/* $OpenBSD$ */

/*
 * Copyright (c) 2023 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>
#include <wchar.h>

#include "tmux.h"

enum hanguljamo_subclass {
	HANGULJAMO_SUBCLASS_NOT_HANGULJAMO,
	HANGULJAMO_SUBCLASS_CHOSEONG,			// U+1100 - U+1112
	HANGULJAMO_SUBCLASS_OLD_CHOSEONG,		// U+1113 - U+115E
	HANGULJAMO_SUBCLASS_CHOSEONG_FILLER,		// U+115F
	HANGULJAMO_SUBCLASS_JUNGSEONG_FILLER,		// U+1160
	HANGULJAMO_SUBCLASS_JUNGSEONG,			// U+1161 - U+1175
	HANGULJAMO_SUBCLASS_OLD_JUNGSEONG,		// U+1176 - U+11A7
	HANGULJAMO_SUBCLASS_JONGSEONG,			// U+11A8 - U+11C2
	HANGULJAMO_SUBCLASS_OLD_JONGSEONG,		// U+11C3 - U+11FF
	HANGULJAMO_SUBCLASS_EXTENDED_OLD_CHOSEONG,	// U+A960 - U+A97C
	HANGULJAMO_SUBCLASS_EXTENDED_OLD_JUNGSEONG,	// U+D7B0 - U+D7C6
	HANGULJAMO_SUBCLASS_EXTENDED_OLD_JONGSEONG	// U+D7CB - U+D7FB
};

enum hanguljamo_class {
	HANGULJAMO_CLASS_NOT_HANGULJAMO,
	HANGULJAMO_CLASS_CHOSEONG,
	HANGULJAMO_CLASS_JUNGSEONG,
	HANGULJAMO_CLASS_JONGSEONG
};

/* Has this got a zero width joiner at the end? */
int
utf8_has_zwj(const struct utf8_data *ud)
{
	if (ud->size < 3)
		return (0);
	return (memcmp(ud->data + ud->size - 3, "\342\200\215", 3) == 0);
}

/* Is this zero width joiner U+200D? */
int
utf8_is_zwj(const struct utf8_data *ud)
{
	if (ud->size != 3)
		return (0);
	return (memcmp(ud->data, "\342\200\215", 3) == 0);
}

/* Is this variation selector U+FE0F? */
int
utf8_is_vs(const struct utf8_data *ud)
{
	if (ud->size != 3)
		return (0);
	return (memcmp(ud->data, "\357\270\217", 3) == 0);
}

/* Is this Hangul filler U+3164? */
int
utf8_is_hangul_filler(const struct utf8_data *ud)
{
	if (ud->size != 3)
		return (0);
	return (memcmp(ud->data, "\343\205\244", 3) == 0);
}

/* Count regional indicator characters. */
static u_int
utf8_regional_count(const struct utf8_data *ud)
{
	u_int	count = 0, i;

	for (i = 0; i + 4 <= ud->size; i++) {
		if (ud->data[i] == 0xf0 &&
		    ud->data[i + 1] == 0x9f &&
		    ud->data[i + 2] == 0x87 &&
		    ud->data[i + 3] >= 0xa6 &&
		    ud->data[i + 3] <= 0xbf)
			count++;
	}
	return (count);
}

/* Should these two characters combine? */
int
utf8_should_combine(const struct utf8_data *with, const struct utf8_data *add)
{
	wchar_t	w, a;

	if (utf8_towc(with, &w) != UTF8_DONE)
		return (0);
	if (utf8_towc(add, &a) != UTF8_DONE)
		return (0);

	/* Regional indicators. */
	if ((a >= 0x1F1E6 && a <= 0x1F1FF) && (w >= 0x1F1E6 && w <= 0x1F1FF)) {
		if (utf8_regional_count(with) != 1)
			return (0);
		if (utf8_regional_count(add) != 1)
			return (0);
		return (1);
	}

	/* Emoji skin tone modifiers. */
	switch (a) {
	case 0x1F44B:
	case 0x1F44C:
	case 0x1F44D:
	case 0x1F44E:
	case 0x1F44F:
	case 0x1F450:
	case 0x1F466:
	case 0x1F467:
	case 0x1F468:
	case 0x1F469:
	case 0x1F46E:
	case 0x1F470:
	case 0x1F471:
	case 0x1F472:
	case 0x1F473:
	case 0x1F474:
	case 0x1F475:
	case 0x1F476:
	case 0x1F477:
	case 0x1F478:
	case 0x1F47C:
	case 0x1F481:
	case 0x1F482:
	case 0x1F483:
	case 0x1F485:
	case 0x1F486:
	case 0x1F487:
	case 0x1F4AA:
	case 0x1F575:
	case 0x1F57A:
	case 0x1F590:
	case 0x1F595:
	case 0x1F596:
	case 0x1F645:
	case 0x1F646:
	case 0x1F647:
	case 0x1F64B:
	case 0x1F64C:
	case 0x1F64D:
	case 0x1F64E:
	case 0x1F64F:
	case 0x1F6B4:
	case 0x1F6B5:
	case 0x1F6B6:
	case 0x1F926:
	case 0x1F937:
	case 0x1F938:
	case 0x1F939:
	case 0x1F93D:
	case 0x1F93E:
	case 0x1F9B5:
	case 0x1F9B6:
	case 0x1F9B8:
	case 0x1F9B9:
	case 0x1F9CD:
	case 0x1F9CE:
	case 0x1F9CF:
	case 0x1F9D1:
	case 0x1F9D2:
	case 0x1F9D3:
	case 0x1F9D4:
	case 0x1F9D5:
	case 0x1F9D6:
	case 0x1F9D7:
	case 0x1F9D8:
	case 0x1F9D9:
	case 0x1F9DA:
	case 0x1F9DB:
	case 0x1F9DC:
	case 0x1F9DD:
	case 0x1F9DE:
	case 0x1F9DF:
		if (w >= 0x1F3FB && w <= 0x1F3FF)
			return (1);
		break;
	}
	return (0);
}

static enum hanguljamo_subclass
hanguljamo_get_subclass(const u_char *s)
{
	switch (s[0]) {
	case 0xE1:
		switch (s[1]) {
		case 0x84:
			if (s[2] >= 0x80 && s[2] <= 0x92)
				return (HANGULJAMO_SUBCLASS_CHOSEONG);
			if (s[2] >= 0x93 && s[2] <= 0xBF)
				return (HANGULJAMO_SUBCLASS_OLD_CHOSEONG);
			break;
		case 0x85:
			if (s[2] == 0x9F)
				return (HANGULJAMO_SUBCLASS_CHOSEONG_FILLER);
			if (s[2] == 0xA0)
				return (HANGULJAMO_SUBCLASS_JUNGSEONG_FILLER);
			if (s[2] >= 0x80 && s[2] <= 0x9E)
				return (HANGULJAMO_SUBCLASS_OLD_CHOSEONG);
			if (s[2] >= 0xA1 && s[2] <= 0xB5)
				return (HANGULJAMO_SUBCLASS_JUNGSEONG);
			if (s[2] >= 0xB6 && s[2] <= 0xBF)
				return (HANGULJAMO_SUBCLASS_OLD_JUNGSEONG);
			break;
		case 0x86:
			if (s[2] >= 0x80 && s[2] <= 0xA7)
				return (HANGULJAMO_SUBCLASS_OLD_JUNGSEONG);
			if (s[2] >= 0xA8 && s[2] <= 0xBF)
				return (HANGULJAMO_SUBCLASS_JONGSEONG);
			break;
		case 0x87:
			if (s[2] >= 0x80 && s[2] <= 0x82)
				return (HANGULJAMO_SUBCLASS_JONGSEONG);
			if (s[2] >= 0x83 && s[2] <= 0xBF)
				return (HANGULJAMO_SUBCLASS_OLD_JONGSEONG);
			break;
		}
		break;
	case 0xEA:
		if (s[1] == 0xA5 && s[2] >= 0xA0 && s[2] <= 0xBC)
			return (HANGULJAMO_SUBCLASS_EXTENDED_OLD_CHOSEONG);
		break;
	case 0xED:
		if (s[1] == 0x9E && s[2] >= 0xB0 && s[2] <= 0xBF)
			return (HANGULJAMO_SUBCLASS_EXTENDED_OLD_JUNGSEONG);
		if (s[1] != 0x9F)
			break;
		if (s[2] >= 0x80 && s[2] <= 0x86)
			return (HANGULJAMO_SUBCLASS_EXTENDED_OLD_JUNGSEONG);
		if (s[2] >= 0x8B && s[2] <= 0xBB)
			return (HANGULJAMO_SUBCLASS_EXTENDED_OLD_JONGSEONG);
		break;
	}
	return (HANGULJAMO_SUBCLASS_NOT_HANGULJAMO);
}

static enum hanguljamo_class
hanguljamo_get_class(const u_char *s)
{
	switch (hanguljamo_get_subclass(s)) {
	case HANGULJAMO_SUBCLASS_CHOSEONG:
	case HANGULJAMO_SUBCLASS_CHOSEONG_FILLER:
	case HANGULJAMO_SUBCLASS_OLD_CHOSEONG:
	case HANGULJAMO_SUBCLASS_EXTENDED_OLD_CHOSEONG:
		return (HANGULJAMO_CLASS_CHOSEONG);
	case HANGULJAMO_SUBCLASS_JUNGSEONG:
	case HANGULJAMO_SUBCLASS_JUNGSEONG_FILLER:
	case HANGULJAMO_SUBCLASS_OLD_JUNGSEONG:
	case HANGULJAMO_SUBCLASS_EXTENDED_OLD_JUNGSEONG:
		return (HANGULJAMO_CLASS_JUNGSEONG);
	case HANGULJAMO_SUBCLASS_JONGSEONG:
	case HANGULJAMO_SUBCLASS_OLD_JONGSEONG:
	case HANGULJAMO_SUBCLASS_EXTENDED_OLD_JONGSEONG:
		return (HANGULJAMO_CLASS_JONGSEONG);
	case HANGULJAMO_SUBCLASS_NOT_HANGULJAMO:
		return (HANGULJAMO_CLASS_NOT_HANGULJAMO);
	}
	return (HANGULJAMO_CLASS_NOT_HANGULJAMO);
}

enum hanguljamo_state
hanguljamo_check_state(const struct utf8_data *p_ud, const struct utf8_data *ud)
{
	const u_char	*s;

	if (ud->size != 3)
		return (HANGULJAMO_STATE_NOT_HANGULJAMO);

	switch (hanguljamo_get_class(ud->data)) {
	case HANGULJAMO_CLASS_CHOSEONG:
		return (HANGULJAMO_STATE_CHOSEONG);
	case HANGULJAMO_CLASS_JUNGSEONG:
		if (p_ud->size < 3)
			return (HANGULJAMO_STATE_NOT_COMPOSABLE);
		s = p_ud->data + p_ud->size - 3;
		if (hanguljamo_get_class(s) == HANGULJAMO_CLASS_CHOSEONG)
			return (HANGULJAMO_STATE_COMPOSABLE);
		return (HANGULJAMO_STATE_NOT_COMPOSABLE);
	case HANGULJAMO_CLASS_JONGSEONG:
		if (p_ud->size < 3)
			return (HANGULJAMO_STATE_NOT_COMPOSABLE);
		s = p_ud->data + p_ud->size - 3;
		if (hanguljamo_get_class(s) == HANGULJAMO_CLASS_JUNGSEONG)
			return (HANGULJAMO_STATE_COMPOSABLE);
		return (HANGULJAMO_STATE_NOT_COMPOSABLE);
	case HANGULJAMO_CLASS_NOT_HANGULJAMO:
		return (HANGULJAMO_STATE_NOT_HANGULJAMO);
	}
	return (HANGULJAMO_STATE_NOT_HANGULJAMO);
}
