import java.util.ArrayList;

public interface GameState
{
  /** @return true if the game is in an ending state;
   *          false otherwise
   */
  boolean isGameOver();

  /** Precondition: isGameOver() returns true
   *  @return the player that won the game or null if there was no winner
   */
  Player getWinner();

  /** Precondition: isGameOver() returns false
   *  @return the player who is to make the next move
   */
  Player getCurrentPlayer();

  /** @return a list of valid moves for the current player;
   * the size of the returned list is 0 if there are no valid moves.
   */
  ArrayList<String> getCurrentMoves();

  /** Updates game state to reflect the effect of  the specified move.
   * @param move a description of the move to be made
   */
  void makeMove(String move);

  /** @return a string representing the current GameState
   */
  String toString();
}