import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dialog;
import java.awt.Event;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Label;
import java.awt.Panel;
import java.awt.TextArea;
import java.awt.TextField;

import net.sourceforge.matex.CalculateException;
import net.sourceforge.matex.Parser;

/*
 * Created on 20.12.2003
 *
 * Copyright 2003, by Josef Lüth
 * 
 */

/**
 * @author Josef Lüth <josef.lueth@web.de>
 * 
 * @version 1.0
 *
 * A software that can be used to calculate terms.
 * It uses Matex to calculate the terms.
 * 
 */
public class MatexRechnerPCE extends Applet
{
	TextArea results = new TextArea();
	TextField term = new TextField(20);
	Object anchorpoint;

	/** Build a GUI
	 */
	public void init()
	{
		setLayout(new BorderLayout());

		//add a panel where the user can enter his term
		Panel dialogue = new Panel();
		add("North", dialogue);
		dialogue.setLayout(new FlowLayout(FlowLayout.CENTER));
		dialogue.add(new Label("Term"));
		dialogue.add(term);
		dialogue.add(new Button("Berechnen"));
		dialogue.add(new Button("Reset"));
		dialogue.add(new Button("Hilfe"));
		dialogue.add(new Button("Info"));

		//add a panel where the calculated terms will show
		Panel result = new Panel();
		add("Center", result);
		//add a textarea where the result will show
		result.add(results);

		//get the frame of the applet (need to open new frames)
		anchorpoint = getParent();
		while (!(anchorpoint instanceof Frame))
			anchorpoint = ((Component) anchorpoint).getParent();
	}

	/**
	 * Calculate the term and show it in the TextArea
	 */
	public void calculate(String term)
	{
		if (!term.equals(""))
		{
			//get the result of the term from Matex
			String result;
			try
			{
				result = Parser.parse(term).eval();
			}
			catch (CalculateException e)
			{
				result = "Fehler bei der Berechnung: " + e.getMessage();
			}
			//show to the user the result
			results.setText(results.getText() + term + " = " + result + "\n");
		}
	}

	/** 
	 * calculate the term, if the user press Enter or click a button
	 */
	public boolean handleEvent(Event evt)
	{
		if (evt.id == Event.KEY_PRESS && evt.key == Event.ENTER)
		{
			calculate(term.getText());
			term.setText("");
			return true;
		}
		if (evt.target instanceof Button && evt.arg != null)
		{
			if (evt.arg.equals("Berechnen"))
			{
				calculate(term.getText());
				term.setText("");
				return true;
			}
			if (evt.arg.equals("Reset"))
			{
				term.setText("");
				results.setText("");
				return true;
			}
			if (evt.arg.equals("Info"))
			{
				//				start info gue
				ShowInfo si = new ShowInfo((Frame) anchorpoint, "Info", true);
				si.resize(350, 150);
				si.show();
				return true;
			}
			if (evt.arg.equals("Hilfe"))
			{
				//				start info gue
				Help helpDialogue = new Help((Frame) anchorpoint, "Info", true);
				helpDialogue.resize(500, 500);
				helpDialogue.show();
				return true;
			}
		}
		return false;
	}

	class ShowInfo extends Dialog
	{
		ShowInfo(Frame parent, String title, boolean modal)
		{
			super(parent, title, modal);
			setBackground(Color.white);
			setLayout(new GridLayout(5, 1));
			add(new Label("Entwickelt von Josef Lüth"));
			add(new Label("Download unter www.MatexSoft.com"));
			add(
				new Label("Kopieren und weitergeben der Software ist genehmigt"));
			add(new Label("Basiert auf dem Matex Modul (www.MatexSoft.com)"));
			add(new Button("Schließen"));
		}

		public Insets insets()
		{
			return new Insets(30, 10, 10, 10);
		}

		public boolean handleEvent(Event evt)
		{
			//			if the user press enter
			if (evt.key == Event.ENTER)
			{
				hide();
				return true;
			}
			else
				//if the user wants to close the dialog
				if (evt.id == Event.WINDOW_DESTROY)
				{
					hide();
					return true;
				}
				else
					if (evt.target instanceof Button && evt.arg != null)
					{
						if (evt.arg.equals("Schließen"))
						{
							hide();
							return true;
						}
					}

			return false;

		}

	}
	class Help extends Dialog
	{
		Help(Frame parent, String title, boolean modal)
		{
			super(parent, title, modal);
			setBackground(Color.white);
			setLayout(new GridLayout(11, 1));
			add(new Label("Ausdrücke für die Eingabe von Termen:"));
			add(new Label("Addieren   +"));
			add(new Label("Subtrahieren   -"));
			add(new Label("Multiplizieren   *"));
			add(new Label("Dividieren   /"));
			add(new Label("Potenzierem   ^"));
			add(new Label("Radizieren(Wurzelziehen)   ^(1/Radikand)"));
			add(new Label("Klammern   (  )"));
			add(new Label("Pi   !pi"));
			add(new Label("e   !e"));
			add(new Button("Schließen"));
		}

		public Insets insets()
		{
			return new Insets(30, 10, 10, 10);
		}

		public boolean handleEvent(Event evt)
		{
			//			if the user press enter
			if (evt.key == Event.ENTER)
			{
				hide();
				return true;
			}
			else
				//if the user wants to close the dialog
				if (evt.id == Event.WINDOW_DESTROY)
				{
					hide();
					return true;
				}
				else
					if (evt.target instanceof Button && evt.arg != null)
					{
						if (evt.arg.equals("Schließen"))
						{
							hide();
							return true;
						}
					}

			return false;

		}

	}
}