// A simple Java chat client
// David Powell 8/8/97
// Department of Computer Science, Monash University, Australia 3168

import java.applet.*;
import java.awt.*;
import java.lang.*;
import java.net.*;
import java.io.*;
import java.util.*;


public class Client extends Applet implements Runnable {
  TextArea output;
  TextField input;
  Button connect;
  Button disconn;
  Connection c;
  Thread thread;
  String host;
  int port;


  public void init() {
    host = getParameter("host");
    port = (new Integer(getParameter("port"))).intValue();

    setLayout(new BorderLayout());

    // Input area
    input  = new TextField(60);

    // Output area
    output = new TextArea(20, 60);
    output.setEditable(false);

    // Buttons to connect and disconnect from the server
    connect = new Button("Connect");
    disconn = new Button("Disconnect");

    add("North",input);
    add("Center",output);

    Panel buttons = new Panel();
    buttons.add(connect);
    buttons.add(disconn);
    add("South", buttons);

    // Create a new connection class, but don't actually connect to the server.
    c = new Connection();
  }


  public void start() {
    thread = new Thread(this);
    thread.start();
  }

  public void stop() {
    thread.stop();
    thread = null;
  }


  public void disconn() {
    if (!c.connected()) {
      output.appendText("Not connected.\n");
    } else {
      c.close();
      output.appendText("Disconnected.\n");
      stop();
    }
  }


  public void connect() {
    if (c.connected()) {
      output.appendText("Already connected!\n");
      return;
    }

    // Try to connect to the server
    output.appendText("Attempting to connect...\n");
    c.connect(host, port);

    if (c.connected()) {
      output.appendText("Connection established.\n");
      start();
    } else {
      output.appendText("Unable to connect.\n");
    }
  }


  // Allow it to be run as an application.
  public static void main(String args[]) {
        Frame f = new Frame("Client");
        Client client = new Client();

        client.init();

        f.add("Center", client);
        f.pack();
        f.show();
  }


  // run() is used to read the socket and print anything sent to us.
  // Note: this routine uses `canRead' so it will not block in the read(),
  //       (not necessary for this simple example. ie. blocking would be ok.)
  public void run() {
    while(c.connected()) {
      if (c.canRead()) {         // If there is data pending on the connection,
        String s = c.read();     // print it out.
        if (s.length() > 0)
          output.appendText("READ: "+s);
      }
      try { thread.sleep(100); } // Pause briefly.
      catch (Exception e) { }
    }
  }


  // Handle any button clicks, or an enter line of text.
  public boolean handleEvent(Event e) {
    switch(e.id) {
      case Event.ACTION_EVENT:    // Strings are read a line at a time and
        if (e.target == input) {  // written to the connection.
          if (c.connected()) {
            c.write((String)e.arg);
          } else {
            output.appendText("Not connected.\n");
          }
          input.setText("");
          return true;
        } else if (e.target == connect) {
          connect();
        } else if (e.target == disconn) {
          disconn();
        }
    }
    return false;
  }

}//Client

// ----------------------------------------------------------------------------


// class Connection handles low level reads and writes to a socket.
// A Connection can be 'connected', can be 'read' from and 'write' to.
// 'canRead' is true is there is data to be 'read'.

class Connection {
  final int MAXLENGTH = 1024;   // Maximum length to be read at a time
  Socket socket;
  PrintStream out;
  DataInputStream in;

  Connection() { }


  public boolean connected() {
    return (socket!=null);
  }


  public boolean connect(String h, int p) {
    try { socket = new Socket(h, p); }
    catch (Exception e)
	{ System.err.println("Socket open: "+e); }
    if (socket==null)
      return false;
    try {
      in  = new DataInputStream(socket.getInputStream());
      out = new PrintStream(socket.getOutputStream());
    } catch (Exception e)
	{ System.err.println("Socket getInput: "+e); }
    return true;
  }


  public void close() {
    try {
      socket.close();
    } catch (Exception e)
	{ System.err.println("Socket close: "+e); }
    socket=null;
  }


  // Send data to the socket
  public void write(String s) {
    out.println(s);
  }


  // Is there data available?
  public boolean canRead() {
    try { return in.available()!=0; }
    catch (Exception e)
	{ System.err.println("Socket available: "+e); socket=null;}
    return false;
  }


  // Read some data.  Will block if nothing available.
  public String read() {
    String s;
    byte b[] = new byte[MAXLENGTH];

    int num = 0;
    try { num = in.read(b, 0, MAXLENGTH); }
    catch (Exception e)
	{ System.err.println("Socket read: "+e); socket=null;}
    if (num>0)
      s = new String(b, 0, 0, num);
    else
      s = "";
    return s;
  }

}//Connection

// David Powell 8/8/1997
// Department of Computer Science, Monash University, Australia 3168