model ) {
            //ItemType typ = static_cast<ItemType>( model->data( index(),
            //                                                   ItemTypeRole ).toInt() );
            QList<Constraint> constraints;
            for ( QList<ConstraintGraphicsItem*>::iterator it1 = m_startConstraints.begin() ;
                 it1 != m_startConstraints.end() ;
                 ++it1 )
                constraints.push_back((*it1)->proxyConstraint());
            for ( QList<ConstraintGraphicsItem*>::iterator it2 = m_endConstraints.begin() ;
                 it2 != m_endConstraints.end() ;
                 ++it2 )
                constraints.push_back((*it2)->proxyConstraint());
            if ( scene()->getGrid()->mapFromChart( Span( scenePos().x(), rect().width() ),
                                                index(),
                                                constraints ) ) {
                scene()->updateRow( index().parent() );
            }
        }
    }
}

void GraphicsItem::hoverMoveEvent( QGraphicsSceneHoverEvent* event )
{
    if ( !isEditable() ) return;
    StyleOptionGanttItem opt = getStyleOption();
    ItemDelegate::InteractionState istate = scene()->itemDelegate()->interactionStateFor( event->pos(), opt, index() );
    switch ( istate ) {
    case ItemDelegate::State_ExtendLeft:
#ifndef QT_NO_CURSOR
        setCursor( Qt::SizeHorCursor );
#endif
        scene()->itemEntered( index() );
        break;
    case ItemDelegate::State_ExtendRight:
#ifndef QT_NO_CURSOR
        setCursor( Qt::SizeHorCursor );
#endif
        scene()->itemEntered( index() );
        break;
    case ItemDelegate::State_Move:
#ifndef QT_NO_CURSOR
        setCursor( Qt::SplitHCursor );
#endif
        scene()->itemEntered( index() );
        break;
    default:
#ifndef QT_NO_CURSOR
        unsetCursor();
#endif
        break;
    };
}

void GraphicsItem::hoverLeaveEvent( QGraphicsSceneHoverEvent* )
{
#ifndef QT_NO_CURSOR
    unsetCursor();
#endif
}

void GraphicsItem::mousePressEvent( QGraphicsSceneMouseEvent* event )
{
    //qDebug() << "GraphicsItem::mousePressEvent("<<event<<")";
    StyleOptionGanttItem opt = getStyleOption();
    int istate = scene()->itemDelegate()->interactionStateFor( event->pos(), opt, index() );
    // If State_None is returned by interactionStateFor(), we ignore this event so that
    // it can get forwarded to another item that's below this one. Needed, for example,
    // to allow items to be moved that are placed below the label of another item.
    if ( istate != ItemDelegate::State_None ) {
        m_istate = istate;
        m_presspos = event->pos();
        m_pressscenepos = event->scenePos();

        scene()->itemPressed( index(), event );

        switch ( m_istate ) {
        case ItemDelegate::State_ExtendLeft:
        case ItemDelegate::State_ExtendRight:
        default: /* State_Move */
            if (!(flags() & ItemIsMovable)) {
                event->ignore();
            }
            break;
        }
    } else {
        event->ignore();
    }
}

void GraphicsItem::mouseReleaseEvent( QGraphicsSceneMouseEvent* event )
{
    //qDebug() << "GraphicsItem::mouseReleaseEvent("<<event << ")";
    if ( !m_presspos.isNull() ) {
        scene()->itemClicked( index() );
    }
    delete m_dragline; m_dragline = nullptr;
    if ( scene()->dragSource() ) {
        // Create a new constraint
        GraphicsItem* other = qgraphicsitem_cast<GraphicsItem*>( scene()->itemAt( event->scenePos(), QTransform() ) );
        if ( other && scene()->dragSource()!=other &&
             other->index().data(KGantt::ItemTypeRole) == KGantt::TypeEvent )
        {
            // The code below fixes bug KDCH-696.
            // Modified the code to add constraint even if the user drags and drops
            // constraint on left part of the TypeEvent symbol(i.e diamond symbol)
            QRectF itemRect = other->rect().adjusted(-other->rect().height()/2.0, 0, 0, 0 );
            if ( other->mapToScene( itemRect ).boundingRect().contains( event->scenePos() ))
            {
                GraphicsView* view = qobject_cast<GraphicsView*>( event->widget()->parentWidget() );
                if ( view ) {
                    view->addConstraint( scene()->summaryHandlingModel()->mapToSource( scene()->dragSource()->index() ),
                                         scene()->summaryHandlingModel()->mapToSource( other->index() ), event->modifiers() );
                }
            }
        }
        else
        {
            if ( other && scene()->dragSource()!=other &&
                 other->mapToScene( other->rect() ).boundingRect().contains( event->scenePos() )) {
                GraphicsView* view = qobject_cast<GraphicsView*>( event->widget()->parentWidget() );
                if ( view ) {
                    view->addConstraint( scene()->summaryHandlingModel()->mapToSource( scene()->dragSource()->index() ),
                                         scene()->summaryHandlingModel()->mapToSource( other->index() ), event->modifiers() );
                }
            }
        }

        scene()->setDragSource( nullptr );
        //scene()->update();
    } else {
        if ( isEditable() ) {
            updateItemFromMouse(event->scenePos());

            // It is important to set m_presspos to null here because
            // when the sceneRect updates because we move the item
            // a MouseMoveEvent will be delivered, and we have to
            // protect against that
            m_presspos = QPointF();
            updateModel();
            // without this command we sometimes get a white area at the left side of a task item
            // after we moved that item right-ways into a grey weekend section of the scene:
            scene()->update();
        }
    }

    m_presspos = QPointF();
}

void GraphicsItem::mouseDoubleClickEvent( QGraphicsSceneMouseEvent* event )
{
    const int typ = static_cast<ItemType>( index().model()->data( index(), ItemTypeRole ).toInt() );
    StyleOptionGanttItem opt = getStyleOption();
    ItemDelegate::InteractionState istate = scene()->itemDelegate()->interactionStateFor( event->pos(), opt, index() );
    if ( (istate != ItemDelegate::State_None) || (typ == TypeSummary)) {
        scene()->itemDoubleClicked( index() );
    }
    BASE::mouseDoubleClickEvent( event );
}

void GraphicsItem::updateItemFromMouse( const QPointF& scenepos )
{
    //qDebug() << "GraphicsItem::updateItemFromMouse("<<scenepos<<")";
    const QPointF p = scenepos - m_presspos;
    QRectF r = rect();
    QRectF br = boundingRect();
    switch ( m_istate ) {
    case ItemDelegate::State_Move:
        setPos( p.x(), pos().y() );
        break;
    case ItemDelegate::State_ExtendLeft: {
        const qreal brr = br.right();
        const qreal rr = r.right();
        const qreal delta = pos().x()-p.x();
        setPos( p.x(), QGraphicsItem::pos().y() );
        br.setRight( brr+delta );
        r.setRight( rr+delta );
        break;
    }
    case ItemDelegate::State_ExtendRight: {
        const qreal rr = r.right();
        r.setRight( scenepos.x()-pos().x() );
        br.setWidth( br.width() + r.right()-rr );
        break;
    }
    default: return;
    }
    setRect( r );
    setBoundingRect( br );
}

void GraphicsItem::mouseMoveEvent( QGraphicsSceneMouseEvent* event )
{
    if ( !isEditable() ) return;
    if ( m_presspos.isNull() ) return;

    //qDebug() << "GraphicsItem::mouseMoveEvent("<<event<<"), m_istate="<< static_cast<ItemDelegate::InteractionState>( m_istate );
    switch ( m_istate ) {
    case ItemDelegate::State_ExtendLeft:
    case ItemDelegate::State_ExtendRight:
    case ItemDelegate::State_Move:
        // Check for constraint drag
      if ( qAbs( m_pressscenepos.x()-event->scenePos().x() ) < 10.
           && qAbs( m_pressscenepos.y()-event->scenePos().y() ) > 5. ) {
            m_istate = ItemDelegate::State_DragConstraint;
            m_dragline = new QGraphicsLineItem( this );
            m_dragline->setPen( QPen( Qt::DashLine ) );
            m_dragline->setLine(QLineF( rect().center(), event->pos() ));
            scene()->setDragSource( this );
            break;
        }

        updateItemFromMouse(event->scenePos());
        //BASE::mouseMoveEvent(event);
        break;
    case ItemDelegate::State_DragConstraint: {
        QLineF line = m_dragline->line();
        m_dragline->setLine( QLineF( line.p1(), event->pos() ) );
        //QGraphicsItem* item = scene()->itemAt( event->scenePos() );
        break;
    }
    }
}
