159.326-Software-Architecture/Week 11 - TTTLib/GameWinnerService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Week_11___TTTLib
{
    public class GameWinnerService : IGameWinnerService
    {
        private const char NO_WINNER = ' ';

        public char Validate(char[,] board)
        {
            return CheckRow(board,2);
        }

        private static char CheckRow(char[,] board, int rowLimit=2)
        {
            char leftDiag = board[0, 0];
            char rightDiag = board[rowLimit, 0];

            for (int row = 0; row < rowLimit; row++)
            {
                char rowResult = board[0,row];
                char colResult = board[row, 0];

                
                // loop through the row and check it; reset the value if not correct
                for (int col = 1; col < rowLimit; col++)
                {
                    if (board[col, row] != rowResult)
                    {
                        rowResult = NO_WINNER;
                        break;
                    }
                }

                // loop through the col and check it; reset the value if not correct (transposed)
                for (int col = 1; col < rowLimit; col++)
                {
                    if (board[row, col] != colResult)
                    {
                        colResult = NO_WINNER;
                        break;
                    }
                }

                // Verify the the results were won
                if (rowResult != NO_WINNER)
                    return rowResult;
                else if (colResult != NO_WINNER)
                    return colResult;


                // Verify diagonals
                if (board[row, row] != leftDiag)
                {
                    leftDiag = NO_WINNER;
                }
                if (board[rowLimit - row, row] != rightDiag)
                {
                    rightDiag = NO_WINNER;
                }
            }
            
            if (leftDiag != NO_WINNER)
                return leftDiag;
            if (rightDiag != NO_WINNER)
                return rightDiag;

            // return no result otherwise
            return NO_WINNER;
        }
    }

    public interface IGameWinnerService
    {
        char Validate(char[,] board);

    }
}