/* xscreensaver, Copyright (c) 1991-1993 Jamie Zawinski <jwz@mcom.com>
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation.  No representations are made about the suitability of this
 * software for any purpose.  It is provided "as is" without express or 
 * implied warranty.
 */

#include <stdio.h>

#ifdef VMS
#include <unixlib.h> /*to pick up getpid*/
typedef char * caddr_t;
#endif

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
#include <X11/Xos.h>
#ifndef VMS
#include <X11/Xmu/SysUtil.h>
#else
#include "sys$common:[decw$include.xmu]SysUtil.h"
#endif

#include <signal.h>		/* for the signal names */

#include "xscreensaver.h"

#if __STDC__
#ifndef __DECC
extern int kill (pid_t, int);		/* signal() is in sys/signal.h... */
#else
extern int kill (int, int);
#endif
#endif /* __STDC__ */

extern Bool lock_p, demo_mode_p;

Atom XA_VROOT, XA_XSETROOT_ID;
Atom XA_SCREENSAVER_VERSION, XA_SCREENSAVER_ID;

#if __STDC__
extern void describe_visual (FILE *, Display *, Visual *);
#endif

Window screensaver_window = 0;
Cursor cursor;
Colormap cmap, cmap2;
Bool install_cmap_p;
Bool fade_p, unfade_p;
int fade_seconds, fade_ticks;

static unsigned long black_pixel;
static Window real_vroot, real_vroot_value;

#define ALL_POINTER_EVENTS \
	(ButtonPressMask | ButtonReleaseMask | EnterWindowMask | \
	 LeaveWindowMask | PointerMotionMask | PointerMotionHintMask | \
	 Button1MotionMask | Button2MotionMask | Button3MotionMask | \
	 Button4MotionMask | Button5MotionMask | ButtonMotionMask)

/* I don't really understand Sync vs Async, but these seem to work... */
#define grab_kbd(win) \
  XGrabKeyboard (dpy, (win), True, GrabModeSync, GrabModeAsync, CurrentTime)
#define grab_mouse(win) \
  XGrabPointer (dpy, (win), True, ALL_POINTER_EVENTS, \
		GrabModeAsync, GrabModeAsync, None, cursor, CurrentTime)

void
grab_keyboard_and_mouse P((void))
{
  Status status;
  XSync (dpy, False);

  if (demo_mode_p) return;

  status = grab_kbd (screensaver_window);
  if (status != GrabSuccess)
    {	/* try again in a second */
      sleep (1);
      status = grab_kbd (screensaver_window);
      if (status != GrabSuccess)
	fprintf (stderr, "%s: %scouldn't grab keyboard!  (%d)\n",
		 progname, (verbose_p ? "## " : ""), status);
    }
  status = grab_mouse (screensaver_window);
  if (status != GrabSuccess)
    {	/* try again in a second */
      sleep (1);
      status = grab_mouse (screensaver_window);
      if (status != GrabSuccess)
	fprintf (stderr, "%s: %scouldn't grab pointer!  (%d)\n",
		 progname, (verbose_p ? "## " : ""), status);
    }
}

void
ungrab_keyboard_and_mouse P((void))
{
  XUngrabPointer (dpy, CurrentTime);
  XUngrabKeyboard (dpy, CurrentTime);
}


void
ensure_no_screensaver_running ()
{
  int i;
  Window root = RootWindowOfScreen (screen);
  Window root2, parent, *kids;
  unsigned int nkids;
  int (*old_handler) ();

  old_handler = XSetErrorHandler (BadWindow_ehandler);

  if (! XQueryTree (dpy, root, &root2, &parent, &kids, &nkids))
    abort ();
  if (root != root2)
    abort ();
  if (parent)
    abort ();
  for (i = 0; i < nkids; i++)
    {
      Atom type;
      int format;
      unsigned long nitems, bytesafter;
      char *version;

      if (XGetWindowProperty (dpy, kids[i], XA_SCREENSAVER_VERSION, 0, 1,
			      False, XA_STRING, &type, &format, &nitems,
			      &bytesafter, (unsigned char **) &version)
	  == Success
	  && type != None)
	{
	  char *id;
	  if (!XGetWindowProperty (dpy, kids[i], XA_SCREENSAVER_ID, 0, 512,
				   False, XA_STRING, &type, &format, &nitems,
				   &bytesafter, (unsigned char **) &id)
	      == Success
	      || type == None)
	    id = "???";

	  fprintf (stderr,
      "%s: %salready running on display %s (window 0x%x)\n from process %s.\n",
		   progname, (verbose_p ? "## " : ""), DisplayString (dpy),
		   (int) kids [i], id);
	  exit (1);
	}
    }

  if (kids) XFree ((char *) kids);
  XSync (dpy, False);
  XSetErrorHandler (old_handler);
}


void
disable_builtin_screensaver ()
{
  int timeout, interval, prefer_blank, allow_exp;
  XForceScreenSaver (dpy, ScreenSaverReset);
  XGetScreenSaver (dpy, &timeout, &interval, &prefer_blank, &allow_exp);
  if (timeout != 0)
    {
      XSetScreenSaver (dpy, 0, interval, prefer_blank, allow_exp);
      printf ("%s%sisabling server builtin screensaver.\n\
	You can re-enable it with \"xset s on\".\n",
	      (verbose_p ? "" : progname), (verbose_p ? "\n\tD" : ": d"));
    }
}


/* Virtual-root hackery */

#ifdef _VROOT_H_
ERROR!  You must not include vroot.h in this file.
#endif

static void
#if __STDC__
store_vroot_property (Window win, Window value)
#else
store_vroot_property (win, value)
     Window win, value;
#endif
{
#if 0
  printf ("%s: storing XA_VROOT = 0x%x (%s) = 0x%x (%s)\n", progname, 
	  win,
	  (win == screensaver_window ? "ScreenSaver" :
	   (win == real_vroot ? "VRoot" :
	    (win == real_vroot_value ? "Vroot_value" : "???"))),
	  value,
	  (value == screensaver_window ? "ScreenSaver" :
	   (value == real_vroot ? "VRoot" :
	    (value == real_vroot_value ? "Vroot_value" : "???"))));
#endif
  XChangeProperty (dpy, win, XA_VROOT, XA_WINDOW, 32, PropModeReplace,
		   (unsigned char *) &value, 1);
}

static void
#if __STDC__
remove_vroot_property (Window win)
#else
remove_vroot_property (win)
     Window win;
#endif
{
#if 0
  printf ("%s: removing XA_VROOT from 0x%x (%s)\n", progname, win, 
	  (win == screensaver_window ? "ScreenSaver" :
	   (win == real_vroot ? "VRoot" :
	    (win == real_vroot_value ? "Vroot_value" : "???"))));
#endif
  XDeleteProperty (dpy, win, XA_VROOT);
}


static void
kill_xsetroot_data P((void))
{
  Atom type;
  int format;
  unsigned long nitems, bytesafter;
  Pixmap *dataP = 0;

  /* If the user has been using xv or xsetroot as a screensaver (to display
     an image on the screensaver window, as a kind of slideshow) then the
     pixmap and its associated color cells have been put in RetainPermanent
     CloseDown mode.  Since we're not destroying the xscreensaver window,
     but merely unmapping it, we need to free these resources or those
     colormap cells will stay allocated while the screensaver is off.  (We
     could just delete the screensaver window and recreate it later, but
     that could cause other problems.)  This code does an atomic read-and-
     delete of the _XSETROOT_ID property, and if it held a pixmap, then we
     cause the RetainPermanent resources of the client which created it
     (and which no longer exists) to be freed.
   */
  if (XGetWindowProperty (dpy, screensaver_window, XA_XSETROOT_ID, 0, 1,
			  True, AnyPropertyType, &type, &format, &nitems, 
			  &bytesafter, (unsigned char **) &dataP)
      == Success
      && type != None)
    {
      if (dataP && *dataP && type == XA_PIXMAP && format == 32 &&
	  nitems == 1 && bytesafter == 0)
	{
	  if (verbose_p)
	    printf ("%s: destroying xsetroot data (0x%X).\n",
		    progname, *dataP);
	  XKillClient (dpy, *dataP);
	}
      else
	fprintf (stderr, "%s: %sdeleted unrecognised _XSETROOT_ID property: \n\
	%d, %d; type: %d, format: %d, nitems: %d, bytesafter %d\n",
		 progname, (verbose_p ? "## " : ""),
		 dataP, (dataP ? *dataP : 0), type,
		 format, nitems, bytesafter);
    }
}


static void handle_signals P((Bool on_p));

static void
save_real_vroot P((void))
{
  int i;
  Window root = RootWindowOfScreen (screen);
  Window root2, parent, *kids;
  unsigned int nkids;

  real_vroot = 0;
  real_vroot_value = 0;
  if (! XQueryTree (dpy, root, &root2, &parent, &kids, &nkids))
    abort ();
  if (root != root2)
    abort ();
  if (parent)
    abort ();
  for (i = 0; i < nkids; i++)
    {
      Atom type;
      int format;
      unsigned long nitems, bytesafter;
      Window *vrootP = 0;

      if (XGetWindowProperty (dpy, kids[i], XA_VROOT, 0, 1, False, XA_WINDOW,
			      &type, &format, &nitems, &bytesafter,
			      (unsigned char **) &vrootP)
	  != Success)
	continue;
      if (! vrootP)
	continue;
      if (real_vroot)
	{
	  if (*vrootP == screensaver_window) abort ();
	  fprintf (stderr,
	    "%s: %smore than one virtual root window found (0x%x and 0x%x).\n",
		   progname, (verbose_p ? "## " : ""),
		   (int) real_vroot, (int) kids [i]);
	  exit (1);
	}
      real_vroot = kids [i];
      real_vroot_value = *vrootP;
    }

  if (real_vroot)
    {
      handle_signals (True);
      remove_vroot_property (real_vroot);
      XSync (dpy, False);
    }

  XFree ((char *) kids);
}

static Bool
restore_real_vroot_1 P((void))
{
  if (verbose_p && real_vroot)
    printf ("%s: restoring __SWM_VROOT property on the real vroot (0x%x).\n",
	    progname, real_vroot);
  remove_vroot_property (screensaver_window);
  if (real_vroot)
    {
      store_vroot_property (real_vroot, real_vroot_value);
      real_vroot = 0;
      real_vroot_value = 0;
      /* make sure the property change gets there before this process
	 terminates!  We might be doing this because we have intercepted
	 SIGTERM or something. */
      XSync (dpy, False);
      return True;
    }
  return False;
}

void
restore_real_vroot ()
{
  if (restore_real_vroot_1 ())
    handle_signals (False);
}


/* Signal hackery to ensure that the vroot doesn't get left in an 
   inconsistent state
 */

static const char *sig_names [255] = { 0 };

static void
restore_real_vroot_handler (sig)
     int sig;
{
  signal (sig, SIG_DFL);
  if (restore_real_vroot_1 ())
    fprintf (stderr, "\n%s: %s%s (%d) intercepted, vroot restored.\n",
	     progname, (verbose_p ? "## " : ""),
	     ((sig < sizeof(sig_names) && sig >= 0 && sig_names [sig])
	      ? sig_names [sig] : "unknown signal"),
	     sig);
  kill (getpid (), sig);
}


static void
#if __STDC__
catch_signal (int sig, char *signame, Bool on_p)
#else
catch_signal (sig, signame, on_p)
     int sig;
     char *signame;
     Bool on_p;
#endif
{
  if (! on_p)
    signal (sig, SIG_DFL);
  else
    {
      sig_names [sig] = signame;
      if (((int) signal (sig, restore_real_vroot_handler)) == -1)
	{
	  char buf [255];
	  sprintf (buf, "%s: %scouldn't catch %s (%d)", progname,
		   (verbose_p ? "## " : ""), signame, sig);
	  perror (buf);
	  restore_real_vroot ();
	  exit (1);
	}
    }
}

static void
handle_signals (on_p)
     Bool on_p;
{
#if 0
  if (on_p) printf ("handling signals\n");
  else printf ("unhandling signals\n");
#endif

  catch_signal (SIGHUP,  "SIGHUP",  on_p);
  catch_signal (SIGINT,  "SIGINT",  on_p);
  catch_signal (SIGQUIT, "SIGQUIT", on_p);
  catch_signal (SIGILL,  "SIGILL",  on_p);
  catch_signal (SIGTRAP, "SIGTRAP", on_p);
  catch_signal (SIGIOT,  "SIGIOT",  on_p);
#ifndef VMS
  catch_signal (SIGABRT, "SIGABRT", on_p);
#endif
#ifdef SIGEMT
  catch_signal (SIGEMT,  "SIGEMT",  on_p);
#endif
  catch_signal (SIGFPE,  "SIGFPE",  on_p);
  catch_signal (SIGBUS,  "SIGBUS",  on_p);
  catch_signal (SIGSEGV, "SIGSEGV", on_p);
#ifdef SIGSYS
  catch_signal (SIGSYS,  "SIGSYS",  on_p);
#endif
  catch_signal (SIGTERM, "SIGTERM", on_p);
#ifdef SIGXCPU
  catch_signal (SIGXCPU, "SIGXCPU", on_p);
#endif
#ifdef SIGXFSZ
  catch_signal (SIGXFSZ, "SIGXFSZ", on_p);
#endif
#ifdef SIGDANGER
  catch_signal (SIGDANGER, "SIGDANGER", on_p);
#endif
}


/* Managing the actual screensaver window */

void
initialize_screensaver_window P((void))
{
  /* This resets the screensaver window as fully as possible, since there's
     no way of knowing what some random client may have done to us in the
     meantime.  We could just destroy and recreate the window, but that has
     its own set of problems...
   */
  XColor black;
  XClassHint class_hints;
  XSetWindowAttributes attrs;
  unsigned long attrmask;
  int width = WidthOfScreen (screen);
  int height = HeightOfScreen (screen);
  char id [2048];

  black.red = black.green = black.blue = 0;

  if (cmap == DefaultColormapOfScreen (screen))
    cmap = 0;

  if ((install_cmap_p && !demo_mode_p) ||
      (visual != DefaultVisualOfScreen (screen)))
    {
      if (! cmap)
	{
	  cmap = XCreateColormap (dpy, RootWindowOfScreen (screen),
				  visual, AllocNone);
	  if (! XAllocColor (dpy, cmap, &black)) abort ();
	  black_pixel = black.pixel;
	}
    }
  else
    {
      if (cmap)
	{
	  XFreeColors (dpy, cmap, &black_pixel, 1, 0);
	  XFreeColormap (dpy, cmap);
	}
      cmap = DefaultColormapOfScreen (screen);
      black_pixel = BlackPixelOfScreen (screen);
    }

  if (cmap2)
    {
      XFreeColormap (dpy, cmap2);
      cmap2 = 0;
    }

  if (fade_p)
    {
      cmap2 = copy_colormap (dpy, cmap, 0);
      if (! cmap2)
	fade_p = unfade_p = 0;
    }

  attrmask = (CWOverrideRedirect | CWEventMask | CWBackingStore | CWColormap |
	      CWBackPixel | CWBackingPixel | CWBorderPixel);
  attrs.override_redirect = True;
  attrs.event_mask = (KeyPressMask | KeyReleaseMask |
		      ButtonPressMask | ButtonReleaseMask |
		      PointerMotionMask);
  attrs.backing_store = NotUseful;
  attrs.colormap = cmap;
  attrs.background_pixel = black_pixel;
  attrs.backing_pixel = black_pixel;
  attrs.border_pixel = black_pixel;

/*  if (demo_mode_p || lock_p) width = width / 2;   #### */

  if (screensaver_window)
    {
      XWindowChanges changes;
      unsigned int changesmask = CWX|CWY|CWWidth|CWHeight|CWBorderWidth;
      changes.x = 0;
      changes.y = 0;
      changes.width = width;
      changes.height = height;
      changes.border_width = 0;

      XConfigureWindow (dpy, screensaver_window, changesmask, &changes);
      XChangeWindowAttributes (dpy, screensaver_window, attrmask, &attrs);
    }
  else
    {
      if (! verbose_p)
	;
      else if (visual == DefaultVisualOfScreen (screen))
	{
	  fprintf (stderr, "%s: using default visual ", progname);
	  describe_visual (stderr, dpy, visual);
	}
      else
	{
	  fprintf (stderr, "%s: using visual:   ", progname);
	  describe_visual (stderr, dpy, visual);
	  fprintf (stderr, "%s: default visual: ", progname);
	  describe_visual (stderr, dpy, DefaultVisualOfScreen (screen));
	}

      screensaver_window =
	XCreateWindow (dpy, RootWindowOfScreen (screen), 0, 0, width, height,
		       0, visual_depth, InputOutput, visual, attrmask,
		       &attrs);
    }

  class_hints.res_name = progname;
  class_hints.res_class = progclass;
  XSetClassHint (dpy, screensaver_window, &class_hints);
  XStoreName (dpy, screensaver_window, "screensaver");
  XChangeProperty (dpy, screensaver_window, XA_SCREENSAVER_VERSION,
		   XA_STRING, 8, PropModeReplace,
		   (unsigned char *) screensaver_version,
		   strlen (screensaver_version));

  sprintf (id, "%d on host ", getpid ());
  if (! XmuGetHostname (id + strlen (id), sizeof (id) - strlen (id) - 1))
    strcat (id, "???");
  XChangeProperty (dpy, screensaver_window, XA_SCREENSAVER_ID, XA_STRING, 8,
		   PropModeReplace, (unsigned char *) id, strlen (id));

  if (!cursor)
    {
      Pixmap bit;
      bit = XCreatePixmapFromBitmapData (dpy, screensaver_window, "\000", 1, 1,
					 BlackPixelOfScreen (screen),
					 BlackPixelOfScreen (screen), 1);
      cursor = XCreatePixmapCursor (dpy, bit, bit, &black, &black, 0, 0);
      XFreePixmap (dpy, bit);
    }

  XSetWindowBackground (dpy, screensaver_window, black_pixel);
  if (! demo_mode_p)
    XDefineCursor (dpy, screensaver_window, cursor);
  else
    XUndefineCursor (dpy, screensaver_window);
}


void 
raise_window (inhibit_fade, between_hacks_p)
     Bool inhibit_fade, between_hacks_p;
{
  initialize_screensaver_window ();

  if (fade_p && !inhibit_fade && !demo_mode_p)
    {
      int grabbed;
      Colormap current_map = (between_hacks_p
			      ? cmap
			      : DefaultColormapOfScreen (screen));
      copy_colormap (dpy, current_map, cmap2);
      XGrabServer (dpy);
      /* grab and blacken mouse on the root window (saver not mapped yet) */
      grabbed = grab_mouse (RootWindowOfScreen (screen));
      /* fade what's on the screen to black */
      XInstallColormap (dpy, cmap2);
      fade_colormap (dpy, current_map, cmap2, fade_seconds, fade_ticks, True);
      XClearWindow (dpy, screensaver_window);
      XMapRaised (dpy, screensaver_window);
      /* Once the saver window is up, restore the colormap.
	 (The "black" pixels of the two colormaps are compatible.) */
      XInstallColormap (dpy, cmap);
      if (grabbed == GrabSuccess)
	XUngrabPointer (dpy, CurrentTime);
      XUngrabServer (dpy);
    }
  else
    {
      XClearWindow (dpy, screensaver_window);
      XMapRaised (dpy, screensaver_window);
    }

  if (install_cmap_p && !demo_mode_p)
    XInstallColormap (dpy, cmap);
}

void
blank_screen ()
{
  save_real_vroot ();
  store_vroot_property (screensaver_window, screensaver_window);
  raise_window (False, False);
  grab_keyboard_and_mouse ();
#ifdef __hpux
  if (lock_p)
    XHPDisableReset (dpy);	/* turn off C-Sh-Reset */
#endif
}

void
unblank_screen ()
{
  if (unfade_p && !demo_mode_p)
    {
      int grabbed;
      Colormap default_map = DefaultColormapOfScreen (screen);
      blacken_colormap (dpy, cmap2);
      XGrabServer (dpy);
      /* grab and blacken mouse on the root window. */
      grabbed = grab_mouse (RootWindowOfScreen (screen));
      XInstallColormap (dpy, cmap2);
      XUnmapWindow (dpy, screensaver_window);
      fade_colormap (dpy, default_map, cmap2, fade_seconds, fade_ticks, False);
      XInstallColormap (dpy, default_map);
      if (grabbed == GrabSuccess)
	XUngrabPointer (dpy, CurrentTime);
      XUngrabServer (dpy);
    }
  else
    {
      if (install_cmap_p && !demo_mode_p)
	{
	  XClearWindow (dpy, screensaver_window); /* avoid technicolor */
	  XInstallColormap (dpy, DefaultColormapOfScreen (screen));
	}
      XUnmapWindow (dpy, screensaver_window);
    }
  kill_xsetroot_data ();
  ungrab_keyboard_and_mouse ();
  restore_real_vroot ();
#ifdef __hpux
  if (lock_p)
    XHPEnableReset (dpy);	/* turn C-Sh-Reset back on */
#endif
}
