fix(webapi): unique username/email check on change user

webapi/src/main/scala/org/knora/webapi/responders/admin/UsersResponderADM.scala

@@ -265,32 +265,15 @@ class UsersResponderADM(responderData: ResponderData) extends Responder(responde
             }
 
             // check if we want to change the email
-            _ = if (changeUserRequest.email.isDefined) {
-                stringFormatter.validateEmailAndThrow(changeUserRequest.email.get, throw BadRequestException(s"The email: '${changeUserRequest.email.get}' is invalid"))
-                currentUserInformation.map { user =>
-                    // check if current email differs from the one in the change request
-                    if (!user.email.equals(changeUserRequest.email.get)) {
-                        // check if new email is free
-                        userByEmailExists(changeUserRequest.email.get).map(result =>
-                            if (result) throw DuplicateValueException("A user with this email exists already. Cannot change")
-                        )
-                    }
-                }
+            emailTaken: Boolean <- userByEmailExists(changeUserRequest.email.getOrElse(""), currentUserInformation.get.email)
+            _ = if (emailTaken) {
+                throw DuplicateValueException(s"User with the email: '${changeUserRequest.email.get}' already exists")
             }
 
             // check if we want to change the username
-            _ = if (changeUserRequest.username.isDefined) {
-                stringFormatter.validateUsername(changeUserRequest.username.get, throw BadRequestException(s"The username: '${changeUserRequest.username.get}' contains invalid characters"))
-                currentUserInformation.map { user =>
-                    // check if the current username differs from the one in the change request
-                    if (!user.username.equals(changeUserRequest.username.get)) {
-                        // check if new username is free
-                        userByUsernameExists(changeUserRequest.email.get).map(result =>
-                            if (result) throw DuplicateValueException("A user with this username exists already. Cannot change")
-                        )
-                    }
-
-                }
+            usernameTaken: Boolean <- userByUsernameExists(changeUserRequest.username.getOrElse(""), currentUserInformation.get.username)
+            _ = if (usernameTaken) {
+                throw DuplicateValueException(s"User with the username: '${changeUserRequest.username.get}' already exists")
             }
 
             userUpdatePayload = UserUpdatePayloadADM(
@@ -1420,34 +1403,50 @@ class UsersResponderADM(responderData: ResponderData) extends Responder(responde
       * Helper method for checking if an username is already registered.
       *
       * @param username the username of the user.
+      * @param current the current username of the user.
       * @return a [[Boolean]].
       */
-    private def userByUsernameExists(username: String): Future[Boolean] = {
-        for {
-            askString <- Future(queries.sparql.admin.txt.checkUserExistsByUsername(username = username).toString)
-            // _ = log.debug("userExists - query: {}", askString)
-
-            checkUserExistsResponse <- (storeManager ? SparqlAskRequest(askString)).mapTo[SparqlAskResponse]
-            result = checkUserExistsResponse.result
-
-        } yield result
+    private def userByUsernameExists(username: String, current: String = ""): Future[Boolean] = {
+        username match {
+            case "" => FastFuture.successful(false)
+            case `current` => FastFuture.successful(true)
+            case _ => {
+                stringFormatter.validateUsername(username, throw BadRequestException(s"The username: '${username}' contains invalid characters"))
+                for {
+                    askString <- Future(queries.sparql.admin.txt.checkUserExistsByUsername(username = username).toString)
+                    // _ = log.debug("userExists - query: {}", askString)
+
+                    checkUserExistsResponse <- (storeManager ? SparqlAskRequest(askString)).mapTo[SparqlAskResponse]
+                    result = checkUserExistsResponse.result
+
+                } yield result
+            }
+        }
     }
 
     /**
       * Helper method for checking if an email is already registered.
       *
       * @param email the email of the user.
+      * @param current the current email of the user.
       * @return a [[Boolean]].
       */
-    private def userByEmailExists(email: String): Future[Boolean] = {
-        for {
-            askString <- Future(queries.sparql.admin.txt.checkUserExistsByEmail(email = email).toString)
-            // _ = log.debug("userExists - query: {}", askString)
-
-            checkUserExistsResponse <- (storeManager ? SparqlAskRequest(askString)).mapTo[SparqlAskResponse]
-            result = checkUserExistsResponse.result
-
-        } yield result
+    private def userByEmailExists(email: String, current: String = ""): Future[Boolean] = {
+        email match {
+            case "" => FastFuture.successful(false)
+            case `current` => FastFuture.successful(true)
+            case _ => {
+                stringFormatter.validateEmailAndThrow(email, throw BadRequestException(s"The email: '${email}' is invalid"))
+                for {
+                    askString <- Future(queries.sparql.admin.txt.checkUserExistsByEmail(email = email).toString)
+                    // _ = log.debug("userExists - query: {}", askString)
+
+                    checkUserExistsResponse <- (storeManager ? SparqlAskRequest(askString)).mapTo[SparqlAskResponse]
+                    result = checkUserExistsResponse.result
+
+                } yield result
+            }
+        }
     }
 
     /**

webapi/src/test/scala/org/knora/webapi/responders/admin/UsersResponderADMSpec.scala

@@ -388,6 +388,30 @@ class UsersResponderADMSpec extends CoreSpec(UsersResponderADMSpec.config) with
                 response3.user.familyName should equal (SharedTestDataADM.normalUser.familyName)
 
             }
+
+            "return a 'DuplicateValueException' if the supplied 'username' is not unique" in {
+                responderManager ! UserChangeBasicUserInformationRequestADM(
+                    userIri = SharedTestDataADM.normalUser.id,
+                    changeUserRequest = ChangeUserApiRequestADM(
+                        username = Some("root")
+                    ),
+                    SharedTestDataADM.superUser,
+                    UUID.randomUUID
+                )
+                expectMsg(Failure(DuplicateValueException(s"User with the username: 'root' already exists")))
+            }
+
+            "return a 'DuplicateValueException' if the supplied 'email' is not unique" in {
+                responderManager ! UserChangeBasicUserInformationRequestADM(
+                    userIri = SharedTestDataADM.normalUser.id,
+                    changeUserRequest = ChangeUserApiRequestADM(
+                        email = Some("root@example.com")
+                    ),
+                    SharedTestDataADM.superUser,
+                    UUID.randomUUID
+                )
+                expectMsg(Failure(DuplicateValueException(s"User with the email: 'root@example.com' already exists")))
+            }
 
             "return 'BadRequest' if the new 'username' contains invalid characters (@)" in {