// Animals.java: Animal guissing game
//
// AUTHOR
//   Michael J. Gourlay
//   Programming Langauges, CS 3155, Fall 1998
//
// DESCRIPTION
//   Think of an animal. This program will then ask a series of
//   yes-or-no questions to try to figure out the animal.
//
// NOTES
//   Use this line in an HTML file for applet use:
//   <applet code=Animals.class WIDTH=550 HEIGHT=200> </applet>

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.text.*;
import java.util.*;

public class Animals extends Applet {
  Label welcomeL = new Label("Welcome to the animal-guessing applet.");
  Label pleaseL  = new Label(
           "Please think of an animal and answer the series of questions.");

  Label        questionL       = new Label("??");
  Button       yesB            = new Button("Yes");
  YesBhClass   yesBH           = new YesBhClass();
  Button       noB             = new Button("No");
  NoBhClass    noBH            = new NoBhClass();
  Hashtable    ht              = new Hashtable();
  final String INITIAL_ANSWERS = "A";
  String       question        = "";
  String       answers         = INITIAL_ANSWERS;

  // Methods

  private void addHorizontalLine(Color c) {
    // Add a Canvas 10000 pixels wide but only 1 pixel high, which acts as
    // a horizontal line to separate one group of components from the next.
    Canvas line = new Canvas( );
    line.setSize(10000,1);
    line.setBackground(c);
    add(line);
  }

  private void addNewLine( ) {
     // Add a horizontal line in the background color. The line itself is
     // invisible, but it serves to force the next Component onto a new line.
     addHorizontalLine(getBackground( ));
  }

  private void setLabel(String s) {
    questionL.setText(s);
    // System.out.println(s);  // for debugging
    // Attempt to redo the GUI layout to accomodate label size change.
    questionL.getParent().invalidate();
    questionL.getParent().validate();
  }

  private int readDataFile () {
    // Read questions/answers database from URL

    URL               u   = null;
    InputStreamReader isr = null;
    BufferedReader    br  = null;

    try {
      // u = new URL("http://csel.cs.colorado.edu/~main/Animals.dat");
      u = new URL("http://michelangelo.colorado-research.com/~gourlay/software/Java/Animals/Animals.dat");
    } catch (MalformedURLException e) {
      setLabel("URL failed: " + e);
      return 1;                                 // tell caller we failed
    }

    try {
      br = new BufferedReader
           (new InputStreamReader(u.openConnection().getInputStream()));
    } catch (IOException e) {
      setLabel("BufferedReader failed: " + e);
      return 2;                                 // tell caller we failed
    }

    // Read the answer/question strings and store in Hashtable
    try {
      String answer_line;
      String question_line;
      while((answer_line = br.readLine()) != null) {
        // This assumes a question will always follow an answer,
        // because no EOF check is done with this readLine.
        question_line = br.readLine();
        // setLabel(question_line + ":" + answer_line); // debugging
        ht.put(answer_line, question_line);             // store in hash table
      }
    } catch (IOException e) {
      setLabel("readLine failed:" + e);
      return 3;                                 // tell caller we failed
    }
    return 0;                                   // tell caller we succeeded
  }

  public void init () {
    // init: called when the applet starts

    // Establish layout of GUI widgets.
    add(welcomeL);
    addNewLine();
    add(pleaseL);
    addHorizontalLine(Color.blue);
    add(questionL);
    addNewLine();
    add(yesB);
    yesB.addActionListener(yesBH);
    add(noB);
    noB.addActionListener(noBH);

    if(readDataFile() != 0) {
      // readDataFile failed so bail out now.
      //   Presumably, readDataFile set the label to an error message.
      // Disable buttons.  This serves two purposes:
      //   (1) Inidicates that there is nothing the applet can do.
      //   (2) Prevents applet from trying to access empty HashTable.
      yesB.setEnabled(false);
      noB.setEnabled(false);
      return;
    }

    // Set the initial question.
    // This assumes that "answers" was initialized.
    setQuestion();
  }

  public void setQuestion() {
    // Given the current set of answers, set the current question.
    if(question.startsWith("I think")) {
      // Previous question was a final question, so restart the system.
      answers = INITIAL_ANSWERS;
      question = (String) ht.get(answers);
      setLabel("Let's play again. " + question);
    } else {
      question = (String) ht.get(answers);
      setLabel(question);
    }
  }

  class YesBhClass implements java.awt.event.ActionListener {
    public void actionPerformed(ActionEvent ev) {
      // This gets called when "Yes" button is pressed.
      answers = answers + "Y" ;
      setQuestion();
    }
  }

  class NoBhClass implements java.awt.event.ActionListener {
    public void actionPerformed(ActionEvent ev) {
      // This gets called when "No" button is pressed.
      answers = answers + "N" ;
      setQuestion();
    }
  }
}