move pieces around

game/src/Taquin.gd

@@ -40,10 +40,46 @@ func _ready() -> void:
 
 func _input(event):
 	if event.is_action_pressed("ui_up"):
-		print("up")
+		move_piece(Direction.UP)
 	if event.is_action_pressed("ui_down"):
-		print("down")
+		move_piece(Direction.DOWN)
 	if event.is_action_pressed("ui_left"):
-		print("left")
+		move_piece(Direction.LEFT)
 	if event.is_action_pressed("ui_right"):
+		move_piece(Direction.RIGHT)
+
+enum Direction { UP, DOWN, LEFT, RIGHT }
+
+func move_piece(direction) -> bool:
+	var destination: Vector2 = missing_piece
+	match direction:
+		Direction.UP:
+			print("up")
+			destination.y -= 1
+		Direction.DOWN:
+			destination.y += 1
+			print("down")
+		Direction.LEFT:
+			destination.x -= 1
+			print("left")
+		Direction.RIGHT:
+			destination.x += 1
 			print("right")
+	
+	print(destination)
+	if (destination.x < 0 || destination.x >= columns
+	|| destination.y < 0 || destination.y >= rows):
+		print("impossible move")
+		return false
+
+	swap(missing_piece, destination)
+	missing_piece = destination
+	update()
+	return true
+
+func swap(src: Vector2, dst: Vector2) -> void:
+	var tmp: Piece = pieces[src.x][src.y]
+	pieces[src.x][src.y] = pieces[dst.x][dst.y]
+	pieces[dst.x][dst.y] = tmp
+	pieces[src.x][src.y].position = position_for_index(src, tmp.size)
+	pieces[dst.x][dst.y].position = position_for_index(dst, tmp.size)