From d5b8bdf6304d70e75ff666d862528c8d373df473 Mon Sep 17 00:00:00 2001
From: Marco <mgross@sw-gross.de>
Date: Wed, 14 Jun 2023 19:46:46 +0200
Subject: [PATCH] Start detecting checks.

---
 chess/board.go  | 62 +++++++++++++++++++++++++++++++++++--------------
 types/common.go |  8 +++++++
 2 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/chess/board.go b/chess/board.go
index 3e65695..3a1c13a 100644
--- a/chess/board.go
+++ b/chess/board.go
@@ -45,32 +45,60 @@ 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 {
-        if pieceAtEndSquare.Color == pieceAtStartSquare.Color {
-            return false, "same-coloured piece at end square"
-        }
+	pieceAtEndSquare, found := b.GetPieceAt(move.EndSquare)
+	if found {
+		if pieceAtEndSquare.Color == pieceAtStartSquare.Color {
+			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 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.
+	//Check for checkmate
+	//Is every square that the king can move to attacked? And can no other
+	//piece block? -> checkmate
 
-    //Check for checkmate
-    //Is every square that the king can move to attacked? And can no other
-    //piece block? -> checkmate
+	//Maybe for checking checkmate, we have to check the 'path' in which the
+	//checkmate is given
 
-    //Maybe for checking checkmate, we have to check the 'path' in which the
-    //checkmate is given
-
-    // |K| | | | |Q|
-    // in this scenaria the path are all the squares between queen and king.
-    // If a piece can be moved into the path, it is no checkmate
+	// |K| | | | |Q|
+	// in this scenaria the path are all the squares between queen and king.
+	// If a piece can be moved into the path, it is no checkmate
 
 	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
+}
diff --git a/types/common.go b/types/common.go
index db03bd2..a38b767 100644
--- a/types/common.go
+++ b/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