refactor(indexeddb): add helper fns for EventCacheStore::load_last_chunk

Signed-off-by: Michael Goldenberg <m@mgoldenberg.net>

Author: mgoldenberg

crates/matrix-sdk-indexeddb/src/event_cache_store/transaction.rs

@@ -406,6 +406,18 @@ impl<'a> IndexeddbEventCacheStoreTransaction<'a> {
         self.get_item_by_key_components::<Chunk, IndexedChunkIdKey>(room_id, chunk_id).await
     }
 
+    /// Query IndexedDB for chunks such that the next chunk matches the given
+    /// chunk identifier in the given room. If more than one item is found,
+    /// an error is returned.
+    pub async fn get_chunk_by_next_chunk_id(
+        &self,
+        room_id: &RoomId,
+        next_chunk_id: &Option<ChunkIdentifier>,
+    ) -> Result<Option<Chunk>, IndexeddbEventCacheStoreTransactionError> {
+        self.get_item_by_key_components::<Chunk, IndexedNextChunkIdKey>(room_id, next_chunk_id)
+            .await
+    }
+
     /// Query IndexedDB for all chunks in the given room
     pub async fn get_chunks_in_room(
         &self,
@@ -414,6 +426,22 @@ impl<'a> IndexeddbEventCacheStoreTransaction<'a> {
         self.get_items_in_room::<Chunk, IndexedChunkIdKey>(room_id).await
     }
 
+    /// Query IndexedDB for the number of chunks in the given room.
+    pub async fn get_chunks_count_in_room(
+        &self,
+        room_id: &RoomId,
+    ) -> Result<usize, IndexeddbEventCacheStoreTransactionError> {
+        self.get_items_count_in_room::<Chunk, IndexedChunkIdKey>(room_id).await
+    }
+
+    /// Query IndexedDB for the chunk with the maximum key in the given room.
+    pub async fn get_max_chunk_by_id(
+        &self,
+        room_id: &RoomId,
+    ) -> Result<Option<Chunk>, IndexeddbEventCacheStoreTransactionError> {
+        self.get_max_item_by_key::<Chunk, IndexedChunkIdKey>(room_id).await
+    }
+
     /// Query IndexedDB for given chunk in given room and additionally query
     /// for events or gap, depending on chunk type, in order to construct the
     /// full chunk.