/*
 * Copyright (c) 2003, KNOPFLERFISH project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 * - Neither the name of the KNOPFLERFISH project nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.knopflerfish.bundle.consoletelnet;

  /**
   ** The echo command has no sub negotiable parameters
   */

public class TelnetCommandEcho extends TelnetCommand {
  public TelnetCommandEcho (TelnetSession ts,
                            int commandCode,
                            boolean doStatus,
                            boolean show) 
  {
    super(ts, commandCode, doStatus, show);
  }

  /**
   ** Option negotiation and execution mechanism
   **
   ** To follow the intentions of RFC 854, a change in status
   ** is always followed by a response but if trying to enter a mode
   ** that we are already in, no response is returned.
   **
   ** This is essential to prevent negotiation loops.
   **
   ** @parameter action, one of the telnet protocol basic actions
   **            DO, DONT, WILL, WONT or  SE
   ** @parameter optionCode, the option code
   ** @parameter parameters, a byte array with optional parameters to the option code.
   **
   ** @return a String with the response to the command.
   */

  public String execute (int action, int optionCode, byte[] parameters) {
    // printCommand(action, optionCode, parameters);
    StringBuffer sb = new StringBuffer();

    switch (action) {
    case TCC.DO:
      if (doStatus == true) {
        // willing and ready, send no resonse, 
        // to prevent creation of negotiation loop
      } else {
        doStatus = true;
        sb.append(getWILL());
      }
      break;

    case TCC.WILL:
      if (doStatus == true) {
        // willing and ready, send no resonse, 
        // to prevent creation of negotiation loop
      } else {
        doStatus = true;
      }
      break;

    case TCC.DONT:
      if (doStatus == true) {
        sb.append(getWONT());
        doStatus = false;
        // now not willing, send no resonse, 
        // to prevent creation of negotiation loop
      } else {
        doStatus = false;
      }
      break;

    // handle the case of WONT, which means that
    // the other end wont echo but this end will still echo
    case TCC.WONT:
      if (doStatus == true) {
        // no appropriate answer to send
        doStatus = true;
        // now not willing, send no resonse, 
        // to prevent creation of negotiation loop
      } else {
        doStatus = false;
      }
      break;

    // SB .... SE, command execution, when negotiations 
    // are finished and both parties have agreed

    case TCC.SE:
      if (doStatus == true) {
        ;
      } else { // not in right state 
        sb.append(getDONT());
      }
      break;

    default:
      break;
    }
    return sb.toString();
  }
}