/**
   TicTacToe
   @author John Doe Period 3
*/

import java.util.Scanner;

public class TicTacToe 
{
    
    public static void main(String[] args)
    {
        String[][] board = new String[3][3];    // tic tac toe board
        boolean gameOver = false;               // flag variable determining whether current game is over or not
        boolean validMove = false;              // flag variable determining whether move is valid or not
        Scanner keyboard = new Scanner(System.in);  // user input thru keyboard
        final String COMPUTER_SYMBOL = "o";     // computer's game piece
        final String PLAYER_SYMBOL = "x";       // player's game piece
        
        // initializing board with blank spaces
        for (int row = 0; row < board.length; row++)
        {
            
            for (int col = 0; col < board[row].length; col++)
            {
                board[row][col] = " ";
            }
            
        } 
        
        while (!gameOver)
        {
            // ************************ player's move **************************
            validMove = false;

            while (!validMove)
            {
                System.out.print("Enter row of next move (0 - 2): ");
                int nextMoveRow = keyboard.nextInt();
                System.out.print("Enter column of next move (0 - 2): ");
                int nextMoveColumn = keyboard.nextInt();
                
                if (checkValidMove(board, nextMoveRow, nextMoveColumn))
                {
                    board[nextMoveRow][nextMoveColumn] = PLAYER_SYMBOL;
                    validMove = true;
                }
                else
                {
                    System.out.println("Invalid move!");
                    System.out.println(displayBoard(board));
                }
                
            }
            
            // ************************ computer's move ************************

            // TODO: make random but valid computer move or add AI
            
            System.out.println(displayBoard(board));
        }
        
        
    }// end of main
    
    public static boolean checkValidMove(String[][] board, int row, int col)
    {

        if (row >= 0 && row < 3 && col >= 0 && col < 3 && board[row][col].equals(" "))
        {
            return true;
        }

        return false;
    }// end of checkValidMove
    
    
    public static String displayBoard(String[][] board)
    {
        String str = "";        // board representation
          
        for (int row = 0; row < 3; row++)
        {
            str += "|";
            
            for (int col = 0; col < 3; col++)
            {   
                str += board[row][col] + " ";
            }
            
            str += "|\n";
        }
          
        return str;
    }// end of displayBoard
    
}