Add checks on the login and creating of user

Back/skydiveLogs-api.Business/Interface/IUserService.cs

@@ -8,6 +8,6 @@ namespace skydiveLogs_api.Business.Interface
 
         User GetById(int userId);
 
-        void AddNewUser(User user);
+        bool AddNewUser(User user);
     }
 }

Back/skydiveLogs-api.Business/UserService.cs

@@ -27,10 +27,19 @@ namespace skydiveLogs_api.Business
             return _userRepository.GetByLogin(login, EncryptPassword(password));
         }
 
-        public void AddNewUser(User newUser)
+        public bool AddNewUser(User newUser)
         {
             newUser.Password = EncryptPassword(newUser.Password);
-            _userRepository.Add(newUser);
+            var foundUser = _userRepository.GetByLogin(newUser.Login, newUser.Password);
+            var result = false;
+
+            if (foundUser == null)
+            {
+                _userRepository.Add(newUser);
+                result = true;
+            }
+
+            return result;
         }
 
         private string EncryptPassword(string password)