/*
  Copyright 2011-2018 David Robillard <http://drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#ifndef SERD_STRING_UTILS_H
#define SERD_STRING_UTILS_H

#include "serd/serd.h"

#include <ctype.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

/** Unicode replacement character in UTF-8 */
static const uint8_t replacement_char[] = { 0xEF, 0xBF, 0xBD };

/** Return true if `c` lies within [`min`...`max`] (inclusive) */
static inline bool
in_range(const char c, const char min, const char max)
{
	return (c >= min && c <= max);
}

/** RFC2234: ALPHA ::= %x41-5A / %x61-7A  ; A-Z / a-z */
static inline bool
is_alpha(const char c)
{
	return in_range(c, 'A', 'Z') || in_range(c, 'a', 'z');
}

/** RFC2234: DIGIT ::= %x30-39  ; 0-9 */
static inline bool
is_digit(const char c)
{
	return in_range(c, '0', '9');
}

/** RFC2234: HEXDIG ::= DIGIT / "A" / "B" / "C" / "D" / "E" / "F" */
static inline bool
is_hexdig(const uint8_t c)
{
	return is_digit(c) || in_range(c, 'A', 'F');
}

/** Turtle / JSON / C: XDIGIT ::= DIGIT / A-F / a-f */
static inline bool
is_xdigit(const uint8_t c)
{
	return is_hexdig(c) || in_range(c, 'a', 'f');
}

/** Return true iff `c` is ASCII whitespace. */
static inline bool
is_space(const char c)
{
	switch (c) {
	case ' ': case '\f': case '\n': case '\r': case '\t': case '\v':
		return true;
	default:
		return false;
	}
}

/** Return true iff `c` is a valid encoded base64 character. */
static inline bool
is_base64(const char c)
{
	return is_alpha(c) || is_digit(c) || c == '+' || c == '/' || c == '=';
}

/** Return true iff `path` looks like a Windows path with a drive letter. */
static inline bool
is_windows_path(const char* path)
{
	return is_alpha(path[0]) && (path[1] == ':' || path[1] == '|')
		&& (path[2] == '/' || path[2] == '\\');
}

static inline void
serd_update_flags(const uint8_t c, SerdNodeFlags* const flags)
{
	switch (c) {
	case '\r': case '\n':
		*flags |= SERD_HAS_NEWLINE;
		break;
	case '"':
		*flags |= SERD_HAS_QUOTE;
	}
}

static inline size_t
serd_substrlen(const char* const    str,
               const size_t         len,
               SerdNodeFlags* const flags)
{
	if (flags) {
		size_t i = 0;
		*flags = 0;
		for (; i < len && str[i]; ++i) {
			serd_update_flags(str[i], flags);
		}
		return i;
	}
	return strlen(str);
}

static inline int
serd_strncasecmp(const char* s1, const char* s2, size_t n)
{
	for (; n > 0 && *s2; s1++, s2++, --n) {
		if (toupper(*s1) != toupper(*s2)) {
			return ((*(const uint8_t*)s1 < *(const uint8_t*)s2) ? -1 : +1);
		}
	}
	return 0;
}

static inline uint32_t
utf8_num_bytes(const uint8_t c)
{
	if ((c & 0x80) == 0) {  // Starts with `0'
		return 1;
	} else if ((c & 0xE0) == 0xC0) {  // Starts with `110'
		return 2;
	} else if ((c & 0xF0) == 0xE0) {  // Starts with `1110'
		return 3;
	} else if ((c & 0xF8) == 0xF0) {  // Starts with `11110'
		return 4;
	}
	return 0;
}

/// Return the code point of a UTF-8 character with known length
static inline uint32_t
parse_counted_utf8_char(const uint8_t* utf8, size_t size)
{
	uint32_t c = utf8[0] & ((1 << (8 - size)) - 1);
	for (size_t i = 1; i < size; ++i) {
		const uint8_t in = utf8[i] & 0x3F;
		c = (c << 6) | in;
	}
	return c;
}

/// Parse a UTF-8 character, set *size to the length, and return the code point
static inline uint32_t
parse_utf8_char(const uint8_t* utf8, size_t* size)
{
	switch (*size = utf8_num_bytes(utf8[0])) {
	case 1: case 2: case 3: case 4:
		return parse_counted_utf8_char(utf8, *size);
	default:
		return *size = 0;
	}
}

#endif  // SERD_STRING_UTILS_H