package dcj.examples.messageV2;

import java.util.Vector;
import java.io.*;

/**
 * Source code from "Java Distributed Computing", by Jim Farley.
 *
 * Class: BasicMessage
 * Example: 6-6
 * Description: An updated version of the BasicMessage that handles
 *      heterogeneous argument lists.
 */

abstract class BasicMessage
{
  protected String id;
  protected Vector argList;
  String endToken = "END";

  public BasicMessage() {
    argList = new Vector();
  }

  public BasicMessage(String mid) {
    id = mid;
    argList = new Vector();
  }

  protected void setId(String mid) {
    id = mid;
  }

  public void addArg(Object arg) {
    argList.addElement(arg);
  }

  public String messageID() {
    return id;
  }

  public Vector argList() {
    Vector listCopy = (Vector)argList.clone();
    return listCopy;
  }

  public boolean readArgs(InputStream ins) {
    boolean success = true;
    DataInputStream din = new DataInputStream(ins);

    // Read tokens until the "end-of-message" token is seen.
    try {
      String token = din.readUTF();
      while (token.compareTo(endToken) != 0) {
        addArg(token);
        token = din.readUTF();
      }
    }
    catch (IOException e) {
      // Failed to read complete argument list.
      success = false;
    }
    return success;
  }

  public boolean writeArgs(OutputStream outs) {
    int len = argList.size();
    boolean success = true;
    DataOutputStream dout = new DataOutputStream(outs);

    // Write each argument in order
    try {
      for (int i = 0; i < len; i++) {
        String arg = (String)argList.elementAt(i);
        dout.writeUTF(arg);
      }

      // Finish with the end-of-message token
      dout.writeUTF(endToken);
    }
    catch (IOException e) {
      success = false;
    }
    return success;
  }

  public abstract boolean Do();
}