// File: IO2.java
//
// Author: Rahul Simha
// Created: Nov 18, 1998
//
// Concurrent Producer-Consumer.

import java.awt.*;
import java.awt.event.*;
import java.io.*;


class Producer extends Frame implements Runnable {

  Label L;     // A place to write stuff.
  Buffer buf;  // Reference to the buffer.

  public Producer (Buffer buf)
  {
    // Store the reference to the buffer.
    this.buf = buf;

    // Create the frame.
    this.setSize (600,100);
    this.setLocation (0,100);
    this.setTitle ("Producer");
    this.setBackground (Color.white);
    // this.setLayout (new BorderLayout());

    // This is where we will write to.
    L = new Label ("");
    this.add (L, BorderLayout.CENTER);

    this.setVisible (true);
  }


  // Must implement the run() method.

  public void run ()
  {
    // Write 25 random bytes to the buffer.

    for (int i=1; i<=25; i++) {
      // Create a random byte
      byte k = (byte) UniformRandom.uniform (1, 100);

      // Write to label first.
      L.setText (L.getText() + " " + k);

      // Write it to the screen.
      System.out.println ("Producer: writing " + k);

      // Write integer to buffer.
      buf.write_byte (k);

      // Sleep for a while.
      try {
	Thread.sleep ((int)UniformRandom.uniform(100,1000));
      }
      catch (InterruptedException e) {
	System.out.println (e);
      }
    }
    buf.write_byte ((byte)-1);
    L.setText (L.getText() + " Done!");
  }

}


class Consumer extends Frame implements Runnable {

  Label L;     // Data similar to Producer.
  Buffer buf;

  public Consumer (Buffer buf)
  {
    this.buf = buf;

    this.setSize (600,100);
    this.setLocation (0, 200);
    this.setTitle ("Consumer");
    this.setBackground (Color.white);
    // this.setLayout (new BorderLayout());

    L = new Label ("");
    this.add (L, BorderLayout.CENTER);

    this.setVisible (true);
  }


  public void run ()
  {
    // Read byte values until EOF.

    while (true) {
      // Get the next byte
      byte k = buf.read_byte ();

      // Check if end-of-data.
      if (k < 0) break;

      System.out.println ("Consumer: just read " + k);

      // Write it on the frame.
      L.setText (L.getText() + " " + k);

      // Sleep for a while.
      try {
	Thread.sleep ((int)UniformRandom.uniform(500,1000));
      }
      catch (InterruptedException e) {
	System.out.println (e);
      }
    }
    L.setText (L.getText() + " Done!");
  }

}


// A buffer written as a monitor.

class Buffer {

  byte[] buf;                      // The buffer.
  int write_cursor = 0;            // Pointer to last written entry.
  int read_cursor = 0;             // Pointer to last read entry.
  boolean consumer_waiting =false; // A waiting flag.

  public Buffer ()
  {
    // Allocate space.
    buf = new byte[1000];
  }

  public synchronized void write_byte (byte x)
  {
    // Write to next available space.
    buf [++write_cursor] = x;

    // If consumer was waiting, notify.
    if (consumer_waiting)
      notify ();
  }

  public synchronized byte read_byte ()
  {
    // If there isn't enough to read, wait.
    if (read_cursor == write_cursor) {
      consumer_waiting = true;
      try {
	wait ();
      }
      catch (InterruptedException e) {
	System.out.println (e);
      }
      consumer_waiting = false;
    }

    // Now read next value.
    byte k = buf [++read_cursor];
    return k;
  }

}



// This is an independent quit button to quit the application.

class QuitButton extends Frame {

  public QuitButton ()
  {
    this.setSize (80,50);
    this.setLocation (0, 0);
    this.setTitle ("Quit button");
    Button quitb = new Button ("QUIT");
    quitb.setBackground (Color.red);
    quitb.addActionListener (
      new ActionListener () {
        public void actionPerformed (ActionEvent a)
	{
	  System.exit (0);
	}
      }
    );
    this.add (quitb, BorderLayout.CENTER);
    this.setVisible (true);
  }

}


public class IO2 {

  public static void main (String[] argv)
  {
    // Create an independent quit button.
    QuitButton q = new QuitButton ();

    // A buffer instance.
    Buffer buf = new Buffer ();

    // Create a producer instance and thread.
    Producer p = new Producer (buf);
    Thread pthread = new Thread (p);

    // Create a consumer instance and thread.
    Consumer c = new Consumer (buf);
    Thread cthread = new Thread (c);

    // Start the threads.
    pthread.start();
    cthread.start();
  }

}