/*
 * LXImage-Qt - a simple and fast image viewer
 * Copyright (C) 2013  PCMan <pcman.tw@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.
 *
 */

#include "screenshotdialog.h"
#include "screenshotselectarea.h"
#include <QTimer>
#include <QPixmap>
#include <QImage>
#include <QPainter>
#include "application.h"
#include <QDesktopWidget>
#include <QScreen>

#include <QX11Info>
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/extensions/Xfixes.h>

using namespace LxImage;

ScreenshotDialog::ScreenshotDialog(QWidget* parent, Qt::WindowFlags f): QDialog(parent, f) {
  ui.setupUi(this);

  Application* app = static_cast<Application*>(qApp);
  app->addWindow();

  int event_base, error_base;
  hasXfixes_ = XFixesQueryExtension(QX11Info::display(), &event_base, &error_base) ? true : false;
  if(!hasXfixes_)
    ui.includeCursor->hide();
}

ScreenshotDialog::~ScreenshotDialog() {
  Application* app = static_cast<Application*>(qApp);
  app->removeWindow();
}

void ScreenshotDialog::done(int r) {
  if(r == QDialog::Accepted) {
    hide();
    QDialog::done(r);
    XSync(QX11Info::display(), 0); // is this useful?

    int delay = ui.delay->value();
    if(delay == 0) {
      // NOTE:
      // Well, we need to give X and the window manager some time to
      // really hide our own dialog from the screen.
      // Nobody knows how long it will take, and there is no reliable
      // way to ensure that. Let's wait for 400 ms here for it.
      delay = 400;
    }
    else
      delay *= 1000;
    // the dialog object will be deleted in doScreenshot().
    QTimer::singleShot(delay, this, SLOT(doScreenshot()));
  }
  else {
    deleteLater();
  }
}

QRect ScreenshotDialog::windowFrame(WId wid) {
  QRect result;
  XWindowAttributes wa;
  if(XGetWindowAttributes(QX11Info::display(), wid, &wa)) {
    Window child;
    int x, y;
    // translate to root coordinate
    XTranslateCoordinates(QX11Info::display(), wid, wa.root, 0, 0, &x, &y, &child);
    //qDebug("%d, %d, %d, %d", x, y, wa.width, wa.height);
    result.setRect(x, y, wa.width, wa.height);

    // get the frame widths added by the window manager
    Atom atom = XInternAtom(QX11Info::display(), "_NET_FRAME_EXTENTS", false);
    unsigned long type, resultLen, rest;
    int format;
    unsigned char* data = nullptr;
    if(XGetWindowProperty(QX11Info::display(), wid, atom, 0, G_MAXLONG, false,
      XA_CARDINAL, &type, &format, &resultLen, &rest, &data) == Success) {
    }
    if(data) { // left, right, top, bottom
      long* offsets = reinterpret_cast<long*>(data);
      result.setLeft(result.left() - offsets[0]);
      result.setRight(result.right() + offsets[1]);
      result.setTop(result.top() - offsets[2]);
      result.setBottom(result.bottom() + offsets[3]);
      XFree(data);
    }
  }
  return result;
}

WId ScreenshotDialog::activeWindowId() {
  WId root = WId(QX11Info::appRootWindow());
  Atom atom = XInternAtom(QX11Info::display(), "_NET_ACTIVE_WINDOW", false);
  unsigned long type, resultLen, rest;
  int format;
  WId result = 0;
  unsigned char* data = nullptr;
  if(XGetWindowProperty(QX11Info::display(), root, atom, 0, 1, false,
      XA_WINDOW, &type, &format, &resultLen, &rest, &data) == Success) {
    result = *reinterpret_cast<long*>(data);
    XFree(data);
  }
  return result;
}

void ScreenshotDialog::doScreenshot() {
  WId wid = 0;
  int x = 0, y = 0, width = -1, height = -1;
  wid = QApplication::desktop()->winId(); // get desktop window
  if(ui.currentWindow->isChecked()) {
    WId activeWid = activeWindowId();
    if(activeWid) {
      if(ui.includeFrame->isChecked()) {
        QRect rect = windowFrame(activeWid);
        x = rect.x();
        y = rect.y();
        width = rect.width();
        height = rect.height();
      }
      else
        wid = activeWid;
    }
  }

  QImage image;
  QScreen *screen = QGuiApplication::primaryScreen();
  if(screen) {
    QPixmap pixmap = screen->grabWindow(wid, x, y, width, height);
    image = pixmap.toImage();

    if(hasXfixes_ && ui.includeCursor->isChecked()) {
      // capture the cursor if needed
      XFixesCursorImage* cursor = XFixesGetCursorImage(QX11Info::display());
      if(cursor) {
        if(cursor->pixels) { // pixles should be an ARGB array
          QImage cursorImage;
          if(sizeof(long) == 4) {
            // FIXME: will we encounter byte-order problems here?
            cursorImage = QImage((uchar*)cursor->pixels, cursor->width, cursor->height, QImage::Format_ARGB32);
          }
          else { // XFixes returns long integers which is not 32 bit on 64 bit systems.
            long len = cursor->width * cursor->height;
            quint32* buf = new quint32[len];
            for(long i = 0; i < len; ++i)
              buf[i] = (quint32)cursor->pixels[i];
            cursorImage = QImage((uchar*)buf, cursor->width, cursor->height, QImage::Format_ARGB32, [](void* b) { delete[] (quint32*)b; }, buf);
          }
          // paint the cursor on the current image
          QPainter painter(&image);
          painter.drawImage(cursor->x - cursor->xhot, cursor->y - cursor->yhot, cursorImage);
        }
        XFree(cursor);
      }
    }
  }

  if(ui.screenArea->isChecked() && !image.isNull()) {
    ScreenshotSelectArea selectArea(image);
    if(QDialog::Accepted == selectArea.exec()) {
      image = image.copy(selectArea.selectedArea());
    }
  }

  Application* app = static_cast<Application*>(qApp);
  MainWindow* window = app->createWindow();
  if(!image.isNull())
    window->pasteImage(image);
  window->show();

  deleteLater(); // destroy ourself
}
