refactor - direction String에서 ENUM 선언

game-server/src/main/kotlin/game/server/dto/Direction.kt

@@ -0,0 +1,5 @@
+package game.server.dto
+
+enum class Direction {
+    UP, DOWN, LEFT, RIGHT
+}

game-server/src/main/kotlin/game/server/dto/PlayerMoveRequest.kt

@@ -4,6 +4,6 @@ import game.server.domain.Position
 
 data class PlayerMoveRequest(
     val currentPosition: Position,
-    val direction: String,
+    val direction: Direction,
     val speed: Int
 ) : Request

game-server/src/main/kotlin/game/server/handler/PlayerMoveHandler.kt

@@ -1,8 +1,9 @@
 package game.server.handler
 
-import com.fasterxml.jackson.databind.ObjectMapper
 import game.server.Player
 import game.server.domain.Position
+import game.server.dto.Direction
+import game.server.dto.Direction.*
 import game.server.dto.PlayerMoveRequest
 import game.server.dto.response.ApiResponse
 import game.server.dto.response.Error
@@ -37,13 +38,12 @@ class PlayerMoveHandler(
         }
     }
 
-    private fun calculateNewPosition(x: Int, y: Int, direction: String, speed: Int): Position {
+    private fun calculateNewPosition(x: Int, y: Int, direction: Direction, speed: Int): Position {
         return when (direction) {
-            "UP" -> Position(x, y - speed)
-            "DOWN" -> Position(x, y + speed)
-            "LEFT" -> Position(x - speed, y)
-            "RIGHT" -> Position(x + speed, y)
-            else -> Position(x, y)
+            UP -> Position(x, y - speed)
+            DOWN -> Position(x, y + speed)
+            LEFT -> Position(x - speed, y)
+            RIGHT -> Position(x + speed, y)
         }
     }