import java.io.*;
import java.util.Random;

/*
 * A class to illustrate some potentially useful ideas for the
 * WheelOfFortune project.
 */
public class WheelOfFortuneHints
  {

  /* Some instance variables. */
  private Random theRandomGenerator;
  private boolean theLoopGoesOn; 
  private BufferedReader theFileReader;
  private String oneLineFromFile;
  private StringBuffer theStringBuffer;
  private int numLines;

  /*
   * The main program creates a WheelOfFortuneHints object
   * and then calls instance methods on it. 
   */
  public static void main(String[] args)
    {
    /* Create an instance of the WheelOfFortuneHints class. */ 
    WheelOfFortuneHints hinter = new WheelOfFortuneHints();

    /* Now we can call the instance methods on this instance. */
    hinter.initializeHints();
    hinter.runHint();

    /* Also we can access the instance variables of this instance. */ 
    System.out.println("The number of lines is " + hinter.numLines); 
    }

  /*
   * Initialize some of the instance variables of a WheelOfFortuneHints
   * object. Although the WheelOfFortuneHints object is not a parameter,
   * we have access to it implicitly because this is a non-static 
   * instance method.
   */
  private void initializeHints()
    {
    theRandomGenerator = new Random(5); // Seed a Random object with seed 5.
    try
      {
      theFileReader = new BufferedReader(new FileReader("wheel.txt"));
      }
    catch(IOException e)
      {
      System.out.println("File wheel.txt not found.");
      e.printStackTrace();
      }
    }

  /* 
   * This function reads each line from a file, keeps a count of the
   * number of lines, and prints out the line with a random character 
   * replaced with a '*' character. 
   */
  private void runHint()
    {
    numLines = 0;
    theLoopGoesOn = true;
    try
      {
      while (theLoopGoesOn) // Note use of boolean variable to control loop.
        {
        oneLineFromFile = theFileReader.readLine();
        if (oneLineFromFile == null)
          {
          theLoopGoesOn = false; // Something happened to end the loop.
          }
        else
	  {
          numLines++;
	  theStringBuffer = new StringBuffer(oneLineFromFile);
	  System.out.println("Before:);
	  System.out.println(theStringBuffer);
          replaceRandomCharacter();
	  System.out.println("After:");
	  System.out.println(theStringBuffer);
	  }
	}
      }
    catch(IOException e)
      {
      System.out.println("Problem reading from file.");
      e.printStackTrace();
      }
    }

  /*
   * This function replaces a character at a random position in the
   * StringBuffer with an '*' character. 
   * Illustrates the setCharAt method in the StringBuffer class. 
   */
  public void replaceRandomCharacter()
    {
    int replacementPos = theRandomGenerator.nextInt(theStringBuffer.length()); 
    theStringBuffer.setCharAt(replacementPos, '*'); 
    }
  }