feat(indexeddb): add type for building IndexeddbEventCacheStore

Signed-off-by: Michael Goldenberg <[email protected]>

Author: mgoldenberg

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

@@ -0,0 +1,76 @@
+// Copyright 2025 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::sync::Arc;
+
+use matrix_sdk_base::event_cache::store::MemoryStore;
+use matrix_sdk_store_encryption::StoreCipher;
+use web_sys::DomException;
+
+use crate::{
+    event_cache_store::{
+        migrations::open_and_upgrade_db, serializer::IndexeddbEventCacheStoreSerializer,
+        IndexeddbEventCacheStore,
+    },
+    serializer::IndexeddbSerializer,
+};
+
+/// A type for conveniently building an [`IndexeddbEventCacheStore`]
+pub struct IndexeddbEventCacheStoreBuilder {
+    // The name of the IndexedDB database which will be opened
+    database_name: String,
+    // The store cipher, if any, to use when encrypting data
+    // before it is persisted to the IndexedDB database
+    store_cipher: Option<Arc<StoreCipher>>,
+}
+
+impl Default for IndexeddbEventCacheStoreBuilder {
+    fn default() -> Self {
+        Self { database_name: Self::DEFAULT_DATABASE_NAME.to_owned(), store_cipher: None }
+    }
+}
+
+impl IndexeddbEventCacheStoreBuilder {
+    /// The default name of the IndexedDB database used to back the
+    /// [`IndexeddbEventCacheStore`]
+    pub const DEFAULT_DATABASE_NAME: &'static str = "event_cache";
+
+    /// Sets the name of the IndexedDB database which will be opened. This
+    /// defaults to [`Self::DEFAULT_DATABASE_NAME`].
+    pub fn database_name(mut self, name: String) -> Self {
+        self.database_name = name;
+        self
+    }
+
+    /// Sets the store cipher to use when encrypting data before it is persisted
+    /// to the IndexedDB database. By default, no store cipher is used -
+    /// i.e., data is not encrypted before it is persisted.
+    pub fn store_cipher(mut self, store_cipher: Arc<StoreCipher>) -> Self {
+        self.store_cipher = Some(store_cipher);
+        self
+    }
+
+    /// Opens the IndexedDB database with the provided name. If successfully
+    /// opened, builds the [`IndexeddbEventCacheStore`] with that database
+    /// and the provided store cipher.
+    pub async fn build(self) -> Result<IndexeddbEventCacheStore, DomException> {
+        Ok(IndexeddbEventCacheStore {
+            inner: open_and_upgrade_db(&self.database_name).await?,
+            serializer: IndexeddbEventCacheStoreSerializer::new(IndexeddbSerializer::new(
+                self.store_cipher,
+            )),
+            memory_store: MemoryStore::new(),
+        })
+    }
+}

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

@@ -20,12 +20,15 @@ use web_sys::IdbTransactionMode;
 
 use crate::event_cache_store::serializer::IndexeddbEventCacheStoreSerializer;
 
+mod builder;
 mod error;
 mod migrations;
 mod serializer;
 mod transaction;
 mod types;
 
+pub use builder::IndexeddbEventCacheStoreBuilder;
+
 /// A type for providing an IndexedDB implementation of [`EventCacheStore`][1].
 /// This is meant to be used as a backend to [`EventCacheStore`][1] in browser
 /// contexts.
@@ -43,3 +46,11 @@ pub struct IndexeddbEventCacheStore {
     // functions in `EventCacheStore`.
     memory_store: MemoryStore,
 }
+
+impl IndexeddbEventCacheStore {
+    /// Provides a type with which to conveniently build an
+    /// [`IndexeddbEventCacheStore`]
+    pub fn builder() -> IndexeddbEventCacheStoreBuilder {
+        IndexeddbEventCacheStoreBuilder::default()
+    }
+}