/*
 *   Copyright 2007 by Dan Meltzer <hydrogen@notyetimplemented.com>
 *   Copyright (C) 2008 by Alexis Ménard <darktears31@gmail.com>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2, 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 Library 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.
 */

#include "windowpreview_p.h"

#include <QPainter>
#include <QVarLengthArray>

#include <kwindowsystem.h>
#include <kdebug.h>

#include <plasma/framesvg.h>

#ifdef Q_WS_X11
#include <QX11Info>

#include <X11/Xlib.h>
#include <fixx11h.h>
#endif

namespace Plasma {

bool WindowPreview::previewsAvailable() // static
{
    if (!KWindowSystem::compositingActive()) {
        return false;
    }
#ifdef Q_WS_X11
    // hackish way to find out if KWin has the effect enabled,
    // TODO provide proper support
    Display *dpy = QX11Info::display();
    Atom atom = XInternAtom(dpy, "_KDE_WINDOW_PREVIEW", False);
    int cnt;
    Atom *list = XListProperties(dpy, DefaultRootWindow(dpy), &cnt);
    if (list != NULL) {
        bool ret = (qFind(list, list + cnt, atom) != list + cnt);
        XFree(list);
        return ret;
    }
#endif
    return false;
}

WindowPreview::WindowPreview(QWidget *parent)
    : QWidget(parent)
{
    m_background = new Plasma::FrameSvg(this);
    m_background->setImagePath("widgets/frame");
    m_background->setElementPrefix("raised");
}

void WindowPreview::setWindowIds(const QList<WId> wids)
{
    if (!previewsAvailable()) {
        setMinimumSize(0,0);
        setMaximumSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);
        ids.clear();
        return;
    }
    ids = wids;
    readWindowSizes();
    QSize s(sizeHint());
    if (s.isValid()) {
        setFixedSize(sizeHint());
    }
}

QList<WId> WindowPreview::windowIds() const
{
    return ids;
}

QSize WindowPreview::sizeHint() const
{
    if (ids.size() == 0) {
        return QSize();
    }
    if (!windowSizes.size() == 0) {
        readWindowSizes();
    }

    int maxHeight = 0;
    int totalWidth = 0;
    foreach (QSize s, windowSizes) {
        if (s.height() > maxHeight) {
            maxHeight = s.height();
        }

        totalWidth += s.width();
    }

    QSize s(totalWidth, maxHeight);

    qreal left, top, right, bottom;
    m_background->getMargins(left, top, right, bottom);

    s.scale(WINDOW_WIDTH*windowSizes.size(), WINDOW_HEIGHT, Qt::KeepAspectRatio);

    s = s + QSize(left+right+WINDOW_MARGIN*(windowSizes.size()-1), top+bottom);

    return s;
}

void WindowPreview::readWindowSizes() const
{
    windowSizes.clear();
    foreach (WId id, ids) {
#ifdef Q_WS_X11
        if (id > 0) {
            KWindowInfo info = KWindowSystem::windowInfo(id, NET::WMGeometry|NET::WMFrameExtents);
            windowSizes.append(info.frameGeometry().size());
        } else {
            windowSizes.append(QSize());
        }
#else
        windowSizes.append(QSize());
#endif
    }
}

bool WindowPreview::isEmpty() const
{
  if (ids.size() == 0) {
      return true;
  }
  foreach (WId id, ids) {
      if (id != 0) {
          return false;
      }
  }
  return true;
}

void WindowPreview::setInfo()
{
#ifdef Q_WS_X11
    Display *dpy = QX11Info::display();
    Atom atom = XInternAtom(dpy, "_KDE_WINDOW_PREVIEW", False);
    if (isEmpty()) {
        XDeleteProperty(dpy, parentWidget()->winId(), atom);
        return;
    }
    if (windowSizes.size() == 0) {
        readWindowSizes();
    }
    if (windowSizes.size() == 0) {
        XDeleteProperty(dpy, parentWidget()->winId(), atom);
        return;
    }
    Q_ASSERT(parentWidget()->isWindow()); // parent must be toplevel

    QSize thumbnailSize = sizeHint();
    thumbnailSize.scale(size(), Qt::KeepAspectRatio);
    m_background->resizeFrame(thumbnailSize);

    qreal left, top, right, bottom;
    m_background->getMargins(left, top, right, bottom);
    QRect thumbnailRect = geometry().adjusted(left, top, -right, -bottom);

    const int numWindows = ids.size();

    QList <QRect> thumbnailRects;
    int x = thumbnailRect.x();

    foreach (QSize s, windowSizes) {
        s.scale((qreal)(thumbnailRect.width()-5*(numWindows-1))/numWindows, thumbnailRect.height(), Qt::KeepAspectRatio);
        int y = thumbnailRect.y() + (thumbnailRect.height() - s.height())/2;
        thumbnailRects.append(QRect(QPoint(x,y), s));
        x += s.width() + 5;
    }

    QVarLengthArray<long, 1024> data(1 + 6*numWindows);
    data[0] = numWindows;

    for (int i = 0; i<numWindows; ++i) {
        const int start = i*6+1;
        const QRect thumbnailRect = thumbnailRects[i];

        data[start] = 5;
        data[start+1] = ids[i];
        data[start+2] = thumbnailRect.x();
        data[start+3] = thumbnailRect.y();
        data[start+4] = thumbnailRect.width();
        data[start+5] = thumbnailRect.height();
    }

    XChangeProperty(dpy, parentWidget()->winId(), atom, atom, 32, PropModeReplace,
                    reinterpret_cast<unsigned char *>(data.data()), data.size());
#endif
}

void WindowPreview::paintEvent(QPaintEvent *e)
{
    Q_UNUSED(e)
#ifdef Q_WS_X11
    QPainter painter(this);
    QRect r(QPoint(0,0), m_background->frameSize().toSize());
    r.moveCenter(QPoint(size().width()/2, size().height()/2));
    m_background->paintFrame(&painter, r.topLeft());
#endif
}

} // namespace Plasma

#include "windowpreview_p.moc"