/*
 * x1_skeleton.java code skeleton for simple calculator SJ 251007
 * Requires Java 1.6 (for evaluating values).
 */

/*
 * PLACE YOUR SELF-EVALUATION HERE
 */

/*
 * Hints:
   * JTextComponent.setEditable()
   * Component.setFocusable()
   * KeyEvent.getKeyText(KeyEvent.getKeyCode())
   * 
 */

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;        
import javax.script.*;
import java.util.HashMap;
import java.util.Scanner;
import java.io.File;


public class yourusername
        extends JFrame
        // uncomment following if you implement the interfaces
        // implements ActionListener, KeyListener
{

    // String array for the buttons
    private static final String[][] bstrings = { 
          {"+", "-", "*", "/"},
          {"1", "2", "3", "("},
          {"4", "5", "6", ")"},
          {"7", "8", "9", "<-"},
          {".", "0", "=", "C"}
    };

    // used for evaluation
    private ScriptEngine scriptE;
    // used for tool tips
    private static HashMap<String, String> tips = null;

    public yourusername() {
        if (tips == null) {
            tips = new HashMap<String, String>();
            // take calctips.txt from www-page
            readToolTips(tips, "calctips.txt");
        }

        draw();

        // initialize expression evaluator
        ScriptEngineManager mgr = new ScriptEngineManager();
        scriptE = mgr.getEngineByExtension("js");
    }

  
    /*
     * Draw the UI initially and bind actions to handlers.
     */
    private void draw() {
        JFrame mainFrame = new JFrame("yourusername");
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // TODO

        //Display the window.
        mainFrame.pack();
        mainFrame.setVisible(true);

    }   // draw()

    // TODO


    /*
     * Evaluates an expression.
     *
     * @param buf the input expression
     * @return the result of the expression, or "error"
     */
    private String evaluateExpression(String buf) {
        String res = "";
        try {
            res = scriptE.eval(buf).toString();
        } catch (ScriptException ex) {
            res = "error";
        }
        return res;
    }   // evaluateExpression()

   
    /*
     * Read tootips from a file to a {@linkplain java.util.HashMap java.util.HashMap}.
     * In case of error (e.g., wrong format in file), results empty or incomplete HashMap
     *
     * @param fileName name of the source file
     * @param tips the destination {@linkplain java.util.HashMap java.util.HashMap}
     */
    private static void readToolTips(HashMap<String, String> tips, String fileName) {
        try {
            Scanner in = new Scanner(new File(fileName));
            while (in.hasNext()) {
                String key = in.next(); // read one token as key
                String val = in.nextLine(); // the rest is tooltip text
                tips.put(key, val);
            }
        } catch (Exception e) { }
    }   // readToolTips()


    /*
     * Start the gui.
     */
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                yourusername cgui = new yourusername();
            }
        });
    } // main()

}   // class yourusername