import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

//A simple calculator, containing  a +, -, /, *, Clear and Equal button.  It is an exercise in event handling and if then loops

public class SimpleCalc extends Applet implements ActionListener
{ //Declare all the variables and buttons for the form
	Label Prompt1, Prompt2;
	TextField value1, value2;
	Button addButton;
	Button subButton;
	Button divButton;
	Button multButton;
	Button clrButton;
	Button equButton;
	double num1, num2, result, temp1, temp2;
	int addFlag = 0, subFlag = 0 , multFlag = 0, divFlag = 0, clrFlag = 0, errFlag = 0; // for checking when a button is presses
	String s1, s2;
	
	public void init()
	{  // add the buttons and Prompts to the init()
		addButton = new Button("+");
		add (addButton);
		subButton = new Button("-");
		add (subButton);
		divButton = new Button("/");
		add (divButton);
		multButton =  new Button("*");
		add (multButton);
		clrButton = new Button("Clear");
		add (clrButton);
		equButton = new Button("=");
		add (equButton);
		Prompt1 = new Label("Type your first value here");
		add (Prompt1);
		value1 = new TextField(10);
		add (value1);
		Prompt2 = new Label("Type your second value here");
		add (Prompt2);
		value2 = new TextField(10);
		add (value2);
		
		addButton.addActionListener(this);
		subButton.addActionListener(this);
		divButton.addActionListener(this);
		multButton.addActionListener(this);
		clrButton.addActionListener(this);
		equButton.addActionListener(this);
	}
	
	public void actionPerformed (ActionEvent event)
	{  // if the button has been pressed, then its flag is set to 1, and in the next method....
		
		
		if (event.getSource() == addButton){
			addFlag = 1;
		} else
		if (event.getSource() == subButton){
			subFlag = 1;
		} else
		if (event.getSource() == divButton){
			divFlag = 1;
		} else
		if (event.getSource() == multButton){
			multFlag = 1;
		} else
		if (event.getSource() == clrButton){
			value1.setText("");
			value2.setText("");
			clrFlag = 1;
			repaint();
		} else
		if (event.getSource() == equButton){  //check to see if input is a number, not a string.  If it is a string, then set errFlag to 1
			try {
				num1 = Integer.parseInt(value1.getText());	
				num2 = Integer.parseInt(value2.getText());
			}
			catch (NumberFormatException e) {
				errFlag = 1;
			}
			repaint();  //process the button handling section when pressed
		}
	}
	public void paint (Graphics g) // we check the value of the various flags, and then do the arithmetic
	{
		if (errFlag == 1) { //if errFlag is 1 then the user fucked up somewhere
			g.drawString("Please make sure values are numbers only", 25, 100);
			errFlag = 0;
		} else
		
		
		
		if (addFlag == 1){
			result = num1 + num2;
			g.drawString("Answer : " + result, 25, 100);
			result = 0;
		}else
		if (subFlag == 1){
			result = num1 - num2;
			g.drawString("Answer : " + result, 25, 100);
			result = 0;
		}else
		if (divFlag == 1){
			result = num1 / num2;
			g.drawString("Answer : " + result, 25, 100);
			result = 0;
		}else
		if (multFlag == 1){
			result = num1 * num2;
			g.drawString("Answer : " + result, 25, 100);
			result = 0;
		}else
		if (clrFlag == 1){
			result = 0;
			num1 = 0;
			num2 = 0;
			addFlag = 0;
			subFlag = 0;
			divFlag = 0;
			multFlag = 0;
			clrFlag = 0;
			g.drawString("Answer : " + result, 25, 100);
		}
		result = 0;
			num1 = 0;
			num2 = 0;
			addFlag = 0;
			subFlag = 0;
			divFlag = 0;
			multFlag = 0;
			clrFlag = 0;
			
	}
}