/*
    *  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.
   *
   */
  package org.apache.mina.filter.codec.textline;
  
  import java.nio.charset.Charset;
  import java.nio.charset.CharsetEncoder;
  
  import org.apache.mina.core.buffer.IoBuffer;
  import org.apache.mina.core.session.AttributeKey;
  import org.apache.mina.core.session.IoSession;
  import org.apache.mina.filter.codec.ProtocolEncoder;
  import org.apache.mina.filter.codec.ProtocolEncoderAdapter;
  import org.apache.mina.filter.codec.ProtocolEncoderOutput;
  
  /**
   * A {@link ProtocolEncoder} which encodes a string into a text line
   * which ends with the delimiter.
   *
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   */
  public class TextLineEncoder extends ProtocolEncoderAdapter {
      private static final AttributeKeyAttributeKey.html#AttributeKey">AttributeKey ENCODER = new AttributeKey(TextLineEncoder.class, "encoder");
  
      private final Charset charset;
  
      private final LineDelimiter delimiter;
  
      private int maxLineLength = Integer.MAX_VALUE;
  
      /**
       * Creates a new instance with the current default {@link Charset}
       * and {@link LineDelimiter#UNIX} delimiter.
       */
      public TextLineEncoder() {
          this(Charset.defaultCharset(), LineDelimiter.UNIX);
      }
  
      /**
       * Creates a new instance with the current default {@link Charset}
       * and the specified <tt>delimiter</tt>.
       * 
       * @param delimiter The line delimiter to use
       */
      public TextLineEncoder(String delimiter) {
          this(new LineDelimiter(delimiter));
      }
  
      /**
       * Creates a new instance with the current default {@link Charset}
       * and the specified <tt>delimiter</tt>.
       * 
       * @param delimiter The line delimiter to use
       */
      public TextLineEncoder(LineDelimiter delimiter) {
          this(Charset.defaultCharset(), delimiter);
      }
  
      /**
       * Creates a new instance with the specified <tt>charset</tt>
       * and {@link LineDelimiter#UNIX} delimiter.
       * 
       * @param charset The {@link Charset} to use
       */
      public TextLineEncoder(Charset charset) {
          this(charset, LineDelimiter.UNIX);
      }
  
      /**
       * Creates a new instance with the specified <tt>charset</tt>
       * and the specified <tt>delimiter</tt>.
       * 
       * @param charset The {@link Charset} to use
       * @param delimiter The line delimiter to use
       */
      public TextLineEncoder(Charset charset, String delimiter) {
          this(charset, new LineDelimiter(delimiter));
      }
  
      /**
       * Creates a new instance with the specified <tt>charset</tt>
       * and the specified <tt>delimiter</tt>.
       * 
      * @param charset The {@link Charset} to use
      * @param delimiter The line delimiter to use
      */
     public TextLineEncoder(Charset charset, LineDelimiter delimiter) {
         if (charset == null) {
             throw new IllegalArgumentException("charset");
         }
         if (delimiter == null) {
             throw new IllegalArgumentException("delimiter");
         }
         if (LineDelimiter.AUTO.equals(delimiter)) {
             throw new IllegalArgumentException("AUTO delimiter is not allowed for encoder.");
         }
 
         this.charset = charset;
         this.delimiter = delimiter;
     }
 
     /**
      * @return the allowed maximum size of the encoded line.
      * If the size of the encoded line exceeds this value, the encoder
      * will throw a {@link IllegalArgumentException}.  The default value
      * is {@link Integer#MAX_VALUE}.
      */
     public int getMaxLineLength() {
         return maxLineLength;
     }
 
     /**
      * Sets the allowed maximum size of the encoded line.
      * If the size of the encoded line exceeds this value, the encoder
      * will throw a {@link IllegalArgumentException}.  The default value
      * is {@link Integer#MAX_VALUE}.
      * 
      * @param maxLineLength The maximum line length
      */
     public void setMaxLineLength(int maxLineLength) {
         if (maxLineLength <= 0) {
             throw new IllegalArgumentException("maxLineLength: " + maxLineLength);
         }
 
         this.maxLineLength = maxLineLength;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void encode(IoSession session, Object message, ProtocolEncoderOutput out) throws Exception {
         CharsetEncoder encoder = (CharsetEncoder) session.getAttribute(ENCODER);
 
         if (encoder == null) {
             encoder = charset.newEncoder();
             session.setAttribute(ENCODER, encoder);
         }
 
         String value = message == null ? "" : message.toString();
         IoBuffer buf = IoBuffer.allocate(value.length()).setAutoExpand(true);
         buf.putString(value, encoder);
 
         if (buf.position() > maxLineLength) {
             throw new IllegalArgumentException("Line length: " + buf.position());
         }
 
         buf.putString(delimiter.getValue(), encoder);
         buf.flip();
         out.write(buf);
     }
 
     /**
      * Dispose the encoder
      * 
      * @throws Exception If the dispose failed
      */
     public void dispose() throws Exception {
         // Do nothing
     }
 }