Filter useless state events on the server side.

This means that presence events appear in the timeline, which is
something we DO want.

src/Scylla/Http.elm

@@ -5,12 +5,25 @@ import Scylla.Route exposing (RoomId)
 import Scylla.Sync exposing (syncResponseDecoder, historyResponseDecoder)
 import Scylla.Login exposing (loginResponseDecoder, Username, Password)
 import Scylla.UserData exposing (userDataDecoder, UserData)
-import Json.Encode exposing (object, string, int, bool)
+import Url.Builder
+import Json.Encode exposing (object, string, int, bool, list)
 import Http exposing (request, emptyBody, jsonBody, fileBody, expectJson, expectWhatever)
 import File exposing (File, name, mime)
 import Url.Builder as Builder
 import Json.Decode
 
+firstSyncFilter : Json.Decode.Value
+firstSyncFilter = object
+    [ ("room", object
+        [ ("state", object
+            [ ("types", list string [ "m.room.name" ])
+            ])
+        ])
+    ]
+
+firstSyncFilterString : String
+firstSyncFilterString = Json.Encode.encode 0 firstSyncFilter
+
 fullClientUrl : ApiUrl -> ApiUrl
 fullClientUrl s = s ++ "/_matrix/client/r0"
 
@@ -22,7 +35,7 @@ firstSync : ApiUrl -> ApiToken -> Cmd Msg
 firstSync apiUrl token = request
     { method = "GET"
     , headers = authenticatedHeaders token
-    , url = (fullClientUrl apiUrl) ++ "/sync"
+    , url = Url.Builder.crossOrigin (fullClientUrl apiUrl) [ "sync" ] [ Url.Builder.string "filter" firstSyncFilterString ]
     , body = emptyBody
     , expect = expectJson ReceiveFirstSyncResponse syncResponseDecoder
     , timeout = Nothing

src/Scylla/Sync.elm

@@ -392,19 +392,11 @@ mergeRooms r1 r2 =
     }
 
 mergeSyncResponse : SyncResponse -> SyncResponse -> SyncResponse
-mergeSyncResponse l r = filterUselessState <| 
+mergeSyncResponse l r = 
     { r | rooms = mergeMaybe mergeRooms l.rooms r.rooms
     , accountData = mergeMaybe mergeAccountData l.accountData r.accountData
     }
 
-filterUselessState : SyncResponse -> SyncResponse
-filterUselessState sr =
-    let
-        filterUselessRoomState _ r = { r | state = Maybe.map (\s -> { s | events = Maybe.map (List.filter (((==) "m.room.name") << .type_)) s.events }) r.state }
-        filterUselessRoomsState rs = { rs | join = Maybe.map (Dict.map filterUselessRoomState) rs.join }
-    in
-        { sr | rooms = Maybe.map (filterUselessRoomsState) sr.rooms }
-
 appendRoomHistoryResponse : JoinedRoom -> HistoryResponse -> JoinedRoom
 appendRoomHistoryResponse jr hr =
     let