package edu.marlboro.cs.prisoner;
/**
 * <p> Implement one round of the iterated prisoner's dilemma.
 * </p>
 * <p> The two possible strategies are COOPERATE and DEFECT.
 * </p>
 * <p> The four possible outcomes (following the 
 *     definitions from the wikipedia's Prisononer's Dilemma article
 *     as of Feb 2007) are (T, R, P, S) with the properites.
 * </p>
 * <pre>
 *   (1)  T > R > P > S
 *   (2)  2 R > T + S for cooperation to be optimal in repeated play
 * </pre>
 *
 * @see <a href="http://en.wikipedia.org/wiki/Prisoner's_dilemma">Wikipedia: Prisoner's Dilemma</a>
 * @author Jim Mahoney
 * @version $Id: Game.java 12775 2007-04-17 15:23:12Z mahoney $
 */
public class Game {

    /**
     * The first of the two possible strategies.
     */
    public static int COOPERATE = 0;
    /**
     * The second of the two possible strategies.
     */
    public static int DEFECT = 1;

    /**
     * Temptation to defect = 5
     */
    public static int T = 5;
    /**
     * Reward for mutual cooperation = 3
     */
    public static int R = 3;
    /**
     * Punishment for mutual defection = 1
     */
    public static int P = 1;
    /**
     * Sucker's payoff = 0
     */
    public static int S = 0;

    /**
     * payoff for player A is payoffMatrix[A's move][B's move]
     * = {{R,S},{T,P}}
     */
    public static int[][] payoffMatrix = {{R, S}, 
                                          {T, P}};

    /**
     * playerA and playerB go at it in a prisoner's dilemma game,
     * and each of their internal scores is updated appropriately.
     */
    public static void play(Player playerA, Player playerB){
	int strategyA = playerA.getNextMove(playerB.getId());
	int strategyB = playerB.getNextMove(playerA.getId());

	int payoffA = payoffMatrix[strategyA][strategyB];
	playerA.setScore(playerA.getScore() + payoffA);

	int payoffB = payoffMatrix[strategyB][strategyA];
	playerB.setScore(playerB.getScore() + payoffB);
    }

    public static int getPayoff(int A_strategy, int B_strategy){
        return payoffMatrix[A_strategy][B_strategy];
    }
}