import java.util.Observable;

/**
 * A Game object represents a series of rounds of play of Rock-Paper-Scissors.
 * This class implements the Observable and Singleton design patterns.
 * Observers can be attached to be notified about changes to the game state.
 * @author Marty Stepp
 * @version CSE 331 Spring 2011, 5/2/2011
 */
public class Game extends Observable {
	private static Game instance = null;
	
	/**
	 * Returns access to the one and only Game instance (Singleton pattern).
	 * @return the sole Game instance
	 */
	public static Game getInstance() {
		if (instance == null) {
			instance = new Game();
		}
		return instance;
	}
	
	// fields
	private Weapon weapon1;   // player 1's weapon in last game round
	private Weapon weapon2;   // player 2's weapon in last game round
	
	// private constructor forbids constructing additional instances
	private Game() {}

	/**
	 * Returns the weapon used by player 1 in this game.
	 * @return player 1's weapon, or null if no games have been played
	 */
	public Weapon getWeapon1() {
		return weapon1;
	}

	/**
	 * Returns the weapon used by player 2 in this game.
	 * @return player 2's weapon, or null if no games have been played
	 */
	public Weapon getWeapon2() {
		return weapon2;
	}
	
	/**
	 * Plays a new round, drawing random weapons for both players.
	 * Also notifies any observers of the change in state of this game.
	 * @modifies this 
	 */
	public void playRound() {
		weapon1 = Weapon.random();
		weapon2 = Weapon.random();
		setChanged();
		notifyObservers();
	}
	
	/**
	 * Returns an integer representing which player won the most recent
	 * round that was played.
	 * @return 1 if player 1 won, 2 if player 2 won, or 0 for a tie.
	 */
	public int winner() {
		if (weapon1.defeats(weapon2)) {
			return 1;
		} else if (weapon2.defeats(weapon1)) {
			return 2;
		} else {
			return 0;
		}
	}
}