initProtocol endpoint returns success when already initialized (#10542)

* initProtocol endpoint returns success when already initialized

* Fix test

* Docs and return error when clientId differs

* fmt

* fix: session management test

* misc: json connection controller

---------

Co-authored-by: Dmitry Bushev <bushevdv@gmail.com>

Issue with Vector nothing to do with this.

docs/language-server/protocol-language-server.md

@@ -1440,6 +1440,9 @@ This message initializes the connection used to send the textual protocol
 messages. This initialization is important such that the client identifier can
 be correlated between the textual and data connections.
 
+The subsequent `session/initProtocolConnection` calls with same clientId will
+immediately return success message.
+
 - **Type:** Request
 - **Direction:** Client -> Server
 - **Connection:** Protocol
@@ -1464,7 +1467,7 @@ interface SessionInitProtocolConnectionResult {
 #### Errors
 
 - [`SessionAlreadyInitialisedError`](#sessionalreadyinitializederror) to signal
-  that the session is already initialized.
+  that the session is already initialized with different clientId.
 - [`ResourcesInitializationError`](#resourcesinitializationerror) to signal
   about the error during the initialization of Language Server resources.
 

engine/language-server/src/main/scala/org/enso/languageserver/protocol/json/JsonConnectionController.scala

@@ -284,17 +284,18 @@ class JsonConnectionController(
         cancellable.cancel()
         unstashAll()
 
+        val allContentRoots = allRoots.map(_.toContentRoot).toSet
         receiver ! ResponseResult(
           InitProtocolConnection,
           request.id,
           InitProtocolConnection.Result(
             buildinfo.Info.ensoVersion,
             buildinfo.Info.currentEdition,
-            allRoots.map(_.toContentRoot).toSet
+            allContentRoots
           )
         )
 
-        initialize(webActor, rpcSession)
+        initialize(webActor, rpcSession, allContentRoots)
       } else {
         context.become(
           waitingForContentRoots(
@@ -303,7 +304,7 @@ class JsonConnectionController(
             request     = request,
             receiver    = receiver,
             cancellable = cancellable,
-            rootsSoFar  = roots ++ rootsSoFar
+            rootsSoFar  = allRoots
           )
         )
       }
@@ -319,10 +320,11 @@ class JsonConnectionController(
 
   private def initialize(
     webActor: ActorRef,
-    rpcSession: JsonSession
+    rpcSession: JsonSession,
+    roots: Set[ContentRoot]
   ): Unit = {
     val requestHandlers = createRequestHandlers(rpcSession)
-    context.become(initialised(webActor, rpcSession, requestHandlers))
+    context.become(initialised(webActor, rpcSession, requestHandlers, roots))
 
     context.system.eventStream
       .subscribe(self, classOf[Api.ProgressNotification])
@@ -331,10 +333,27 @@ class JsonConnectionController(
   private def initialised(
     webActor: ActorRef,
     rpcSession: JsonSession,
-    requestHandlers: Map[Method, Props]
+    requestHandlers: Map[Method, Props],
+    roots: Set[ContentRoot]
   ): Receive = LoggingReceive {
-    case Request(InitProtocolConnection, id, _) =>
-      sender() ! ResponseError(Some(id), SessionAlreadyInitialisedError)
+    case Request(
+          InitProtocolConnection,
+          id,
+          InitProtocolConnection.Params(clientId)
+        ) =>
+      if (clientId == rpcSession.clientId) {
+        sender() ! ResponseResult(
+          InitProtocolConnection,
+          id,
+          InitProtocolConnection.Result(
+            buildinfo.Info.ensoVersion,
+            buildinfo.Info.currentEdition,
+            roots
+          )
+        )
+      } else {
+        sender() ! ResponseError(Some(id), SessionAlreadyInitialisedError)
+      }
 
     case MessageHandler.Disconnected(_) =>
       logger.info("Session terminated [{}].", rpcSession.clientId)

engine/language-server/src/test/scala/org/enso/languageserver/websocket/json/SessionManagementTest.scala

@@ -65,25 +65,49 @@ class SessionManagementTest extends BaseServerTest with ReportLogsOnFailure {
 
     "connection is initialised" must {
 
-      "reply with an error if client tries initialise connection second time" in {
+      "reply with a standard message if client tries initialise connection second time" in {
+        val (client, clientId) = getInitialisedWsClientAndId()
+        client.send(json"""
+          { "jsonrpc": "2.0",
+            "method": "session/initProtocolConnection",
+            "id": 1,
+            "params": {
+              "clientId": $clientId
+            }
+          }
+          """)
+        val response = client.expectSomeJson().asObject.value
+        response("jsonrpc") shouldEqual Some("2.0".asJson)
+        response("id") shouldEqual Some(1.asJson)
+        val result = response("result").value.asObject.value
+        result("contentRoots").value.asArray.value should contain(
+          json"""
+          {
+            "id" : $testContentRootId,
+            "type" : "Project"
+          }
+          """
+        )
+      }
+
+      "reply with an error if client tries initialise connection second time with different clientId" in {
         val client = getInitialisedWsClient()
         client.send(json"""
           { "jsonrpc": "2.0",
             "method": "session/initProtocolConnection",
             "id": 1,
             "params": {
-              "clientId": "e3d99192-2edc-4613-bdf4-db35e4b9b956"
+              "clientId": "f3d99192-2edc-4613-bdf4-db35e4b9b957"
             }
           }
           """)
         client.expectJson(json"""
-            { "jsonrpc":"2.0",
-              "id":1,
-              "error": { "code": 6002, "message": "Session already initialised" }
-            }
-              """)
+          { "jsonrpc":"2.0",
+            "id":1,
+            "error": { "code": 6002, "message": "Session already initialised" }
+          }
+          """)
       }
-
     }
 
   }