/*
 * unicode.h -- UTF-8 to UTF-32 conversions and various operations
 *
 * Copyright (c) 2013-2016 David Demelier <markand@malikania.fr>
 *
 * 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.
 *
 * THE 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 _IRCCD_UNICODE_H_
#define _IRCCD_UNICODE_H_

/**
 * @file Unicode.h
 * @brief UTF-8 to UTF-32 conversions
 */

#include <stdexcept>
#include <string>

namespace irccd {

namespace unicode {

void encode(char32_t point, char res[5]) noexcept;
void decode(char32_t &c, const char *res) noexcept;

/**
 * Get the number of bytes for the first multi byte character from a
 * utf-8 string.
 *
 * This can be used to iterate a valid UTF-8 string to jump to the next
 * real character.
 *
 * @param c the first multi byte character
 * @return the number of bytes [1-4]
 */
int nbytesUtf8(char c) noexcept;

/**
 * Get the number of bytes for the unicode point.
 *
 * @param point the unicode point
 * @return the number of bytes [1-4] or -1 on invalid
 */
int nbytesPoint(char32_t point) noexcept;

/**
 * Get real number of character in a string.
 *
 * @param str the string
 * @return the length
 * @throw std::invalid_argument on invalid sequence
 */
int length(const std::string &str);

/**
 * Iterate over all real characters in the UTF-8 string.
 *
 * The function must have the following signature:
 *	void f(char ch)
 *
 * @param str the UTF-8 string
 * @throw std::invalid_argument on invalid sequence
 */
template <typename Func>
void forEach(const std::string &str, Func function)
{
	for (size_t i = 0; i < str.size(); ) {
		char32_t point = 0;
		int size = nbytesUtf8(str[i]);

		if (size < 0) {
			throw std::invalid_argument("invalid sequence");
		}

		decode(point, str.data() + i);
		function(point);

		i += size;
	}
}

/**
 * Convert a UTF-32 string to UTF-8 string.
 *
 * @param array the UTF-32 string
 * @return the UTF-8 string
 * @throw std::invalid_argument on invalid sequence
 */
std::string toUtf8(const std::u32string &array);

/**
 * Convert a UTF-8 string to UTF-32 string.
 *
 * @param str the UTF-8 string
 * @return the UTF-32 string
 * @throw std::invalid_argument on invalid sequence
 */
std::u32string toUtf32(const std::string &str);

/**
 * Check if the unicode character is space.
 *
 * @param c the character
 * @return true if space
 */
bool isspace(char32_t c) noexcept;

/**
 * Check if the unicode character is digit.
 *
 * @param c the character
 * @return true if digit
 */
bool isdigit(char32_t c) noexcept;

/**
 * Check if the unicode character is alpha category.
 *
 * @param c the character
 * @return true if alpha
 */
bool isalpha(char32_t c) noexcept;

/**
 * Check if the unicode character is upper case.
 *
 * @param c the character
 * @return true if upper case
 */
bool isupper(char32_t c) noexcept;

/**
 * Check if the unicode character is lower case.
 *
 * @param c the character
 * @return true if lower case
 */
bool islower(char32_t c) noexcept;

/**
 * Check if the unicode character is title case.
 *
 * @param c the character
 * @return true if title case
 */
bool istitle(char32_t c) noexcept;

/**
 * Convert to upper case.
 *
 * @param c the character
 * @return the upper case character
 */
char32_t toupper(char32_t c) noexcept;

/**
 * Convert to lower case.
 *
 * @param c the character
 * @return the lower case character
 */
char32_t tolower(char32_t c) noexcept;

/**
 * Convert to title case.
 *
 * @param c the character
 * @return the title case character
 */
char32_t totitle(char32_t c) noexcept;

/**
 * Convert the UTF-32 string to upper case.
 *
 * @param str the str
 * @return the upper case string
 */
inline std::u32string toupper(std::u32string str)
{
	for (size_t i = 0; i < str.size(); ++i) {
		str[i] = toupper(str[i]);
	}

	return str;
}

/**
 * Convert the UTF-8 string to upper case.
 *
 * @param str the str
 * @return the upper case string
 * @warning very slow at the moment
 */
inline std::string toupper(const std::string &str)
{
	return toUtf8(toupper(toUtf32(str)));
}

/**
 * Convert the UTF-32 string to lower case.
 *
 * @param str the str
 * @return the lower case string
 */
inline std::u32string tolower(std::u32string str)
{
	for (size_t i = 0; i < str.size(); ++i) {
		str[i] = tolower(str[i]);
	}

	return str;
}

/**
 * Convert the UTF-8 string to lower case.
 *
 * @param str the str
 * @return the lower case string
 * @warning very slow at the moment
 */
inline std::string tolower(const std::string &str)
{
	return toUtf8(tolower(toUtf32(str)));
}

} // !unicode

} // !irccd

#endif // !_UTF8_H_