// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2023 SASANO Takayoshi <uaa@uaa.org.uk>

#include <wchar.h>
#include "conv.h"

extern uint16_t ucs2euc[65536];
extern wchar_t zh[];
extern wchar_t ja[];

// half width character, U+FF5E〜 (U+FF5F, U+FF60 unimplemented)
// reference: https://www.asahi-net.or.jp/~ax2s-kmtn/ref/unicode/uff00.html
static uint16_t ucshalf2full[] = {
	                                                0x301C, 0x0000,
	0x0000, 0x3002, 0x300C, 0x300D, 0x3001, 0x30FB, 0x30F2, 0x30A1,
	0x30A3, 0x30A5, 0x30A7, 0x30A9, 0x30E3, 0x30E5, 0x30E7, 0x30C3,
	0x30FC, 0x30A2, 0x30A4, 0x30A6, 0x30A8, 0x30AA, 0x30AB, 0x30AD,
	0x30AF, 0x30B1, 0x30B3, 0x30B5, 0x30B7, 0x30B9, 0x30BB, 0x30BD,
	0x30BF, 0x30C1, 0x30C4, 0x30C6, 0x30C8, 0x30CA, 0x30CB, 0x30CC,
	0x30CD, 0x30CE, 0x30CF, 0x30D2, 0x30D5, 0x30D8, 0x30DB, 0x30DE,
	0x30DF, 0x30E0, 0x30E1, 0x30E2, 0x30E4, 0x30E6, 0x30E8, 0x30E9,
	0x30EA, 0x30EB, 0x30EC, 0x30ED, 0x30EF, 0x30F3, 0x3099, 0x309A,
};

#define UCS2EUC_SIZE		(sizeof(ucs2euc) / sizeof(uint16_t))
#define	UCSHALF2FULL_SIZE	(sizeof(ucshalf2full) / sizeof(uint16_t))

wchar_t convert_ja_zh(wchar_t wc)
{
	wchar_t *p;

	if ((p = wcschr(ja, wc)) != NULL)
		return zh[p - ja];
	else
		return wc;
}

size_t convert_euc(uint8_t *euc, wchar_t *wc)
{
	size_t i;
	wchar_t c;

	i = 0;
	for (; *wc;  wc++) {
		c = *wc;

		if (c >= UCS2EUC_SIZE)
			c = 0x3013; // '〓' in UCS
		else if (c >= 0xff5e && c < 0xff5e + UCSHALF2FULL_SIZE)
			c = ucshalf2full[c - 0xff5e]; // hankaku -> zenkaku

		switch (c) {
		case '(':
		case ')':
			// avoid ')', end of LCD command
			c = 0xff08 + (c - '('); // '（' in UCS
			/*FALLTHROUGH*/

		case 0x80 ... UCS2EUC_SIZE:
			switch (c) {
			case 0x30fc: // '―' in GB2312 (no 'ー')
				c = 0xa1aa;
				break;
			case 0x3099:
				c = 0xa1a7; // '¨' in GB2312 (no '゛')
				break;
			case 0x309a:
				c = 0xa1e3; // '°' in GB2312 (no '゜')
				break;
			default:
				c = ucs2euc[convert_ja_zh(c)];
				if (!c)
					c = 0xa1fe; // '〓' in GB2312
				break;
			}

			if (euc != NULL) {
				euc[i] = c >> 8;
				euc[i + 1] = c;
			}
			i += 2;
			break;

		default:
			if (euc != NULL) euc[i] = c;
			i++;
			break;
		}

	}

	if (euc != NULL)
		euc[i] = 0;
	i++;

	return i;
}