/*
 * Copyright (C) 2000-2001  Ken McCrary
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Email: jkmccrary@yahoo.com
 */
package com.kenmccrary.jtella;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import com.kenmccrary.jtella.util.Log;

/**
 *  Abstract base class for GNUTella messages
 *
 */
abstract class Message
{
  public final static int SIZE = 23;

  final static short PING =  (short)0x00;
  final static short PONG =  (short)0x01;
  final static short PUSH =  (short)0x40;
  final static short QUERY = (short)0x80;
  final static short QUERYREPLY = (short)0x81;

  final static int SIZE_PING_PAYLOAD = 0;
  final static int SIZE_PONG_PAYLOAD = 14;
  final static int SIZE_PUSH_PAYLOAD = 26;
  final static int SIZE_QUERY_PAYLOAD = 257;
  final static int SIZE_QUERYREPLY_PAYLOAD = 65536;

  protected Connection originatingConnection;
  protected GUID guid;
  protected short type;
  protected byte ttl;
  protected byte hops;
  protected short[] payload;
  protected int payloadSize; 
  
  /**
   *  Constructs a new message
   *
   *
   *  @param type function type
   */
   Message(int type)
   {
     this(new GUID(), type);
   }
   
   
   /**
    *  Construct a message with a specific guid
    *
    *  @param guid
    *  @type message type
    */
   Message(GUID guid, int type)
   {
     this.guid = guid;
     this.type = (short)type;
     ttl = 7;
     hops = 0;
   }

  /**
   *  Query the type of message
   *
   *  @return type
   */
  int getType()
  {
    return type;  
  }

   /**
    *  Constructs a message from data read from network
    *
    *  @param rawMessage bytes
    */
   Message(short[] rawMessage, Connection originatingConnection)
   {
     this.originatingConnection = originatingConnection;
     StringBuffer buffer = new StringBuffer();

     for (int i = 0; i < rawMessage.length; i++) 
     {
       buffer.append("[" +
                     Integer.toHexString(rawMessage[i]) +
                     "]");

     }

     Log.getLog().logDebug("Raw Message Bytes: " +
                           buffer.toString());

     // Copy the GUID
     short[] guidData = new short[16];
     System.arraycopy(rawMessage, 0, guidData, 0, guidData.length);
     guid = new GUID(guidData);

     // Copy the function identifier
     type = rawMessage[16];

     // Copy the TTL 
     ttl = (byte)rawMessage[17];

     // Copy the hop count
     hops = (byte)rawMessage[18];

     // Copy the payoad size (little endian)
     int byte1 = rawMessage[19];
     int byte2 = rawMessage[20];
     int byte3 = rawMessage[21];
     int byte4 = rawMessage[22];

     payloadSize += byte1;
     payloadSize += (byte2 << 8);
     payloadSize += (byte3 << 16);
     payloadSize += (byte4 << 24);

   }


   /**
    *  Query the GUID 
    *
    *  @return 16 byte array
    */
   
   GUID getGUID()
   {
     return guid;
   }

   /**
    *  Apply a guid to the message
    *
    *  @param guid new guid
    */
   void setGUID(GUID guid)
   {
     this.guid = guid;
   }

   /**
    *  Get the Time to live for the message
    *
    */
  int getTTL()
  {
    return ttl;   
  }

  /**
   *  Set the ttl value for the message
   *
   */
  void setTTL(byte ttl)
  {
    this.ttl = ttl;
  }

  /**
   *  Get the hop count for this message
   *
   */
  int getHops()
  {
    return hops;
  }

  /**
   *  Set the hop count for this message, seven is the recommended maximum
   *
   */
  void setHops(byte hops)
  {
    this.hops = hops;
  }
   

   /**
    *  Add a payload to the message
    *
    *  @param payload payload for the message
    */
   void addPayload(short[] payload)
   {
     this.payload = payload;
     payloadSize = payload.length;
   }

   /**
    *  Add a payload to the message
    *
    *  @param payload payload for the message
    */
   void addPayload(byte[] payload)
   {
     short[] shortPayload = new short[payload.length];

     for (int i = 0; i < payload.length; i++) 
     {
       shortPayload[i] = payload[i];
     }

     addPayload(shortPayload);
   }

   /**
    *  Query the payload size for this message
    *
    */
   int getPayloadLength()
   {
     return payloadSize;
   }
   
   /**
    *  Retrieve the message payload
    *
    *  @return payload
    */
   short[] getPayload()
   {
     return payload;
   }

   /**
    *  Produces a byte[] suitable for 
    *  GNUTELLA network
    *
    */
   byte[] getByteArray()
   {
     // TODO handle expection avoid null pointer
     ByteArrayOutputStream byteStream = null;

     try
     {
     
       byteStream = new ByteArrayOutputStream();
       DataOutputStream payloadStream = new DataOutputStream(byteStream);

       // Write the guid
       short[] guidData = guid.getData();
       for (int i = 0; i < guidData.length; i++) 
       {
         payloadStream.writeByte((byte)guidData[i]);
       }

       // Write the function (payload descriptor)
       payloadStream.writeByte(type);

       // Write the time to live
       payloadStream.writeByte(ttl);

       // Write the hop count
       payloadStream.writeByte(0);

      // Write the Payload size in little-endian
      int payloadSize1 = 0x000000FF & payloadSize;
      int payloadSize2 = (0x0000FF00 & payloadSize) >> 8;
      int payloadSize3 = (0x00FF0000 & payloadSize) >> 16;
      int payloadSize4 = (0xFF000000 & payloadSize) >> 24;
       
      payloadStream.writeByte(payloadSize1);
      payloadStream.writeByte(payloadSize2);
      payloadStream.writeByte(payloadSize3);
      payloadStream.writeByte(payloadSize4);

       // Write the payload
       if ( null != payload ) 
       {
         // Message may not have a payload (ex. Ping)
         for (int i = 0; i < payload.length; i++) 
         {
           byte payloadByte = (byte)payload[i];
           payloadStream.writeByte(payloadByte);
         }
       }
       

       // all done
       payloadStream.close();

     }
     catch (IOException io)
     {
       Log.getLog().log(io);
     }

     return byteStream.toByteArray();
   }
   
   /**
    *  Checks validity of a payloads size
    *
    *  @param message to test
    *  @return true if valid, false otherwise
    */
   boolean validatePayloadSize()
   {
     boolean result = false;
 
     switch ( type ) 
     {
       case PING:
       {
         if ( SIZE_PING_PAYLOAD == payloadSize ) 
         {
           result = true;
         }
         break;
       }

       case PONG:
       {
         if ( SIZE_PONG_PAYLOAD == payloadSize ) 
         {
           result = true;
         }
         break;
       }

       case PUSH:
       {
         if ( SIZE_PUSH_PAYLOAD == payloadSize ) 
         {
           result = true;
         }
         break;
       }

       case QUERY:
       {
         if ( payloadSize < SIZE_QUERY_PAYLOAD ) 
         {
           result = true;
         }
         break;
       }

       case QUERYREPLY:
       {
         if ( payloadSize < SIZE_QUERYREPLY_PAYLOAD) 
         {
           result = true;
         }
         break;
       }
     }
 
     return result;
   }

   /**
    *  String representation of the message
    *
    */
   public String toString()
   {
     StringBuffer message = new StringBuffer();

     message.append("GUID: ");

     short[] guidData = getGUID().getData();
     for (int i = 0; i < guidData.length; i++) 
     {
       message.append( "[" +
                       Integer.toHexString( guidData[i]) +
                       "]");
     }

     message.append("\n");

     switch (type) 
     {
       case PING:
       {
         message.append("PING message\n");
         break;
       }

       case PONG:
       {
         message.append("PONG message\n");
         break;
       }

       case QUERY:
       {
         message.append("QUERY message\n");
         break;
       }

       case QUERYREPLY:
       {
         message.append("QUERY REPLY message\n");
         break;
       }

       case PUSH:
       {
         message.append("PUSH message\n");
         break;
       }

       default:
       {
         message.append("Unknown message");
         break;
       }
     }

     message.append("Payload length: " + payloadSize + "\n");
     message.append("Payload: \n");

     if (null != payload) 
     {
       for (int i = 0; i < payload.length; i++) 
       {
         message.append( "[" +
                         Integer.toHexString(payload[i]) + 
                         "]");
       }

       message.append("\n");
     }
     else
     {
       message.append("No payload");
     }


     return message.toString();
   }
   
  /**
   *  Returns a String containing the flattened message
   *
   *  @return message string
   */
  public String toRawString()
  {
    StringBuffer buffer = new StringBuffer();
    byte[] rawMessage = getByteArray();
    
    for (int i = 0; i < rawMessage.length; i++) 
    {
      buffer.append("[" +
                    Integer.toHexString(rawMessage[i]) +
                   "]");
   
    }
   
    return buffer.toString();
  } 

  
  /**
   *  Get the connection that was the source for this message
   *
   * 
   *  @return originating connection or null if this <code>Message</code> was
   *  not read from the network
   */
   public Connection getOriginatingConnection()
   {
     return originatingConnection; 
   }
}