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

#include <xcb/xcb.h>
#include <xkbcommon/xkbcommon.h>
#include <xcb-imdkit/imdkit.h>
#include <xcb-imdkit/encoding.h>

u32int keymaplookup(const u32int*, int, u16int);
char *ximcompound(const char*, size_t, size_t*);

typedef struct Ic Ic;
struct Ic
{
	Ic	*next;
	int	engaged;
};

static xcb_connection_t *conn;
static xcb_im_t *xim;
static xcb_keysym_t *kmap;
static uint8_t minkc, maxkc;
static uint8_t symsper;
static int opened;
static Ic *ics;
static Channel *replyc;

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

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

static int
kinit(void)
{
	xcb_get_keyboard_mapping_cookie_t c;
	xcb_get_keyboard_mapping_reply_t *r;
	const xcb_setup_t *setup;
	xcb_keysym_t *syms;
	uint8_t newmin, newmax, newper;
	int n;

	setup = xcb_get_setup(conn);
	if(setup == nil)
		return -1;
	newmin = setup->min_keycode;
	newmax = setup->max_keycode;
	c = xcb_get_keyboard_mapping(conn, newmin, newmax - newmin + 1);
	r = xcb_get_keyboard_mapping_reply(conn, c, nil);
	if(r == nil)
		return -1;
	newper = r->keysyms_per_keycode;
	n = xcb_get_keyboard_mapping_keysyms_length(r);
	syms = malloc(n * sizeof(xcb_keysym_t));
	if(syms == nil){
		free(r);
		return -1;
	}
	memcpy(syms, xcb_get_keyboard_mapping_keysyms(r),
		n * sizeof(xcb_keysym_t));
	free(kmap);
	kmap = syms;
	minkc = newmin;
	maxkc = newmax;
	symsper = newper;
	free(r);
	return 0;
}

static u32int
kget(uint8_t kc, u16int state)
{
	if(kmap == nil || kc < minkc || kc > maxkc)
		return 0;
	return keymaplookup(kmap + (kc - minkc) * symsper, symsper, state);
}

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

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

static void
commit(xcb_im_input_context_t *ic, char *s, int len)
{
	char *ct;
	size_t clen;

	if(len == 0)
		return;
	ct = ximcompound(s, len, &clen);
	if(ct == nil)
		return;
	xcb_im_commit_string(xim, ic, XCB_XIM_LOOKUP_CHARS, ct, clen, 0);
	xcb_flush(conn);
	free(ct);
}

static int
meaningful(u32int key)
{
	return key != 0 && (key < Kmodfirst || key > Kmodlast);
}

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

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

static void
keypress(Ic *state, u32int key, u32int mod, Keyres *res)
{
	if(meaningful(key))
		state->engaged = 1;
	sendrequest(state, Keypress, key, mod, res);
}

static void
release(Ic *state)
{
	Keyres res;

	if(state == nil || !state->engaged)
		return;
	sendrequest(state, Keyrelease, 0, 0, &res);
	state->engaged = 0;
}

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

	key = kget(ev->detail, ev->state);
	rune = xkb_keysym_to_utf32(key);
	if(rune >= ' ' && rune != 0x7f)
		key = rune;
	else if(key >= 0xff00 && key <= 0xffff)
		key = Kspec + (key - 0xff00);
	else
		key = rune;
	keypress(state, key, ev->state, &res);
	n = stoutf(&res.commit, buf, sizeof buf);
	commit(ic, buf, n);
	if(!res.eaten)
		xcb_im_forward_event(xim, ic, 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_input_context_t *ic)
{
	Ic *state;

	if(ic == nil || xcb_im_input_context_get_data(ic) != nil)
		return;
	state = calloc(1, sizeof *state);
	if(state == nil)
		return;
	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;
	Ic *state;

	USED(im);
	USED(client);
	USED(frame);
	USED(user);

	if(hdr->major_opcode == XCB_XIM_CREATE_IC){
		iccreate(ic);
		return;
	}
	if(ic == nil)
		return;
	state = xcb_im_input_context_get_data(ic);
	if(state == nil)
		return;
	switch(hdr->major_opcode){
	case XCB_XIM_FORWARD_EVENT:
		ev = arg;
		if(ev != nil && (ev->response_type & ~0x80) == XCB_KEY_PRESS)
			kpress(state, ic, ev);
		break;
	case XCB_XIM_RESET_IC:
	case XCB_XIM_UNSET_IC_FOCUS:
		release(state);
		break;
	}
}

static void
ximclose(void)
{
	Ic *state, *next;

	for(state = ics; state != nil; state = state->next)
		release(state);
	if(xim != nil){
		if(opened)
			xcb_im_close_im(xim);
		xcb_im_destroy(xim);
		xim = nil;
	}
	opened = 0;
	for(state = ics; state != nil; state = next){
		next = state->next;
		free(state);
	}
	ics = nil;
	free(kmap);
	kmap = nil;
	if(conn != nil){
		xcb_disconnect(conn);
		conn = nil;
	}
	if(replyc != nil){
		chanfree(replyc);
		replyc = nil;
	}
}

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);
	if(replyc == nil){
		ximlog("cannot create reply channel");
		return -1;
	}
	st.nStyles = nelem(styles);
	st.styles = styles;
	enc.nEncodings = nelem(encs);
	enc.encodings = encs;
	xcb_compound_text_init();
	conn = xcb_connect(nil, &scr);
	if(conn == nil || 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;
	}
	if(kinit() < 0){
		ximlog("cannot read keyboard mapping");
		return -1;
	}
	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;
	}
	opened = 1;
	return 0;
}

void
ximthread(void *arg)
{
	xcb_generic_event_t *ev;
	uint8_t type;

	USED(arg);
	threadsetname("xim");
	if(ximinit() < 0){
		ximclose();
		return;
	}
	for(;;){
		ev = xcb_wait_for_event(conn);
		if(ev == nil)
			break;
		type = ev->response_type & ~0x80;
		if(type == XCB_MAPPING_NOTIFY){
			if(kinit() < 0)
				ximlog("cannot refresh keyboard mapping");
		}else
			xcb_im_filter_event(xim, ev);
		free(ev);
	}
	if(xcb_connection_has_error(conn))
		ximlog("X server disconnected");
	ximclose();
}