/*
 * Attempt to implement picture viewer XCB with kbd and pointer grabbing, fullscreen
 *
 * Author: Peter Wu <lekensteyn@gmail.com>
 * Date: 2012-09-24
 * gcc -o xcbviewfs xcbviewfs.c -lxcb-image -lxcb-shm -lxcb
 */

#include <xcb/xcb.h>
//#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#define die(msg) do { \
	fprintf(stderr, msg); \
	exit(EXIT_FAILURE); \
} while (0)

#define bail(lbl, msg) do { \
	fprintf(stderr, msg); \
	goto lbl; \
} while (0)

static const char empty_cursor_data[32];

int main(int argc, char **argv) {
	xcb_connection_t *c;
	xcb_screen_t *screen;
	xcb_window_t win;
	xcb_cursor_t cursor;
	if (argc < 2) {
		fprintf(stderr, "Usage: %s filename\n", *argv);
		return 1;
	}
	c = xcb_connect(NULL, NULL);
	if (!c) {
		fprintf(stderr, "Cannot open display\n");
		return 1;
	}
	screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
	win = xcb_generate_id(c);
	/* For each mask, need to add valwin item in order as defined by the
	 * enum, see See http://xcb.freedesktop.org/tutorial/events/ */
	uint32_t mask = XCB_CW_EVENT_MASK;
	uint32_t valwin[] = {
		XCB_EVENT_MASK_KEY_PRESS,
	};
	xcb_create_window(c, 0, win, /* conn, depth, WinID */
		screen->root, /* parent */
		0, 0, /* x y */
		100, 100, /* width height */
		0, /* border_width */
		XCB_WINDOW_CLASS_INPUT_OUTPUT, /* class */
		screen->root_visual,
		mask, valwin);
	xcb_map_window(c, win);
	xcb_flush(c);

	/* options */
	int grab_pointer = 0;
	int hide_cursor  = 0;
	int grab_kbd     = 0;
	int fullscreen   = 0;
	grab_kbd = !(fullscreen = grab_pointer = hide_cursor = 0 );

	if (grab_pointer) {
		xcb_grab_pointer_cookie_t cookie;
		xcb_grab_pointer_reply_t *reply;
		cookie = xcb_grab_pointer(c, 1, screen->root, XCB_NONE,
			XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC,
			XCB_NONE, XCB_NONE,
			XCB_CURRENT_TIME);
		if (!(reply = xcb_grab_pointer_reply(c, cookie, NULL))) {
			bail(disconnect, "No pointer grab reply\n");
		}
		if (reply->status != XCB_GRAB_STATUS_SUCCESS) {
			bail(disconnect, "Grab pointer FAILED\n");
		}
		free(reply);
	}
	if (hide_cursor) {
		xcb_pixmap_t cp = xcb_create_pixmap_from_bitmap_data(c, win,
			empty_cursor_data, 16, 16, 1, 0, 0, 0);
		xcb_pixmap_t mp = xcb_create_pixmap_from_bitmap_data(c, win,
			empty_cursor_data, 16, 16, 1, 0, 0, 0);

		cursor = xcb_generate_id(c);
		xcb_create_cursor(c, cursor, cp, mp, 0, 0, 0, 0xFFFF, 0xFFFF, 0xFFFF, 8, 8);
		xcb_free_pixmap(c, cp);
		xcb_free_pixmap(c, mp);

		xcb_change_window_attributes(c, win, XCB_CW_CURSOR, &cursor);
		xcb_free_cursor(c, cursor);
		xcb_flush(c);
	}
	if (grab_kbd) {
		xcb_grab_keyboard_cookie_t cookie;
		xcb_grab_keyboard_reply_t *reply;
		cookie = xcb_grab_keyboard(c, 1, screen->root, XCB_CURRENT_TIME,
			XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC);
		if (!(reply = xcb_grab_keyboard_reply(c, cookie, NULL))) {
			bail(ungrab_pointer, "No kbd grab reply\n");
		}
		if (reply->status != XCB_GRAB_STATUS_SUCCESS) {
			bail(ungrab_pointer, "Grab kbd FAILED\n");
		}
		free(reply);
	}
	if (fullscreen) {
		xcb_intern_atom_cookie_t cookie;
		xcb_intern_atom_reply_t *reply;
		xcb_atom_t property, data;

		cookie = xcb_intern_atom(c, 0, 13, "_NET_WM_STATE");
		if (!(reply = xcb_intern_atom_reply(c, cookie, 0))) {
			bail(ungrab_kbd, "Failed to get _NET_WM_STATE atom\n");
		}
		property = reply->atom;
		free(reply);

		cookie = xcb_intern_atom(c, 0, 24, "_NET_WM_STATE_FULLSCREEN");
		if (!(reply = xcb_intern_atom_reply(c, cookie, 0))) {
			bail(ungrab_kbd, "Failed to get _NET_WM_STATE_FULLSCREEN atom\n");
		}
		data = reply->atom;
		free(reply);

		xcb_change_property(c, XCB_PROP_MODE_REPLACE, win,
			property, XCB_ATOM_ATOM, 32, 1, &data);
		xcb_flush(c);
	}
	xcb_generic_event_t *e;
	int running = 1;
	while (running && (e = xcb_wait_for_event(c))) {
		switch (e->response_type) {
		case XCB_KEY_PRESS: ;
			xcb_button_press_event_t *press = (xcb_button_press_event_t *)e;
			xcb_keycode_t key = press->detail;
			if (key == 9 /* ESC */)
				running = 0;
			break;
		}
		free(e);
	}
ungrab_kbd:
	xcb_ungrab_keyboard(c, XCB_CURRENT_TIME);
ungrab_pointer:
	xcb_ungrab_pointer(c, XCB_CURRENT_TIME);
disconnect:
	xcb_disconnect(c);
	return 0;
}