From d40c7577765dd093d409ac756e0b9e05873ef46a Mon Sep 17 00:00:00 2001
From: Marco <mgross@sw-gross.de>
Date: Fri, 10 May 2024 02:29:11 +0200
Subject: [PATCH] fix bug that prevented king from moving because server
 thought it wanted to castling (but it was not a castling move)

---
 chess/board_castling_test.go | 31 +++++++++++++++++++++++++++++++
 chess/king.go                | 26 ++++++++++++++++++++++++++
 chess/violation.go           |  1 +
 3 files changed, 58 insertions(+)

diff --git a/chess/board_castling_test.go b/chess/board_castling_test.go
index a2ad144..00440f0 100644
--- a/chess/board_castling_test.go
+++ b/chess/board_castling_test.go
@@ -296,3 +296,34 @@ func Test_Board_BlackCastlesRight_NoRook(t *testing.T) {
 
 	assert.False(t, valid)
 }
+
+func Test_Board_fixBugThatPreventsCastling(t *testing.T) {
+	board := newBoard()
+	board.Init()
+
+	//white move
+	valid, violation := board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 5, Row: 2}, EndSquare: types.Coordinate{Col: 5, Row: 3}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+	//black move
+	valid, violation = board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 5, Row: 7}, EndSquare: types.Coordinate{Col: 5, Row: 6}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+	//white move
+	valid, violation = board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 4, Row: 2}, EndSquare: types.Coordinate{Col: 4, Row: 3}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+	//black move
+	valid, violation = board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 6, Row: 7}, EndSquare: types.Coordinate{Col: 6, Row: 6}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+	//queen moves to check the king
+	valid, violation = board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 4, Row: 1}, EndSquare: types.Coordinate{Col: 8, Row: 5}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+
+	//this moves should be valid but it was not because of a bug
+	valid, violation = board.CheckAndPlay(&types.Move{StartSquare: types.Coordinate{Col: 5, Row: 8}, EndSquare: types.Coordinate{Col: 5, Row: 7}})
+	assert.True(t, valid)
+	assert.Empty(t, violation)
+}
diff --git a/chess/king.go b/chess/king.go
index b59bc4d..a8b7df2 100644
--- a/chess/king.go
+++ b/chess/king.go
@@ -30,6 +30,10 @@ func (k King) AfterMoveAction(board *Board, fromSquare types.Coordinate) {
 }
 
 func (k King) HandleCastling(board *Board, move types.Move) (bool, Violation) {
+	if !k.isMoveCastlingMove(board, move) {
+		return false, ""
+	}
+
 	if k.hadMovedBefore(board) {
 		return false, ""
 	}
@@ -66,6 +70,28 @@ const (
 	CastlingLeft  CastlingDirection = "left"
 )
 
+func (k King) isMoveCastlingMove(b *Board, move types.Move) bool {
+	var destinationSquareForKingRight types.Coordinate
+	var destinationSquareForKingLeft types.Coordinate
+
+	switch k.Color {
+	case types.White:
+		destinationSquareForKingRight = types.Coordinate{Col: 7, Row: 1}
+		destinationSquareForKingLeft = types.Coordinate{Col: 3, Row: 1}
+
+	case types.Black:
+		destinationSquareForKingRight = types.Coordinate{Col: 7, Row: 8}
+		destinationSquareForKingLeft = types.Coordinate{Col: 3, Row: 8}
+	}
+
+	if move.EndSquare == destinationSquareForKingRight ||
+		move.EndSquare == destinationSquareForKingLeft {
+		return true
+	}
+
+	return false
+}
+
 func (k King) isCastlingAllowed(b *Board, move types.Move) (bool, CastlingDirection) {
 	var valid = false
 
diff --git a/chess/violation.go b/chess/violation.go
index 8cc45c7..1bc22ef 100644
--- a/chess/violation.go
+++ b/chess/violation.go
@@ -11,6 +11,7 @@ var (
 	SomethingWentWrong       Violation = "something went wrong"
 	CastlingThroughCheck     Violation = "king would move through check"
 	CastlingWhileKingInCheck Violation = "king cannot castle while in check"
+	CastlingKingMovedBefore  Violation = "king cannot caslte because he moved before"
 )
 
 func (v Violation) String() string {