/* $OpenBSD: utf8-combined.c,v 1.8 2025/12/04 06:04:21 nicm Exp $ */

/*
 * 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);
}

/* 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))
                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);
}