From 9bac80db8e9c5ceb2fe22f6ed42ef1a0597df476 Mon Sep 17 00:00:00 2001
From: Xavier Fontanet <xavier.fontanet@edreamsodigeo.com>
Date: Thu, 20 Jun 2024 21:04:31 +0200
Subject: [PATCH] make Coordinates immutable

---
 .../codingtests/marsrover/Coordinates.java    | 24 +++++++++----------
 .../codingtests/marsrover/MarsRover.java      |  8 +++----
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/src/main/java/cat/hack3/codingtests/marsrover/Coordinates.java b/src/main/java/cat/hack3/codingtests/marsrover/Coordinates.java
index 739bf38..60aa99e 100644
--- a/src/main/java/cat/hack3/codingtests/marsrover/Coordinates.java
+++ b/src/main/java/cat/hack3/codingtests/marsrover/Coordinates.java
@@ -14,8 +14,8 @@ import java.util.logging.Logger;
  * 3  3-1  3-2  3-3
  */
 public class Coordinates {
-    private int latitude;
-    private int longitude;
+    private final int latitude;
+    private final int longitude;
     private final Logger logger = Logger.getLogger(Coordinates.class.getName());
 
     public static Coordinates of(int latitude, int longitude) {
@@ -27,16 +27,19 @@ public class Coordinates {
         this.longitude = longitude;
     }
 
-    public Coordinates updatePositionTowards(Direction direction) {
+    public Coordinates getNextPositionTowards(Direction direction) {
+        var newLatitude = latitude;
+        var newLongitude = longitude;
         switch (direction) {
-            case NORTH -> latitude--;
-            case SOUTH -> latitude++;
-            case WEST -> longitude--;
-            case EAST -> longitude++;
+            case NORTH -> newLatitude--;
+            case SOUTH -> newLatitude++;
+            case WEST -> newLongitude--;
+            case EAST -> newLongitude++;
         }
         logger.info(String.format("Updated coordinates towards %s, now is %d-%d",
-                direction, latitude, longitude));
-        return this;
+                direction, newLatitude, newLongitude));
+
+        return new Coordinates(newLatitude, newLongitude);
     }
 
     @Override
@@ -58,7 +61,4 @@ public class Coordinates {
                 '}';
     }
 
-    public Coordinates copy() {
-        return new Coordinates(latitude, longitude);
-    }
 }
diff --git a/src/main/java/cat/hack3/codingtests/marsrover/MarsRover.java b/src/main/java/cat/hack3/codingtests/marsrover/MarsRover.java
index 715d5da..446f799 100644
--- a/src/main/java/cat/hack3/codingtests/marsrover/MarsRover.java
+++ b/src/main/java/cat/hack3/codingtests/marsrover/MarsRover.java
@@ -2,7 +2,7 @@ package cat.hack3.codingtests.marsrover;
 
 public class MarsRover {
     private final MarsMap marsMap;
-    private final Coordinates currentCoordinates;
+    private Coordinates currentCoordinates;
     private Direction currentDirection;
 
     public MarsRover(MarsMap marsMap, Coordinates startingCoordinates, Direction startingDirection) {
@@ -12,11 +12,11 @@ public class MarsRover {
     }
 
     public Coordinates moveForward() {
-        return currentCoordinates.updatePositionTowards(currentDirection);
+        return currentCoordinates = currentCoordinates.getNextPositionTowards(currentDirection);
     }
 
     public Coordinates moveBackwards() {
-        return currentCoordinates.updatePositionTowards(currentDirection.reversed());
+        return currentCoordinates = currentCoordinates.getNextPositionTowards(currentDirection.reversed());
     }
 
     public Direction turnLeft() {
@@ -25,7 +25,7 @@ public class MarsRover {
     }
 
     public Coordinates getCurrentCoordinates() {
-        return currentCoordinates.copy();
+        return currentCoordinates;
     }
 
     public Direction getCurrentDirection() {