/*
   Copyright (C) 2001-2006, William Joseph.
   All Rights Reserved.

   This file is part of GtkRadiant.

   GtkRadiant is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   GtkRadiant is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GtkRadiant; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#if !defined( INCLUDED_CONVERT_H )
#define INCLUDED_CONVERT_H

/// \file
/// \brief Character encoding conversion.

#include "debugging/debugging.h"
#include <algorithm>
#include <glib.h>

#include "character.h"

/// \brief Returns the number of bytes required to represent \p character in UTF-8 encoding.
inline std::size_t utf8_character_length( const char* character ){
	if ( ( *character & 0xE0 ) == 0xC0 ) { // 110xxxxx
		return 2;
	}
	else if ( ( *character & 0xF0 ) == 0xE0 ) { // 1110xxxx
		return 3;
	}
	else if ( ( *character & 0xF8 ) == 0xF0 ) { // 11110xxx
		return 4;
	}
	else if ( ( *character & 0xFC ) == 0xF8 ) { // 111110xx
		return 5;
	}
	else if ( ( *character & 0xFE ) == 0xFC ) { // 1111110x
		return 6;
	}
	ERROR_MESSAGE( "" );
	return 0;
}

struct UTF8Character
{
	const char* buffer;
	std::size_t length;
	UTF8Character() : buffer( 0 ), length( 0 ){
	}
	UTF8Character( const char* bytes ) : buffer( bytes ), length( utf8_character_length( bytes ) ){
	}
};

inline bool operator<( const UTF8Character& self, const UTF8Character& other ){
	return std::lexicographical_compare( self.buffer, self.buffer + self.length, other.buffer, other.buffer + other.length );
}

/// \brief Writes \p c to \p ostream in Hex form. Useful for debugging.
template<typename TextOutputStreamType>
inline TextOutputStreamType& ostream_write( TextOutputStreamType& ostream, const UTF8Character& c ){
	for ( const char* p = c.buffer; p != c.buffer + c.length; ++p )
	{
		ostream << HexChar( *p );
	}
	return ostream;
}



/// \brief The character-set encoding for the current C locale.
///
/// Obtain the global instance with globalCharacterSet().
class CharacterSet
{
const char* m_charSet;
public:
CharacterSet(){
	if ( g_get_charset( &m_charSet ) != FALSE ) {
		m_charSet = 0;
	}
}
bool isUTF8() const {
	return m_charSet == 0;
}
const char* get() const {
	return m_charSet;
}
};

typedef LazyStatic<CharacterSet> GlobalCharacterSet;

/// \brief Returns the global instance of CharacterSet.
inline CharacterSet& globalCharacterSet(){
	return GlobalCharacterSet::instance();
}


class UTF8CharacterToExtendedASCII
{
public:
UTF8Character m_utf8;
char m_c;
UTF8CharacterToExtendedASCII() : m_c( '\0' ){
}
UTF8CharacterToExtendedASCII( const UTF8Character& utf8, char c ) : m_utf8( utf8 ), m_c( c ){
}
};

inline bool operator<( const UTF8CharacterToExtendedASCII& self, const UTF8CharacterToExtendedASCII& other ){
	return self.m_utf8 < other.m_utf8;
}

inline std::size_t extended_ascii_to_index( char c ){
	return static_cast<std::size_t>( c & 0x7F );
}

inline char extended_ascii_for_index( std::size_t i ){
	return static_cast<char>( i | 0x80 );
}

/// \brief The active extended-ascii character set encoding.
/// Performs UTF-8 encoding and decoding of extended-ascii characters.
///
/// Obtain the global instance with globalExtendedASCIICharacterSet().
class ExtendedASCIICharacterSet
{
typedef char UTF8CharBuffer[6];
UTF8CharBuffer m_converted[128];
UTF8Character m_decodeMap[128];
UTF8CharacterToExtendedASCII m_encodeMap[128];
public:
ExtendedASCIICharacterSet(){
	if ( !globalCharacterSet().isUTF8() ) {
		GIConv descriptor = g_iconv_open( "UTF-8", globalCharacterSet().get() );
		for ( std::size_t i = 1; i < 128; ++i )
		{
			char c = extended_ascii_for_index( i );
			char* inbuf = &c;
			std::size_t inbytesleft = 1;
			char* outbuf = m_converted[i];
			std::size_t outbytesleft = 6;
			if ( g_iconv( descriptor, &inbuf, &inbytesleft, &outbuf, &outbytesleft ) != (size_t)( -1 ) ) {
				UTF8Character utf8( m_converted[i] );
				m_decodeMap[i] = utf8;
				m_encodeMap[i] = UTF8CharacterToExtendedASCII( utf8, c );
			}
		}
		g_iconv_close( descriptor );
		std::sort( m_encodeMap, m_encodeMap + 128 );
	}
}
/// \brief Prints the (up to) 128 characters in the current extended-ascii character set.
/// Useful for debugging.
void print() const {
	globalOutputStream() << "UTF-8 conversion required from charset: " << globalCharacterSet().get() << "\n";
	for ( std::size_t i = 1; i < 128; ++i )
	{
		if ( m_decodeMap[i].buffer != 0 ) {
			globalOutputStream() << extended_ascii_for_index( i ) << " = " << m_decodeMap[i] << "\n";
		}
	}
}
/// \brief Returns \p c decoded from extended-ascii to UTF-8.
/// \p c must be an extended-ascii character.
const UTF8Character& decode( char c ) const {
	ASSERT_MESSAGE( !globalCharacterSet().isUTF8(), "locale is utf8, no conversion required" );
	ASSERT_MESSAGE( !char_is_ascii( c ), "decode: ascii character" );
	ASSERT_MESSAGE( m_decodeMap[extended_ascii_to_index( c )].buffer != 0, "decode: invalid character: " << HexChar( c ) );
	return m_decodeMap[extended_ascii_to_index( c )];
}
/// \brief Returns \p c encoded to extended-ascii from UTF-8.
/// \p c must map to an extended-ascii character.
char encode( const UTF8Character& c ) const {
	ASSERT_MESSAGE( !globalCharacterSet().isUTF8(), "locale is utf8, no conversion required" );
	ASSERT_MESSAGE( !char_is_ascii( *c.buffer ), "encode: ascii character" );
	std::pair<const UTF8CharacterToExtendedASCII*, const UTF8CharacterToExtendedASCII*> range
		= std::equal_range( m_encodeMap, m_encodeMap + 128, UTF8CharacterToExtendedASCII( c, 0 ) );
	ASSERT_MESSAGE( range.first != range.second, "encode: invalid character: " << c );
	return ( *range.first ).m_c;
}
};

typedef LazyStatic<ExtendedASCIICharacterSet> GlobalExtendedASCIICharacterSet;

/// \brief Returns the global instance of ExtendedASCIICharacterSet.
inline ExtendedASCIICharacterSet& globalExtendedASCIICharacterSet(){
	return GlobalExtendedASCIICharacterSet::instance();
}

class ConvertUTF8ToLocale
{
public:
StringRange m_range;
ConvertUTF8ToLocale( const char* string ) : m_range( StringRange( string, string + strlen( string ) ) ){
}
ConvertUTF8ToLocale( const StringRange& range ) : m_range( range ){
}
};

/// \brief Writes \p convert to \p ostream after encoding each character to extended-ascii from UTF-8.
template<typename TextOutputStreamType>
inline TextOutputStreamType& ostream_write( TextOutputStreamType& ostream, const ConvertUTF8ToLocale& convert ){
	if ( globalCharacterSet().isUTF8() ) {
		return ostream << convert.m_range;
	}

	for ( const char* p = convert.m_range.first; p != convert.m_range.last; )
	{
		if ( !char_is_ascii( *p ) ) {
			UTF8Character c( p );
			ostream << globalExtendedASCIICharacterSet().encode( c );
			p += c.length;
		}
		else
		{
			ostream << *p++;
		}
	}
	return ostream;
}


class ConvertLocaleToUTF8
{
public:
StringRange m_range;
ConvertLocaleToUTF8( const char* string ) : m_range( StringRange( string, string + strlen( string ) ) ){
}
ConvertLocaleToUTF8( const StringRange& range ) : m_range( range ){
}
};

/// \brief Writes \p convert to \p ostream after decoding each character from extended-ascii to UTF-8.
template<typename TextOutputStreamType>
inline TextOutputStreamType& ostream_write( TextOutputStreamType& ostream, const ConvertLocaleToUTF8& convert ){
	if ( globalCharacterSet().isUTF8() ) {
		return ostream << convert.m_range;
	}

	for ( const char* p = convert.m_range.first; p != convert.m_range.last; ++p )
	{
		if ( !char_is_ascii( *p ) ) {
			UTF8Character c( globalExtendedASCIICharacterSet().decode( *p ) );
			ostream.write( c.buffer, c.length );
		}
		else
		{
			ostream << *p;
		}
	}
	return ostream;
}


#endif