#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <locale.h>
#include <langinfo.h>
#include <assert.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>

static Atom atom_wm_protocols;
static Atom atom_wm_delete;
static Atom atom_wm_state;
static Atom atom_wm_fullscreen;
static Display *dpy;
static Window win;
static GC gc;
static XIM im;
static XIC ic;

static void set_fullscreen()
{
	XEvent e = { 0 };
	e.type = ClientMessage;
	e.xclient.window = win;
	e.xclient.message_type = atom_wm_state;
	e.xclient.format = 32;
	e.xclient.data.l[0] = 1;
	e.xclient.data.l[1] = atom_wm_fullscreen;
	e.xclient.data.l[2] = 0;

	XSendEvent(dpy, DefaultRootWindow(dpy), False, SubstructureNotifyMask, &e);
}

static int preedit_start_cb(XIC ic, XPointer client_data, XPointer p)
{
	printf("start preedit\n");
	return -1;
}

static int preedit_stop_cb(XIC ic, XPointer client_data, XPointer p)
{
	printf("stop preedit\n");
	return 0;
}

static int preedit_draw_cb(XIC ic, XPointer client_data, XIMPreeditDrawCallbackStruct *s)
{
	printf("draw preedit %d'%s'\n", s->text->length, s->text->string.multi_byte);
	return 0;
}

int main(int argc, char ** argv)
{
	bool quit = false;
	setlocale(LC_ALL, "");
	XSetLocaleModifiers("@im=xmim");

	char *nl = nl_langinfo(CODESET);
	printf("codeset %s\n", nl);

	dpy = XOpenDisplay(NULL);
	assert(dpy);
	int scr = DefaultScreen(dpy);

	atom_wm_protocols = XInternAtom(dpy, "WM_PROTOCOLS", True);
	atom_wm_delete = XInternAtom(dpy, "WM_DELETE_WINDOW", True);
	atom_wm_state = XInternAtom(dpy, "_NET_WM_STATE", True);
	atom_wm_fullscreen = XInternAtom(dpy, "_NET_WM_STATE_FULLSCREEN", True);

	win = XCreateSimpleWindow(dpy, RootWindow(dpy, scr), 0, 0, 400, 400, 0,
	                          WhitePixel(dpy, scr), WhitePixel(dpy, scr));

	im = XOpenIM(dpy, NULL, NULL, NULL);
	assert(im);

	XIMStyles *xim_styles = NULL;
	if (XGetIMValues(im, XNQueryInputStyle, &xim_styles, NULL) == 0) {
		printf("styles: (%u)\n", xim_styles->count_styles);
		for (int i = 0; i < xim_styles->count_styles; i++) {
			const XIMStyle style = xim_styles->supported_styles[i];
			printf(" style %lu\n", style);
		}
	}

	XIMCallback preedit_start = { NULL, (XIMProc) preedit_start_cb };
	XIMCallback preedit_stop = { NULL, (XIMProc) preedit_stop_cb };
	XIMCallback preedit_draw = { NULL, (XIMProc) preedit_draw_cb };

	XVaNestedList preedit_list =
	        XVaCreateNestedList(0,
	                            XNPreeditStartCallback, &preedit_start,
	                            XNPreeditDoneCallback, &preedit_stop,
	                            XNPreeditDrawCallback, &preedit_draw,
	                            NULL);

	ic = XCreateIC(im,
	               XNInputStyle, XIMPreeditCallbacks | XIMStatusNothing,
	               XNClientWindow, win, XNFocusWindow, win,
	               XNPreeditAttributes, preedit_list,
	               NULL);
	assert(ic);

	XGCValues gc_values;
	gc = XCreateGC(dpy, win, 0, &gc_values);

	unsigned long im_event_mask;
	XGetICValues(ic, XNFilterEvents, &im_event_mask, NULL);
	printf("im event mask 0x%lx\n", im_event_mask);

	im_event_mask |= KeyPressMask | KeyReleaseMask | ButtonPressMask | FocusChangeMask | ClientMessage;
	XSelectInput(dpy, win, im_event_mask);
	XSetWMProtocols(dpy, win, &atom_wm_delete, 1);

	set_fullscreen();

	XMapWindow(dpy, win);

	while (!quit) {
		XEvent e;
		XNextEvent(dpy, &e);
		if (XFilterEvent(&e, None)) {
			continue;
		}
		switch (e.type) {
		case KeyPress: {
			printf("key press\n");
			KeySym keysym;
			Status status;
			int buflength;
			static int bufsize = 16;
			static char *buf;
			if (buf == NULL) {
				buf = malloc(bufsize + 1);
				assert(buf);
			}
			buflength = Xutf8LookupString(ic, &e.xkey, buf, bufsize, &keysym, &status);
			if (status == XBufferOverflow) {
				bufsize = buflength;
				buf = realloc(buf, bufsize + 1);
				assert(buf);
				buflength = Xutf8LookupString(ic, &e.xkey, buf, bufsize, &keysym, &status);
			}
			switch(status) {
			case XLookupKeySym:
				printf("keysim(0x%lx)\n", keysym);
				break;
			case XLookupBoth:
				printf("keysim(0x%lx)+", keysym);
				// Fallthrough
			case XLookupChars:
				buf[buflength] = '\0';
				printf("string(%d'%s')\n", buflength, buf);
				break;
			case XLookupNone:
				printf("none\n");
				break;
			default:
				printf("weirdo\n");
				break;
			}
		}	break;
		case KeyRelease:
			printf("key release\n");
			break;
		case ButtonPress:
			printf("button press\n");
			break;
		case FocusIn:
			printf("focus in\n");
			XSetICFocus(ic);
			break;
		case FocusOut:
			printf("focus out\n");
			XUnsetICFocus(ic);
			break;
		case ClientMessage:
			printf("client message\n");
			if (e.xclient.message_type == atom_wm_protocols) {
				if (e.xclient.data.l[0] == atom_wm_delete) {
					quit = true;
				}
			}
			break;
		default:
			printf("unknown event\n");
			break;
		}
	}

	XFreeGC(dpy, gc);
	XDestroyIC(ic);
	XCloseIM(im);
	XDestroyWindow(dpy, win);
	XFlush(dpy);
	XCloseDisplay(dpy);

	return EXIT_SUCCESS;
}