/**************************************************************
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * 
 *************************************************************/


#include <string.h>

#include <sal/types.h>

#include <rtl/textenc.h>
#include <rtl/tencinfo.h>


#include <com/sun/star/io/XInputStream.hpp>

using namespace rtl;
using namespace ::com::sun::star::uno;
using namespace ::com::sun::star::io;

#include "xml2utf.hxx"

namespace sax_expatwrap {

sal_Int32 XMLFile2UTFConverter::readAndConvert( Sequence<sal_Int8> &seq , sal_Int32 nMaxToRead )
	throw ( IOException, NotConnectedException , BufferSizeExceededException , RuntimeException )
{

	Sequence<sal_Int8> seqIn;

	if( ! m_in.is() ) {
		throw NotConnectedException();
	}
	if( ! m_bStarted ) {
		nMaxToRead = Max( 512 , nMaxToRead );  	// it should be possible to find the encoding attribute
						     					// within the first 512 bytes == 128 chars in UCS-4
	}

	sal_Int32 nRead;
	Sequence< sal_Int8 > seqStart;
	while( sal_True )
	{
		nRead = m_in->readSomeBytes( seq , nMaxToRead );

		if( nRead + seqStart.getLength())
		{
			// if nRead is 0, the file is already eof.
			if( ! m_bStarted && nRead )
			{
				// ensure that enough data is available to parse encoding
				if( seqStart.getLength() )
				{
				  // prefix with what we had so far.
				  sal_Int32 nLength = seq.getLength();
				  seq.realloc( seqStart.getLength() + nLength );

				  memmove (seq.getArray() + seqStart.getLength(),
					   seq.getConstArray(),
					   nLength);
				  memcpy  (seq.getArray(),
					   seqStart.getConstArray(),
					   seqStart.getLength());
				}

				// autodetection with the first bytes
				if( ! isEncodingRecognizable( seq ) )
				{
				  // remember what we have so far.
				  seqStart = seq;

				  // read more !
				  continue;
				}
				if( scanForEncoding( seq ) || m_sEncoding.getLength() ) {
					// initialize decoding
					initializeDecoding();
				}
				nRead = seq.getLength();
				seqStart = Sequence < sal_Int8 > ();
			}

			// do the encoding
			if( m_pText2Unicode && m_pUnicode2Text &&
				m_pText2Unicode->canContinue() && m_pUnicode2Text->canContinue() ) {

				Sequence<sal_Unicode> seqUnicode = m_pText2Unicode->convert( seq );
				seq = m_pUnicode2Text->convert(	seqUnicode.getConstArray(),	seqUnicode.getLength() );
			}

			if( ! m_bStarted )
			{
				// it must now be ensured, that no encoding attribute exist anymore
				// ( otherwise the expat-Parser will crash )
				// This must be done after decoding !
				// ( e.g. Files decoded in ucs-4 cannot be read properly )
				m_bStarted = sal_True;
				removeEncoding( seq );
			}
			nRead = seq.getLength();
		}

		break;
	}
	return nRead;
}


XMLFile2UTFConverter::~XMLFile2UTFConverter()
{
	if( m_pText2Unicode )
		delete m_pText2Unicode;
	if( m_pUnicode2Text )
		delete m_pUnicode2Text;
}


void XMLFile2UTFConverter::removeEncoding( Sequence<sal_Int8> &seq )
{
	const sal_Int8 *pSource = seq.getArray();
	if( ! strncmp( (const char * ) pSource , "<?xml" , 4) )
	{

		// scan for encoding
		OString str( (sal_Char * ) pSource , seq.getLength() );

		// cut sequence to first line break
		// find first line break;
		int nMax = str.indexOf( 10 );
		if( nMax >= 0 )
		{
			str = str.copy( 0 , nMax );
		}

		int nFound = str.indexOf( " encoding" );
		if( nFound >= 0 ) {
			int nStop;
			int nStart = str.indexOf( "\"" , nFound );
			if( nStart < 0 || str.indexOf( "'" , nFound ) < nStart )
			{
				nStart = str.indexOf( "'" , nFound );
				nStop  = str.indexOf( "'" , nStart +1 );
			}
			else
			{
				nStop  = str.indexOf( "\"" , nStart +1);
			}

			if( nStart >= 0 && nStop >= 0 && nStart+1 < nStop )
			{
				// remove encoding tag from file
				memmove(        &( seq.getArray()[nFound] ) ,
								&( seq.getArray()[nStop+1]) ,
								seq.getLength() - nStop -1);
				seq.realloc( seq.getLength() - ( nStop+1 - nFound ) );
//				str = String( (char * ) seq.getArray() , seq.getLen() );
			}
		}
	}
}

// Checks, if enough data has been accumulated to recognize the encoding
sal_Bool XMLFile2UTFConverter::isEncodingRecognizable( const Sequence< sal_Int8 > &seq)
{
	const sal_Int8 *pSource = seq.getConstArray();
	sal_Bool bCheckIfFirstClosingBracketExsists = sal_False;

	if( seq.getLength() < 8 ) {
		// no recognition possible, when less than 8 bytes are available
		return sal_False;
	}

	if( ! strncmp( (const char * ) pSource , "<?xml" , 4 ) ) {
		// scan if the <?xml tag finishes within this buffer
		bCheckIfFirstClosingBracketExsists = sal_True;
	}
	else if( ('<' == pSource[0] || '<' == pSource[2] ) &&
			 ( ('?' == pSource[4] || '?' == pSource[6] ) ) )
	{
		// check for utf-16
		bCheckIfFirstClosingBracketExsists = sal_True;
	}
	else if( ( '<' == pSource[1] || '<' == pSource[3] ) &&
		     ( '?' == pSource[5] || '?' == pSource[7] ) )
	{
		// check for
		bCheckIfFirstClosingBracketExsists = sal_True;
	}

	if( bCheckIfFirstClosingBracketExsists )
	{
		for( sal_Int32 i = 0; i < seq.getLength() ; i ++ )
		{
			// whole <?xml tag is valid
			if( '>' == pSource[ i ] )
			{
				return sal_True;
			}
		}
		return sal_False;
	}

	// No <? tag in front, no need for a bigger buffer
	return sal_True;
}

sal_Bool XMLFile2UTFConverter::scanForEncoding( Sequence< sal_Int8 > &seq )
{
	const sal_uInt8 *pSource = reinterpret_cast<const sal_uInt8*>( seq.getConstArray() );
	sal_Bool bReturn = sal_True;

	if( seq.getLength() < 4 ) {
		// no recognition possible, when less than 4 bytes are available
		return sal_False;
	}

	// first level : detect possible file formats
	if( ! strncmp( (const char * ) pSource , "<?xml" , 4 ) ) {

		// scan for encoding
		OString str( (const sal_Char *) pSource , seq.getLength() );

		// cut sequence to first line break
		//find first line break;
		int nMax = str.indexOf( 10 );
		if( nMax >= 0 )
		{
			str = str.copy( 0 , nMax );
		}

		int nFound = str.indexOf( " encoding" );
		if( nFound < str.getLength() ) {
			int nStop;
			int nStart = str.indexOf( "\"" , nFound );
			if( nStart < 0 || str.indexOf( "'" , nFound ) < nStart )
			{
				nStart = str.indexOf( "'" , nFound );
				nStop  = str.indexOf( "'" , nStart +1 );
			}
			else
			{
				nStop  = str.indexOf( "\"" , nStart +1);
			}
			if( nStart >= 0 && nStop >= 0 && nStart+1 < nStop )
			{
				// encoding found finally
				m_sEncoding = str.copy( nStart+1 , nStop - nStart - 1 );
			}
		}
	}
	else if( 0xFE == pSource[0] &&
	         0xFF == pSource[1] ) {
		// UTF-16 big endian
		// conversion is done so that encoding information can be easily extracted
		m_sEncoding = "utf-16";
	}
	else if( 0xFF == pSource[0] &&
	         0xFE == pSource[1] ) {
		// UTF-16 little endian
		// conversion is done so that encoding information can be easily extracted
		m_sEncoding = "utf-16";
	}
	else if( 0x00 == pSource[0] && 0x3c == pSource[1]  && 0x00 == pSource[2] && 0x3f == pSource[3] ) {
		// UTF-16 big endian without byte order mark (this is (strictly speaking) an error.)
		// The byte order mark is simply added

		// simply add the byte order mark !
		seq.realloc( seq.getLength() + 2 );
		memmove( &( seq.getArray()[2] ) , seq.getArray() , seq.getLength() - 2 );
		((sal_uInt8*)seq.getArray())[0] = 0xFE;
		((sal_uInt8*)seq.getArray())[1] = 0xFF;

		m_sEncoding = "utf-16";
	}
	else if( 0x3c == pSource[0] && 0x00 == pSource[1]  && 0x3f == pSource[2] && 0x00 == pSource[3] ) {
		// UTF-16 little endian without byte order mark (this is (strictly speaking) an error.)
		// The byte order mark is simply added

		seq.realloc( seq.getLength() + 2 );
		memmove( &( seq.getArray()[2] ) , seq.getArray() , seq.getLength() - 2 );
		((sal_uInt8*)seq.getArray())[0] = 0xFF;
		((sal_uInt8*)seq.getArray())[1] = 0xFE;

		m_sEncoding = "utf-16";
	}
    else if( 0xEF == pSource[0] && 
             0xBB == pSource[1] &&
             0xBF == pSource[2] )
    {
        // UTF-8 BOM (byte order mark); signifies utf-8, and not byte order
        // The BOM is removed.
        memmove( seq.getArray(), &( seq.getArray()[3] ), seq.getLength()-3 );
        seq.realloc( seq.getLength() - 3 );
        m_sEncoding = "utf-8";
    }
	else if( 0x00 == pSource[0] && 0x00 == pSource[1]  && 0x00 == pSource[2] && 0x3c == pSource[3] ) {
		// UCS-4 big endian
		m_sEncoding = "ucs-4";
	}
	else if( 0x3c == pSource[0] && 0x00 == pSource[1]  && 0x00 == pSource[2] && 0x00 == pSource[3] ) {
		// UCS-4 little endian
		m_sEncoding = "ucs-4";
	}
	else if( 0x4c == pSource[0] && 0x6f == pSource[1]  &&
	         0xa7 == static_cast<unsigned char> (pSource[2]) &&
	         0x94 == static_cast<unsigned char> (pSource[3]) ) {
		// EBCDIC
		bReturn = sal_False;   // must be extended
	}
	else {
		// other
		// UTF8 is directly recognized by the parser.
		bReturn = sal_False;
	}

	return bReturn;
}

void XMLFile2UTFConverter::initializeDecoding()
{

	if( m_sEncoding.getLength() )
	{
		rtl_TextEncoding encoding = rtl_getTextEncodingFromMimeCharset( m_sEncoding.getStr() );
		if( encoding != RTL_TEXTENCODING_UTF8 )
		{
			m_pText2Unicode = new Text2UnicodeConverter( m_sEncoding );
			m_pUnicode2Text = new Unicode2TextConverter( RTL_TEXTENCODING_UTF8 );
		}
	}
}


//----------------------------------------------
//
// Text2UnicodeConverter
//
//----------------------------------------------
Text2UnicodeConverter::Text2UnicodeConverter( const OString &sEncoding )
{
	rtl_TextEncoding encoding = rtl_getTextEncodingFromMimeCharset( sEncoding.getStr() );
	if( RTL_TEXTENCODING_DONTKNOW == encoding )
	{
		m_bCanContinue = sal_False;
		m_bInitialized = sal_False;
	}
	else
	{
		init( encoding );
	}
}

Text2UnicodeConverter::~Text2UnicodeConverter()
{
	if( m_bInitialized )
	{
		rtl_destroyTextToUnicodeContext( m_convText2Unicode , m_contextText2Unicode );
		rtl_destroyUnicodeToTextConverter( m_convText2Unicode );
	}
}

void Text2UnicodeConverter::init( rtl_TextEncoding encoding )
{
	m_bCanContinue = sal_True;
	m_bInitialized = sal_True;

	m_convText2Unicode 	= rtl_createTextToUnicodeConverter(encoding);
	m_contextText2Unicode = rtl_createTextToUnicodeContext( m_convText2Unicode );
	m_rtlEncoding = encoding;
}


Sequence<sal_Unicode> Text2UnicodeConverter::convert( const Sequence<sal_Int8> &seqText )
{
	sal_uInt32 uiInfo;
	sal_Size nSrcCvtBytes 	= 0;
	sal_Size nTargetCount 	= 0;
	sal_Size nSourceCount   = 0;

	// the whole source size
	sal_Int32 	nSourceSize = seqText.getLength() + m_seqSource.getLength();
	Sequence<sal_Unicode> 	seqUnicode ( nSourceSize );

	const sal_Int8 *pbSource = seqText.getConstArray();
	sal_Int8 *pbTempMem = 0;

	if( m_seqSource.getLength() ) {
		// put old rest and new byte sequence into one array
		pbTempMem = new sal_Int8[ nSourceSize ];
		memcpy( pbTempMem , m_seqSource.getConstArray() , m_seqSource.getLength() );
		memcpy( &(pbTempMem[ m_seqSource.getLength() ]) , seqText.getConstArray() , seqText.getLength() );
		pbSource = pbTempMem;

		// set to zero again
		m_seqSource = Sequence< sal_Int8 >();
	}

	while( sal_True ) {

		/* All invalid characters are transformed to the unicode undefined char */
		nTargetCount += 	rtl_convertTextToUnicode(
									m_convText2Unicode,
									m_contextText2Unicode,
									( const sal_Char * ) &( pbSource[nSourceCount] ),
									nSourceSize - nSourceCount ,
									&( seqUnicode.getArray()[ nTargetCount ] ),
									seqUnicode.getLength() - nTargetCount,
									RTL_TEXTTOUNICODE_FLAGS_UNDEFINED_DEFAULT   |
									RTL_TEXTTOUNICODE_FLAGS_MBUNDEFINED_DEFAULT |
									RTL_TEXTTOUNICODE_FLAGS_INVALID_DEFAULT,
									&uiInfo,
									&nSrcCvtBytes );
		nSourceCount += nSrcCvtBytes;

		if( uiInfo & RTL_TEXTTOUNICODE_INFO_DESTBUFFERTOSMALL ) {
			// save necessary bytes for next conversion
			seqUnicode.realloc( seqUnicode.getLength() * 2 );
			continue;
		}
		break;
	}
	if( uiInfo & RTL_TEXTTOUNICODE_INFO_SRCBUFFERTOSMALL ) {
		m_seqSource.realloc( nSourceSize - nSourceCount );
		memcpy( m_seqSource.getArray() , &(pbSource[nSourceCount]) , nSourceSize-nSourceCount );
	}


	if( pbTempMem ) {
		delete [] pbTempMem;
	}

	// set to correct unicode size
	seqUnicode.realloc( nTargetCount );

	return seqUnicode;
}


//----------------------------------------------
//
// Unicode2TextConverter
//
//----------------------------------------------
Unicode2TextConverter::Unicode2TextConverter( rtl_TextEncoding encoding )
{
	init( encoding );
}


Unicode2TextConverter::~Unicode2TextConverter()
{
	if( m_bInitialized ) {
		rtl_destroyUnicodeToTextContext( m_convUnicode2Text , m_contextUnicode2Text );
		rtl_destroyUnicodeToTextConverter( m_convUnicode2Text );
	}
}


Sequence<sal_Int8> Unicode2TextConverter::convert(const sal_Unicode *puSource , sal_Int32 nSourceSize)
{
	sal_Unicode *puTempMem = 0;

	if( m_seqSource.getLength() ) {
		// For surrogates !
		// put old rest and new byte sequence into one array
		// In general when surrogates are used, they should be rarely
		// cut off between two convert()-calls. So this code is used
		// rarely and the extra copy is acceptable.
		puTempMem = new sal_Unicode[ nSourceSize + m_seqSource.getLength()];
		memcpy( puTempMem ,
				m_seqSource.getConstArray() ,
				m_seqSource.getLength() * sizeof( sal_Unicode ) );
		memcpy(
			&(puTempMem[ m_seqSource.getLength() ]) ,
			puSource ,
			nSourceSize*sizeof( sal_Unicode ) );
		puSource = puTempMem;
		nSourceSize += m_seqSource.getLength();

		m_seqSource = Sequence< sal_Unicode > ();
	}


	sal_Size nTargetCount = 0;
	sal_Size nSourceCount = 0;

	sal_uInt32 uiInfo;
	sal_Size nSrcCvtChars;

	// take nSourceSize * 3 as preference
	// this is an upper boundary for converting to utf8,
	// which most often used as the target.
	sal_Int32 nSeqSize =  nSourceSize * 3;

	Sequence<sal_Int8> 	seqText( nSeqSize );
	sal_Char *pTarget = (sal_Char *) seqText.getArray();
	while( sal_True ) {

		nTargetCount += rtl_convertUnicodeToText(
									m_convUnicode2Text,
									m_contextUnicode2Text,
									&( puSource[nSourceCount] ),
									nSourceSize - nSourceCount ,
									&( pTarget[nTargetCount] ),
									nSeqSize - nTargetCount,
									RTL_UNICODETOTEXT_FLAGS_UNDEFINED_DEFAULT |
									RTL_UNICODETOTEXT_FLAGS_INVALID_DEFAULT ,
									&uiInfo,
									&nSrcCvtChars);
		nSourceCount += nSrcCvtChars;

		if( uiInfo & RTL_UNICODETOTEXT_INFO_DESTBUFFERTOSMALL ) {
			nSeqSize = nSeqSize *2;
			seqText.realloc( nSeqSize );  // double array size
			pTarget = ( sal_Char * ) seqText.getArray();
			continue;
		}
		break;
	}

	// for surrogates
	if( uiInfo & RTL_UNICODETOTEXT_INFO_SRCBUFFERTOSMALL ) {
		m_seqSource.realloc( nSourceSize - nSourceCount );
		memcpy( m_seqSource.getArray() ,
				&(puSource[nSourceCount]),
				(nSourceSize - nSourceCount) * sizeof( sal_Unicode ) );
	}

	if( puTempMem ) {
		delete [] puTempMem;
	}

	// reduce the size of the buffer (fast, no copy necessary)
	seqText.realloc( nTargetCount );

	return seqText;
}

void Unicode2TextConverter::init( rtl_TextEncoding encoding )
{
	m_bCanContinue = sal_True;
	m_bInitialized = sal_True;

	m_convUnicode2Text 	= rtl_createUnicodeToTextConverter( encoding );
	m_contextUnicode2Text = rtl_createUnicodeToTextContext( m_convUnicode2Text );
	m_rtlEncoding = encoding;
};


}