/* See LICENSE file for copyright and license details. */
#include "lib-common.h"


static struct {
	uint_least32_t a;
	uint_least32_t b;
} pairs[] = {
	{0x2032, 0x2035},
	{0x2033, 0x2036},
	{0x2034, 0x2037},
	{0x204F, 0x003B},
	{0x2E2E, 0x003F},
	{0x2143, 0x004C},
	{UINT32_C(0xA4ED), (uint_least32_t)'B'},
	{UINT32_C(0xA4DB), (uint_least32_t)'C'},
	{UINT32_C(0xA4F7), (uint_least32_t)'D'},
	{UINT32_C(0xA4F1), (uint_least32_t)'E'},
	{UINT32_C(0xA4D8), (uint_least32_t)'K'},
	{UINT32_C(0x1F12F), UINT32_C(0x00A9)}
};


enum libcharconv_result
libcharconv_mirrored(const char *s, size_t slen, size_t *n, uint_least32_t *cp, size_t *ncp)
{
	uint_least32_t c;
	size_t i, clen;
	*n = 0;
	while (slen) {
		clen = libcharconv_decode_utf8_(s, slen, &c);
		if (clen > slen) {
			if (*n)
				goto no_conv;
			return LIBCHARCONV_INDETERMINATE;
		}
		if (!clen) {
			*n += 1u;
			slen -= 1u;
			s = &s[1];
			continue;
		}

		if (UINT32_C(0x1F031) <= c && c <= UINT32_C(0x1F061)) {
			c -= UINT32_C(0x1F031);
			c = c % 7u * 7u + c / 7u;
			c += UINT32_C(0x1F031);
			goto conv;
		} else {
			for (i = 0u; i < sizeof(pairs) / sizeof(*pairs); i++) {
				if (c == pairs[i].a) {
					c = pairs[i].b;
					goto conv;
				}
				if (c == pairs[i].b) {
					c = pairs[i].a;
					goto conv;
				}
			}
		}

		*n += clen;
		s = &s[clen];
		slen -= clen;
	}
no_conv:
	return LIBCHARCONV_NO_CONVERT;

conv:
	if (*n)
		goto no_conv;
	if (*ncp)
		*cp = c;
	*n += clen;
	*ncp = 1u;
	return LIBCHARCONV_CONVERTED;
}