#include "dat.h"
#include "fn.h"

#include <errno.h>
#include <locale.h>
#include <poll.h>
#include <xcb/xcb.h>
#include <xcb/xkb.h>
#include <xkbcommon/xkbcommon.h>
#include <xkbcommon/xkbcommon-compose.h>
#include <xkbcommon/xkbcommon-x11.h>
#include <xcb-imdkit/imdkit.h>
#include <xcb-imdkit/encoding.h>

u32int keymaplookup(struct xkb_state*, uint8_t, u16int);

/*
 * One XIM input context.  Only PreeditCallbacks clients draw the preedit
 * themselves (cap); the popup shows it for the others.  engaged means the
 * engine has seen a real key from this context and owes it a release.
 */
typedef struct Ic Ic;
struct Ic
{
	Ic		*next;
	xcb_im_input_context_t	*xic;
	xcb_im_client_t	*client;
	int		engaged;
	int		cap;
	int		prestarted;
	int		nprerune;
	Caret		caret;
};

static xcb_connection_t *conn;
static xcb_im_t *xim;
static struct xkb_state *kstate;
static struct xkb_compose_state *compose;
static uint8_t xkbevent;
static xcb_window_t rootwin;
static Ic *ics;
static Ic *preowner;
static Channel *replyc;

static char *encs[] = {"COMPOUND_TEXT"};
static u32int styles[] = {
	XCB_IM_PreeditPosition | XCB_IM_StatusNothing,
	XCB_IM_PreeditCallbacks | XCB_IM_StatusNothing,
	XCB_IM_PreeditNothing | XCB_IM_StatusNothing,
};

static void
ximlog(char *msg)
{
	fprint(2, "strans: xim: %s\n", msg);
}

/* Reads the server's keymap; XKB-aware clients get XKB events, not MappingNotify. */
static int
kinit(void)
{
	struct xkb_context *context;
	struct xkb_keymap *keymap;
	struct xkb_state *state;
	int32_t device;
	int ok;

	keymap = nil;
	state = nil;
	ok = -1;
	context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
	if(context == nil || !xkb_x11_setup_xkb_extension(conn,
	   XKB_X11_MIN_MAJOR_XKB_VERSION, XKB_X11_MIN_MINOR_XKB_VERSION,
	   XKB_X11_SETUP_XKB_EXTENSION_NO_FLAGS, nil, nil, &xkbevent, nil))
		goto out;
	device = xkb_x11_get_core_keyboard_device_id(conn);
	if(device < 0)
		goto out;
	keymap = xkb_x11_keymap_new_from_device(context, conn, device,
		XKB_KEYMAP_COMPILE_NO_FLAGS);
	if(keymap == nil)
		goto out;
	state = xkb_state_new(keymap);
	if(state == nil)
		goto out;
	xkb_state_unref(kstate);
	kstate = state;
	state = nil;
	ok = 0;
out:
	xkb_state_unref(state);
	xkb_keymap_unref(keymap);
	xkb_context_unref(context);
	return ok;
}

/* Dead keys and Compose: Xlib leaves them to the input method server. */
static void
cinit(void)
{
	struct xkb_context *context;
	struct xkb_compose_table *table;
	char *locale;

	locale = setlocale(LC_CTYPE, "");
	context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
	if(context == nil)
		return;
	table = xkb_compose_table_new_from_locale(context,
		locale != nil ? locale : "C", XKB_COMPOSE_COMPILE_NO_FLAGS);
	if(table != nil)
		compose = xkb_compose_state_new(table, XKB_COMPOSE_STATE_NO_FLAGS);
	xkb_compose_table_unref(table);
	xkb_context_unref(context);
}

static void
kwatch(void)
{
	u16int events, parts;

	events = XCB_XKB_EVENT_TYPE_NEW_KEYBOARD_NOTIFY |
		XCB_XKB_EVENT_TYPE_MAP_NOTIFY;
	parts = XCB_XKB_MAP_PART_KEY_TYPES | XCB_XKB_MAP_PART_KEY_SYMS |
		XCB_XKB_MAP_PART_MODIFIER_MAP |
		XCB_XKB_MAP_PART_EXPLICIT_COMPONENTS |
		XCB_XKB_MAP_PART_KEY_ACTIONS | XCB_XKB_MAP_PART_VIRTUAL_MODS |
		XCB_XKB_MAP_PART_VIRTUAL_MOD_MAP;
	xcb_xkb_select_events(conn, XCB_XKB_ID_USE_CORE_KBD, events, 0,
		events, parts, parts, nil);
}

static xcb_screen_t*
getscreen(int scr)
{
	xcb_screen_iterator_t iter;

	iter = xcb_setup_roots_iterator(xcb_get_setup(conn));
	for(; iter.rem; scr--, xcb_screen_next(&iter))
		if(scr == 0)
			return iter.data;
	return nil;
}

static int
translate(xcb_window_t win, int x, int y, Caret *caret)
{
	xcb_translate_coordinates_cookie_t cookie;
	xcb_translate_coordinates_reply_t *reply;

	if(win == XCB_NONE)
		return 0;
	cookie = xcb_translate_coordinates(conn, win, rootwin, x, y);
	reply = xcb_translate_coordinates_reply(conn, cookie, nil);
	if(reply == nil || !reply->same_screen){
		free(reply);
		return 0;
	}
	caret->valid = 1;
	caret->x = reply->dst_x;
	caret->y = reply->dst_y;
	caret->h = 0;
	free(reply);
	return 1;
}

static int
placebottom(Ic *state, xcb_window_t win)
{
	xcb_get_geometry_cookie_t gcookie;
	xcb_get_geometry_reply_t *geometry;
	int height;

	if(win == XCB_NONE)
		return 0;
	gcookie = xcb_get_geometry(conn, win);
	geometry = xcb_get_geometry_reply(conn, gcookie, nil);
	if(geometry == nil)
		return 0;
	height = geometry->height;
	free(geometry);
	if(!translate(win, 0, 0, &state->caret))
		return 0;
	state->caret.y += height;
	return 1;
}

/*
 * The popup goes at the client's spot location when it sends one, else
 * under the focus window, else under the client window.  An unset focus
 * window means the client window, as the XIM spec says.
 */
static void
place(Ic *state)
{
	const xcb_im_preedit_attr_t *attr;
	xcb_window_t clientwin, focuswin;

	memset(&state->caret, 0, sizeof state->caret);
	clientwin = xcb_im_input_context_get_client_window(state->xic);
	focuswin = xcb_im_input_context_get_focus_window(state->xic);
	if(focuswin == XCB_NONE)
		focuswin = clientwin;
	if(xcb_im_input_context_get_preedit_attr_mask(state->xic) &
	   XCB_XIM_XNSpotLocation_MASK){
		attr = xcb_im_input_context_get_preedit_attr(state->xic);
		if(translate(focuswin, attr->spot_location.x,
		   attr->spot_location.y, &state->caret))
			return;
	}
	if(placebottom(state, focuswin))
		return;
	if(clientwin != focuswin)
		placebottom(state, clientwin);
}

/* XIM text goes out as COMPOUND_TEXT; imdkit wraps UTF-8 in ESC%G. */
static void
commit(Ic *state, char *s, int nbyte)
{
	char *wire;
	size_t nwire;

	if(nbyte == 0)
		return;
	wire = xcb_utf8_to_compound_text(s, nbyte, &nwire);
	if(wire == nil)
		return;
	xcb_im_commit_string(xim, state->xic, XCB_XIM_LOOKUP_CHARS,
		wire, (u32int)nwire, 0);
	free(wire);
}

static void
clearpreedit(Ic *state)
{
	xcb_im_preedit_draw_fr_t frame;

	if(!state->prestarted)
		return;
	memset(&frame, 0, sizeof frame);
	frame.chg_length = state->nprerune;
	frame.status = 1;
	xcb_im_preedit_draw_callback(xim, state->xic, &frame);
	xcb_im_preedit_done_callback(xim, state->xic);
	state->prestarted = 0;
	state->nprerune = 0;
	if(preowner == state)
		preowner = nil;
	xcb_flush(conn);
}

static void
updatepreedit(Ic *state, Str *pre)
{
	xcb_im_preedit_draw_fr_t frame;
	u32int feedback[Maxrunes];
	char utf[Maxutf], *wire;
	size_t nwire;
	int i, nbyte;

	if(!(state->cap & Cclientpreedit))
		return;
	if(pre->n == 0){
		clearpreedit(state);
		return;
	}
	nbyte = stoutf(pre, utf, sizeof utf);
	wire = xcb_utf8_to_compound_text(utf, nbyte, &nwire);
	if(wire == nil)
		return;
	for(i = 0; i < pre->n; i++)
		feedback[i] = XCB_XIM_UNDERLINE;
	if(!state->prestarted){
		xcb_im_preedit_start_callback(xim, state->xic);
		state->prestarted = 1;
	}
	memset(&frame, 0, sizeof frame);
	frame.caret = pre->n;
	frame.chg_length = state->nprerune;
	frame.length_of_preedit_string = (u16int)nwire;
	frame.preedit_string = (uchar*)wire;
	frame.feedback_array.size = pre->n;
	frame.feedback_array.items = feedback;
	xcb_im_preedit_draw_callback(xim, state->xic, &frame);
	state->nprerune = pre->n;
	preowner = state;
	free(wire);
}

static void
sendrequest(Ic *state, int op, u32int key, u32int mod, Keyres *res)
{
	Keyreq kr;

	memset(&kr, 0, sizeof kr);
	kr.owner = state;
	kr.cap = state->cap;
	kr.op = op;
	kr.ks = key;
	kr.mod = ipcmod(mod);
	kr.caret = state->caret;
	kr.reply = replyc;
	chansend(keyc, &kr);
	chanrecv(replyc, res);
}

/* Another frontend may have taken the engine; then our preedit is stale. */
static void
checkpreowner(void)
{
	Keyres res;

	if(preowner == nil)
		return;
	sendrequest(preowner, Keycap, 0, 0, &res);
	if(!res.eaten)
		clearpreedit(preowner);
}

static void
keypress(Ic *state, u32int key, u32int mod, Keyres *res)
{
	if(keymeaningful(key)){
		if(preowner != nil && preowner != state)
			clearpreedit(preowner);
		state->engaged = 1;
	}
	sendrequest(state, Keypress, key, mod, res);
}

/* Losing the engine commits the pending text; the release hands it back. */
static void
release(Ic *state)
{
	Keyres res;
	char buf[Maxutf];
	int n;

	if(!state->engaged){
		clearpreedit(state);
		return;
	}
	sendrequest(state, Keyrelease, 0, 0, &res);
	state->engaged = 0;
	n = stoutf(&res.commit, buf, sizeof buf);
	commit(state, buf, n);
	clearpreedit(state);
	xcb_flush(conn);
}

/* XIM reset hands the pending text back to the client as committed text. */
static void
resetic(Ic *state, xcb_im_reset_ic_reply_fr_t *reply)
{
	Keyres res;
	char utf[Maxutf], *wire;
	size_t nwire;
	int nbyte;

	if(!state->engaged){
		clearpreedit(state);
		return;
	}
	sendrequest(state, Keyreset, 0, 0, &res);
	clearpreedit(state);
	if(reply == nil || res.commit.n == 0)
		return;
	nbyte = stoutf(&res.commit, utf, sizeof utf);
	wire = xcb_utf8_to_compound_text(utf, nbyte, &nwire);
	if(wire == nil)
		return;
	reply->committed_string = (uchar*)wire;
	reply->byte_length_of_committed_string = nwire;
}

static void
kpress(Ic *state, xcb_key_press_event_t *ev)
{
	Keyres res;
	char buf[Maxutf];
	u32int key, sym;
	int composed, n;

	sym = keymaplookup(kstate, ev->detail, ev->state);
	composed = 0;
	if(compose != nil &&
	   xkb_compose_state_feed(compose, sym) == XKB_COMPOSE_FEED_ACCEPTED)
		switch(xkb_compose_state_get_status(compose)){
		case XKB_COMPOSE_COMPOSING:
		case XKB_COMPOSE_CANCELLED:
			return;
		case XKB_COMPOSE_COMPOSED:
			sym = xkb_compose_state_get_one_sym(compose);
			composed = 1;
			break;
		default:
			break;
		}
	key = ipckeysym(sym, xkb_keysym_to_utf32(sym));
	if(keymeaningful(key))
		place(state);
	keypress(state, key, ev->state, &res);
	n = stoutf(&res.commit, buf, sizeof buf);
	commit(state, buf, n);
	updatepreedit(state, &res.preedit);
	if(res.eaten)
		;
	else if(composed){
		/* The event holds the last key of the sequence, not its result. */
		n = xkb_keysym_to_utf8(sym, buf, sizeof buf);
		commit(state, buf, max(n - 1, 0));
	}else
		xcb_im_forward_event(xim, state->xic, ev);
	xcb_flush(conn);
}

static void
icunlink(Ic *state)
{
	Ic **p;

	for(p = &ics; *p != nil; p = &(*p)->next)
		if(*p == state){
			*p = state->next;
			return;
		}
}

static void
icfree(void *p)
{
	Ic *state;

	state = p;
	/* The owner remains valid until imthread acknowledges its release. */
	release(state);
	icunlink(state);
	free(state);
}

static void
iccreate(xcb_im_client_t *client, xcb_im_input_context_t *ic)
{
	Ic *state;

	state = emalloc(sizeof(Ic));
	state->xic = ic;
	state->client = client;
	if(xcb_im_input_context_get_input_style(ic) ==
	   (XCB_IM_PreeditCallbacks | XCB_IM_StatusNothing))
		state->cap = Cclientpreedit;
	state->next = ics;
	ics = state;
	xcb_im_input_context_set_data(ic, state, icfree);
}

static void
callback(xcb_im_t *im, xcb_im_client_t *client, xcb_im_input_context_t *ic,
	const xcb_im_packet_header_fr_t *hdr, void *frame, void *arg, void *user)
{
	xcb_key_press_event_t *ev;
	Keyres res;
	Ic *state;

	USED(im);
	USED(frame);
	USED(user);
	if(hdr->major_opcode == XCB_XIM_DISCONNECT ||
	   hdr->major_opcode == XCB_XIM_CLOSE){
		for(state = ics; state != nil; state = state->next)
			if(state->client == client)
				release(state);
		return;
	}
	if(hdr->major_opcode == XCB_XIM_CREATE_IC){
		iccreate(client, ic);
		return;
	}
	if(ic == nil)
		return;
	state = xcb_im_input_context_get_data(ic);
	switch(hdr->major_opcode){
	case XCB_XIM_FORWARD_EVENT:
		ev = arg;
		if(ev != nil && (ev->response_type & ~0x80) == XCB_KEY_PRESS)
			kpress(state, ev);
		break;
	case XCB_XIM_SET_IC_VALUES:
	case XCB_XIM_SET_IC_FOCUS:
		place(state);
		if(state->engaged)
			sendrequest(state, Keycaret, 0, 0, &res);
		break;
	case XCB_XIM_DESTROY_IC:
	case XCB_XIM_UNSET_IC_FOCUS:
		release(state);
		break;
	case XCB_XIM_RESET_IC:
		resetic(state, arg);
		break;
	}
}

static int
ximinit(void)
{
	xcb_screen_t *screen;
	xcb_window_t win;
	xcb_im_styles_t st;
	xcb_im_encodings_t enc;
	int scr;

	replyc = chancreate(sizeof(Keyres), 0);
	st.nStyles = nelem(styles);
	st.styles = styles;
	enc.nEncodings = nelem(encs);
	enc.encodings = encs;
	xcb_compound_text_init();
	conn = xcb_connect(nil, &scr);
	if(xcb_connection_has_error(conn)){
		ximlog("cannot connect to X server");
		return -1;
	}
	screen = getscreen(scr);
	if(screen == nil){
		ximlog("cannot find X screen");
		return -1;
	}
	rootwin = screen->root;
	if(kinit() < 0){
		ximlog("cannot read keyboard mapping");
		return -1;
	}
	cinit();
	kwatch();
	win = xcb_generate_id(conn);
	xcb_create_window(conn, XCB_COPY_FROM_PARENT, win, screen->root,
		0, 0, 1, 1, 0, XCB_WINDOW_CLASS_INPUT_OUTPUT,
		screen->root_visual, 0, nil);
	xim = xcb_im_create(conn, scr, win, "strans",
		XCB_IM_ALL_LOCALES, &st, nil, nil, &enc,
		XCB_EVENT_MASK_KEY_PRESS, callback, nil);
	if(xim == nil){
		ximlog("cannot create XIM server");
		return -1;
	}
	if(!xcb_im_open_im(xim)){
		ximlog("cannot claim XIM selection");
		return -1;
	}
	return 0;
}

void
ximthread(void *arg)
{
	struct pollfd pfd;
	xcb_generic_event_t *ev;
	uint8_t type;
	int n;

	USED(arg);
	threadsetname("xim");
	if(ximinit() < 0)
		die("xim: initialization failed");
	pfd.fd = xcb_get_file_descriptor(conn);
	pfd.events = POLLIN;
	for(;;){
		pfd.revents = 0;
		n = poll(&pfd, 1, preowner != nil ? Ownerpoll : -1);
		if(n < 0 && errno != EINTR)
			break;
		while((ev = xcb_poll_for_event(conn)) != nil){
			type = ev->response_type & ~0x80;
			if(type == xkbevent){
				if(kinit() < 0)
					ximlog("cannot refresh keyboard mapping");
			}else
				xcb_im_filter_event(xim, ev);
			free(ev);
		}
		checkpreowner();
		if(pfd.revents & (POLLERR|POLLHUP|POLLNVAL))
			break;
	}
	if(xcb_connection_has_error(conn))
		die("xim: X server disconnected");
	die("xim: frontend stopped");
}