/******************************* FILE HEADER **********************************
    Program:          Tic Tac Toe, version 1
    File:             Rules.java
    Main File:        TicTacToe1.java
    
    Author:           James D. Skrentny
                      copyright 2000, all rights reserved
    Course:           CS 302, Fall 2000, Lectures 1 & 2
    
    Compiler:         CodeWarrior IDE 4.0 (JDK 1.2)
    Platform:         Windows NT 4.0
 **************************** 80 columns wide *********************************/

/**
 * The Rules class is used to verify that players are playing by the
 * rules for the game Tic Tac Toe.
 *
 * Bugs: none known
 **/
 
/*
 * The following concepts are illustrated:
 *     - public class methods (see checkMove and checkWin)
 *     - private class method (see win)
 *     - sequenced if statements (see checkMove and checkWin)
 *     - simple conditions (see checkMove and checkWin)
 *     - conditions using messages (see checkMove and checkWin)
 *     - complex conditions (see checkWin)
 */

public class Rules {

    /**         
    * Checks if a specified move is valid for the specified board. If the move
    * isn't valid, an error message is displayed and the program is terminated.
    *
    * @param move the specified move to be checked
    * @param board the specified board on which the move would be made
    **/
    public static void checkMove (Move move, Board board) {

        // check if row and column are valid
        int row = move.getRow();
        int col = move.getCol();
        boolean invalid = false;
        if (row < 1 || row > 3) {
            System.out.println("Invalid row:    " + row);
            invalid = true;
        }
        if (col < 1 || col > 3) {
            System.out.println("Invalid column: " + col);
            invalid = true;
        }
        // terminate the program if invalid row or column
        if (invalid) {
            System.out.println("BYE!");
            System.exit(1);
        }
        // check if cell is taken and terminate the program if so
        else if (!board.cellFree(move)) {
            System.out.println("Invalid Move, cell taken.  BYE!");
            System.exit(1);
        }
    }
    
    /**    
    * Checks if a specified move results in a win for the specified mark
    * on the board. The row, column, and possibly a diagonal are checked for
    * three of the player's marks "in a row".
    * If there is a winner, the mark of the winner is displayed and the program
    * is terminated.
    *
    * @param move the specified move where the checking is to be based
    * @param board the board to be checked for a win
    * @param mark the mark of the player that is to be checked for a win
    **/
    public static void checkWin (Board board, Move move, Mark mark) {
        int row = move.getRow();
        int col = move.getCol();
        
        // check if win in a row or column, and if so call win()
        if (board.checkRow(row, mark)) win(board, mark);
        if (board.checkCol(col, mark)) win(board, mark);
                
        // check if win along a diagonal, and if so call win()
        if (row == 1 && col == 1 || row == 2 && col == 2
            || row == 3 && col == 3)
            if (board.checkDiag(1, mark)) win(board, mark);
            
        if (row == 1 && col == 3 || row == 2 && col == 2
            || row == 3 && col == 1)
            if (board.checkDiag(2, mark)) win(board, mark);
    }   

    /**         
    * Displays the board with the win and terminates the program.
    *
    * @param board the board with a win
    * @param mark the winning player's mark
    **/

    private static void win (Board board, Mark mark) {
        System.out.println("\n");
        board.display();
        System.out.println(mark + " wins!  Game over.  BYE!");
        System.exit(0);     
    }
    
}