Add king rules.

chess/free_squares.go

@@ -30,6 +30,10 @@ func (b *Board) GetNonBlockedDiagonals(fromSquare types.Coordinate) []types.Coor
 	return nonBlocked
 }
 
+func (b *Board) GetNonBlockedKingMoves(fromSquare types.Coordinate) []types.Coordinate {
+    return b.getNonBlockedConsecutive(fromSquare.GetAllKingMoves(), fromSquare)
+}
+
 func (b *Board) GetNonBlockedKnightMoves(fromSquare types.Coordinate) []types.Coordinate {
 	allKnightMoves := fromSquare.GetAllKnightMoves()
 	return b.getNonBlockedForKnights(allKnightMoves, fromSquare)

types/coordinate.go

@@ -1,6 +1,8 @@
 package types
 
-import "github.com/samber/lo"
+import (
+	"github.com/samber/lo"
+)
 
 // coordinates starting at 1:1 and end at 8:8
 type Coordinate struct {
@@ -58,6 +60,22 @@ func (b *CoordinateBuilder) Resolve() *Coordinate {
 	return nil
 }
 
+func (c *Coordinate) GetAllKingMoves() []Coordinate {
+	squares := make([]*Coordinate, 0, 8)
+
+	squares = append(squares, c.Up(1))
+	squares = append(squares, c.Down(1))
+	squares = append(squares, c.Left(1))
+	squares = append(squares, c.Right(1))
+
+	squares = append(squares, newCoordinateBuilder(*c).Up(1).Right(1).Resolve())
+	squares = append(squares, newCoordinateBuilder(*c).Up(1).Left(1).Resolve())
+	squares = append(squares, newCoordinateBuilder(*c).Down(1).Right(1).Resolve())
+	squares = append(squares, newCoordinateBuilder(*c).Down(1).Left(1).Resolve())
+
+	return filterNilSquares(squares)
+}
+
 func (c *Coordinate) GetAllKnightMoves() []Coordinate {
 	unfilteredMoves := make([]*Coordinate, 0, 8)
 
@@ -70,9 +88,13 @@ func (c *Coordinate) GetAllKnightMoves() []Coordinate {
 	unfilteredMoves = append(unfilteredMoves, newCoordinateBuilder(*c).Up(1).Left(2).Resolve())
 	unfilteredMoves = append(unfilteredMoves, newCoordinateBuilder(*c).Up(2).Left(1).Resolve())
 
-	return lo.FilterMap(unfilteredMoves, func(unfilteredMove *Coordinate, _ int) (Coordinate, bool) {
-		if unfilteredMove != nil {
-			return *unfilteredMove, true
+	return filterNilSquares(unfilteredMoves)
+}
+
+func filterNilSquares(squares []*Coordinate) []Coordinate {
+	return lo.FilterMap(squares, func(square *Coordinate, _ int) (Coordinate, bool) {
+		if square != nil {
+			return *square, true
 		}
 		return Coordinate{}, false
 	})