/*

  *   SONEWS News Server

  *   see AUTHORS for the list of contributors

  *

  *   This program 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 3 of the License, or

  *   (at your option) any later version.

  *

  *   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

  */

 package org.sonews.util.io;

 import java.io.IOException;

 import java.io.InputStream;

 import java.nio.ByteBuffer;

 import java.nio.charset.Charset;

 /**

  * InputStream that can change its decoding charset while reading from the

  * underlying byte based stream.

  * @author Christian Lins

  * @since sonews/0.5.0

  */

 public class VarCharsetReader

 {

   private final ByteBuffer buf = ByteBuffer.allocate(4096);

   private InputStream in;

   public VarCharsetReader(final InputStream in)

   {

     if(in == null)

     {

       throw new IllegalArgumentException("null InputStream");

     }

     this.in = in;

   }

   /**

    * Reads up to the next newline character and returns the line as String.

    * The String is decoded using the given charset.

    */

   public String readLine(Charset charset)

     throws IOException

   {    

     byte[] byteBuf = new byte[1];

     String bufStr;

     for(;;)

     {

       int read = this.in.read(byteBuf);

       if(read == 0)

       {

         continue;

       }

       else if(read == -1)

       {

         this.in = null;

         bufStr  = new String(this.buf.array(), 0, this.buf.position(), charset);

         break;

       }

       else if(byteBuf[0] == 10) // Is this safe? \n

       {

         bufStr  = new String(this.buf.array(), 0, this.buf.position(), charset);

         break;

       }

       else if(byteBuf[0] == 13) // \r

       { // Skip

         continue;

       }

       else

       {

         this.buf.put(byteBuf[0]);

       }

     }

     this.buf.clear();

     return bufStr;

   }

 }