Admin API endpoint to delete a reported event (#15116)

* Admin api to delete event report

* lint +  tests

* newsfile

* Apply suggestions from code review

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

* revert changes - move to WorkerStore

* update unit test

* Note that timestamp is in millseconds

---------

Co-authored-by: David Robertson <david.m.robertson1@gmail.com>

2 files changed, 68 insertions, 9 deletions

diff --git a/synapse/rest/admin/event_reports.py b/synapse/rest/admin/event_reports.py
index a3beb74e2c..c546ef7e23 100644
--- a/synapse/rest/admin/event_reports.py
+++ b/synapse/rest/admin/event_reports.py
@@ -53,11 +53,11 @@ class EventReportsRestServlet(RestServlet):
     PATTERNS = admin_patterns("/event_reports$")
 
     def __init__(self, hs: "HomeServer"):
-        self.auth = hs.get_auth()
-        self.store = hs.get_datastores().main
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastores().main
 
     async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
-        await assert_requester_is_admin(self.auth, request)
+        await assert_requester_is_admin(self._auth, request)
 
         start = parse_integer(request, "from", default=0)
         limit = parse_integer(request, "limit", default=100)
@@ -79,7 +79,7 @@ class EventReportsRestServlet(RestServlet):
                 errcode=Codes.INVALID_PARAM,
             )
 
-        event_reports, total = await self.store.get_event_reports_paginate(
+        event_reports, total = await self._store.get_event_reports_paginate(
             start, limit, direction, user_id, room_id
         )
         ret = {"event_reports": event_reports, "total": total}
@@ -108,13 +108,13 @@ class EventReportDetailRestServlet(RestServlet):
     PATTERNS = admin_patterns("/event_reports/(?P<report_id>[^/]*)$")
 
     def __init__(self, hs: "HomeServer"):
-        self.auth = hs.get_auth()
-        self.store = hs.get_datastores().main
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastores().main
 
     async def on_GET(
         self, request: SynapseRequest, report_id: str
     ) -> Tuple[int, JsonDict]:
-        await assert_requester_is_admin(self.auth, request)
+        await assert_requester_is_admin(self._auth, request)
 
         message = (
             "The report_id parameter must be a string representing a positive integer."
@@ -131,8 +131,33 @@ class EventReportDetailRestServlet(RestServlet):
                 HTTPStatus.BAD_REQUEST, message, errcode=Codes.INVALID_PARAM
             )
 
-        ret = await self.store.get_event_report(resolved_report_id)
+        ret = await self._store.get_event_report(resolved_report_id)
         if not ret:
             raise NotFoundError("Event report not found")
 
         return HTTPStatus.OK, ret
+
+    async def on_DELETE(
+        self, request: SynapseRequest, report_id: str
+    ) -> Tuple[int, JsonDict]:
+        await assert_requester_is_admin(self._auth, request)
+
+        message = (
+            "The report_id parameter must be a string representing a positive integer."
+        )
+        try:
+            resolved_report_id = int(report_id)
+        except ValueError:
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST, message, errcode=Codes.INVALID_PARAM
+            )
+
+        if resolved_report_id < 0:
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST, message, errcode=Codes.INVALID_PARAM
+            )
+
+        if await self._store.delete_event_report(resolved_report_id):
+            return HTTPStatus.OK, {}
+
+        raise NotFoundError("Event report not found")
diff --git a/synapse/storage/databases/main/room.py b/synapse/storage/databases/main/room.py
index 39f89291b2..a2e9519cb6 100644
--- a/synapse/storage/databases/main/room.py
+++ b/synapse/storage/databases/main/room.py
@@ -1417,6 +1417,27 @@ class RoomWorkerStore(CacheInvalidationWorkerStore):
             get_un_partial_stated_rooms_from_stream_txn,
         )
 
+    async def delete_event_report(self, report_id: int) -> bool:
+        """Remove an event report from database.
+
+        Args:
+            report_id: Report to delete
+
+        Returns:
+            Whether the report was successfully deleted or not.
+        """
+        try:
+            await self.db_pool.simple_delete_one(
+                table="event_reports",
+                keyvalues={"id": report_id},
+                desc="delete_event_report",
+            )
+        except StoreError:
+            # Deletion failed because report does not exist
+            return False
+
+        return True
+
 
 class _BackgroundUpdates:
     REMOVE_TOMESTONED_ROOMS_BG_UPDATE = "remove_tombstoned_rooms_from_directory"
@@ -2139,7 +2160,19 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
         reason: Optional[str],
         content: JsonDict,
         received_ts: int,
-    ) -> None:
+    ) -> int:
+        """Add an event report
+
+        Args:
+            room_id: Room that contains the reported event.
+            event_id: The reported event.
+            user_id: User who reports the event.
+            reason: Description that the user specifies.
+            content: Report request body (score and reason).
+            received_ts: Time when the user submitted the report (milliseconds).
+        Returns:
+            Id of the event report.
+        """
         next_id = self._event_reports_id_gen.get_next()
         await self.db_pool.simple_insert(
             table="event_reports",
@@ -2154,6 +2187,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
             },
             desc="add_event_report",
         )
+        return next_id
 
     async def get_event_report(self, report_id: int) -> Optional[Dict[str, Any]]:
         """Retrieve an event report