/*
 * @(#)ChoiceApplet.java	0.0.0 99/09/02
 *
 * Copyright (c) 1999 by Willie Wheeler.  All rights reserved.
 */
package exercise.choice;

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import javax.swing.border.*;
import exercise.*;
import widget.*;

/**
 * An applet to allow the student to do multiple choice exercises, submit
 * them for evaluation, and receive post-evaluation feedback.
 *
 * @version	0.0.0 09/02/99
 * @author	Willie Wheeler
 */
public class ChoiceApplet extends JApplet implements ActionListener {

    // Applet parameters.
    protected static final String	EXERCISE_ID_PARAM = "exercise_id";

    // Action commands.
    protected static final String	SUBMIT_CMD = "submit";

    // Resource names.
    protected static final String	SUBMIT_RESOURCE =
					"images/submit_exercise.gif";

    // Resources.
    protected static ImageIcon		submitIcon;
    static {
	Class cl = ChoiceApplet.class;
	submitIcon = new ImageIcon(cl.getResource(SUBMIT_RESOURCE));
    }

    // Colors.
    protected static final Color	BORDER_COLOR =
					new Color(51, 51, 102);

    protected static final Color	INSTRUCTIONS_COLOR =
					new Color(51, 102, 153);

    protected static final Color	CHOICES_COLOR =
					new Color(255, 255, 204);

    // Other stuff.
    protected String			exerciseID;
    protected ChoiceExercise		exercise;
    protected ChoicePane		choicePane;

    // Architecturally, the evaluator belongs on the server, not on the
    // client.  (It's easier for the students to cheat if the evaluator sits
    // on the client.)  But since we can't run servlets from CMU Online, and
    // since we have to use CMU Online, we have to put the evaluator here.
    protected static ChoiceEvaluator	evaluator = new ChoiceEvaluator();

    public void init() {
	try {
 
	    // Load an exercise.
	    exerciseID = getParameter(EXERCISE_ID_PARAM);
	    exercise = ChoiceExercise.loadExercise(exerciseID);

	    // Install the exercise workbench.
	    widget.ConcretePLAF.install();	// hack
	    Container cp = getContentPane();
	    cp.setBackground(BORDER_COLOR);
	    cp.setLayout(new GridBagLayout());

	    // Install the instruction panel.
	    addComponent(cp, buildInstructionPanel(), 0, 0, 1, 1,
			 new Insets(2, 2, 0, 2), 1.0, 0.0,
			 GridBagConstraints.BOTH, GridBagConstraints.CENTER);

	    // Install the choice panel.
	    int type = exercise.getType();
	    String[] choices = exercise.getChoices();
	    choicePane = new ChoicePane(type, choices);
	    choicePane.setOpaque(true);
	    choicePane.setBackground(CHOICES_COLOR);
	    addComponent(cp, choicePane, 0, 1, 1, 1,
			 new Insets(2, 2, 2, 2), 1.0, 1.0,
			 GridBagConstraints.BOTH, GridBagConstraints.CENTER);

	} catch (IOException e) {
	    String msg = "Choice.Applet.init(): Failed to load exercise.";
	    System.err.println(msg);
	}
    }

    protected JPanel buildInstructionPanel() {
	JPanel panel = new JPanel();
	panel.setOpaque(true);
	panel.setBackground(INSTRUCTIONS_COLOR);
	panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
	panel.setBorder(new EmptyBorder(10, 10, 10, 10));

	// Add the instructions.
	String instr = "INSTRUCTIONS: " + exercise.getInstructions();
	JTextArea area = new JTextArea(instr, 4, 30);
	Dimension d = area.getPreferredScrollableViewportSize();
	Insets in = area.getInsets();
	d.width += in.left + in.right;
	d.height += in.top + in.bottom;
	area.setPreferredSize(d);

	area.setOpaque(false);
	area.setForeground(Color.white);
	area.setEditable(false);
	area.setLineWrap(true);
	area.setWrapStyleWord(true);
	panel.add(area);

	// Add a strut.
	panel.add(Box.createHorizontalStrut(10));
	
	// Add the submit button.
	JButton submitButton = new JButton("Submit", submitIcon) {
	    public float getAlignmentX() { return Component.CENTER_ALIGNMENT; }
	};
	submitButton.setHorizontalTextPosition(JButton.CENTER);
	submitButton.setVerticalTextPosition(JButton.BOTTOM);
	submitButton.setActionCommand(SUBMIT_CMD);
	submitButton.addActionListener(this);
	panel.add(submitButton);

	// Return the panel.
	return panel;
    }

    /**
     * Adapted from O'Reilly's <i>Java AWT Reference</i>, p. 276,
     */
    public static void addComponent(Container container, Component component,
				    int gridx, int gridy,
				    int gridwidth, int gridheight,
				    Insets insets,
				    double weightx, double weighty,
				    int fill, int anchor) {

	GridBagLayout gbl = (GridBagLayout)container.getLayout();
	GridBagConstraints gbc = new GridBagConstraints();
	gbc.gridx = gridx;
	gbc.gridy = gridy;
	gbc.gridwidth = gridwidth;
	gbc.gridheight = gridheight;
	gbc.insets = insets;
	gbc.weightx = weightx;
	gbc.weighty = weighty;
	gbc.fill = fill;
	gbc.anchor = anchor;
	gbl.setConstraints(component, gbc);
	container.add(component);
    }

    public void actionPerformed(ActionEvent e) {
	String cmd = e.getActionCommand();
	if (cmd == SUBMIT_CMD) { doSubmit(); }
    }

    protected void doSubmit() {

	// Build the student's submission.
	int numChoices = choicePane.getNumChoices();
	boolean[] selected = new boolean[numChoices];
	for (int i = 0; i < numChoices; i++) {
	    selected[i] = choicePane.isSelected(i);
	}
	ChoiceSubmission subn = new ChoiceSubmission(
		null, exercise.getExerciseID(), null, selected);

	// Submit it to the evaluator.
	ChoiceEvaluation eval = evaluator.evaluateSubmission(subn);

	// Present feedback to the student.
	String msg = (eval.studentPassed() ? "Correct!" : "Incorrect.");
	JOptionPane.showMessageDialog(this, msg);
    }
}