Don't allow to close polls twice

Signed-off-by: Joas Schilling <coding@schilljs.com>

docs/poll.md

@@ -77,6 +77,7 @@ Base endpoint is: `/ocs/v2.php/apps/spreed/api/v1`
 * Response:
     - Status code:
         + `200 OK`
+        + `400 Bad Request` When the poll is already closed
         + `403 Forbidden` When the participant is not the author of the poll or a moderator
         + `404 Not Found` When the conversation could not be found for the participant
         + `404 Not Found` When the poll id could not be found in the conversation

lib/Controller/PollController.php

@@ -202,6 +202,10 @@ class PollController extends AEnvironmentAwareController {
 			return new DataResponse([], Http::STATUS_NOT_FOUND);
 		}
 
+		if ($poll->getStatus() === Poll::STATUS_CLOSED) {
+			return new DataResponse([], Http::STATUS_BAD_REQUEST);
+		}
+
 		$poll->setStatus(Poll::STATUS_CLOSED);
 
 		try {

tests/integration/features/chat/poll.feature

@@ -382,6 +382,7 @@ Feature: chat/poll
       | actorDisplayName    | participant1-displayname |
       | status     | closed |
       | votedSelf  | [0] |
+    Then user "participant1" closes poll "What is the question?" in room "room" with 400
     Then user "participant1" sees the following system messages in room "room" with 200 (v1)
       | room | actorType | actorId      | actorDisplayName         | systemMessage        |
       | room | users     | participant1 | participant1-displayname | poll_closed          |