/// <summary>
/// Performs a step in the game and notifies all associated clients using a push notification.
/// </summary>
/// <param name="SessionID">Identifier of the client who performed the move.</param>
/// <param name="x">The X position of the move performed.</param>
/// <param name="y">The Y position of the move performed.</param>
/// <param name="playerLetter">Letter representing the player's move. Either "X" or "O".</param>
public void GameStep(Guid SessionID, int x, int y, string player)
{
TicTacToeMove move = new TicTacToeMove()
{
X = x, Y = y, Player = player
};
if (!ValidateTicTacToeMove(move))
{
return;
}
gameState.StepsMade++;
// Perform the requested move
MakeMove(move);
// Update the game state in light of the move performed
UpdateState(move);
byte[] bytes = GetBytes <TicTacToeMove>(move);
// Notify all the relevant clients of the move
foreach (KeyValuePair <Guid, Subscription> sub in subscribers)
{
if (sub.Value.SessionID != SessionID)
{
SendMessage(sub.Value.ChannelUri, bytes);
}
}
}
/// <summary>
/// Check if a move is legal.
/// </summary>
/// <param name="move">Move the validate.</param>
/// <returns>True if the move is valid and false otherwise.</returns>
private bool ValidateTicTacToeMove(TicTacToeMove move)
{
if (gameState.StepsMade == 0)
{
if (move.Player == ConstData.XString)
{
gameState.CurrentState = TicTacToeState.XPlayerTurn;
}
else
{
gameState.CurrentState = TicTacToeState.OPlayerTurn;
}
}
bool isValid = true;
// Invalidate the move if it is illegal because of the game state
switch (gameState.CurrentState)
{
case TicTacToeState.XPlayerTurn:
if (move.Player == ConstData.OString)
{
isValid = false;
}
break;
case TicTacToeState.OPlayerTurn:
if (move.Player == ConstData.XString)
{
isValid = false;
}
break;
case TicTacToeState.XPlayerWin:
case TicTacToeState.OPlayerWin:
case TicTacToeState.Tie:
isValid = false;
break;
default:
break;
}
// Check if the requested cell is off the board
if (move.X < 0 || move.X > ColumnMaxSize || move.Y < 0 || move.Y > RowMaxSize)
{
isValid = false;
}
// Checks that the cell is empty
if (gameState.Board[move.X][move.Y] != string.Empty)
{
isValid = false;
}
return(isValid);
}
/// <summary>
/// Put a move on the board.
/// </summary>
/// <param name="move">Move to perform.</param>
private void MakeMove(TicTacToeMove move)
{
gameState.Board[move.X][move.Y] = move.Player;
}
/// <summary>
/// Update the state of the game in light of a move performed by one of the clients. This checks whether or
/// not the game has ended. If the game ended determines the game result and otherwise changes the currently
/// active player.
/// </summary>
/// <param name="move">The move performed by one of the clients.</param>
private void UpdateState(TicTacToeMove move)
{
bool isGameOver = false;
// In order to win this game, a player must perform at least 3 steps.
// Therefore, if we count 5 steps for both players it means that player "X" already made 3 steps.
if (gameState.StepsMade >= MinimumStepsToCheckVictory)
{
int col = 0;
int row = 0;
int leftDiagonal = 0;
int rightDiagonal = 0;
// See if the player won by performing the supplied move
for (int i = 0; i < RowMaxSize; i++)
{
// Checks the move's column
if (gameState.Board[move.X][i] == move.Player)
{
col++;
}
// Checks the move's row
if (gameState.Board[i][move.Y] == move.Player)
{
row++;
}
// Checks the primary diagonal
if (gameState.Board[i][i] == move.Player)
{
leftDiagonal++;
}
// Checks the secondary diagonal
if (gameState.Board[i][2 - i] == move.Player)
{
rightDiagonal++;
}
}
// If we have a winner: change the state
if (row == RowMaxSize || col == ColumnMaxSize ||
leftDiagonal == RowMaxSize || rightDiagonal == RowMaxSize)
{
if (move.Player == ConstData.XString)
{
gameState.CurrentState = TicTacToeState.XPlayerWin;
}
else
{
gameState.CurrentState = TicTacToeState.OPlayerWin;
}
isGameOver = true;
}
// If all the board is full and no one wins then there is a tie
if (gameState.StepsMade == TotalCellCount && !isGameOver)
{
gameState.CurrentState = TicTacToeState.Tie;
isGameOver = true;
}
}
// If there is no winner and the board is not full, change the active player
if (!isGameOver)
{
if (gameState.CurrentState == TicTacToeState.XPlayerTurn)
{
gameState.CurrentState = TicTacToeState.OPlayerTurn;
}
else
{
gameState.CurrentState = TicTacToeState.XPlayerTurn;
}
}
move.GameFlow = gameState.CurrentState.ToString();
}