/*
    This file is part of the Konsole Terminal.

    Copyright 2006-2008 Robert Knight <robertknight@gmail.com>

    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.
*/

// Own
#include "ViewContainerTabBar.h"
#include "ViewContainer.h"

// Qt
#include <QtCore/QMimeData>
#include <QLabel>
#include <QtGui/QPainter>
#include <QtGui/QDragMoveEvent>
#include <QtGui/QIcon>
#include <QTabBar>
#include <QApplication>

// KDE
#include <KLocalizedString>

using Konsole::ViewContainerTabBar;
using Konsole::TabbedViewContainer;

ViewContainerTabBar::ViewContainerTabBar(QWidget* parent, TabbedViewContainer* container)
    : QTabBar(parent)
    , _dropIndicator(0)
    , _dropIndicatorIndex(-1)
    , _drawIndicatorDisabled(false)
    , _connectedContainer(container)
{
    setDrawBase(true);
    setDocumentMode(true);
    setFocusPolicy(Qt::NoFocus);
    setSelectionBehaviorOnRemove(QTabBar::SelectPreviousTab);
    setElideMode(Qt::ElideLeft);

    setAcceptDrops(true);
    setMouseTracking(true);

    setWhatsThis(xi18nc("@info:whatsthis",
                       "<title>Tab Bar</title>"
                       "<para>The tab bar allows you to switch and move tabs. You can double-click a tab to change its name.</para>"));
}

void ViewContainerTabBar::mousePressEvent(QMouseEvent* event)
{
    if (event->buttons() == Qt::LeftButton) {
        _dragStart = event->pos();
    }
    QTabBar::mousePressEvent(event);
}

void ViewContainerTabBar::mouseMoveEvent(QMouseEvent* event)
{
    if (event->buttons() == Qt::LeftButton) {
        QPoint dragPos = _dragStart - event->pos();
        if (dragPos.manhattanLength() > QApplication::startDragDistance()) {
            int tab = tabAt(_dragStart);
            if (tab != -1) {
                emit initiateDrag(tab);
            }
        }
    }
    QTabBar::mouseMoveEvent(event);
}


void ViewContainerTabBar::dragEnterEvent(QDragEnterEvent* event)
{
    if (event->mimeData()->hasFormat(_supportedMimeType) &&
            event->source() != 0)
        event->acceptProposedAction();
}

void ViewContainerTabBar::dragLeaveEvent(QDragLeaveEvent*)
{
    setDropIndicator(-1);
}

void ViewContainerTabBar::dragMoveEvent(QDragMoveEvent* event)
{
    if (event->mimeData()->hasFormat(_supportedMimeType)
            && event->source() != 0) {
        int index = dropIndex(event->pos());
        if (index == -1)
            index = count();

        setDropIndicator(index, proposedDropIsSameTab(event));

        event->acceptProposedAction();
    }
}

void ViewContainerTabBar::dropEvent(QDropEvent* event)
{
    setDropIndicator(-1);

    if (!event->mimeData()->hasFormat(_supportedMimeType)) {
        event->ignore();
        return;
    }

    if (proposedDropIsSameTab(event)) {
        event->setDropAction(Qt::IgnoreAction);
        event->accept();
        return;
    }

    const int index = dropIndex(event->pos());
    bool success = false;

    ViewContainerTabBar* sourceContainerTabBar = static_cast<ViewContainerTabBar*>(event->source());

    // check if the moved tab is the last of source view.
    if (sourceContainerTabBar->count() == 1) {
        TabbedViewContainer* sourceTabbedContainer = sourceContainerTabBar->connectedTabbedViewContainer();
        emit moveViewRequest(index, event, success, sourceTabbedContainer);
    } else {
        emit moveViewRequest(index, event, success, NULL);
    }

    if (success)
        event->accept();
    else
        event->ignore();
}

TabbedViewContainer* ViewContainerTabBar::connectedTabbedViewContainer()
{
    return _connectedContainer;
}

void ViewContainerTabBar::setDropIndicator(int index, bool drawDisabled)
{
    if (!parentWidget() || _dropIndicatorIndex == index)
        return;

    _dropIndicatorIndex = index;
    const int ARROW_SIZE = 32;
    const bool north = shape() == QTabBar::RoundedNorth || shape() == QTabBar::TriangularNorth;

    if (!_dropIndicator || _drawIndicatorDisabled != drawDisabled) {
        if (!_dropIndicator) {
            _dropIndicator = new QLabel(parentWidget());
            _dropIndicator->resize(ARROW_SIZE, ARROW_SIZE);
        }

        QIcon::Mode drawMode = drawDisabled ? QIcon::Disabled : QIcon::Normal;
        const QString iconName = north ? "arrow-up" : "arrow-down";
        _dropIndicator->setPixmap(QIcon::fromTheme(iconName).pixmap(ARROW_SIZE, ARROW_SIZE, drawMode));
        _drawIndicatorDisabled = drawDisabled;
    }

    if (index < 0) {
        _dropIndicator->hide();
        return;
    }

    const QRect rect = tabRect(index < count() ? index : index - 1);

    QPoint pos;
    if (index < count())
        pos = rect.topLeft();
    else
        pos = rect.topRight();

    if (north)
        pos.ry() += ARROW_SIZE;
    else
        pos.ry() -= ARROW_SIZE;

    pos.rx() -= ARROW_SIZE / 2;

    _dropIndicator->move(mapTo(parentWidget(), pos));
    _dropIndicator->show();
}

void ViewContainerTabBar::setSupportedMimeType(const QString& mimeType)
{
    _supportedMimeType = mimeType;
}

int ViewContainerTabBar::dropIndex(const QPoint& pos) const
{
    int tab = tabAt(pos);
    if (tab < 0)
        return tab;

    // pick the closest tab boundary
    QRect rect = tabRect(tab);
    if ((pos.x() - rect.left()) > (rect.width() / 2))
        tab++;

    if (tab == count())
        return -1;

    return tab;
}

bool ViewContainerTabBar::proposedDropIsSameTab(const QDropEvent* event) const
{
    const bool sameTabBar = event->source() == this;
    if (!sameTabBar)
        return false;

    const int index = dropIndex(event->pos());
    int sourceIndex = -1;
    emit querySourceIndex(event, sourceIndex);

    const bool sourceAndDropAreLast = sourceIndex == count() - 1 && index == -1;
    if (sourceIndex == index || sourceIndex == index - 1 || sourceAndDropAreLast)
        return true;
    else
        return false;
}


QPixmap ViewContainerTabBar::dragDropPixmap(int tab)
{
    Q_ASSERT(tab >= 0 && tab < count());

    // TODO - grabWidget() works except that it includes part
    // of the tab bar outside the tab itself if the tab has
    // curved corners
    const QRect rect = tabRect(tab);
    const int borderWidth = 1;

    QPixmap tabPixmap(rect.width() + borderWidth,
                      rect.height() + borderWidth);
    QPainter painter(&tabPixmap);
    painter.drawPixmap(0, 0, QPixmap::grabWidget(this, rect));
    QPen borderPen;
    borderPen.setBrush(palette().dark());
    borderPen.setWidth(borderWidth);
    painter.setPen(borderPen);
    painter.drawRect(0, 0, rect.width(), rect.height());
    painter.end();

    return tabPixmap;
}
