/// <summary>
/// Method to place to valid position in Grid
/// </summary>
/// <param name="player"></param>
/// <param name="selectedColumn"></param>
/// <param name="gameBoard"></param>
/// <returns></returns>
private bool PushBall(Player player, int selectedColumn, ref int?[,] board, ref LastMovePosition lastMove, int rows, int columns)
{
try
{
int row = 0;
while (row < rows && !board[selectedColumn, row].HasValue)
{
row++;
}
if (row == 0)
{
return(false);
}
//var playerId = player.ToDictionary();
var playedId = (int)Enum.Parse(typeof(Player), player.ToString());
lastMove.column = selectedColumn;
lastMove.cell = row - 1;
board[selectedColumn, row - 1] = playedId;
_changed = true;
return(true);
}
catch (Exception ex)
{
return(false);
}
}
/// <summary>
///
/// </summary>
/// <param name="depth"></param>
/// <param name="board"></param>
/// <param name="maximizingPlayer"></param>
/// <returns></returns>
private int MinMax(int depth, ref int?[,] gameboard, ref LastMovePosition lastMove, bool maximizingPlayer, int rows, int columns)
{
if (depth <= 0)
{
return(0);
}
var winner = GetWinner(ref gameboard, rows, columns);
if (winner == 2)
{
return(depth);
}
if (winner == 1)
{
return(-depth);
}
if (IsGameBoardFull(columns, ref gameboard))
{
return(0);
}
int bestValue = maximizingPlayer ? -1 : 1;
for (int i = 0; i < columns; i++)
{
if (!PushBall(maximizingPlayer?Player.Computer:Player.User, i, ref gameboard, ref lastMove, rows, columns))
{
continue;
}
int v = MinMax(depth - 1, ref gameboard, ref lastMove, !maximizingPlayer, rows, columns);
bestValue = maximizingPlayer ? Math.Max(bestValue, v) : Math.Min(bestValue, v);
PopTopBall(i, ref gameboard, rows);
}
return(bestValue);
}
public async Task <bool> Handle(GameBoardUserRequest message, IOutputPort <GameBoardUserResponse> outputPort)
{
responseMessage = string.Empty;
bool responseStatus = false;
List <string> errors = new List <string>();
int?[,] board = message.gameboard;
LastMovePosition lastMove = new LastMovePosition();
int? boardWinner = -1;
bool boardIsFull = false;
bool gameOver = false;
try
{
switch (message.player)
{
case Player.User:
if (!PushBall(Player.User, message.selectedColumn - 1, ref board, ref lastMove, message.rows, message.columns))
{
responseMessage = "Select different Column, Column full";
}
boardWinner = GetWinner(ref board, message.rows, message.columns) ?? -1;
if (boardWinner == 1)
{
responseMessage = $"{Player.User.ToString()} Won!";
WinningPositions(ref board, boardWinner);
gameOver = true;
}
break;
case Player.Computer:
var random = new Random();
var moves = new List <Tuple <int, int> >();
for (int position = 0; position < message.columns; position++)
{
if (!PushBall(Player.Computer, position, ref board, ref lastMove, message.rows, message.columns))
{
continue;
}
var item = await Task.Run(() => MinMax(5, ref board, ref lastMove, false, message.rows, message.columns));
moves.Add(Tuple.Create(position, item));
PopTopBall(position, ref board, message.rows);
}
int maxMoveScore = moves.Max(t => t.Item2);
var bestMoves = moves.Where(t => t.Item2 == maxMoveScore).ToList();
PushBall(Player.Computer, bestMoves[random.Next(0, bestMoves.Count)].Item1, ref board, ref lastMove, message.rows, message.columns);
boardWinner = GetWinner(ref board, message.rows, message.columns) ?? -1;
if (boardWinner == 2)
{
responseMessage = $"{Player.Computer.ToString()} Won!";
WinningPositions(ref board, boardWinner);
gameOver = true;
}
break;
default:
responseMessage = "Welcome to Connect 4. Make your first move...";
break;
}
boardIsFull = IsGameBoardFull(message.columns, ref board);
if (boardIsFull)
{
responseMessage = "Game Board Full. Its a Tie!";
gameOver = true;
}
responseStatus = true;
}
catch (Exception ex)
{
responseStatus = false;
responseMessage = "Unexpectd Error Occured";
gameOver = true;
}
finally
{
outputPort.Handle(new GameBoardUserResponse(board, lastMove, message.player, boardWinner, message.rows, message.columns, gameOver, errors, responseStatus, responseMessage));
}
return(responseStatus);
}
