/* This file is (c) 2008-2012 Konstantin Isakov <ikm@goldendict.org>
 * Part of GoldenDict. Licensed under GPLv3 or later, see the LICENSE file */

#include "iconv.hh"
#include <vector>
#include <errno.h>
#include <string.h>
#include <QDebug>
#include "wstring_qt.hh"

char const * const Iconv::GdWchar = "UTF-32LE";
char const * const Iconv::Utf16Le = "UTF-16LE";
char const * const Iconv::Utf8 = "UTF-8";

using gd::wchar;

Iconv::Iconv( char const * to, char const * from )
#ifdef USE_ICONV
    :state( iconv_open( to, from ) )
#endif
{
#ifdef USE_ICONV
  if( state == (iconv_t) -1 )
    throw exCantInit( strerror( errno ) );
#else
  codec = QTextCodec::codecForName( from );
#endif
}

Iconv::~Iconv()
{
 #ifdef USE_ICONV
 iconv_close( state );
  #endif
}

QString Iconv::convert(void const* & inBuf, size_t& inBytesLeft)
{
#ifdef USE_ICONV
 size_t dsz = inBytesLeft;
 //avoid most realloc
 std::vector< char > outBuf( dsz + 32 );

 void * outBufPtr = &outBuf.front();

 size_t outBufLeft = outBuf.size();
 size_t result;
 while( inBytesLeft > 0 )
 {
    result = iconv( state, (char **) &inBuf, &inBytesLeft, (char **) &outBufPtr, &outBufLeft );
    if( result == (size_t) -1 )
    {
      if( errno == E2BIG || outBufLeft == 0 )
      {

        if( inBytesLeft > 0 )
        {
          // Grow the buffer and retry
          // The pointer may get invalidated so we save the diff and restore it
          size_t offset = (char *) outBufPtr - &outBuf.front();
          outBuf.resize( outBuf.size() + dsz );
          outBufPtr = &outBuf.front() + offset;
          outBufLeft += dsz;
          continue;
        }
      }
      break;
    }
 }

 //flush output
 if( result != (size_t) ( -1 ) )
 {
    /* flush the shift-out sequences */
    for( ;; )
    {
      result = iconv( state, NULL, NULL, (char **) &outBufPtr, &outBufLeft );

      if( result != (size_t) ( -1 ) )
      {
        break;
      }

      if( errno == E2BIG )
      {
        size_t offset = (char *) outBufPtr - &outBuf.front();
        outBuf.resize( outBuf.size() + 256 );
        outBufPtr = &outBuf.front() + offset;
        outBufLeft += 256;
      }
      else
      {
        break;
      }
    }
 }

 size_t datasize = outBuf.size() - outBufLeft;
 QByteArray ba( &outBuf.front(), datasize );
 return QString( ba );
#else
  if( codec )
    return codec->toUnicode( static_cast< const char * >( inBuf ), inBytesLeft );
  QByteArray ba( static_cast< const char * >( inBuf ), inBytesLeft );
  return QString( ba );
#endif
}

gd::wstring Iconv::toWstring( char const * fromEncoding, void const * fromData,
                              size_t dataSize )
  
{
  /// Special-case the dataSize == 0 to avoid any kind of iconv-specific
  /// behaviour in that regard.

  if ( !dataSize )
    return gd::wstring();

  Iconv ic( GdWchar, fromEncoding );

  QString outStr = ic.convert(fromData, dataSize);
  return gd::toWString(outStr);
}

std::string Iconv::toUtf8( char const * fromEncoding, void const * fromData,
                           size_t dataSize )
  
{
  // Similar to toWstring

  if ( !dataSize )
    return std::string();

  Iconv ic( Utf8, fromEncoding );

  QString outStr = ic.convert(fromData, dataSize);
  return gd::toStdString(outStr);
}