#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <xcb/xcb.h>
#include <xkbcommon/xkbcommon.h>
#include <xcb-imdkit/imdkit.h>
#include <xcb-imdkit/encoding.h>
#include "ipc.h"
#include "keymap.h"
#include "ximtext.h"

typedef struct Ic Ic;
struct Ic
{
	int fd;
};

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 char *encs[] = {"COMPOUND_TEXT"};
static uint32_t styles[] = {
	XCB_IM_PreeditNothing | XCB_IM_StatusNothing,
	XCB_IM_PreeditNone | XCB_IM_StatusNone,
};

static void
die(char *msg)
{
	fprintf(stderr, "strans-xim: %s\n", msg);
	exit(1);
}

static void
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;
	int n;

	setup = xcb_get_setup(conn);
	if(setup == NULL)
		die("xcb_get_setup failed");
	minkc = setup->min_keycode;
	maxkc = setup->max_keycode;
	c = xcb_get_keyboard_mapping(conn, minkc, maxkc - minkc + 1);
	r = xcb_get_keyboard_mapping_reply(conn, c, NULL);
	if(r == NULL)
		die("keyboard mapping failed");
	symsper = r->keysyms_per_keycode;
	n = xcb_get_keyboard_mapping_keysyms_length(r);
	syms = malloc(n * sizeof(xcb_keysym_t));
	if(syms == NULL)
		die("malloc failed");
	memcpy(syms, xcb_get_keyboard_mapping_keysyms(r),
		n * sizeof(xcb_keysym_t));
	free(kmap);
	kmap = syms;
	free(r);
}

static uint32_t
kget(uint8_t kc, uint16_t state)
{
	if(kmap == NULL || 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 == NULL)
		die("xcb_get_setup failed");
	iter = xcb_setup_roots_iterator(setup);
	for(; iter.rem; scr--, xcb_screen_next(&iter))
		if(scr == 0)
			return iter.data;
	die("no screen");
	return NULL;
}

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 == NULL)
		return;
	xcb_im_commit_string(xim, ic, XCB_XIM_LOOKUP_CHARS, ct, clen, 0);
	xcb_flush(conn);
	free(ct);
}

static void
srvclose(Ic *state)
{
	if(state == NULL || state->fd < 0)
		return;
	close(state->fd);
	state->fd = -1;
}

static int
srvconnect(Ic *state)
{
	if(state->fd >= 0)
		return 0;
	state->fd = ipcconnect();
	if(state->fd < 0)
		return -1;
	return 0;
}

static int
readresp(Ic *state, xcb_im_input_context_t *ic)
{
	char buf[Ipcfieldmax+1];
	Ipcresp resp;

	if(ipcreadresp(state->fd, 0, buf, sizeof buf, NULL, 0, &resp) < 0)
		return -1;
	if(resp.ncommit > 0)
		commit(ic, buf, resp.ncommit);
	return resp.eaten;
}

static void
kpress(Ic *state, xcb_im_input_context_t *ic, xcb_key_press_event_t *ev)
{
	unsigned char buf[Ipcreqsz];
	uint32_t key, rune;
	int eaten;

	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;
	ipcpackreq(buf, 0, ev->state, key);
	eaten = 0;
	if(srvconnect(state) == 0){
		if(ipcsend(state->fd, buf, sizeof buf) < 0 ||
		   (eaten = readresp(state, ic)) < 0){
			srvclose(state);
			eaten = 0;
		}
	}
	if(eaten == 0)
		xcb_im_forward_event(xim, ic, ev);
	xcb_flush(conn);
}

static void
reset(Ic *state, xcb_im_input_context_t *ic, int release)
{
	unsigned char buf[Ipcreqsz];

	if(state == NULL || state->fd < 0)
		return;
	ipcpackreset(buf, 0);
	if(ipcsend(state->fd, buf, sizeof buf) < 0 ||
	   readresp(state, ic) < 0)
		release = 1;
	if(release)
		srvclose(state);
}

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

	state = p;
	/* imdkit frees this data on context destruction and client loss. */
	srvclose(state);
	free(state);
}

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

	if(ic == NULL || xcb_im_input_context_get_data(ic) != NULL)
		return;
	state = calloc(1, sizeof *state);
	if(state == NULL)
		return;
	state->fd = -1;
	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;

	(void)im;
	(void)client;
	(void)frame;
	(void)user;

	if(hdr->major_opcode == XCB_XIM_CREATE_IC){
		iccreate(ic);
		return;
	}
	if(ic == NULL)
		return;
	state = xcb_im_input_context_get_data(ic);
	if(state == NULL)
		return;
	switch(hdr->major_opcode){
	case XCB_XIM_FORWARD_EVENT:
		ev = arg;
		if(ev != NULL && (ev->response_type & ~0x80) == XCB_KEY_PRESS)
			kpress(state, ic, ev);
		break;
	case XCB_XIM_RESET_IC:
		/* ResetIC ends this context's ownership, like focus loss. */
		reset(state, ic, 1);
		break;
	case XCB_XIM_UNSET_IC_FOCUS:
		reset(state, ic, 1);
		break;
	}
}

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

	st.nStyles = 2;
	st.styles = styles;
	enc.nEncodings = 1;
	enc.encodings = encs;
	xcb_compound_text_init();
	conn = xcb_connect(NULL, &scr);
	if(conn == NULL || xcb_connection_has_error(conn))
		die("xcb_connect failed");
	screen = getscreen(scr);
	kinit();
	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, NULL);
	xim = xcb_im_create(conn, scr, win, "strans",
		XCB_IM_ALL_LOCALES, &st, NULL, NULL, &enc,
		XCB_EVENT_MASK_KEY_PRESS, callback, NULL);
	if(xim == NULL || !xcb_im_open_im(xim))
		die("xcb_im failed");
}

int
main(void)
{
	xcb_generic_event_t *ev;
	uint8_t type;

	ximinit();
	for(;;){
		ev = xcb_wait_for_event(conn);
		if(ev == NULL)
			break;
		type = ev->response_type & ~0x80;
		if(type == XCB_MAPPING_NOTIFY)
			kinit();
		else
			xcb_im_filter_event(xim, ev);
		free(ev);
	}
	return 0;
}