refactor(timeline): get rid of the optional in is_room_encrypted field

The `EventTimelineItem` would get from a bool to an `Option<bool>`. If
the metadata's `is_room_encrypted` was set to `None`, then it would use
`false` as the value, before wrapping it again into an `Option`.

Since the only reader of `EventTimelineItem::is_room_encrypted()`
doesn't really care about the difference between `Some(false)` and
`None`, in `EventTimelineItem::get_shield()`, we can use a plain `bool`
instead of an `Option`, and not distinguish `Some(false)` from `None`.
At worst, it means that sometimes we don't know the room encryption
status yet, and consider the room unencrypted; as soon as we'll get an
update about encryption state, all the items will be marked as encrypted
anyways, if needs be.

Author: bnjbvr

crates/matrix-sdk-ui/src/timeline/builder.rs

@@ -163,7 +163,7 @@ impl TimelineBuilder {
         let (_, mut event_subscriber) = room_event_cache.subscribe().await?;
 
         let is_pinned_events = matches!(focus, TimelineFocus::PinnedEvents { .. });
-        let is_room_encrypted = room.is_encrypted().await.ok();
+        let is_room_encrypted = room.is_encrypted().await.ok().unwrap_or_default();
 
         let controller = TimelineController::new(
             room,

crates/matrix-sdk-ui/src/timeline/controller/metadata.rs

@@ -48,7 +48,9 @@ pub(in crate::timeline) struct TimelineMetadata {
 
     /// A boolean indicating whether the room the timeline is attached to is
     /// actually encrypted or not.
-    pub is_room_encrypted: Option<bool>,
+    ///
+    /// May be false until we fetch the actual room encryption state.
+    pub is_room_encrypted: bool,
 
     /// Matrix room version of the timeline's room, or a sensible default.
     ///
@@ -104,7 +106,7 @@ impl TimelineMetadata {
         room_version: RoomVersionId,
         internal_id_prefix: Option<String>,
         unable_to_decrypt_hook: Option<Arc<UtdHookManager>>,
-        is_room_encrypted: Option<bool>,
+        is_room_encrypted: bool,
     ) -> Self {
         Self {
             subscriber_skip_count: SkipCount::new(),

crates/matrix-sdk-ui/src/timeline/controller/mod.rs

@@ -262,7 +262,7 @@ impl<P: RoomDataProvider> TimelineController<P> {
         focus: TimelineFocus,
         internal_id_prefix: Option<String>,
         unable_to_decrypt_hook: Option<Arc<UtdHookManager>>,
-        is_room_encrypted: Option<bool>,
+        is_room_encrypted: bool,
     ) -> Self {
         let (focus_data, focus_kind) = match focus {
             TimelineFocus::Live => (TimelineFocusData::Live, TimelineFocusKind::Live),
@@ -378,17 +378,23 @@ impl<P: RoomDataProvider> TimelineController<P> {
     pub async fn handle_encryption_state_changes(&self) {
         let mut room_info = self.room_data_provider.room_info();
 
+        // Small function helper to help mark as encrypted.
+        let mark_encrypted = || async {
+            let mut state = self.state.write().await;
+            state.meta.is_room_encrypted = true;
+            state.mark_all_events_as_encrypted();
+        };
+
         if room_info.get().is_encrypted() {
             // If the room was already encrypted, it won't toggle to unencrypted, so we can
             // shut down this task early.
+            mark_encrypted().await;
             return;
         }
 
         while let Some(info) = room_info.next().await {
             if info.is_encrypted() {
-                let mut state = self.state.write().await;
-                state.meta.is_room_encrypted = Some(true);
-                state.mark_all_events_as_encrypted();
+                mark_encrypted().await;
                 // Once the room is encrypted, it cannot switch back to unencrypted, so our work
                 // here is done.
                 break;

crates/matrix-sdk-ui/src/timeline/controller/state.rs

@@ -64,7 +64,7 @@ impl TimelineState {
         room_version: RoomVersionId,
         internal_id_prefix: Option<String>,
         unable_to_decrypt_hook: Option<Arc<UtdHookManager>>,
-        is_room_encrypted: Option<bool>,
+        is_room_encrypted: bool,
     ) -> Self {
         Self {
             items: ObservableItems::new(),

crates/matrix-sdk-ui/src/timeline/controller/state_transaction.rs

@@ -575,8 +575,12 @@ impl<'a> TimelineStateTransaction<'a> {
             let item = &self.items[idx];
 
             if let Some(event) = item.as_event() {
+                if event.is_room_encrypted {
+                    continue;
+                }
+
                 let mut cloned_event = event.clone();
-                cloned_event.is_room_encrypted = Some(true);
+                cloned_event.is_room_encrypted = true;
 
                 // Replace the existing item with a new version with the right encryption flag
                 let item = item.with_kind(cloned_event);

crates/matrix-sdk-ui/src/timeline/date_dividers.rs

@@ -672,13 +672,7 @@ mod tests {
     }
 
     fn test_metadata() -> TimelineMetadata {
-        TimelineMetadata::new(
-            owned_user_id!("@a:b.c"),
-            ruma::RoomVersionId::V11,
-            None,
-            None,
-            Some(false),
-        )
+        TimelineMetadata::new(owned_user_id!("@a:b.c"), ruma::RoomVersionId::V11, None, None, false)
     }
 
     #[test]

crates/matrix-sdk-ui/src/timeline/event_handler.rs

@@ -1021,7 +1021,7 @@ impl<'a, 'o> TimelineEventHandler<'a, 'o> {
             }
         };
 
-        let is_room_encrypted = self.meta.is_room_encrypted.unwrap_or_default();
+        let is_room_encrypted = self.meta.is_room_encrypted;
 
         let mut item = EventTimelineItem::new(
             sender,

crates/matrix-sdk-ui/src/timeline/event_item/mod.rs

@@ -78,9 +78,8 @@ pub struct EventTimelineItem {
     pub(super) kind: EventTimelineItemKind,
     /// Whether or not the event belongs to an encrypted room.
     ///
-    /// When `None` it is unknown if the room is encrypted and the item won't
-    /// return a ShieldState.
-    pub(super) is_room_encrypted: Option<bool>,
+    /// May be false when we don't know about the room encryption status yet.
+    pub(super) is_room_encrypted: bool,
 }
 
 #[derive(Clone, Debug)]
@@ -120,7 +119,6 @@ impl EventTimelineItem {
         kind: EventTimelineItemKind,
         is_room_encrypted: bool,
     ) -> Self {
-        let is_room_encrypted = Some(is_room_encrypted);
         Self { sender, sender_profile, timestamp, content, kind, is_room_encrypted }
     }
 
@@ -211,7 +209,7 @@ impl EventTimelineItem {
             TimelineDetails::Unavailable
         };
 
-        Some(Self { sender, sender_profile, timestamp, content, kind, is_room_encrypted: None })
+        Some(Self { sender, sender_profile, timestamp, content, kind, is_room_encrypted: false })
     }
 
     /// Check whether this item is a local echo.
@@ -398,7 +396,7 @@ impl EventTimelineItem {
     /// Gets the [`ShieldState`] which can be used to decorate messages in the
     /// recommended way.
     pub fn get_shield(&self, strict: bool) -> Option<ShieldState> {
-        if self.is_room_encrypted != Some(true) || self.is_local_echo() {
+        if !self.is_room_encrypted || self.is_local_echo() {
             return None;
         }
 

crates/matrix-sdk-ui/src/timeline/tests/mod.rs

@@ -104,7 +104,7 @@ impl TestTimeline {
                 TimelineFocus::Live,
                 Some(prefix),
                 None,
-                Some(false),
+                false,
             ),
             factory: EventFactory::new(),
         }
@@ -117,7 +117,7 @@ impl TestTimeline {
                 TimelineFocus::Live,
                 None,
                 None,
-                Some(false),
+                false,
             ),
             factory: EventFactory::new(),
         }
@@ -130,7 +130,7 @@ impl TestTimeline {
                 TimelineFocus::Live,
                 None,
                 Some(hook),
-                Some(true),
+                true,
             ),
             factory: EventFactory::new(),
         }
@@ -144,7 +144,7 @@ impl TestTimeline {
                 TimelineFocus::Live,
                 None,
                 None,
-                Some(encrypted),
+                encrypted,
             ),
             factory: EventFactory::new(),
         }