/*
  This file is part of libkdepim.

  Copyright (c) 2008 Thomas Thrainer <tom_t@gmx.at>
  Copyright (c) 2010 Bertjan Broeksema <broeksema@kde.org>

  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, write to the Free Software Foundation, Inc.,
  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

  As a special exception, permission is given to link this program
  with any edition of Qt, and distribute the resulting executable,
  without including the source code for Qt in the source distribution.
*/

#include "kcheckcombobox.h"

#include <KLineEdit>
#include <KDebug>

#include <QAbstractItemView>
#include <QKeyEvent>
#include <QLineEdit>
#include <QStandardItemModel>

using namespace KPIM;

/// Class KCheckComboBox::Private

namespace KPIM {

class KCheckComboBox::Private
{
    KCheckComboBox *q;

public:
    Private( KCheckComboBox *qq )
        : q( qq )
        , mSeparator( QLatin1Char( ',' ) )
        , mSqueezeText( false )
        , mIgnoreHide( false )
        , mAlwaysShowDefaultText( false )
    { }

    void makeInsertedItemsCheckable(const QModelIndex &, int start, int end);
    QString squeeze( const QString &text );
    void updateCheckedItems( const QModelIndex &topLeft = QModelIndex(),
                             const QModelIndex &bottomRight = QModelIndex(),
                             int role = Qt::DisplayRole );
    void toggleCheckState();

public:
    QString mSeparator;
    QString mDefaultText;
    bool mSqueezeText;
    bool mIgnoreHide;
    bool mAlwaysShowDefaultText;
};

}

void KCheckComboBox::Private::makeInsertedItemsCheckable(const QModelIndex &parent, int start, int end)
{
    Q_UNUSED( parent );
    QStandardItemModel *model = qobject_cast<QStandardItemModel *>( q->model() );
    if ( model ) {
        for ( int r = start; r <= end; ++r ) {
            QStandardItem *item = model->item( r, 0 );
            item->setCheckable( true );
        }
    } else {
        kWarning() << "KCheckComboBox: model is not a QStandardItemModel but a" << q->model() << ". Cannot proceed.";
    }
}

QString KCheckComboBox::Private::squeeze( const QString &text )
{
    QFontMetrics fm( q->fontMetrics() );
    // The 4 pixels is 2 * horizontalMargin from QLineEdit.
    // The rest is code from QLineEdit::paintEvent, where it determines whether to scroll the text
    // (on my machine minLB=2 and minRB=2, so this removes 8 pixels in total)
    const int minLB = qMax(0, -fm.minLeftBearing());
    const int minRB = qMax(0, -fm.minRightBearing());
    const int lineEditWidth = q->lineEdit()->width() - 4 - minLB - minRB;
    const int textWidth = fm.width( text );
    if ( textWidth > lineEditWidth ) {
        return fm.elidedText( text, Qt::ElideMiddle, lineEditWidth );
    }

    return text;
}

void KCheckComboBox::Private::updateCheckedItems( const QModelIndex &topLeft,
                                                  const QModelIndex &bottomRight,
                                                  int role )
{
    Q_UNUSED( topLeft );
    Q_UNUSED( bottomRight );

    const QStringList items = q->checkedItems( role );
    QString text;
    if ( items.isEmpty() || mAlwaysShowDefaultText ) {
        text = mDefaultText;
    } else {
        text = items.join( mSeparator );
    }

    if ( mSqueezeText )
        text = squeeze( text );

    q->lineEdit()->setText( text );

    emit q->checkedItemsChanged( items );
}

void KCheckComboBox::Private::toggleCheckState()
{
    if (q->view()->isVisible()) {
        const QModelIndex index = q->view()->currentIndex();
        QVariant value = index.data( Qt::CheckStateRole );
        if ( value.isValid() ) {
            Qt::CheckState state = static_cast<Qt::CheckState>( value.toInt() );
            q->model()->setData( index, state == Qt::Unchecked ? Qt::Checked : Qt::Unchecked,
                                 Qt::CheckStateRole );
        }
    }
}

/// Class KCheckComboBox

KCheckComboBox::KCheckComboBox( QWidget *parent )
    : KComboBox( parent )
    , d( new KCheckComboBox::Private( this ) )
{
    connect( this, SIGNAL(activated(int)), this, SLOT(toggleCheckState()) );
    connect( model(), SIGNAL(rowsInserted(QModelIndex,int,int)),
             SLOT(makeInsertedItemsCheckable(QModelIndex,int,int)) );
    connect( model(), SIGNAL(dataChanged(QModelIndex,QModelIndex)),
             this, SLOT(updateCheckedItems(QModelIndex,QModelIndex)) );

    // read-only contents
    setEditable( true );
    lineEdit()->setAlignment( Qt::AlignLeft );
    // The cast is a workaround for the fact that QLineEdit::setReadOnly isn't virtual.
    // KLineEdit copes with this case since kdelibs-4.6 though.
    qobject_cast<KLineEdit *>(lineEdit())->setReadOnly( true );
    setInsertPolicy( KComboBox::NoInsert );

    view()->installEventFilter( this );
    view()->viewport()->installEventFilter( this );

    lineEdit()->installEventFilter( this );

    d->updateCheckedItems();
}

KCheckComboBox::~KCheckComboBox()
{
    delete d;
}

void KCheckComboBox::hidePopup()
{
    if ( !d->mIgnoreHide ) {
        KComboBox::hidePopup();
    }
    d->mIgnoreHide = false;
}

Qt::CheckState KCheckComboBox::itemCheckState( int index ) const
{
    return static_cast<Qt::CheckState>( itemData( index, Qt::CheckStateRole ).toInt() );
}

void KCheckComboBox::setItemCheckState( int index, Qt::CheckState state )
{
    setItemData( index, state, Qt::CheckStateRole );
}

QStringList KCheckComboBox::checkedItems( int role ) const
{
    QStringList items;
    if ( model() ) {
        const QModelIndex index = model()->index( 0, modelColumn(), rootModelIndex() );
        const QModelIndexList indexes = model()->match( index, Qt::CheckStateRole,
                                                        Qt::Checked, -1, Qt::MatchExactly );
        foreach ( const QModelIndex &index, indexes ) {
            items += index.data( role ).toString();
        }
    }
    return items;
}

void KCheckComboBox::setCheckedItems( const QStringList &items, int role )
{
    for ( int r = 0; r < model()->rowCount( rootModelIndex() ); ++r ) {
        const QModelIndex indx = model()->index( r, modelColumn(), rootModelIndex() );

        const QString text = indx.data( role ).toString();
        const bool found = items.contains( text );
        model()->setData( indx, found ? Qt::Checked : Qt::Unchecked, Qt::CheckStateRole );
    }
    d->updateCheckedItems( QModelIndex(), QModelIndex(), role );
}

QString KCheckComboBox::defaultText() const
{
    return d->mDefaultText;
}

void KCheckComboBox::setDefaultText( const QString &text )
{
    if ( d->mDefaultText != text ) {
        d->mDefaultText = text;
        d->updateCheckedItems();
    }
}

bool KCheckComboBox::squeezeText() const
{
    return d->mSqueezeText;
}

void KCheckComboBox::setSqueezeText( bool squeeze )
{
    if ( d->mSqueezeText != squeeze ) {
        d->mSqueezeText = squeeze;
        d->updateCheckedItems();
    }
}

bool KCheckComboBox::itemEnabled( int index )
{
    Q_ASSERT( index >= 0 && index <= count() );

    QStandardItemModel *itemModel = qobject_cast<QStandardItemModel *>( model() );
    Q_ASSERT( itemModel );

    QStandardItem *item = itemModel->item( index, 0 );
    return item->isEnabled();
}

void KCheckComboBox::setItemEnabled( int index, bool enabled )
{
    Q_ASSERT( index >= 0 && index <= count() );

    QStandardItemModel *itemModel = qobject_cast<QStandardItemModel *>( model() );
    Q_ASSERT( itemModel );

    QStandardItem *item = itemModel->item( index, 0 );
    item->setEnabled( enabled );
}

QString KCheckComboBox::separator() const
{
    return d->mSeparator;
}

void KCheckComboBox::setSeparator( const QString &separator )
{
    if ( d->mSeparator != separator ) {
        d->mSeparator = separator;
        d->updateCheckedItems();
    }
}

void KCheckComboBox::keyPressEvent( QKeyEvent *event )
{
    switch ( event->key() ) {
    case Qt::Key_Up:
    case Qt::Key_Down:
        showPopup();
        event->accept();
        break;
    case Qt::Key_Return:
    case Qt::Key_Enter:
    case Qt::Key_Escape:
        hidePopup();
        event->accept();
        break;
    default:
        break;
    }
    // don't call base class implementation, we don't need all that stuff in there
}

#ifndef QT_NO_WHEELEVENT
void KCheckComboBox::wheelEvent( QWheelEvent *event )
{
    // discard mouse wheel events on the combo box
    event->accept();
}
#endif

void KCheckComboBox::resizeEvent( QResizeEvent * event )
{
    KComboBox::resizeEvent( event );
    if ( d->mSqueezeText )
        d->updateCheckedItems();
}

bool KCheckComboBox::eventFilter( QObject *receiver, QEvent *event )
{
    switch ( event->type() ) {
    case QEvent::KeyPress:
    case QEvent::KeyRelease:
    case QEvent::ShortcutOverride:
    {
        switch ( static_cast<QKeyEvent *>( event )->key() ) {
        case Qt::Key_Space:
            if ( event->type() == QEvent::KeyPress && view()->isVisible() ) {
                d->toggleCheckState();
            }
            // Always eat the event: don't let QItemDelegate toggle the current index when the view is hidden.
            return true;
        case Qt::Key_Return:
        case Qt::Key_Enter:
        case Qt::Key_Escape:
            // ignore Enter keys, they would normally select items.
            // but we select with Space, because multiple selection is possible
            // we simply close the popup on Enter/Escape
            hidePopup();
            return true;
        }
    }
        break;
    case QEvent::MouseButtonDblClick:
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
        d->mIgnoreHide = true;
        if ( receiver == lineEdit() ) {
            showPopup();
            return true;
        }
        break;
    default:
        break;
    }
    return KComboBox::eventFilter( receiver, event );
}

bool KCheckComboBox::alwaysShowDefaultText() const
{
    return d->mAlwaysShowDefaultText;
}

void  KCheckComboBox::setAlwaysShowDefaultText( bool always )
{
    if ( always != d->mAlwaysShowDefaultText ) {
        d->mAlwaysShowDefaultText = always;
        d->updateCheckedItems();
    }
}

#include "moc_kcheckcombobox.cpp"