/*
 * Deskflow -- mouse and keyboard sharing utility
 * Copyright (C) 2012-2016 Symless Ltd.
 * Copyright (C) 2002 Chris Schoeneman
 *
 * This package is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * found in the file LICENSE that should have accompanied this file.
 *
 * This package 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 <http://www.gnu.org/licenses/>.
 */

#include "platform/XWindowsScreenSaver.h"

#include "base/Event.h"
#include "base/IEventQueue.h"
#include "base/Log.h"
#include "base/TMethodEventJob.h"
#include "deskflow/IPlatformScreen.h"
#include "platform/XWindowsUtil.h"

#include <X11/Xatom.h>
#if HAVE_X11_EXTENSIONS_XTEST_H
#include <X11/extensions/XTest.h>
#else
#error The XTest extension is required to build deskflow
#endif
#if HAVE_X11_EXTENSIONS_DPMS_H
extern "C"
{
#include <X11/Xmd.h>
#include <X11/extensions/dpms.h>
#if !HAVE_DPMS_PROTOTYPES
#undef DPMSModeOn
#undef DPMSModeStandby
#undef DPMSModeSuspend
#undef DPMSModeOff
#define DPMSModeOn 0
#define DPMSModeStandby 1
#define DPMSModeSuspend 2
#define DPMSModeOff 3
  extern Bool DPMSQueryExtension(Display *, int *, int *);
  extern Bool DPMSCapable(Display *);
  extern Status DPMSEnable(Display *);
  extern Status DPMSDisable(Display *);
  extern Status DPMSForceLevel(Display *, CARD16);
  extern Status DPMSInfo(Display *, CARD16 *, BOOL *);
#endif
}
#endif

//
// XWindowsScreenSaver
//

XWindowsScreenSaver::XWindowsScreenSaver(Display *display, Window window, void *eventTarget, IEventQueue *events)
    : m_display(display),
      m_xscreensaverSink(window),
      m_eventTarget(eventTarget),
      m_xscreensaver(None),
      m_xscreensaverActive(false),
      m_dpms(false),
      m_disabled(false),
      m_suppressDisable(false),
      m_disableTimer(NULL),
      m_disablePos(0),
      m_events(events)
{
  // get atoms
  m_atomScreenSaver = XInternAtom(m_display, "SCREENSAVER", False);
  m_atomScreenSaverVersion = XInternAtom(m_display, "_SCREENSAVER_VERSION", False);
  m_atomScreenSaverActivate = XInternAtom(m_display, "ACTIVATE", False);
  m_atomScreenSaverDeactivate = XInternAtom(m_display, "DEACTIVATE", False);

  // check for DPMS extension.  this is an alternative screen saver
  // that powers down the display.
#if HAVE_X11_EXTENSIONS_DPMS_H
  int eventBase, errorBase;
  if (DPMSQueryExtension(m_display, &eventBase, &errorBase)) {
    if (DPMSCapable(m_display)) {
      // we have DPMS
      m_dpms = true;
    }
  }
#endif

  // watch top-level windows for changes
  bool error = false;
  {
    XWindowsUtil::ErrorLock lock(m_display, &error);
    Window root = DefaultRootWindow(m_display);
    XWindowAttributes attr;
    XGetWindowAttributes(m_display, root, &attr);
    m_rootEventMask = attr.your_event_mask;
    XSelectInput(m_display, root, m_rootEventMask | SubstructureNotifyMask);
  }
  if (error) {
    LOG((CLOG_DEBUG "didn't set root event mask"));
    m_rootEventMask = 0;
  }

  // get the built-in settings
  XGetScreenSaver(m_display, &m_timeout, &m_interval, &m_preferBlanking, &m_allowExposures);

  // get the DPMS settings
  m_dpmsEnabled = isDPMSEnabled();

  // get the xscreensaver window, if any
  if (!findXScreenSaver()) {
    setXScreenSaver(None);
  }

  // install disable timer event handler
  m_events->adoptHandler(
      Event::kTimer, this, new TMethodEventJob<XWindowsScreenSaver>(this, &XWindowsScreenSaver::handleDisableTimer)
  );
}

XWindowsScreenSaver::~XWindowsScreenSaver()
{
  // done with disable job
  if (m_disableTimer != NULL) {
    m_events->deleteTimer(m_disableTimer);
  }
  m_events->removeHandler(Event::kTimer, this);

  if (m_display != NULL) {
    enableDPMS(m_dpmsEnabled);
    XSetScreenSaver(m_display, m_timeout, m_interval, m_preferBlanking, m_allowExposures);
    clearWatchForXScreenSaver();
    XWindowsUtil::ErrorLock lock(m_display);
    XSelectInput(m_display, DefaultRootWindow(m_display), m_rootEventMask);
  }
}

void XWindowsScreenSaver::destroy()
{
  m_display = NULL;
  delete this;
}

bool XWindowsScreenSaver::handleXEvent(const XEvent *xevent)
{
  switch (xevent->type) {
  case CreateNotify:
    if (m_xscreensaver == None) {
      if (isXScreenSaver(xevent->xcreatewindow.window)) {
        // found the xscreensaver
        setXScreenSaver(xevent->xcreatewindow.window);
      } else {
        // another window to watch.  to detect the xscreensaver
        // window we look for a property but that property may
        // not yet exist by the time we get this event so we
        // have to watch the window for property changes.
        // this would be so much easier if xscreensaver did the
        // smart thing and stored its window in a property on
        // the root window.
        addWatchXScreenSaver(xevent->xcreatewindow.window);
      }
    }
    break;

  case DestroyNotify:
    if (xevent->xdestroywindow.window == m_xscreensaver) {
      // xscreensaver is gone
      LOG((CLOG_DEBUG "xscreensaver died"));
      setXScreenSaver(None);
      return true;
    }
    break;

  case PropertyNotify:
    if (xevent->xproperty.state == PropertyNewValue) {
      if (isXScreenSaver(xevent->xproperty.window)) {
        // found the xscreensaver
        setXScreenSaver(xevent->xcreatewindow.window);
      }
    }
    break;

  case MapNotify:
    if (xevent->xmap.window == m_xscreensaver) {
      // xscreensaver has activated
      setXScreenSaverActive(true);
      return true;
    }
    break;

  case UnmapNotify:
    if (xevent->xunmap.window == m_xscreensaver) {
      // xscreensaver has deactivated
      setXScreenSaverActive(false);
      return true;
    }
    break;
  }

  return false;
}

void XWindowsScreenSaver::enable()
{
  // for xscreensaver
  m_disabled = false;
  updateDisableTimer();

  // for built-in X screen saver
  XSetScreenSaver(m_display, m_timeout, m_interval, m_preferBlanking, m_allowExposures);

  // for DPMS
  enableDPMS(m_dpmsEnabled);
}

void XWindowsScreenSaver::disable()
{
  // for xscreensaver
  m_disabled = true;
  updateDisableTimer();

  // use built-in X screen saver
  XGetScreenSaver(m_display, &m_timeout, &m_interval, &m_preferBlanking, &m_allowExposures);
  XSetScreenSaver(m_display, 0, m_interval, m_preferBlanking, m_allowExposures);

  // for DPMS
  m_dpmsEnabled = isDPMSEnabled();
  enableDPMS(false);

  // FIXME -- now deactivate?
}

void XWindowsScreenSaver::activate()
{
  // remove disable job timer
  m_suppressDisable = true;
  updateDisableTimer();

  // enable DPMS if it was enabled
  enableDPMS(m_dpmsEnabled);

  // try xscreensaver
  findXScreenSaver();
  if (m_xscreensaver != None) {
    sendXScreenSaverCommand(m_atomScreenSaverActivate);
    return;
  }

  // try built-in X screen saver
  if (m_timeout != 0) {
    XForceScreenSaver(m_display, ScreenSaverActive);
  }

  // try DPMS
  activateDPMS(true);
}

void XWindowsScreenSaver::deactivate()
{
  // reinstall disable job timer
  m_suppressDisable = false;
  updateDisableTimer();

  // try DPMS
  activateDPMS(false);

  // disable DPMS if screen saver is disabled
  if (m_disabled) {
    enableDPMS(false);
  }

  // try xscreensaver
  findXScreenSaver();
  if (m_xscreensaver != None) {
    sendXScreenSaverCommand(m_atomScreenSaverDeactivate);
    return;
  }

  // use built-in X screen saver
  XForceScreenSaver(m_display, ScreenSaverReset);
}

bool XWindowsScreenSaver::isActive() const
{
  // check xscreensaver
  if (m_xscreensaver != None) {
    return m_xscreensaverActive;
  }

  // check DPMS
  if (isDPMSActivated()) {
    return true;
  }

  // can't check built-in X screen saver activity
  return false;
}

bool XWindowsScreenSaver::findXScreenSaver()
{
  // do nothing if we've already got the xscreensaver window
  if (m_xscreensaver == None) {
    // find top-level window xscreensaver window
    Window root = DefaultRootWindow(m_display);
    Window rw, pw, *cw;
    unsigned int nc;
    if (XQueryTree(m_display, root, &rw, &pw, &cw, &nc)) {
      for (unsigned int i = 0; i < nc; ++i) {
        if (isXScreenSaver(cw[i])) {
          setXScreenSaver(cw[i]);
          break;
        }
      }
      XFree(cw);
    }
  }

  return (m_xscreensaver != None);
}

void XWindowsScreenSaver::setXScreenSaver(Window window)
{
  LOG((CLOG_DEBUG "xscreensaver window: 0x%08x", window));

  // save window
  m_xscreensaver = window;

  if (m_xscreensaver != None) {
    // clear old watch list
    clearWatchForXScreenSaver();

    // see if xscreensaver is active
    bool error = false;
    XWindowAttributes attr;
    {
      XWindowsUtil::ErrorLock lock(m_display, &error);
      XGetWindowAttributes(m_display, m_xscreensaver, &attr);
    }
    setXScreenSaverActive(!error && attr.map_state != IsUnmapped);

    // save current DPMS state;  xscreensaver may have changed it.
    m_dpmsEnabled = isDPMSEnabled();
  } else {
    // screen saver can't be active if it doesn't exist
    setXScreenSaverActive(false);

    // start watching for xscreensaver
    watchForXScreenSaver();
  }
}

bool XWindowsScreenSaver::isXScreenSaver(Window w) const
{
  // check for m_atomScreenSaverVersion string property
  Atom type;
  return (
      XWindowsUtil::getWindowProperty(m_display, w, m_atomScreenSaverVersion, NULL, &type, NULL, False) &&
      type == XA_STRING
  );
}

void XWindowsScreenSaver::setXScreenSaverActive(bool activated)
{
  if (m_xscreensaverActive != activated) {
    LOG((CLOG_DEBUG "xscreensaver %s on window 0x%08x", activated ? "activated" : "deactivated", m_xscreensaver));
    m_xscreensaverActive = activated;

    // if screen saver was activated forcefully (i.e. against
    // our will) then just accept it.  don't try to keep it
    // from activating since that'll just pop up the password
    // dialog if locking is enabled.
    m_suppressDisable = activated;
    updateDisableTimer();

    if (activated) {
      m_events->addEvent(Event(m_events->forIPrimaryScreen().screensaverActivated(), m_eventTarget));
    } else {
      m_events->addEvent(Event(m_events->forIPrimaryScreen().screensaverDeactivated(), m_eventTarget));
    }
  }
}

void XWindowsScreenSaver::sendXScreenSaverCommand(Atom cmd, long arg1, long arg2)
{
  XEvent event;
  event.xclient.type = ClientMessage;
  event.xclient.display = m_display;
  event.xclient.window = m_xscreensaverSink;
  event.xclient.message_type = m_atomScreenSaver;
  event.xclient.format = 32;
  event.xclient.data.l[0] = static_cast<long>(cmd);
  event.xclient.data.l[1] = arg1;
  event.xclient.data.l[2] = arg2;
  event.xclient.data.l[3] = 0;
  event.xclient.data.l[4] = 0;

  LOG((CLOG_DEBUG "send xscreensaver command: %d %d %d", (long)cmd, arg1, arg2));
  bool error = false;
  {
    XWindowsUtil::ErrorLock lock(m_display, &error);
    XSendEvent(m_display, m_xscreensaver, False, 0, &event);
  }
  if (error) {
    findXScreenSaver();
  }
}

void XWindowsScreenSaver::watchForXScreenSaver()
{
  // clear old watch list
  clearWatchForXScreenSaver();

  // add every child of the root to the list of windows to watch
  Window root = DefaultRootWindow(m_display);
  Window rw, pw, *cw;
  unsigned int nc;
  if (XQueryTree(m_display, root, &rw, &pw, &cw, &nc)) {
    for (unsigned int i = 0; i < nc; ++i) {
      addWatchXScreenSaver(cw[i]);
    }
    XFree(cw);
  }

  // now check for xscreensaver window in case it set the property
  // before we could request property change events.
  if (findXScreenSaver()) {
    // found it so clear out our watch list
    clearWatchForXScreenSaver();
  }
}

void XWindowsScreenSaver::clearWatchForXScreenSaver()
{
  // stop watching all windows
  XWindowsUtil::ErrorLock lock(m_display);
  for (WatchList::iterator index = m_watchWindows.begin(); index != m_watchWindows.end(); ++index) {
    XSelectInput(m_display, index->first, index->second);
  }
  m_watchWindows.clear();
}

void XWindowsScreenSaver::addWatchXScreenSaver(Window window)
{
  // get window attributes
  bool error = false;
  XWindowAttributes attr;
  {
    XWindowsUtil::ErrorLock lock(m_display, &error);
    XGetWindowAttributes(m_display, window, &attr);
  }

  // if successful and window uses override_redirect (like xscreensaver
  // does) then watch it for property changes.
  if (!error && attr.override_redirect == True) {
    error = false;
    {
      XWindowsUtil::ErrorLock lock(m_display, &error);
      XSelectInput(m_display, window, attr.your_event_mask | PropertyChangeMask);
    }
    if (!error) {
      // if successful then add the window to our list
      m_watchWindows.insert(std::make_pair(window, attr.your_event_mask));
    }
  }
}

void XWindowsScreenSaver::updateDisableTimer()
{
  if (m_disabled && !m_suppressDisable && m_disableTimer == NULL) {
    // 5 seconds should be plenty often to suppress the screen saver
    m_disableTimer = m_events->newTimer(5.0, this);
  } else if ((!m_disabled || m_suppressDisable) && m_disableTimer != NULL) {
    m_events->deleteTimer(m_disableTimer);
    m_disableTimer = NULL;
  }
}

void XWindowsScreenSaver::handleDisableTimer(const Event &, void *)
{
  // send fake mouse motion directly to xscreensaver
  if (m_xscreensaver != None) {
    XEvent event;
    event.xmotion.type = MotionNotify;
    event.xmotion.display = m_display;
    event.xmotion.window = m_xscreensaver;
    event.xmotion.root = DefaultRootWindow(m_display);
    event.xmotion.subwindow = None;
    event.xmotion.time = CurrentTime;
    event.xmotion.x = m_disablePos;
    event.xmotion.y = 0;
    event.xmotion.x_root = m_disablePos;
    event.xmotion.y_root = 0;
    event.xmotion.state = 0;
    event.xmotion.is_hint = NotifyNormal;
    event.xmotion.same_screen = True;

    XWindowsUtil::ErrorLock lock(m_display);
    XSendEvent(m_display, m_xscreensaver, False, 0, &event);

    m_disablePos = 20 - m_disablePos;
  }
}

void XWindowsScreenSaver::activateDPMS(bool activate)
{
#if HAVE_X11_EXTENSIONS_DPMS_H
  if (m_dpms) {
    // DPMSForceLevel will generate a BadMatch if DPMS is disabled
    XWindowsUtil::ErrorLock lock(m_display);
    DPMSForceLevel(m_display, activate ? DPMSModeStandby : DPMSModeOn);
  }
#endif
}

void XWindowsScreenSaver::enableDPMS(bool enable)
{
#if HAVE_X11_EXTENSIONS_DPMS_H
  if (m_dpms) {
    if (enable) {
      DPMSEnable(m_display);
    } else {
      DPMSDisable(m_display);
    }
  }
#endif
}

bool XWindowsScreenSaver::isDPMSEnabled() const
{
#if HAVE_X11_EXTENSIONS_DPMS_H
  if (m_dpms) {
    CARD16 level;
    BOOL state;
    DPMSInfo(m_display, &level, &state);
    return (state != False);
  } else {
    return false;
  }
#else
  return false;
#endif
}

bool XWindowsScreenSaver::isDPMSActivated() const
{
#if HAVE_X11_EXTENSIONS_DPMS_H
  if (m_dpms) {
    CARD16 level;
    BOOL state;
    DPMSInfo(m_display, &level, &state);
    return (level != DPMSModeOn);
  } else {
    return false;
  }
#else
  return false;
#endif
}
