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


static struct {
	uint_least32_t a;
	uint_least32_t b;
	uint_least32_t to;
} pairs[] = {
	{UINT32_C(0x00BF), UINT32_C(0x00A1), UINT32_C(0x2E18)},
	{UINT32_C(0x0021), UINT32_C(0x003F), UINT32_C(0x203D)},
	{UINT32_C(0x1FA06), UINT32_C(0x1FA07), UINT32_C(0x1FA08)},
	{UINT32_C(0x1FA1B), UINT32_C(0x1FA1C), UINT32_C(0x1FA1D)},
	{UINT32_C(0x1FA30), UINT32_C(0x1FA31), UINT32_C(0x1FA32)},
	{UINT32_C(0x1FA45), UINT32_C(0x1FA46), UINT32_C(0x1FA47)},
	{UINT32_C(0x1FA48), UINT32_C(0x1FA49), UINT32_C(0x1FA4A)},
	{UINT32_C(0x1FA4B), UINT32_C(0x1FA4C), UINT32_C(0x1FA4D)},
	{UINT32_C(0x2654), UINT32_C(0x265A), UINT32_C(0x1FA00)},
	{UINT32_C(0x2655), UINT32_C(0x265B), UINT32_C(0x1FA01)},
	{UINT32_C(0x2656), UINT32_C(0x265C), UINT32_C(0x1FA02)},
	{UINT32_C(0x2657), UINT32_C(0x265D), UINT32_C(0x1FA03)},
	{UINT32_C(0x2658), UINT32_C(0x265E), UINT32_C(0x1FA04)},
	{UINT32_C(0x2659), UINT32_C(0x265F), UINT32_C(0x1FA05)},
	{UINT32_C(0x1FA09), UINT32_C(0x1FA0F), UINT32_C(0x1FA15)},
	{UINT32_C(0x1FA0A), UINT32_C(0x1FA10), UINT32_C(0x1FA16)},
	{UINT32_C(0x1FA0B), UINT32_C(0x1FA11), UINT32_C(0x1FA17)},
	{UINT32_C(0x1FA0C), UINT32_C(0x1FA12), UINT32_C(0x1FA18)},
	{UINT32_C(0x1FA0D), UINT32_C(0x1FA13), UINT32_C(0x1FA19)},
	{UINT32_C(0x1FA0E), UINT32_C(0x1FA14), UINT32_C(0x1FA1A)},
	{UINT32_C(0x1FA1E), UINT32_C(0x1FA24), UINT32_C(0x1FA2A)},
	{UINT32_C(0x1FA1F), UINT32_C(0x1FA25), UINT32_C(0x1FA2B)},
	{UINT32_C(0x1FA20), UINT32_C(0x1FA26), UINT32_C(0x1FA2C)},
	{UINT32_C(0x1FA21), UINT32_C(0x1FA27), UINT32_C(0x1FA2D)},
	{UINT32_C(0x1FA22), UINT32_C(0x1FA28), UINT32_C(0x1FA2E)},
	{UINT32_C(0x1FA23), UINT32_C(0x1FA29), UINT32_C(0x1FA2F)},
	{UINT32_C(0x1FA33), UINT32_C(0x1FA39), UINT32_C(0x1FA3F)},
	{UINT32_C(0x1FA34), UINT32_C(0x1FA3A), UINT32_C(0x1FA40)},
	{UINT32_C(0x1FA35), UINT32_C(0x1FA3B), UINT32_C(0x1FA41)},
	{UINT32_C(0x1FA36), UINT32_C(0x1FA3C), UINT32_C(0x1FA42)},
	{UINT32_C(0x1FA37), UINT32_C(0x1FA3D), UINT32_C(0x1FA43)},
	{UINT32_C(0x1FA38), UINT32_C(0x1FA3E), UINT32_C(0x1FA44)},
	{UINT32_C(0x2658), UINT32_C(0x2655), UINT32_C(0x1FA4E)},
	{UINT32_C(0x2658), UINT32_C(0x2656), UINT32_C(0x1FA4F)},
	{UINT32_C(0x2658), UINT32_C(0x2657), UINT32_C(0x1FA50)},
	{UINT32_C(0x265E), UINT32_C(0x265B), UINT32_C(0x1FA51)},
	{UINT32_C(0x265E), UINT32_C(0x265C), UINT32_C(0x1FA52)},
	{UINT32_C(0x265E), UINT32_C(0x265D), UINT32_C(0x1FA53)},
	{UINT32_C(0x23CB), UINT32_C(0x23BE), UINT32_C(0x23C9)},
	{UINT32_C(0x23CC), UINT32_C(0x23BF), UINT32_C(0x23CA)},
	{UINT32_C(0x23C9), UINT32_C(0x23C0), UINT32_C(0x23C1)},
	{UINT32_C(0x23C9), UINT32_C(0x23C3), UINT32_C(0x23C4)},
	{UINT32_C(0x23C9), UINT32_C(0x23C6), UINT32_C(0x23C7)},
	{UINT32_C(0x23CA), UINT32_C(0x23C0), UINT32_C(0x23C2)},
	{UINT32_C(0x23CA), UINT32_C(0x23C3), UINT32_C(0x23C5)},
	{UINT32_C(0x23CA), UINT32_C(0x23C6), UINT32_C(0x23C8)}
};


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

		for (i = 0u; i < sizeof(pairs) / sizeof(*pairs); i++) {
			if (a != pairs[i].a && a != pairs[i].b)
				continue;
			if (*n)
				goto no_conv;
			if (slen == alen)
				return LIBCHARCONV_INDETERMINATE;
			blen = libcharconv_decode_utf8_(&s[alen], slen - alen, &b);
			if (blen > slen)
				return LIBCHARCONV_INDETERMINATE;
			if (!blen)
				goto no_conv;
			if ((a ^ b) == (pairs[i].a ^ pairs[i].b))
				goto conv;
		}

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

conv:
	if (*n)
		goto no_conv;
	if (*ncp)
		*cp = pairs[i].to;
	*n += alen + blen;
	*ncp = 1u;
	return LIBCHARCONV_CONVERTED;
}