package LinkedLists;

/**
 * This class uses the QueueAsArray class to demonstrate
 * the use of a queue. A service queue is modelled.
 * 
 * Author:   Richard Jones, UWCSEA, Singapore
 * Date:     May 2001      
 * Hardware: PII 333, 128 Mb RAM
 * Software: Visual Age for Java V2
 * 
 */
import java.applet.*;
import java.awt.*;   
import java.awt.event.*;

public class SingtelQueue extends Applet implements ActionListener
{
	// interface objects
	
	Label greetLabel   = new Label("Serving You Better - That's Your Singtel!");
	Label nextLabel    = new Label("Next in queue:", Label.RIGHT);
	Label lengthLabel  = new Label("Queue length: ", Label.RIGHT);
	Label nameLabel    = new Label("Name: ", Label.RIGHT);
	Label phoneLabel   = new Label("Phone: ", Label.RIGHT);	
	Label messageLabel = new Label("System messages will appear here");
	
	TextField next     = new TextField("details of next person");
	TextField length   = new TextField("q length");
	TextField name     = new TextField(20);
	TextField phone    = new TextField(12);
	
	Button dispenseButton = new Button("Dispense ticket");
	Button nextButton     = new Button("Next customer");

	Panel infoPanel  = new Panel();
	Panel inputPanel = new Panel();

	TextArea display = new TextArea( 10, 40);

	// the queue
	
	CustomerQueue q = new CustomerQueue(6);
/**
 * SingtelQueue constructor comment.
 */
public SingtelQueue() {
	super();
}
//
// Responds to button presses...
//

public void actionPerformed(ActionEvent e)
{
	// Add and remove items from the customer queue
	
	if (e.getSource() == dispenseButton)
	{
	  dispense();	
	}
	else
	{
	  serve();
	}

	updateDisplay();
}
/**
 * Method to add a name and phone to the queue
 * 
 */
public void dispense()
{
	CustomerNode theCustomer; // new customer node
	String nm, ph;

	// Get the text (and check if there is any)
	
	nm = name.getText();
	ph   = phone.getText();
	
	if ( (nm.length() == 0) || (ph.length() == 0) )
	{
		messageLabel.setText("Enter name and phone details");
	}
	else
	{
		try // try to enqueue the details
		{
			theCustomer = new CustomerNode(nm, ph, null);
			q.enqueue(theCustomer);
			length.setText("" + q.getSize());
			messageLabel.setText("Customer added");
		}
		catch (QueueFullException qfe)
		{
			messageLabel.setText(qfe.getMessage());
		}
	}
	
	// clear the input boxes

	name.setText("");
	phone.setText("");
}
/**
 * Method to set up the display
 */
public void init()
{
	add(greetLabel);

	infoPanel.setLayout( new GridLayout( 2, 2, 10, 10 ) );
		
	infoPanel.add(nextLabel);
	infoPanel.add(next);
	infoPanel.add(lengthLabel);
	infoPanel.add(length);

	add(infoPanel);
	
	add(dispenseButton);
	add(nextButton);
	
	dispenseButton.addActionListener(this);
	nextButton.addActionListener(this);

	inputPanel.setLayout( new GridLayout( 2, 2, 10, 10 ) );

	inputPanel.add(nameLabel);
	inputPanel.add(name);
	inputPanel.add(phoneLabel);
	inputPanel.add(phone);

	add(inputPanel);
	add(messageLabel);

	add(display);

}
/**
 * Method to dequeue users as they are served
 */
public void serve()
{
	CustomerNode temp;
	
	// next customer button was pushed

	try // to get the front item
	{
		temp = q.dequeue();
		next.setText(temp.getName());
		length.setText("" + q.getSize());
		messageLabel.setText("OK");
	}
	catch (QueueEmptyException qee)
	{
		messageLabel.setText(qee.getMessage()); // no queue
		next.setText("");
		phone.setText("");
	}
}
/**
 * Method to display the queue
 */
void updateDisplay()
{
	CustomerNode temp = q.getFront();
	int i = 0;

	display.setText("");
	
	if (q.isEmpty())
	{
		display.setText("Nobody waiting...\n");
	}
	else
	{
		do
		{
			display.append("" + ++i + ": " + temp.getName() 
				              + " " + temp.getPhone() + "\n");
			temp = q.getNext(temp);
		}
		while (temp != null);
	}
}
}