package context.arch.service;

import java.awt.Checkbox;
import java.awt.Button;
import java.awt.Label;
import java.awt.Frame;
import java.awt.Panel;
import java.awt.CheckboxGroup;
import java.awt.BorderLayout;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.util.Vector;

/**
 * This class is a frame that runs in it's own thread.  It's able to display
 * a title, question to the user, choices to the user in the form of radio
 * buttons, and to make the user choice available, if any.
 */
public class DisplayChoiceFrame extends Frame implements Runnable, ActionListener {

  /**
   * Tag for the submit button
   */
  public static final String SUBMIT = "submit";

  /**
   * Tag for the cancel button
   */
  public static final String CANCEL = "cancel";

  /**
   * Tag if the user does not select any choice
   */
  public static final String NO_CHOICE = "noChoice";

  private ActionListener listener;
  private String requestId;
  private CheckboxGroup cbg;
  private String choice;
  private Button submit, cancel;

  /**
   * This constructor lays out and creates the frame for the user to view.
   *
   * @param listener ActionListener object to pass events to
   * @param choices List of choices to display to the user
   * @param question Question to pose to the user
   * @param requestId Unique id to identify the result
   */
  public DisplayChoiceFrame(ActionListener listener, Vector choices, String question, String requestId) {
    this.listener = listener;
    this.requestId = requestId;
    setLayout(new BorderLayout());
    GridBagLayout gridbag = new GridBagLayout();
    GridBagConstraints c = new GridBagConstraints();

    Panel p1 = new Panel();
    p1.setLayout(gridbag);
    c.fill = GridBagConstraints.BOTH;
    c.weightx = 1.0;

    Label lQuestion = new Label(question);
    c.gridwidth = GridBagConstraints.REMAINDER;
    gridbag.setConstraints(lQuestion,c);
    p1.add(lQuestion);

    cbg = new CheckboxGroup();
    for (int i=0; i<choices.size(); i++) {
      Checkbox cb = new Checkbox((String)choices.elementAt(i),false,cbg);
      c.gridwidth = GridBagConstraints.REMAINDER;
      gridbag.setConstraints(cb,c);
      p1.add(cb);
      if (i == 0) {
        cbg.setSelectedCheckbox(cb);
      }
    }
    
    add("North",p1);

    Panel p2 = new Panel();
    p2.setLayout(gridbag);
    c.fill = GridBagConstraints.BOTH;
    c.weightx = 1.0;
    
    c.gridwidth = GridBagConstraints.RELATIVE;
    submit = new Button("Submit");
    submit.addActionListener(this);
    submit.setActionCommand(SUBMIT);
    gridbag.setConstraints(submit,c);
    p2.add(submit);

    c.gridwidth = GridBagConstraints.REMAINDER;
    cancel = new Button("Cancel");
    cancel.addActionListener(this);
    cancel.setActionCommand(CANCEL);
    gridbag.setConstraints(cancel,c);
    p2.add(cancel);

    add("South",p2);
  }

  /**
   * This method implements the necessary method for the ActionListener interface.
   * If a user clicks on either button, it collects this information and notifies
   * the listener passed into this class with an ActionEvent containing the
   * object that created the event (submit or cancel button), and the unique
   * id passed into this class.
   *
   * @see ActionEvent
   */
  public void actionPerformed(ActionEvent evt) {
    Object obj;
    if (evt.getActionCommand().equals(SUBMIT)) {
      choice = cbg.getSelectedCheckbox().getLabel();
      obj = submit;
    }
    else {
      choice = NO_CHOICE;
      obj = cancel;
    }
    listener.actionPerformed(new ActionEvent(obj,0,requestId));
  }

  /**
   * This method implements the necessary method for the Runnable interface.
   * It simply makes the frame visible to the user.
   *
   * #setVisible(boolean);
   */
  public void run() {
    setVisible(true);
  }

  /**
   * This method returns the user's choice from the radio buttons.  This 
   * will be one of the input choices, or, if none selected, it will be
   * NO_CHOICE.
   *
   * @return the user's choice
   * @see #NO_CHOICE
   */ 
  public String getChoice() {
    return choice;
  }

}
