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


static struct {
	uint_least32_t a;
	uint_least32_t b;
} pairs[] = {
	{UINT32_C(0x2032), UINT32_C(0x2035)},
	{UINT32_C(0x2033), UINT32_C(0x2036)},
	{UINT32_C(0x2034), UINT32_C(0x2037)},
	{UINT32_C(0x204F), UINT32_C(0x003B)},
	{UINT32_C(0x2E2E), UINT32_C(0x003F)},
	{UINT32_C(0x2143), UINT32_C(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)},
	{UINT32_C(0x230C), UINT32_C(0x230D)},
	{UINT32_C(0x230E), UINT32_C(0x230F)},
	{UINT32_C(0x23BE), UINT32_C(0x23CB)},
	{UINT32_C(0x23BF), UINT32_C(0x23CC)},
	{UINT32_C(0x169B), UINT32_C(0x169C)},
	{UINT32_C(0x2571), UINT32_C(0x2572)},
	{UINT32_C(0x250C), UINT32_C(0x2510)},
	{UINT32_C(0x250D), UINT32_C(0x2511)},
	{UINT32_C(0x250E), UINT32_C(0x2512)},
	{UINT32_C(0x250F), UINT32_C(0x2513)},
	{UINT32_C(0x2514), UINT32_C(0x2518)},
	{UINT32_C(0x2515), UINT32_C(0x2519)},
	{UINT32_C(0x2516), UINT32_C(0x251A)},
	{UINT32_C(0x2517), UINT32_C(0x251B)},
	{UINT32_C(0x251C), UINT32_C(0x2524)},
	{UINT32_C(0x251D), UINT32_C(0x2525)},
	{UINT32_C(0x251E), UINT32_C(0x2526)},
	{UINT32_C(0x251F), UINT32_C(0x2527)},
	{UINT32_C(0x2520), UINT32_C(0x2528)},
	{UINT32_C(0x2521), UINT32_C(0x2529)},
	{UINT32_C(0x2522), UINT32_C(0x252A)},
	{UINT32_C(0x2523), UINT32_C(0x252B)},
	{UINT32_C(0x252E), UINT32_C(0x252D)},
	{UINT32_C(0x2532), UINT32_C(0x2531)},
	{UINT32_C(0x2536), UINT32_C(0x2535)},
	{UINT32_C(0x253A), UINT32_C(0x2539)},
	{UINT32_C(0x253E), UINT32_C(0x253D)},
	{UINT32_C(0x2544), UINT32_C(0x2543)},
	{UINT32_C(0x2546), UINT32_C(0x2545)},
	{UINT32_C(0x254A), UINT32_C(0x2549)},
	{UINT32_C(0x2552), UINT32_C(0x2555)},
	{UINT32_C(0x2553), UINT32_C(0x2556)},
	{UINT32_C(0x2554), UINT32_C(0x2557)},
	{UINT32_C(0x2558), UINT32_C(0x255B)},
	{UINT32_C(0x2559), UINT32_C(0x255C)},
	{UINT32_C(0x255A), UINT32_C(0x255D)},
	{UINT32_C(0x255E), UINT32_C(0x2561)},
	{UINT32_C(0x255F), UINT32_C(0x2562)},
	{UINT32_C(0x2560), UINT32_C(0x2563)},
	{UINT32_C(0x256D), UINT32_C(0x256E)},
	{UINT32_C(0x2570), UINT32_C(0x256F)},
	{UINT32_C(0x2574), UINT32_C(0x2576)},
	{UINT32_C(0x2578), UINT32_C(0x257A)},
	{UINT32_C(0x257C), UINT32_C(0x257E)},
};


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 if (UINT32_C(0x2800) <= c && c <= UINT32_C(0x28FF)) {
			c = ((c & 0x07u) << 3) | ((c & 0x38u) >> 3)
			  | ((c & 0x40u) << 1) | ((c & 0x80u) >> 1)
			  | UINT32_C(0x2800);
			goto conv;
		} else if (UINT32_C(0x1FBA0) <= c && c <= UINT32_C(0x1FBAD)) {
			c ^= 1u;
			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;
}