/*
 *  JFLAP - Formal Languages and Automata Package
 * 
 * 
 *  Susan H. Rodger
 *  Computer Science Department
 *  Duke University
 *  August 27, 2009

 *  Copyright (c) 2002-2009
 *  All rights reserved.

 *  JFLAP is open source software. Please see the LICENSE for terms.
 *
 */





package gui.action;

import gui.environment.Environment;
import gui.environment.EnvironmentFrame;
import gui.environment.Universe;

import java.awt.event.ActionEvent;

import javax.swing.JComboBox;
import javax.swing.JOptionPane;

import automata.UselessStatesDetector;
import automata.fsa.FiniteStateAutomaton;
import automata.graph.FSAEqualityChecker;

/**
 * This tests to see if two finite state automatons accept the same language.
 * 
 * @author Thomas Finley
 */

public class DFAEqualityAction extends FSAAction {
	/**
	 * Instantiates a new <CODE>DFAEqualityAction</CODE>.
	 * 
	 * @param automaton
	 *            the automaton that input will be simulated on
	 * @param environment
	 *            the environment object that we shall add our simulator pane to
	 */
	public DFAEqualityAction(FiniteStateAutomaton automaton,
			Environment environment) {
		super("Compare Equivalence", null);
		this.environment = environment;
		/*
		 * putValue(ACCELERATOR_KEY, KeyStroke.getKeyStroke (KeyEvent.VK_R,
		 * MAIN_MENU_MASK+InputEvent.SHIFT_MASK));
		 */
	}

	/**
	 * Runs a comparison with another automaton.
	 * 
	 * @param e
	 *            the action event
	 */
	public void actionPerformed(ActionEvent e) {
		JComboBox combo = new JComboBox();
		// Figure out what existing environments in the program have
		// the type of structure that we need.
		EnvironmentFrame[] frames = Universe.frames();
		for (int i = 0; i < frames.length; i++) {
			if (!isApplicable(frames[i].getEnvironment().getObject())
					|| frames[i].getEnvironment() == environment)
				continue;
			combo.addItem(frames[i]);
		}
		// Set up our automaton.
		FiniteStateAutomaton automaton = (FiniteStateAutomaton) environment
				.getObject();

		if (combo.getItemCount() == 0) {
			JOptionPane.showMessageDialog(Universe
					.frameForEnvironment(environment), "No other FAs around!");
			return;
		}
		if (automaton.getInitialState() == null) {
			JOptionPane.showMessageDialog(Universe
					.frameForEnvironment(environment),
					"This automaton has no initial state!");
			return;
		}
		// Prompt the user.
		int result = JOptionPane.showOptionDialog(Universe
				.frameForEnvironment(environment), combo, "Compare against FA",
				JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE,
				null, null, null);
		if (result != JOptionPane.YES_OPTION && result != JOptionPane.OK_OPTION)
			return;
		FiniteStateAutomaton other = (FiniteStateAutomaton) ((EnvironmentFrame) combo
				.getSelectedItem()).getEnvironment().getObject();
		if (other.getInitialState() == null) {
			JOptionPane.showMessageDialog(Universe
					.frameForEnvironment(environment),
					"The other automaton has no initial state!");
			return;
		}
		other = (FiniteStateAutomaton) UselessStatesDetector
				.cleanAutomaton(other);
		automaton = (FiniteStateAutomaton) UselessStatesDetector
				.cleanAutomaton(automaton);
		String checkedMessage = checker.equals(other, automaton) ? "They ARE equivalent!"
				: "They AREN'T equivalent!";
		JOptionPane.showMessageDialog(
				Universe.frameForEnvironment(environment), checkedMessage);
	}

	/** The environment. */
	private Environment environment;

	/** The equality checker. */
	private static FSAEqualityChecker checker = new FSAEqualityChecker();
}