package cs3500.tictactoe;

/**
 * A single game of Tic Tac Toe, played on a three-by-three grid with two players,
 * with the object of the game to achieve three markers in a row either vertically,
 * horizontally, or diagonally. {@link Player} X goes first.
 */
public interface TicTacToe {

  /**
   * Execute a move in the position specified by the given row and column.
   *
   * @param r the row of the intended move
   * @param c the column of the intended move
   * @throws IllegalArgumentException if the space is occupied or the position is otherwise invalid
   * @throws IllegalStateException if the game is over
   */
  void move(int r, int c);

  /**
   * Get the current turn, i.e., the player who will mark on the next call to move().
   *
   * @return the {@link Player} whose turn it is
   */
  Player getTurn();

  /**
   * Return whether the game is over. The game is over when either the board is full, or
   * one player has won.
   *
   * @return true if the game is over, false otherwise
   */
  boolean isGameOver();

  /**
   * Return the winner of the game, or {@code null} if there is no winner. If the game is not
   * over, returns {@code null}.
   *
   * @return the winner, or null if there is no winner
   */
  Player getWinner();

  /**
   * Return the current game state, as a 2D array of Player. A {@code null} value in the grid
   * indicates an empty position on the board.
   *
   * @return the current game board
   */
  Player[][] getBoard();

  /**
   * Return the current {@link Player} mark at a given row and column, or {@code null} if the
   * position is empty.
   *
   * @param r the row
   * @param c the column
   * @return the player at the given position, or null if it's empty
   */
  Player getMarkAt(int r, int c);

}