Revert "Revert accidental fast-forward merge from v1.49.0rc1"

This reverts commit 158d73ebdd.

synapse/rest/client/room.py

@@ -716,10 +716,7 @@ class RoomEventContextServlet(RestServlet):
             results["events_after"], time_now
         )
         results["state"] = await self._event_serializer.serialize_events(
-            results["state"],
-            time_now,
-            # No need to bundle aggregations for state events
-            bundle_relations=False,
+            results["state"], time_now
         )
 
         return 200, results
@@ -1070,6 +1067,62 @@ def register_txn_path(
         )
 
 
+class TimestampLookupRestServlet(RestServlet):
+    """
+    API endpoint to fetch the `event_id` of the closest event to the given
+    timestamp (`ts` query parameter) in the given direction (`dir` query
+    parameter).
+
+    Useful for cases like jump to date so you can start paginating messages from
+    a given date in the archive.
+
+    `ts` is a timestamp in milliseconds where we will find the closest event in
+    the given direction.
+
+    `dir` can be `f` or `b` to indicate forwards and backwards in time from the
+    given timestamp.
+
+    GET /_matrix/client/unstable/org.matrix.msc3030/rooms/<roomID>/timestamp_to_event?ts=<timestamp>&dir=<direction>
+    {
+        "event_id": ...
+    }
+    """
+
+    PATTERNS = (
+        re.compile(
+            "^/_matrix/client/unstable/org.matrix.msc3030"
+            "/rooms/(?P<room_id>[^/]*)/timestamp_to_event$"
+        ),
+    )
+
+    def __init__(self, hs: "HomeServer"):
+        super().__init__()
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastore()
+        self.timestamp_lookup_handler = hs.get_timestamp_lookup_handler()
+
+    async def on_GET(
+        self, request: SynapseRequest, room_id: str
+    ) -> Tuple[int, JsonDict]:
+        requester = await self._auth.get_user_by_req(request)
+        await self._auth.check_user_in_room(room_id, requester.user.to_string())
+
+        timestamp = parse_integer(request, "ts", required=True)
+        direction = parse_string(request, "dir", default="f", allowed_values=["f", "b"])
+
+        (
+            event_id,
+            origin_server_ts,
+        ) = await self.timestamp_lookup_handler.get_event_for_timestamp(
+            requester, room_id, timestamp, direction
+        )
+
+        return 200, {
+            "event_id": event_id,
+            "origin_server_ts": origin_server_ts,
+        }
+
+
 class RoomSpaceSummaryRestServlet(RestServlet):
     PATTERNS = (
         re.compile(
@@ -1140,7 +1193,7 @@ class RoomSpaceSummaryRestServlet(RestServlet):
 class RoomHierarchyRestServlet(RestServlet):
     PATTERNS = (
         re.compile(
-            "^/_matrix/client/unstable/org.matrix.msc2946"
+            "^/_matrix/client/(v1|unstable/org.matrix.msc2946)"
             "/rooms/(?P<room_id>[^/]*)/hierarchy$"
         ),
     )
@@ -1168,7 +1221,7 @@ class RoomHierarchyRestServlet(RestServlet):
             )
 
         return 200, await self._room_summary_handler.get_room_hierarchy(
-            requester.user.to_string(),
+            requester,
             room_id,
             suggested_only=parse_boolean(request, "suggested_only", default=False),
             max_depth=max_depth,
@@ -1239,6 +1292,8 @@ def register_servlets(
     RoomAliasListServlet(hs).register(http_server)
     SearchRestServlet(hs).register(http_server)
     RoomCreateRestServlet(hs).register(http_server)
+    if hs.config.experimental.msc3030_enabled:
+        TimestampLookupRestServlet(hs).register(http_server)
 
     # Some servlets only get registered for the main process.
     if not is_worker: