/*
 * Calculator.java
 *
 * Created on October 7, 2003, 10:57 AM
 */

/**
 *
 * @author  hansen
 */
public class Calculator extends javax.swing.JFrame {
    
    private int accumulator = 0;
    private DisplayState dState = new FirstOverwrite();
    private OperatorState oState = new NullOperator();
    
    /** Creates new form Calculator */
    public Calculator() {
        initComponents();
    }
    
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    private void initComponents() {//GEN-BEGIN:initComponents
        display = new javax.swing.JTextField();
        addButton = new javax.swing.JButton();
        subButton = new javax.swing.JButton();
        zeroButton = new javax.swing.JButton();
        oneButton = new javax.swing.JButton();
        clearButton = new javax.swing.JButton();

        getContentPane().setLayout(null);

        addWindowListener(new java.awt.event.WindowAdapter() {
            public void windowClosing(java.awt.event.WindowEvent evt) {
                exitForm(evt);
            }
        });

        display.setEditable(false);
        display.setText("0");
        getContentPane().add(display);
        display.setBounds(0, 0, 400, 40);

        addButton.setText("+");
        addButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                addButtonActionPerformed(evt);
            }
        });

        getContentPane().add(addButton);
        addButton.setBounds(20, 80, 88, 25);

        subButton.setText("-");
        subButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                subButtonActionPerformed(evt);
            }
        });

        getContentPane().add(subButton);
        subButton.setBounds(20, 140, 88, 25);

        zeroButton.setText("0");
        zeroButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                zeroButtonActionPerformed(evt);
            }
        });

        getContentPane().add(zeroButton);
        zeroButton.setBounds(190, 80, 42, 25);

        oneButton.setText("1");
        oneButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                oneButtonActionPerformed(evt);
            }
        });

        getContentPane().add(oneButton);
        oneButton.setBounds(190, 150, 42, 25);

        clearButton.setText("Clear");
        clearButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                clearButtonActionPerformed(evt);
            }
        });

        getContentPane().add(clearButton);
        clearButton.setBounds(30, 210, 66, 25);

        java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
        setBounds((screenSize.width-400)/2, (screenSize.height-300)/2, 400, 300);
    }//GEN-END:initComponents

    private void clearButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_clearButtonActionPerformed
        dState = new FirstOverwrite();
        oState = new NullOperator();
        accumulator = 0;
        display.setText("0");
        // Add your handling code here:
    }//GEN-LAST:event_clearButtonActionPerformed

    private void addButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_addButtonActionPerformed
        dState.operatorChosen();
        oState = new AddOperator();
        // Add your handling code here:
    }//GEN-LAST:event_addButtonActionPerformed

    private void zeroButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_zeroButtonActionPerformed
        dState.digitChosen('0');
        // Add your handling code here:
    }//GEN-LAST:event_zeroButtonActionPerformed

    private void oneButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_oneButtonActionPerformed
        dState.digitChosen('1');
        
        // Add your handling code here:
    }//GEN-LAST:event_oneButtonActionPerformed

    private void subButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_subButtonActionPerformed
        dState.operatorChosen();
        oState = new SubOperator();
        
        // Add your handling code here:
    }//GEN-LAST:event_subButtonActionPerformed
    
    /** Exit the Application */
    private void exitForm(java.awt.event.WindowEvent evt) {//GEN-FIRST:event_exitForm
        System.exit(0);
    }//GEN-LAST:event_exitForm
    
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        new Calculator().show();
    }
    
    
    // Variables declaration - do not modify//GEN-BEGIN:variables
    private javax.swing.JButton addButton;
    private javax.swing.JButton clearButton;
    private javax.swing.JTextField display;
    private javax.swing.JButton oneButton;
    private javax.swing.JButton subButton;
    private javax.swing.JButton zeroButton;
    // End of variables declaration//GEN-END:variables
    
    // This interface is one of two control interfaces
    // for the calculator
    interface DisplayState
    {
        public void digitChosen(char digit);
        public void operatorChosen();
    }
    
    // When we turn on or clear the calculator we enter the
    // FirstOverWrite state.
    class FirstOverwrite implements DisplayState
    {
        public void digitChosen(char digit)
        {
            display.setText(""+digit);
            dState = new FirstConcatenate();
        }
        
        public void operatorChosen()
        {
            accumulator = Integer.parseInt(display.getText(), 2);
            dState = new SecondOverwrite();
        }
            
    }
    
    // After a character is pressed, we concatenate to the display
    // rather than overwrite it.
    class FirstConcatenate implements DisplayState
    {
        public void digitChosen(char digit)
        {
            display.setText(display.getText()+digit);
        }
        
        public void operatorChosen()
        {
            accumulator = Integer.parseInt(display.getText(), 2);
            dState = new SecondOverwrite();
        }
    }
    
    // After an operator is chosen, we look for a second
    // number, starting with SecondOverwrite
    class SecondOverwrite implements DisplayState
    {
        public void digitChosen(char digit)
        {
            display.setText(""+digit);
            dState = new SecondConcatenate();
        }
        
        public void operatorChosen()
        {
        }
            
    }
    
    // Process the second, third, etc bits of the number
    class SecondConcatenate implements DisplayState
    {
        public void digitChosen(char digit)
        {
            display.setText(display.getText()+digit);
        }
        
        public void operatorChosen()
        {
            oState.doOp();
            dState = new SecondOverwrite();
        }
    }    
    
    // The second state machine keeps track of what the previous
    // operation chosen was.
    interface OperatorState
    {
        public int doOp();
    }
    
    // There is no previous operation
    class NullOperator implements OperatorState
    {
        public int doOp()
        {
            return accumulator;
        }
    }
    
    // The previous operation was an add
    class AddOperator implements OperatorState
    {
        public int doOp()
        {
            int temp = Integer.parseInt(display.getText(), 2);
            accumulator += temp;
            display.setText(Integer.toBinaryString(accumulator));
            return accumulator;
        }
    }
    
    // The previous operation was a subtract
    class SubOperator implements OperatorState
    {
        public int doOp()        
        {
            int temp = Integer.parseInt(display.getText(), 2);
            accumulator -= temp;
            display.setText(Integer.toBinaryString(accumulator));
            return accumulator;
        }
    }
    
    
}