/*
 * Unicode.h -- UTF-8 to UTF-32 conversions and various operations
 *
 * Copyright (c) 2013, 2014, 2015 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 _UNICODE_H_
#define _UNICODE_H_

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

#include <stdexcept>
#include <string>

/**
 * @class Unicode
 * @brief Conversion between UTF-8 and UTF-32
 */
class Unicode {
private:
	static void encode(char32_t point, char res[5]) noexcept;
	static void decode(char32_t &c, const char *res) noexcept;

public:
	/**
	 * 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]
	 */
	static 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
	 */
	static 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
	 */
	static 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>
	static 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
	 */
	static 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
	 */
	static std::u32string toUtf32(const std::string &str);

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

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

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

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

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

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

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

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

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

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

	/**
	 * Convert the UTF-32 string to upper case.
	 *
	 * @param str the str
	 * @return the upper case string
	 */
	static 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 lower case.
	 *
	 * @param str the str
	 * @return the lower case string
	 * @warning very slow at the moment
	 */
	static inline std::string tolower(const std::string &str)
	{
		return toUtf8(tolower(toUtf32(str)));
	}

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

		return str;
	}
};

#endif // !_UTF8_H_