Start detecting checks.

chess/board.go

@@ -45,11 +45,13 @@ func (b Board) GetPieceAt(coord types.Coordinate) (types.Piece, bool) {
 
 	return piece, found
 }
-func (b *Board) CheckMove(move types.Move) (bool, string) {
+
+func (b Board) CheckMove(move types.Move) (bool, string) {
 	pieceAtStartSquare, found := b.GetPieceAt(move.StartSquare)
 	if !found {
 		return false, "no piece at start square"
 	}
+	movingColor := pieceAtStartSquare.Color
 
 	pieceAtEndSquare, found := b.GetPieceAt(move.EndSquare)
 	if found {
@@ -57,9 +59,19 @@ func (b *Board) CheckMove(move types.Move) (bool, string) {
 			return false, "same-coloured piece at end square"
 		}
 	}
+	// At the moment, we do not need to check if the correct color is moving,
+	//since we are only reading moves from the player whose turn it is.
 
 	//Check if king of moving color is in check -> move not allowed
 	//Do that by checking if the king is in a square attacked by the other color.
+	oppKingCoordinate := b.getSquareOfPiece(types.Piece{
+		Class: types.King,
+		Color: movingColor})
+    if oppKingCoordinate == nil {
+        return false, string(movingColor) + " king not found" 
+    }
+            
+    b.isSquareAttacked(*oppKingCoordinate, movingColor.Opposite())
 
 	//Check for checkmate
 	//Is every square that the king can move to attacked? And can no other
@@ -74,3 +86,19 @@ func (b *Board) CheckMove(move types.Move) (bool, string) {
 
 	return true, ""
 }
+
+func (b Board) getSquareOfPiece(piece types.Piece) *types.Coordinate {
+	for k, v := range b {
+		if v == piece {
+			return &k
+		}
+	}
+	return nil
+}
+
+func (b Board) isSquareAttacked(square types.Coordinate, byColor types.ChessColor) bool {
+    attacked := false
+    
+    //get every legal move of color to check if this square is attacked
+    return attacked
+}

types/common.go

@@ -28,6 +28,14 @@ const (
 	Black ChessColor = "black"
 )
 
+func (c ChessColor) Opposite() ChessColor {
+	if c == White {
+		return Black
+	} else {
+		return White
+	}
+}
+
 type Piece struct {
 	Class    PieceClass
 	Color    ChessColor