// MindReader.java
// Raja Sooriamurthi

import java.util.*;

public class MindReader 
{
  private Hashtable memory;
  private ShiftBuffer sb;

  // *************************
  //   MindReader
  // *************************

  public MindReader() 
  {
    memory = new Hashtable();
    sb = new ShiftBuffer(4);
  }

  // *************************
  //   getPrediction
  // *************************

  public char getPrediction() 
  {
    String key = sb.toString();
    if (memory.containsKey (key)) 
      {
        HTcounter htc = (HTcounter) memory.get(key);
        return (htc.getHead() > htc.getTail() ? 'h' : 't');
      } 
    else 
      {
        return (Math.random() > 0.5) ? 'h' : 't' ;
      }
  }

  // *************************
  //   storePlayerGuess
  // *************************

  public void storePlayerGuess (char guess) 
  {
    HTcounter htc;
    String key = sb.toString();
    if (memory.containsKey (key)) 
      {
        htc = (HTcounter) memory.get(key);
      } 
    else 
      { // make a new pair of counters and store them in memory
        htc = new HTcounter();
        memory.put(key,htc);
      }

    // htc now contains a -reference- to the object in the hash table
    // hence after incrementing the appropriate counter below
    // we DO NOT have to store it back in the hash table

    if (guess == 'h') 
      htc.incrHead();
    else
      htc.incrTail();

    // finally shift the buffer
    sb.shift(guess);
  }

}