#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <assert.h>

#include "stmd.h"

static const int8_t utf8proc_utf8class[256] = {
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
	3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
	4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0 };

ssize_t utf8proc_charlen(const uint8_t *str, ssize_t str_len)
{
	ssize_t length, i;

	if (!str_len)
		return 0;

	length = utf8proc_utf8class[str[0]];

	if (!length)
		return -1;

	if (str_len >= 0 && length > str_len)
		return -1;

	for (i = 1; i < length; i++) {
		if ((str[i] & 0xC0) != 0x80)
			return -1;
	}

	return length;
}

ssize_t utf8proc_iterate(const uint8_t *str, ssize_t str_len, int32_t *dst)
{
	ssize_t length;
	int32_t uc = -1;

	*dst = -1;
	length = utf8proc_charlen(str, str_len);
	if (length < 0)
		return -1;

	switch (length) {
		case 1:
			uc = str[0];
			break;
		case 2:
			uc = ((str[0] & 0x1F) <<  6) + (str[1] & 0x3F);
			if (uc < 0x80) uc = -1;
			break;
		case 3:
			uc = ((str[0] & 0x0F) << 12) + ((str[1] & 0x3F) <<  6)
				+ (str[2] & 0x3F);
			if (uc < 0x800 || (uc >= 0xD800 && uc < 0xE000) ||
					(uc >= 0xFDD0 && uc < 0xFDF0)) uc = -1;
			break;
		case 4:
			uc = ((str[0] & 0x07) << 18) + ((str[1] & 0x3F) << 12)
				+ ((str[2] & 0x3F) <<  6) + (str[3] & 0x3F);
			if (uc < 0x10000 || uc >= 0x110000) uc = -1;
			break;
	}

	if (uc < 0 || ((uc & 0xFFFF) >= 0xFFFE))
		return -1;

	*dst = uc;
	return length;
}

void utf8proc_encode_char(int32_t uc, gh_buf *buf)
{
	unsigned char dst[4];
	int len = 0;

	if (uc < 0x00) {
		assert(false);
	} else if (uc < 0x80) {
		dst[0] = uc;
		len = 1;
	} else if (uc < 0x800) {
		dst[0] = 0xC0 + (uc >> 6);
		dst[1] = 0x80 + (uc & 0x3F);
		len = 2;
	} else if (uc == 0xFFFF) {
		dst[0] = 0xFF;
		len = 1;
	} else if (uc == 0xFFFE) {
		dst[0] = 0xFE;
		len = 1;
	} else if (uc < 0x10000) {
		dst[0] = 0xE0 + (uc >> 12);
		dst[1] = 0x80 + ((uc >> 6) & 0x3F);
		dst[2] = 0x80 + (uc & 0x3F);
		len = 3;
	} else if (uc < 0x110000) {
		dst[0] = 0xF0 + (uc >> 18);
		dst[1] = 0x80 + ((uc >> 12) & 0x3F);
		dst[2] = 0x80 + ((uc >> 6) & 0x3F);
		dst[3] = 0x80 + (uc & 0x3F);
		len = 4;
	} else {
		assert(false);
	}

	gh_buf_put(buf, dst, len);
}

void utf8proc_case_fold(gh_buf *dest, const unsigned char *str, int len)
{
	int32_t c;

#define bufpush(x) \
	utf8proc_encode_char(x, dest)

	while (len > 0) {
		ssize_t char_len = utf8proc_iterate(str, len, &c);

		if (char_len < 0) {
			bufpush(0xFFFD);
			continue;
		}

#include "case_fold_switch.inc"

		str += char_len;
		len -= char_len;
	}
}