public void PlaceStone(HexCoordinate cord)
{
if (Winner != Player.None)
{
throw new Exception("The game is already over");
}
if (!validPlacements.Contains(cord))
{
throw new Exception("Tried to place a stone in an invalid position!");
}
// Update the chain collection
switch (ActivePlayer)
{
case Player.Black: BlackChains.Add(cord); break;
case Player.White: WhiteChains.Add(cord); break;
}
// Place stone
Board.PlaceStone(cord, ActivePlayer);
lastMoves.Push(cord);
// Switch active player
ActivePlayer = ActivePlayer.GetOpponent();
// Remove the old placement coordinate
if (IsFirstTurn)
{
validPlacements.Clear();
IsFirstTurn = false;
}
else
{
validPlacements.Remove(cord);
}
// Add new placement coordinates
var neighbors = Board.GetNeighbors(cord);
for (var i = 0; i < neighbors.Length; i++)
{
var neighbor = neighbors[i];
// Do not add coordinates where a stone is already placed
if (Board[neighbor] != Player.None)
{
continue;
}
var neighborCount = CountNeighborStones(neighbor);
if (neighborCount >= 2)
{
validPlacements.Add(neighbor);
}
}
// Check if a player won or if it's a draw
Winner = GetWinner(cord);
if (Winner != Player.None || validPlacements.Count == 0)
{
IsGameOver = true;
return;
}
}
public void UndoLastMove()
{
if (lastMoves.Count == 0)
{
throw new Exception("Tried to undo the last move, when no last moves are available");
}
var lastMove = lastMoves.Pop();
// Remove the stone
Board.RemoveStone(lastMove);
validPlacements.Add(lastMove);
// Switch the active player
ActivePlayer = ActivePlayer.GetOpponent();
// Remove enclosed stones
if (moveEnclosedStones.ContainsKey(lastMove))
{
foreach (var tile in moveEnclosedStones[lastMove])
{
EnclosedStones[ActivePlayer].Remove(tile);
}
moveEnclosedStones.Remove(lastMove);
}
// Update the chain collection
switch (ActivePlayer)
{
case Player.Black: BlackChains.Remove(lastMove); break;
case Player.White: WhiteChains.Remove(lastMove); break;
}
// Remove now invalid placements
if (CanUndo)
{
var neighbors = Board.GetNeighbors(lastMove);
for (var i = 0; i < neighbors.Length; i++)
{
var neighbor = neighbors[i];
if (Board[neighbor] != Player.None)
{
continue;
}
var neighborCount = CountNeighborStones(neighbor);
if (neighborCount < 2)
{
validPlacements.Remove(neighbor);
}
}
}
else
{
// We are at the beginning of the game
IsFirstTurn = true;
validPlacements.Clear();
foreach (var neighbor in Center.GetNeighborsClockwise())
{
validPlacements.Add(neighbor);
}
}
// Remove the winning player
Winner = Player.None;
IsGameOver = false;
}