ffi: add RoomPinnedEventsChange enum and a diffing step

bindings/matrix-sdk-ffi/src/timeline/content.rs

@@ -15,7 +15,7 @@
 use std::{collections::HashMap, sync::Arc};
 
 use matrix_sdk::{crypto::types::events::UtdCause, room::power_levels::power_level_user_changes};
-use matrix_sdk_ui::timeline::{PollResult, TimelineDetails};
+use matrix_sdk_ui::timeline::{PollResult, RoomPinnedEventsChange, TimelineDetails};
 use ruma::events::room::{message::RoomMessageEventContentWithoutRelation, MediaSource};
 use tracing::warn;
 
@@ -338,7 +338,7 @@ pub enum OtherState {
     RoomHistoryVisibility,
     RoomJoinRules,
     RoomName { name: Option<String> },
-    RoomPinnedEvents,
+    RoomPinnedEvents { change: RoomPinnedEventsChange },
     RoomPowerLevels { users: HashMap<String, i64>, previous: Option<HashMap<String, i64>> },
     RoomServerAcl,
     RoomThirdPartyInvite { display_name: Option<String> },
@@ -381,7 +381,7 @@ impl From<&matrix_sdk_ui::timeline::AnyOtherFullStateEventContent> for OtherStat
                 };
                 Self::RoomName { name }
             }
-            Content::RoomPinnedEvents(_) => Self::RoomPinnedEvents,
+            Content::RoomPinnedEvents(c) => Self::RoomPinnedEvents { change: c.into() },
             Content::RoomPowerLevels(c) => match c {
                 FullContent::Original { content, prev_content } => Self::RoomPowerLevels {
                     users: power_level_user_changes(content, prev_content)

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

@@ -58,6 +58,9 @@ use tracing::warn;
 use crate::timeline::{polls::PollState, TimelineItem};
 
 mod message;
+pub(crate) mod pinned_events;
+
+pub use pinned_events::RoomPinnedEventsChange;
 
 pub use self::message::{InReplyToDetails, Message, RepliedToEvent};
 

crates/matrix-sdk-ui/src/timeline/event_item/content/pinned_events.rs

@@ -0,0 +1,192 @@
+// Copyright 2024 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::collections::HashSet;
+
+use ruma::{
+    events::{room::pinned_events::RoomPinnedEventsEventContent, FullStateEventContent},
+    OwnedEventId,
+};
+
+#[derive(Clone, Debug)]
+#[cfg_attr(feature = "uniffi", derive(uniffi::Enum))]
+/// The type of change between the previous and current pinned events.
+pub enum RoomPinnedEventsChange {
+    /// Only new event ids were added.
+    Added,
+    /// Only event ids were removed.
+    Removed,
+    /// Some change other than only adding or only removing ids happened.
+    Changed,
+}
+
+impl From<&FullStateEventContent<RoomPinnedEventsEventContent>> for RoomPinnedEventsChange {
+    fn from(value: &FullStateEventContent<RoomPinnedEventsEventContent>) -> Self {
+        match value {
+            FullStateEventContent::Original { content, prev_content } => {
+                if let Some(prev_content) = prev_content {
+                    let mut new_pinned: HashSet<&OwnedEventId> =
+                        HashSet::from_iter(&content.pinned);
+                    if let Some(old_pinned) = &prev_content.pinned {
+                        let mut still_pinned: HashSet<&OwnedEventId> =
+                            HashSet::from_iter(old_pinned);
+
+                        // Newly added elements will be kept in new_pinned, previous ones in
+                        // still_pinned instead
+                        still_pinned.retain(|item| new_pinned.remove(item));
+
+                        let added = !new_pinned.is_empty();
+                        let removed = still_pinned.len() < old_pinned.len();
+                        if added && removed {
+                            RoomPinnedEventsChange::Changed
+                        } else if added {
+                            RoomPinnedEventsChange::Added
+                        } else if removed {
+                            RoomPinnedEventsChange::Removed
+                        } else {
+                            // Any other case
+                            RoomPinnedEventsChange::Changed
+                        }
+                    } else {
+                        // We don't know the previous state, so let's assume a generic change
+                        RoomPinnedEventsChange::Changed
+                    }
+                } else {
+                    // If there is no previous content we can assume the first pinned event id was
+                    // just added
+                    RoomPinnedEventsChange::Added
+                }
+            }
+            FullStateEventContent::Redacted(_) => RoomPinnedEventsChange::Changed,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use assert_matches::assert_matches;
+    use ruma::{
+        events::{
+            room::pinned_events::{
+                PossiblyRedactedRoomPinnedEventsEventContent, RedactedRoomPinnedEventsEventContent,
+                RoomPinnedEventsEventContent,
+            },
+            FullStateEventContent,
+        },
+        owned_event_id,
+        serde::Raw,
+    };
+    use serde_json::json;
+
+    use crate::timeline::event_item::content::pinned_events::RoomPinnedEventsChange;
+
+    #[test]
+    fn redacted_pinned_events_content_has_generic_changes() {
+        let content = FullStateEventContent::Redacted(RedactedRoomPinnedEventsEventContent::new());
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Changed);
+    }
+
+    #[test]
+    fn pinned_events_content_with_no_prev_content_returns_added() {
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(vec![owned_event_id!("$1")]),
+            prev_content: None,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Added);
+    }
+
+    #[test]
+    fn pinned_events_content_with_added_ids_returns_added() {
+        // This is the only way I found to create the PossiblyRedacted content
+        let prev_content = possibly_redacted_content(Vec::new());
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(vec![owned_event_id!("$1")]),
+            prev_content,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Added);
+    }
+
+    #[test]
+    fn pinned_events_content_with_removed_ids_returns_removed() {
+        // This is the only way I found to create the PossiblyRedacted content
+        let prev_content = possibly_redacted_content(vec!["$1"]);
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(Vec::new()),
+            prev_content,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Removed);
+    }
+
+    #[test]
+    fn pinned_events_content_with_added_and_removed_ids_returns_changed() {
+        // This is the only way I found to create the PossiblyRedacted content
+        let prev_content = possibly_redacted_content(vec!["$1"]);
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(vec![owned_event_id!("$2")]),
+            prev_content,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Changed);
+    }
+
+    #[test]
+    fn pinned_events_content_with_changed_order_returns_changed() {
+        // This is the only way I found to create the PossiblyRedacted content
+        let prev_content = possibly_redacted_content(vec!["$1", "$2"]);
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(vec![
+                owned_event_id!("$2"),
+                owned_event_id!("$1"),
+            ]),
+            prev_content,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Changed);
+    }
+
+    #[test]
+    fn pinned_events_content_with_no_changes_returns_changed() {
+        // Returning Changed is counter-intuitive, but it makes no sense to display in
+        // the timeline 'UserFoo didn't change anything in the pinned events'
+
+        // This is the only way I found to create the PossiblyRedacted content
+        let prev_content = possibly_redacted_content(vec!["$1", "$2"]);
+        let content = FullStateEventContent::Original {
+            content: RoomPinnedEventsEventContent::new(vec![
+                owned_event_id!("$1"),
+                owned_event_id!("$2"),
+            ]),
+            prev_content,
+        };
+        let ret: RoomPinnedEventsChange = (&content).into();
+        assert_matches!(ret, RoomPinnedEventsChange::Changed);
+    }
+
+    fn possibly_redacted_content(
+        ids: Vec<&str>,
+    ) -> Option<PossiblyRedactedRoomPinnedEventsEventContent> {
+        // This is the only way I found to create the PossiblyRedacted content
+        Raw::new(&json!({
+            "pinned": ids,
+        }))
+        .unwrap()
+        .cast::<PossiblyRedactedRoomPinnedEventsEventContent>()
+        .deserialize()
+        .ok()
+    }
+}

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

@@ -41,8 +41,8 @@ mod remote;
 pub use self::{
     content::{
         AnyOtherFullStateEventContent, EncryptedMessage, InReplyToDetails, MemberProfileChange,
-        MembershipChange, Message, OtherState, RepliedToEvent, RoomMembershipChange, Sticker,
-        TimelineItemContent,
+        MembershipChange, Message, OtherState, RepliedToEvent, RoomMembershipChange,
+        RoomPinnedEventsChange, Sticker, TimelineItemContent,
     },
     local::EventSendState,
 };

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

@@ -94,7 +94,8 @@ pub use self::{
         AnyOtherFullStateEventContent, EncryptedMessage, EventItemOrigin, EventSendState,
         EventTimelineItem, InReplyToDetails, MemberProfileChange, MembershipChange, Message,
         OtherState, Profile, ReactionInfo, ReactionsByKeyBySender, RepliedToEvent,
-        RoomMembershipChange, Sticker, TimelineDetails, TimelineEventItemId, TimelineItemContent,
+        RoomMembershipChange, RoomPinnedEventsChange, Sticker, TimelineDetails,
+        TimelineEventItemId, TimelineItemContent,
     },
     event_type_filter::TimelineEventTypeFilter,
     inner::default_event_filter,