/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (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.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Mozilla Communicator client code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 */

#include "nsUnicodeToUCS2BE.h"
#include <string.h>

//----------------------------------------------------------------------
// Global functions and data [declaration]

static PRUint16 g_UCS2BEMappingTable[] = {
  0x0001, 0x0004, 0x0005, 0x0008, 0x0000, 0x0000, 0xFFFF, 0x0000
};

static PRInt16 g_UCS2BEShiftTable[] =  {
  0, u2BytesCharset, 
  ShiftCell(0,      0, 0, 0, 0, 0, 0, 0) 
};

//----------------------------------------------------------------------
// Class nsUnicodeToUCS2BE [implementation]

nsUnicodeToUCS2BE::nsUnicodeToUCS2BE() 
: nsTableEncoderSupport((uShiftTable*) &g_UCS2BEShiftTable, 
                        (uMappingTable*) &g_UCS2BEMappingTable)
{
}

nsresult nsUnicodeToUCS2BE::CreateInstance(nsISupports ** aResult) 
{
  *aResult = (nsIUnicodeEncoder*) new nsUnicodeToUCS2BE();
  return (*aResult == NULL)? NS_ERROR_OUT_OF_MEMORY : NS_OK;
}

//----------------------------------------------------------------------
// Subclassing of nsTableEncoderSupport class [implementation]

NS_IMETHODIMP nsUnicodeToUCS2BE::GetMaxLength(const PRUnichar * aSrc, 
                                              PRInt32 aSrcLength,
                                              PRInt32 * aDestLength)
{
  *aDestLength = 2*aSrcLength;
  return NS_OK_UENC_EXACTLENGTH;
}
NS_IMETHODIMP nsUnicodeToUCS2BE::FillInfo(PRUint32 *aInfo)
{
  memset(aInfo, 0xFF, (0x10000L >> 3));
  return NS_OK;
}



class nsUnicodeToUTF16SameEndian: public nsBasicEncoder
{
public:
  /**
   * Class constructor.
   */
  nsUnicodeToUTF16SameEndian( PRUnichar aBOM )
  {
    mBOM = aBOM;
  };

  /**
   * Class destructor.
   */
  virtual ~nsUnicodeToUTF16SameEndian() {};

  //--------------------------------------------------------------------
  // Interface nsIUnicodeEncoder [declaration]

  NS_IMETHOD Convert(const PRUnichar * aSrc, PRInt32 * aSrcLength, 
      char * aDest, PRInt32 * aDestLength)
  {
     PRInt32 srcInLen = *aSrcLength;
     PRInt32 destInLen = *aDestLength;
     PRInt32 srcOutLen = 0;
     PRInt32 destOutLen = 0;
     PRInt32 copyCharLen;
     PRUnichar *p = (PRUnichar*)aDest;
 
     // Handle BOM if necessary 
     if(0!=mBOM)
     {
        if(destInLen <2)
           goto needmoreoutput;
  
        *p++ = mBOM;
        mBOM = 0;
        destOutLen +=2;
     }
     // find out the length of copy 

     copyCharLen = srcInLen;
     if(copyCharLen > (destInLen - destOutLen) / 2) {
        copyCharLen = (destInLen - destOutLen) / 2;
     }

     // copy the data  by swaping 
     CopyData((char*)p , aSrc, copyCharLen );

     srcOutLen += copyCharLen;
     destOutLen += copyCharLen * 2;
     if(copyCharLen < srcInLen)
         goto needmoreoutput;
     
     *aSrcLength = srcOutLen;
     *aDestLength = destOutLen;
     return NS_OK;

  needmoreoutput:
     *aSrcLength = srcOutLen;
     *aDestLength = destOutLen;
     return NS_OK_UENC_MOREOUTPUT;
  };

  NS_IMETHOD GetMaxLength(const PRUnichar * aSrc, PRInt32 aSrcLength, 
      PRInt32 * aDestLength) 
  {
    if(0 != mBOM)
      *aDestLength = 2*(aSrcLength+1);
    else 
      *aDestLength = 2*aSrcLength;
    return NS_OK_UENC_EXACTLENGTH;
  };
  NS_IMETHOD Finish(char * aDest, PRInt32 * aDestLength)
  {
      if(0 != mBOM)
      {
         if(*aDestLength >= 2)
         {
            *((PRUnichar*)aDest)= mBOM;
            mBOM=0;
            *aDestLength = 2;
            return NS_OK;  
         } else {
            *aDestLength = 0;
            return NS_OK;  // xxx should be error
         }
      } else { 
         *aDestLength = 0;
         return NS_OK;
      } 
  };
  NS_IMETHOD Reset()
  {
      mBOM = 0;
      return NS_OK;
  };
  NS_IMETHOD SetOutputErrorBehavior(PRInt32 aBehavior, 
      nsIUnicharEncoder * aEncoder, PRUnichar aChar)
  {
      return NS_OK;
  };

  //--------------------------------------------------------------------
  // Interface nsICharRepresentable [declaration]
  NS_IMETHOD FillInfo(PRUint32 *aInfo)
  {
    ::memset(aInfo, 0xFF, (0x10000L >> 3));
    return NS_OK;
  };
protected:
  PRUnichar mBOM;
  virtual void CopyData(char* aDest, const PRUnichar* aSrc, PRInt32 aLen  )
  {
    ::memcpy(aDest, (void*) aSrc, aLen * 2);
  };
};

class nsUnicodeToUTF16DiffEndian: public nsUnicodeToUTF16SameEndian
{
public:
  /**
   * Class constructor.
   */
  nsUnicodeToUTF16DiffEndian( PRUnichar aBOM )
     : nsUnicodeToUTF16SameEndian(aBOM ) { };

  /**
   * Class destructor.
   */
  virtual ~nsUnicodeToUTF16DiffEndian() {};

  //--------------------------------------------------------------------
  // Interface nsIUnicodeEncoder [declaration]

protected:
  virtual void CopyData(char* aDest, const PRUnichar* aSrc, PRInt32 aLen  )
  {
     PRUnichar *p = (PRUnichar*) aDest;
     // copy the data  by swaping 
     for(PRInt32 i=0; i < aLen; i++)
     {
        PRUnichar aChar = *aSrc++;
        *p++ = (0x00FF & (aChar >> 8)) | (0xFF00 & (aChar << 8));
     }
  };
};
static char BOM[] = {(char)0xfe, (char)0xff};
#define IsBigEndian() (0xFEFF == *((PRUint16*)BOM))
nsresult NEW_UnicodeToUTF16BE(nsISupports **aResult)
{
   if(IsBigEndian()) {
     *aResult = (nsIUnicodeEncoder*)new nsUnicodeToUTF16SameEndian(0);
   } else {
     *aResult = (nsIUnicodeEncoder*)new nsUnicodeToUTF16DiffEndian(0);
   }
   return (NULL == *aResult) ? NS_ERROR_OUT_OF_MEMORY : NS_OK;
}
nsresult NEW_UnicodeToUTF16LE(nsISupports **aResult)
{
   if(IsBigEndian()) {
     *aResult = (nsIUnicodeEncoder*)new nsUnicodeToUTF16DiffEndian(0);
   } else {
     *aResult = (nsIUnicodeEncoder*)new nsUnicodeToUTF16SameEndian(0);
   }
   return (NULL == *aResult) ? NS_ERROR_OUT_OF_MEMORY : NS_OK;
}
nsresult NEW_UnicodeToUTF16(nsISupports **aResult)
{
  *aResult = (nsIUnicodeEncoder*)new nsUnicodeToUTF16SameEndian(0xFEFF);
   return (NULL == *aResult) ? NS_ERROR_OUT_OF_MEMORY : NS_OK;
}