/* This program does:
 *
 * (1) change keysym mapping 'a' -> 'b'
 * (2) emit key press/release event, with XTestFakeKeyEvent
 * (3) change keysym mapping 'b' -> 'a'
 */

#include <X11/extensions/XTest.h>
#include <X11/XKBlib.h>
#include <X11/Xatom.h>
#include <X11/extensions/XInput2.h>
#include <stdio.h>
#include <stdlib.h>

Display *display;
XkbDescRec *xkb;

static unsigned int
get_xtest_device ()
{
  Atom xtest_prop = XInternAtom(display, "XTEST Device", True);
  XIDeviceInfo *info;
  int ndevices, i;

  info = XIQueryDevice(display, XIAllDevices, &ndevices);
  for (i = 0; i < ndevices; i++)
    {
      XIDeviceInfo *device = &info[i];
      if (device->use == XISlaveKeyboard)
	{
	  Atom type;
	  int format;
	  unsigned long num_items;
	  unsigned long bytes_after;
	  unsigned char data[4];
	  XIGetProperty (display,
			 device->deviceid,
			 xtest_prop,
			 0,
			 1,
			 False,
			 XA_INTEGER,
			 &type,
			 &format,
			 &num_items,
			 &bytes_after,
			 (unsigned char **) &data);
	  if (data[3] != 0)
	    return device->deviceid;
	}
    }
  return 0;
}

static Bool
replace_keycode (unsigned int keycode, unsigned int *keysym)
{
  unsigned int offset;
  XkbMapChangesRec changes;
  XkbChangesRec _changes;
  XkbKeyTypeRec *type;
  unsigned int old_keysym;
  Bool retval;

  if (xkb->min_key_code > keycode ||
      keycode > xkb->max_key_code)
    return False;

  if (keysym == NULL)
    return False;

  offset = xkb->map->key_sym_map[keycode].offset;
  old_keysym = xkb->map->syms[offset];
  type = &xkb->map->types[offset];
  xkb->map->syms[offset] = *keysym;

#if USE_XKB
  changes.changed = XkbKeySymsMask;
  changes.first_key_sym = keycode;
  changes.num_key_syms = xkb->map->key_sym_map[keycode].width;

  XkbChangeMap (display, xkb, &changes);
  XSync (display, False);
#else
  XChangeKeyboardMapping (display,
			  keycode,
			  xkb->map->key_sym_map[keycode].width,
			  &xkb->map->syms[offset],
			  1);
  XSync (display, False);
#endif

  *keysym = old_keysym;

  return True;
}

int
main (void)
{
  XkbDeviceInfoRec *device;
  int opcode, event_base, error_base, major_version, minor_version;
  unsigned int keycode;
  unsigned int keysym;
  unsigned int xtest_device;

  display = XOpenDisplay (NULL);

  if (!XTestQueryExtension(display, &event_base, &error_base,
			   &major_version, &minor_version))
    {
      fprintf (stderr, "XTest extension is not available\n");
      exit (1);
    }

  if (!XkbQueryExtension(display, &opcode, &event_base, &error_base,
			 &major_version, &minor_version))
    {
      fprintf (stderr, "Xkb extension is not available\n");
      exit (1);
    }

  if (!XQueryExtension(display, "XInputExtension",
		       &opcode, &event_base, &error_base))
    {
      fprintf (stderr, "X Input extension not available.\n");
      exit (1);
    }

#if defined(USE_XKB) && defined(USE_CORE)
  xtest_device = XkbUseCoreKbd;
#else
  xtest_device = get_xtest_device ();
  if (xtest_device == 0)
    {
      fprintf (stderr, "Can't get XTEST device\n");
      exit (1);
    }
#endif

  xkb = XkbGetMap (display, XkbAllComponentsMask, xtest_device);
  xkb->device_spec = xtest_device;

  keycode = 38;			/* keycode for 'a' key */
  keysym = 0x62;		/* keysym for 'b' */

  printf ("initial %X\n", XkbKeycodeToKeysym (display, keycode, 0, 0));
  replace_keycode (keycode, &keysym);
  printf ("replaced %X - type 'a'\n", XkbKeycodeToKeysym (display, keycode, 0, 0));
  XTestFakeKeyEvent (display, keycode, True, 0);
  XSync (display, False);
  printf ("key pressed %X\n", XkbKeycodeToKeysym (display, keycode, 0, 0));
  XTestFakeKeyEvent (display, keycode, False, 0);
  XSync (display, False);
  printf ("key released %X\n", XkbKeycodeToKeysym (display, keycode, 0, 0));
  replace_keycode (keycode, &keysym);
  printf ("replaced %X\n", XkbKeycodeToKeysym (display, keycode, 0, 0));

  return 0;
}

/* Local Variables:  */
/* compile-command: "gcc -DUSE_XKB test-xkb-xtest.c -o test-xkb-xtest `pkg-config x11 xtst xi --cflags --libs`" */
/* End:              */