/**
 * This is an example of a Stack using Array made in Java Applet 
 * 
 * @author (Vilchor G. Perdido) 
 * @version (January 2010)
 */

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

public class ArrayStack extends Applet implements ActionListener {

    Button bpush,bpop,btop,bsize,bclear;
    TextField tnum,ttop,tsize;
    List list = new List();
    Label ltop,lsize;
    int top=-1, topVal;
    int stack[] = new int[10];
    int inputNum;
    int size=0;
    Font myFont,otherFont,buttonFont;
    Color myColor;
    
    public void init() {
        setLayout(null);
        setSize(530,500);
        myColor = new Color(15,125,25);
        myFont = new Font("Arial",Font.BOLD,14);
        otherFont = new Font("Arial",Font.BOLD,18);
        buttonFont = new Font("Arial",Font.BOLD,16);
        setBackground(Color.darkGray);
        
        list.add("        STACKS using an ARRAY");
        list.add("        Capacity of the Stack: " + stack.length);
        list.add("===============================");
        list.setBounds(10,10,260,480);
        list.setFont(myFont);
        list.setBackground(Color.yellow);
        add(list);
        
        bpush = new Button("PUSH");
        bpush.setBounds(290,10,100,30);
        bpush.setForeground(Color.red);
        bpush.setFont(buttonFont);
        add(bpush);
        bpop = new Button("POP");
        bpop.setBounds(400,10,100,30);
        bpop.setForeground(Color.blue);
        bpop.setFont(buttonFont);
        add(bpop);
     
        btop= new Button("PEEK");
        btop.setBounds(290,50,100,30);
        btop.setForeground(myColor);
        btop.setFont(buttonFont);
        add(btop);
        
        bsize = new Button("Get SIZE");
        bsize.setBounds(400,50,100,30);
        bsize.setFont(buttonFont);
        add(bsize);
        
        bclear = new Button("RESET STACK");
        bclear.setBounds(320,450,140,30);
        bclear.setFont(buttonFont);
        add(bclear);
                
        tnum = new TextField("Please enter any number here...",40);
        tnum.setFont(myFont);
        tnum.setBackground(Color.red);
        tnum.setForeground(Color.white);
        tnum.setBounds(280,105,240,30);
        add(tnum);
        
        ttop = new TextField(10);
        ttop.setBounds(380,150,50,30);
        ttop.setFont(otherFont);
        ttop.setBackground(Color.blue);
        ttop.setEditable(false);
        add(ttop);
        
        ltop = new Label("Top Element:");
        ltop.setForeground(Color.white);
        ltop.setBounds(290,150,80,30);
        add(ltop);
        
        tsize = new TextField(10);
        tsize.setBounds(380,180,50,30);
        tsize.setFont(otherFont);
        tsize.setBackground(Color.red);
        tsize.setEditable(false);
        add(tsize);
        lsize = new Label("Stack Size:");
        lsize.setForeground(Color.white);
        lsize.setBounds(290,180,80,30);
        tsize.setEditable(false);
        add(lsize);
        
        tsize.setText("" + stack.length);
        ttop.setText("Null");
        showStatus("Loading...Initializing...");
        
        tnum.selectAll();
        tnum.requestFocus();
        
        bpush.addActionListener(this);
        bpop.addActionListener(this);
        btop.addActionListener(this);
        bsize.addActionListener(this);
        bclear.addActionListener(this);
        tnum.addActionListener(this);
    }
    
    public void paint(Graphics g)
    {
        showStatus("Developed by: Vilchor G. Perdido (MIT-1)");
        Image stack2 = getImage(getDocumentBase(),"images/stack2.png");
        g.drawImage(stack2,435,240,this);
        Image stack = getImage(getDocumentBase(),"images/stack.png");
        g.drawImage(stack,225,250,this);
    }
   
    public void actionPerformed(ActionEvent evt) {
        
        inputNum = Integer.parseInt(tnum.getText());
               
        if(evt.getSource()==bpush || evt.getSource()==tnum) {
            
            if(top==stack.length-1)
            {
                list.add("ERROR Exception: STACK is FULL!");
            }
            else
            {
                top++;
                stack[top]=inputNum;
                topVal=stack[top];
                list.add("PUSHED Element: " + stack[top]);
                ttop.setText("" + topVal);
                size = (stack.length-1)-top;
                tsize.setText("" + size);
            }
            tnum.selectAll();
            tnum.requestFocus();
        }

        
        if(evt.getSource()==bpop) {
            
            if(top==-1)
            {
                list.add("ERROR Exception: STACK is EMPTY!");
            }
            else if(top==0)
            {
                topVal=stack[top];
                list.add("POPPED Element: " + topVal);
                top=-1;
                ttop.setText("Null");
                size++;
                tsize.setText("" + size);
            }
            else
            {
                
                topVal=stack[top];
                list.add("POPPED Element: " + topVal);
                top--;
                topVal=stack[top];
                ttop.setText("" + topVal);
                size++;
                tsize.setText("" + size);
            }
        }
        
        if(evt.getSource()==btop) {
            
            if(top==-1)
            {
                list.add("ERROR Exception: STACK is EMPTY!");
            }
            else
            {
                list.add("Element at the top: " + stack[top] + " at index " + top);
            }
        }
        if(evt.getSource()==bsize) {
            
            if(top==-1)
            {
                list.add("The size of the stack is: " + stack.length);
            }
            else
            {
                list.add("The size of the stack is: " + size);
            }
        }
        
        if(evt.getSource()==bclear) {
            list.clear();
            list.add("        STACKS using an ARRAY");
            list.add("        Capacity of the Stack: " + stack.length);
            list.add("===============================");
            int stack[] = new int[10];
            top = -1;            
            tsize.setText("" + stack.length);
            ttop.setText("Null");
            tnum.setText("");
        }
    }
}