//
//  Calculator4App
//
//  Created by Edward on 2/12/06
//	Last modified 2/21/06
//

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
import java.text.*; // for DecimalFormat

public class Calculator4App extends JApplet {

	/**
	* Numbers are entered into a string, curDisplay, whose value is stored in cur
	* The booleans help keep track of order of operations and proper display
	* Future improvements:
	* - perhaps stop user from entering too many digits
	*/
	String curDisplay = "0";
	double cur = 0;
	boolean pHold = false; // is there addition waiting to happen?
	boolean mHold = false; // is there subtraction waiting to happen?
	boolean tPend = false; // is there multiplication waiting to happen?
	boolean dPend = false; // is there division waiting to happen?
	boolean fn = false; // was the last button a function key?
	boolean decFlag = false; // should we display a superfluous decimal?
	double addHold = 0;
	double pending = 0;
	double mem = 0;
	JButton but1;
	JButton but2;
	JButton but3;
	JButton but4;
	JButton but5;
	JButton but6;
	JButton but7;
	JButton but8;
	JButton but9;
	JButton but0;
	JButton butDec;
	JButton butEq;
	JButton butC;
	JButton butMRC;
	JButton butMin;
	JButton butPM;
	JButton butDivide;
	JButton butTimes;
	JButton butMinus;
	JButton butPlus;
	Font myFont = new Font("monospaced",0,18);
	DecimalFormat myFormat = new DecimalFormat("0.##########");
	DecimalFormat sciFormat = new DecimalFormat("0.##########E0");

	/**
	* the InputMap and ActionMap stuff allows keyboard entry
	* Future improvements:
	* - make keyboard keys light up the relevant buttons
	*/
	public void setUpGUI() {
        // set the default look and feel
        String laf = UIManager.getSystemLookAndFeelClassName();
        try { UIManager.setLookAndFeel(laf);
        } catch (UnsupportedLookAndFeelException exc) {
            System.err.println ("Warning: UnsupportedLookAndFeel: " + laf);
        } catch (Exception exc) {
            System.err.println ("Error loading " + laf + ": " + exc);
        }
		// define buttons
		but1 = new JButton("1");
		but1.addActionListener(keyAction);
		but1.getInputMap(but1.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('1'),"typed");
		but1.getActionMap().put("typed", keyAction);
		but2 = new JButton("2");
		but2.addActionListener(keyAction);
		but2.getInputMap(but2.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('2'),"typed");
		but2.getActionMap().put("typed", keyAction);
		but3 = new JButton("3");
		but3.addActionListener(keyAction);
		but3.getInputMap(but3.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('3'),"typed");
		but3.getActionMap().put("typed", keyAction);
		but4 = new JButton("4");
		but4.addActionListener(keyAction);
		but4.getInputMap(but4.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('4'),"typed");
		but4.getActionMap().put("typed", keyAction);
		but5 = new JButton("5");
		but5.addActionListener(keyAction);
		but5.getInputMap(but5.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('5'),"typed");
		but5.getActionMap().put("typed", keyAction);
		but6 = new JButton("6");
		but6.addActionListener(keyAction);
		but6.getInputMap(but6.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('6'),"typed");
		but6.getActionMap().put("typed", keyAction);
		but7 = new JButton("7");
		but7.addActionListener(keyAction);
		but7.getInputMap(but7.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('7'),"typed");
		but7.getActionMap().put("typed", keyAction);
		but8 = new JButton("8");
		but8.addActionListener(keyAction);
		but8.getInputMap(but8.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('8'),"typed");
		but8.getActionMap().put("typed", keyAction);
		but9 = new JButton("9");
		but9.addActionListener(keyAction);
		but9.getInputMap(but9.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('9'),"typed");
		but9.getActionMap().put("typed", keyAction);
		but0 = new JButton("0");
		but0.addActionListener(keyAction);
		but0.getInputMap(but0.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('0'),"typed");
		but0.getActionMap().put("typed", keyAction);
		butDec = new JButton(".");
		butDec.addActionListener(keyAction);
		butDec.getInputMap(butDec.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('.'),"typed");
		butDec.getActionMap().put("typed", keyAction);
		butEq = new JButton("=");
		butEq.addActionListener(opAction);
		butEq.getInputMap(butEq.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('='),"typed");
		butEq.getActionMap().put("typed", opAction);
		butC = new JButton("C");
		butC.addActionListener(opAction);
		butMRC = new JButton("MRC");
		butMRC.addActionListener(opAction);
		butMRC.setToolTipText("Memory recall");
		butMin = new JButton("M in");
		butMin.addActionListener(opAction);
		butMin.setToolTipText("Store this value in memory");
		butPM = new JButton("+/-");
		butPM.addActionListener(opAction);
		butDivide = new JButton("/");
		butDivide.addActionListener(opAction);
		butDivide.getInputMap(butDivide.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('/'),"typed");
		butDivide.getActionMap().put("typed", opAction);
		butTimes = new JButton("x");
		butTimes.addActionListener(opAction);
		butTimes.getInputMap(butTimes.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('*'),"typed");
		butTimes.getActionMap().put("typed", opAction);
		butMinus = new JButton("-");
		butMinus.addActionListener(opAction);
		butMinus.getInputMap(butMinus.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('-'),"typed");
		butMinus.getActionMap().put("typed", opAction);
		butPlus = new JButton("+");
		butPlus.addActionListener(opAction);
		butPlus.getInputMap(butPlus.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke('+'),"typed");
		butPlus.getActionMap().put("typed", opAction);
        // set up the button panel, a pain in the...
		JPanel butPane = new JPanel(); 
		butPane.setLayout(new GridLayout(5,4));
		butPane.add(butC);
		butPane.add(butPM);
		butPane.add(butMin);
		butPane.add(butMRC);
		butPane.add(but7);
		butPane.add(but8);
		butPane.add(but9);
		butPane.add(butDivide);
		butPane.add(but4);
		butPane.add(but5);
		butPane.add(but6);
		butPane.add(butTimes);
		butPane.add(but1);
		butPane.add(but2);
		butPane.add(but3);
		butPane.add(butMinus);
		butPane.add(but0);
		butPane.add(butDec);
		butPane.add(butEq);
		butPane.add(butPlus);
		// wasn't that fun? now for the main panel
		JPanel pane = new JPanel(); 
		pane.setLayout(new BoxLayout(pane, BoxLayout.PAGE_AXIS));
		pane.add(Box.createRigidArea(new Dimension(0,32)));
		pane.add(butPane);
		setContentPane(pane);		
	}
	
	/*
	* NumKeyAction handles the number entry buttons
	* OpKeyAction handles the other buttons
	*/
	
	class NumKeyAction extends AbstractAction {
		public void actionPerformed(ActionEvent e) {
			Object src = e.getSource();
			if (src == but1) { keyN(1); } else {
			if (src == but2) { keyN(2); } else {
			if (src == but3) { keyN(3); } else {
			if (src == but4) { keyN(4); } else {
			if (src == but5) { keyN(5); } else {
			if (src == but6) { keyN(6); } else {
			if (src == but7) { keyN(7); } else {
			if (src == but8) { keyN(8); } else {
			if (src == but9) { keyN(9); } else {
			if (src == but0) { keyN(0); } else {
			if (src == butDec) { keyDec(); }}}}}}}}}}}
			}
	}
	NumKeyAction keyAction = new NumKeyAction();
// put some of the boolean stuff into this action to shorten code
	class OpKeyAction extends AbstractAction {
		public void actionPerformed(ActionEvent e) {
		Object src = e.getSource();
		if (src == butPlus) { keyPlus(); } else {
		if (src == butMinus) { keyMinus(); } else {
		if (src == butTimes) { keyTimes(); } else {
		if (src == butDivide) { keyDivide(); } else {
		if (src == butEq) { keyEq(); } else {
		if (src == butC) { keyC(); } else {
		if (src == butMRC) { keyMRC(); } else {
		if (src == butMin) { keyMin(); } else {
		if (src == butPM) { keyPM(); }}}}}}}}}
		}
	}
	OpKeyAction opAction = new OpKeyAction();

	/**
	* keyN handles the entry of a number key
	* the other key things handle their respective buttons
	*/
	public void keyN(int n) {
		curDisplay = ((fn || curDisplay == "0") ? 
			String.valueOf(n) : curDisplay+n);
		repaint();
		fn = false;
	}
	
	public void keyDec() {
		if (fn) { curDisplay = "0."; } else {
			if (curDisplay.indexOf('.') == -1) {
				curDisplay += ".";
			}
		}
		repaint();
		fn = false;
		decFlag = true;
	}	

	public void keyEq() {
		// check if any multiplication or division is pending
		if (tPend) {
			cur *= pending;
			tPend = false;
		} else {
			if (dPend) {
				cur = pending / cur;
				dPend = false;
			}
		}
		// check if any addition or subtraction is pending
		if (pHold) {
			cur += addHold;
			pHold = false;
		} else {
			if (mHold) {
				cur = addHold - cur;
				mHold = false;
			}
		}
		curDisplay = String.valueOf(cur);
		repaint();
		fn = true;
		decFlag = false;
	}
	
	public void keyC() {
		curDisplay = "0";
		repaint();
		pHold = false;
		mHold = false;
		tPend = false;
		dPend = false;
		fn = false;
		decFlag = false;
	}
	
	public void keyMRC() {
		curDisplay = String.valueOf(mem);
		repaint();
		fn = true;
		decFlag = false;
	}
	
	public void keyMin() {
		mem = cur;
		fn = true;
	}
	
	public void keyPM() {
		if (curDisplay != "0") {
			curDisplay = ((curDisplay.charAt(0) == '-') ? 
						curDisplay.substring(1) :
						"-"+curDisplay);
			repaint();
			}
		fn = false;
	}

	public void keyDivide() {
		if (dPend) {
			cur = pending / cur;
		} else {
			if (tPend) {
				cur *= pending;
				tPend = false;
			}
		dPend = true;
		}
		// ignore any pending addition or subtraction
		pending = cur;
		curDisplay = String.valueOf(cur);
		repaint();
		fn = true;
		decFlag = false;
	}
	
	public void keyTimes() {
		if (tPend) {
			cur *= pending;
		} else {
			if (dPend) {
				cur = pending / cur;
				dPend = false;
			}
		tPend = true;
		}
		pending = cur;
		curDisplay = String.valueOf(cur);
		repaint();
		fn = true;
		decFlag = false;
	}
	
	public void keyMinus() {
		if (tPend) {
			cur *= pending;
			tPend = false;
		} else {
			if (dPend) {
				cur = pending / cur;
				dPend = false;
			}
		}
		if (mHold) {
			cur = addHold - cur;
		} else {
			if (pHold) {
				cur += addHold;
				pHold = false;
			}
			mHold = true;
		}
		addHold = cur;
		curDisplay = String.valueOf(cur);
		repaint();
		fn = true;
		decFlag = false;
	}
	
	public void keyPlus() {
		if (tPend) {
			cur *= pending;
			tPend = false;
		} else {
			if (dPend) {
				cur = pending / cur;
				dPend = false;
			}
		}
		if (pHold) {
			cur += addHold;
		} else {
			if (mHold) {
				cur = addHold - cur;
				mHold = false;
			}
			pHold = true;
		}
		addHold = cur;
		curDisplay = String.valueOf(cur);
		repaint();
		fn = true;
		decFlag = false;
	}
	
    public void init() {
		setUpGUI();
	}

    public void paint (Graphics g) {
		super.paint(g);
		g.setFont(myFont);
		cur = Double.valueOf(curDisplay).doubleValue();
		if ((cur < 10000000000.0) && ((cur > .00000001) || (cur == 0) || (cur < -.00000001)) && 
			(!decFlag)) {
			g.drawString(myFormat.format(cur), 32, 24);
		} else {
			if (!decFlag) {
				g.drawString(sciFormat.format(cur), 32, 24);
			} else {
				g.drawString(curDisplay, 32, 24);
			}
		}
    }
}