Leaderboard functionality

src/main/java/com/pecacm/backend/controllers/UserController.java

@@ -110,7 +110,7 @@ public ResponseEntity<Long> getRank(@RequestParam @NonNull Integer score) {
     }
 
     @GetMapping("/leaderboard")
-    public ResponseEntity<List<User>> getLeaderboard() {
-        return ResponseEntity.ok(userService.getLeaderboard());
+    public ResponseEntity<List<User>> getLeaderboard(@RequestParam @NonNull Integer pageSize,@RequestParam @NonNull Integer pageNum ) {
+        return ResponseEntity.ok(userService.getLeaderboard(pageSize,pageNum));
     }
 }

src/main/java/com/pecacm/backend/repository/UserRepository.java

@@ -5,6 +5,7 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
 import java.util.Collection;
@@ -32,8 +33,8 @@ public interface UserRepository extends JpaRepository<User, Integer> {
 
     Long countByXpGreaterThan(Integer xp);
 
-    @Query("SELECT u FROM User u ORDER BY u.xp DESC LIMIT 5")
-    List<User> findAllByByOrderByXpDesc();
+    @Query("SELECT u FROM User u ORDER BY u.xp DESC LIMIT :pageSize OFFSET :offSetSize")
+    List<User> findAllByOrderByXpDesc(Integer pageSize, Integer offSetSize);
 
 
 }

src/main/java/com/pecacm/backend/services/UserService.java

@@ -110,7 +110,8 @@ public Long getRank(Integer score) {
         return userRepository.countByXpGreaterThan(score) + 1;
     }
 
-    public List<User> getLeaderboard() {
-        return userRepository.findAllByByOrderByXpDesc();
+    public List<User> getLeaderboard(Integer pageSize, Integer pageNum) {
+        Integer offSetSize=(pageNum-1)*pageSize;
+        return userRepository.findAllByOrderByXpDesc(pageSize,offSetSize);
     }
 }