/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "bsearch-insert-pos.h"
#include "unichar.h"

#include "unicodemap.c"

#define HANGUL_FIRST 0xac00
#define HANGUL_LAST 0xd7a3

const unsigned char utf8_replacement_char[UTF8_REPLACEMENT_CHAR_LEN] =
	{ 0xef, 0xbf, 0xbd }; /* 0xfffd */

static const uint8_t utf8_non1_bytes[256 - 192 - 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,
	3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,6,6,1,1
};

const uint8_t *const uni_utf8_non1_bytes = utf8_non1_bytes;

unsigned int uni_strlen(const unichar_t *str)
{
	unsigned int len = 0;

	for (len = 0; str[len] != 0; len++) ;

	return len;
}

int uni_utf8_get_char(const char *input, unichar_t *chr_r)
{
	return uni_utf8_get_char_n((const unsigned char *)input, SIZE_MAX,
				   chr_r);
}

int uni_utf8_get_char_n(const void *_input, size_t max_len, unichar_t *chr_r)
{
	static unichar_t lowest_valid_chr_table[] =
		{ 0, 0, 0x80, 0x800, 0x10000, 0x200000, 0x4000000 };
	const unsigned char *input = _input;
	unichar_t chr, lowest_valid_chr;
	unsigned int i, len;
	int ret;

	i_assert(max_len > 0);

	if (*input < 0x80) {
		*chr_r = *input;
		return 1;
	}

	/* first byte has len highest bits set, followed by zero bit.
	   the rest of the bits are used as the highest bits of the value. */
	chr = *input;
	len = uni_utf8_char_bytes(*input);
	switch (len) {
	case 2:
		chr &= 0x1f;
		break;
	case 3:
		chr &= 0x0f;
		break;
	case 4:
		chr &= 0x07;
		break;
	case 5:
		chr &= 0x03;
		break;
	case 6:
		chr &= 0x01;
		break;
	default:
		/* only 7bit chars should have len==1 */
		i_assert(len == 1);
		return -1;
	}

	if (len <= max_len) {
		lowest_valid_chr = lowest_valid_chr_table[len];
		ret = len;
	} else {
		/* check first if the input is invalid before returning 0 */
		lowest_valid_chr = 0;
		ret = 0;
		len = max_len;
	}

	/* the following bytes must all be 10xxxxxx */
	for (i = 1; i < len; i++) {
		if ((input[i] & 0xc0) != 0x80)
			return input[i] == '\0' ? 0 : -1;

		chr <<= 6;
		chr |= input[i] & 0x3f;
	}
	/* these are specified as invalid encodings by standards
	   see RFC3629 */
	if (!uni_is_valid_ucs4(chr))
		return -1;
	if (chr < lowest_valid_chr) {
		/* overlong encoding */
		return -1;
	}

	*chr_r = chr;
	return ret;
}

int uni_utf8_to_ucs4(const char *input, ARRAY_TYPE(unichars) *output)
{
	unichar_t chr;

	while (*input != '\0') {
		int len = uni_utf8_get_char(input, &chr);
		if (len <= 0) {
			/* invalid input */
			return -1;
		}
                input += len;

		array_push_back(output, &chr);
	}
	return 0;
}

int uni_utf8_to_ucs4_n(const unsigned char *input, size_t size,
		       ARRAY_TYPE(unichars) *output)
{
	unichar_t chr;

	while (size > 0) {
		int len = uni_utf8_get_char_n(input, size, &chr);
		if (len <= 0)
			return -1; /* invalid input */
		input += len; size -= len;

		array_push_back(output, &chr);
	}
	return 0;
}

void uni_ucs4_to_utf8(const unichar_t *input, size_t len, buffer_t *output)
{
	for (; len > 0 && *input != '\0'; input++, len--)
		uni_ucs4_to_utf8_c(*input, output);
}

void uni_ucs4_to_utf8_c(unichar_t chr, buffer_t *output)
{
	unsigned char first;
	int bitpos;

	if (chr < 0x80) {
		buffer_append_c(output, chr);
		return;
	}

	i_assert(uni_is_valid_ucs4(chr));

	if (chr < (1 << (6 + 5))) {
		/* 110xxxxx */
		bitpos = 6;
		first = 0x80 | 0x40;
	} else if (chr < (1 << ((2*6) + 4))) {
		/* 1110xxxx */
		bitpos = 2*6;
		first = 0x80 | 0x40 | 0x20;
	} else if (chr < (1 << ((3*6) + 3))) {
		/* 11110xxx */
		bitpos = 3*6;
		first = 0x80 | 0x40 | 0x20 | 0x10;
	} else if (chr < (1 << ((4*6) + 2))) {
		/* 111110xx */
		bitpos = 4*6;
		first = 0x80 | 0x40 | 0x20 | 0x10 | 0x08;
	} else {
		/* 1111110x */
		bitpos = 5*6;
		first = 0x80 | 0x40 | 0x20 | 0x10 | 0x08 | 0x04;
	}
	buffer_append_c(output, first | (chr >> bitpos));

	do {
		bitpos -= 6;
		buffer_append_c(output, 0x80 | ((chr >> bitpos) & 0x3f));
	} while (bitpos > 0);
}

unsigned int uni_utf8_strlen(const char *input)
{
	return uni_utf8_strlen_n(input, strlen(input));
}

unsigned int uni_utf8_strlen_n(const void *input, size_t size)
{
	size_t partial_pos;

	return uni_utf8_partial_strlen_n(input, size, &partial_pos);
}

unsigned int uni_utf8_partial_strlen_n(const void *_input, size_t size,
				       size_t *partial_pos_r)
{
	const unsigned char *input = _input;
	unsigned int count, len = 0;
	size_t i;

	for (i = 0; i < size; ) {
		count = uni_utf8_char_bytes(input[i]);
		if (i + count > size)
			break;
		i += count;
		len++;
	}
	*partial_pos_r = i;
	return len;
}

static bool uint16_find(const uint16_t *data, unsigned int count,
			uint16_t value, unsigned int *idx_r)
{
	BINARY_NUMBER_SEARCH(data, count, value, idx_r);
}

static bool uint32_find(const uint32_t *data, unsigned int count,
			uint32_t value, unsigned int *idx_r)
{
	BINARY_NUMBER_SEARCH(data, count, value, idx_r);
}

unichar_t uni_ucs4_to_titlecase(unichar_t chr)
{
	unsigned int idx;

	if (chr <= 0xff)
		return titlecase8_map[chr];
	else if (chr <= 0xffff) {
		if (!uint16_find(titlecase16_keys, N_ELEMENTS(titlecase16_keys),
				 chr, &idx))
			return chr;
		else
			return titlecase16_values[idx];
	} else {
		if (!uint32_find(titlecase32_keys, N_ELEMENTS(titlecase32_keys),
				 chr, &idx))
			return chr;
		else
			return titlecase32_values[idx];
	}
}

static bool uni_ucs4_decompose_uni(unichar_t *chr)
{
	unsigned int idx;

	if (*chr <= 0xff) {
		if (uni8_decomp_map[*chr] == *chr)
			return FALSE;
		*chr = uni8_decomp_map[*chr];
	} else if (*chr <= 0xffff) {
		if (*chr < uni16_decomp_keys[0])
			return FALSE;

		if (!uint16_find(uni16_decomp_keys,
				 N_ELEMENTS(uni16_decomp_keys), *chr, &idx))
			return FALSE;
		*chr = uni16_decomp_values[idx];
	} else {
		if (!uint32_find(uni32_decomp_keys,
				 N_ELEMENTS(uni32_decomp_keys), *chr, &idx))
			return FALSE;
		*chr = uni32_decomp_values[idx];
	}
	return TRUE;
}

static void uni_ucs4_decompose_hangul_utf8(unichar_t chr, buffer_t *output)
{
#define SBase HANGUL_FIRST
#define LBase 0x1100 
#define VBase 0x1161 
#define TBase 0x11A7
#define LCount 19 
#define VCount 21
#define TCount 28
#define NCount (VCount * TCount)
	unsigned int SIndex = chr - SBase;
        unichar_t L = LBase + SIndex / NCount;
        unichar_t V = VBase + (SIndex % NCount) / TCount;
        unichar_t T = TBase + SIndex % TCount;

	uni_ucs4_to_utf8_c(L, output);
	uni_ucs4_to_utf8_c(V, output);
	if (T != TBase) uni_ucs4_to_utf8_c(T, output);
}

static bool uni_ucs4_decompose_multi_utf8(unichar_t chr, buffer_t *output)
{
	const uint32_t *value;
	unsigned int idx;

	if (chr < multidecomp_keys[0] || chr > 0xffff)
		return FALSE;

	if (!uint32_find(multidecomp_keys, N_ELEMENTS(multidecomp_keys),
			 chr, &idx))
		return FALSE;

	value = &multidecomp_values[multidecomp_offsets[idx]];
	for (; *value != 0; value++)
		uni_ucs4_to_utf8_c(*value, output);
	return TRUE;
}

static void output_add_replacement_char(buffer_t *output)
{
	if (output->used >= UTF8_REPLACEMENT_CHAR_LEN &&
	    memcmp(CONST_PTR_OFFSET(output->data,
				    output->used - UTF8_REPLACEMENT_CHAR_LEN),
		   utf8_replacement_char, UTF8_REPLACEMENT_CHAR_LEN) == 0) {
		/* don't add the replacement char multiple times */
		return;
	}
	buffer_append(output, utf8_replacement_char, UTF8_REPLACEMENT_CHAR_LEN);
}

int uni_utf8_to_decomposed_titlecase(const void *_input, size_t size,
				     buffer_t *output)
{
	const unsigned char *input = _input;
	unichar_t chr;
	int ret = 0;

	while (size > 0) {
		int bytes = uni_utf8_get_char_n(input, size, &chr);
		if (bytes <= 0) {
			/* invalid input. try the next byte. */
			ret = -1;
			input++; size--;
			output_add_replacement_char(output);
			continue;
		}
		input += bytes;
		size -= bytes;

		chr = uni_ucs4_to_titlecase(chr);
		if (chr >= HANGUL_FIRST && chr <= HANGUL_LAST)
			uni_ucs4_decompose_hangul_utf8(chr, output);
		else if (uni_ucs4_decompose_uni(&chr) ||
			 !uni_ucs4_decompose_multi_utf8(chr, output))
			uni_ucs4_to_utf8_c(chr, output);
	}
	return ret;
}

static inline unsigned int
is_valid_utf8_seq(const unsigned char *input, unsigned int size)
{
	unichar_t chr;
	int len = uni_utf8_get_char_n(input, size, &chr);
	return len <= 0 ? 0 : len;
}

static int uni_utf8_find_invalid_pos(const unsigned char *input, size_t size,
				     size_t *pos_r)
{
	size_t i, len;

	/* find the first invalid utf8 sequence */
	for (i = 0; i < size;) {
		if (input[i] < 0x80)
			i++;
		else {
			len = is_valid_utf8_seq(input + i, size-i);
			if (unlikely(len == 0)) {
				*pos_r = i;
				return -1;
			}
			i += len;
		}
	}
	return 0;
}

bool uni_utf8_get_valid_data(const unsigned char *input, size_t size,
			     buffer_t *buf)
{
	size_t i, len;

	if (uni_utf8_find_invalid_pos(input, size, &i) == 0)
		return TRUE;

	/* broken utf-8 input - skip the broken characters */
	buffer_append(buf, input, i++);

	output_add_replacement_char(buf);
	while (i < size) {
		if (input[i] < 0x80) {
			buffer_append_c(buf, input[i++]);
			continue;
		}

		len = is_valid_utf8_seq(input + i, size-i);
		if (len == 0) {
			i++;
			output_add_replacement_char(buf);
			continue;
		}
		buffer_append(buf, input + i, len);
		i += len;
	}
	return FALSE;
}

bool uni_utf8_str_is_valid(const char *str)
{
	size_t i;

	return uni_utf8_find_invalid_pos((const unsigned char *)str,
					 strlen(str), &i) == 0;
}

bool uni_utf8_data_is_valid(const unsigned char *data, size_t size)
{
	size_t i;

	return uni_utf8_find_invalid_pos(data, size, &i) == 0;
}

size_t uni_utf8_data_truncate(const unsigned char *data, size_t old_size,
			      size_t max_new_size)
{
	if (max_new_size >= old_size)
		return old_size;
	if (max_new_size == 0)
		return 0;

	if ((data[max_new_size] & 0x80) == 0)
		return max_new_size;
	while (max_new_size > 0 && (data[max_new_size-1] & 0xc0) == 0x80)
		max_new_size--;
	if (max_new_size > 0 && (data[max_new_size-1] & 0xc0) == 0xc0)
		max_new_size--;
	return max_new_size;
}