feat: add fromLocalStoreOnly to Event.downloadAndDecryptAttachment

Signed-off-by: Romain GUILLOT <romain.guillot@arche-mc2.fr>

lib/src/event.dart

@@ -586,10 +586,13 @@ class Event extends MatrixEvent {
   /// Downloads (and decrypts if necessary) the attachment of this
   /// event and returns it as a [MatrixFile]. If this event doesn't
   /// contain an attachment, this throws an error. Set [getThumbnail] to
-  /// true to download the thumbnail instead.
+  /// true to download the thumbnail instead. Set [fromLocalStoreOnly] to true
+  /// if you want to retrieve the attachment from the local store only without
+  /// making http request.
   Future<MatrixFile> downloadAndDecryptAttachment(
       {bool getThumbnail = false,
-      Future<Uint8List> Function(Uri)? downloadCallback}) async {
+      Future<Uint8List> Function(Uri)? downloadCallback,
+      bool fromLocalStoreOnly = false}) async {
     if (![EventTypes.Message, EventTypes.Sticker].contains(type)) {
       throw ("This event has the type '$type' and so it can't contain an attachment.");
     }
@@ -621,7 +624,8 @@ class Event extends MatrixEvent {
     }
 
     // Download the file
-    if (uint8list == null) {
+    final canDownloadFileFromServer = uint8list == null && !fromLocalStoreOnly;
+    if (canDownloadFileFromServer) {
       final httpClient = room.client.httpClient;
       downloadCallback ??=
           (Uri url) async => (await httpClient.get(url)).bodyBytes;
@@ -633,6 +637,8 @@ class Event extends MatrixEvent {
         await database.storeFile(
             mxcUrl, uint8list, DateTime.now().millisecondsSinceEpoch);
       }
+    } else if (uint8list == null) {
+      throw ('Unable to download file from local store.');
     }
 
     // Decrypt the file

test/event_test.dart

@@ -1549,6 +1549,93 @@ void main() {
 
       await room.client.dispose(closeDatabase: true);
     });
+
+    test('downloadAndDecryptAttachment store only', () async {
+      final FILE_BUFF = Uint8List.fromList([0]);
+      var serverHits = 0;
+      Future<Uint8List> downloadCallback(Uri uri) async {
+        serverHits++;
+        return {
+          '/_matrix/media/v3/download/example.org/newfile': FILE_BUFF,
+        }[uri.path]!;
+      }
+
+      await client.checkHomeserver(Uri.parse('https://fakeserver.notexisting'),
+          checkWellKnown: false);
+      final room = Room(id: '!localpart:server.abc', client: await getClient());
+      final event = Event.fromJson({
+        'type': EventTypes.Message,
+        'content': {
+          'body': 'image',
+          'msgtype': 'm.image',
+          'url': 'mxc://example.org/newfile',
+          'info': {
+            'size': 5,
+          },
+        },
+        'event_id': '\$edit2',
+        'sender': '@alice:example.org',
+      }, room);
+
+      var buffer = await event.downloadAndDecryptAttachment(
+          downloadCallback: downloadCallback);
+      expect(await event.isAttachmentInLocalStore(),
+          event.room.client.database?.supportsFileStoring);
+      expect(buffer.bytes, FILE_BUFF);
+      expect(serverHits, 1);
+
+      if (event.room.client.database?.supportsFileStoring == true) {
+        buffer = await event.downloadAndDecryptAttachment(
+            downloadCallback: downloadCallback, fromLocalStoreOnly: true);
+        expect(buffer.bytes, FILE_BUFF);
+      } else {
+        expect(
+            () async => await event.downloadAndDecryptAttachment(
+                downloadCallback: downloadCallback, fromLocalStoreOnly: true),
+            throwsA(anything));
+      }
+      expect(serverHits, 1);
+
+      await room.client.dispose(closeDatabase: true);
+    });
+
+    test('downloadAndDecryptAttachment store only without file', () async {
+      final FILE_BUFF = Uint8List.fromList([0]);
+      var serverHits = 0;
+      Future<Uint8List> downloadCallback(Uri uri) async {
+        serverHits++;
+        return {
+          '/_matrix/media/v3/download/example.org/newfile': FILE_BUFF,
+        }[uri.path]!;
+      }
+
+      await client.checkHomeserver(Uri.parse('https://fakeserver.notexisting'),
+          checkWellKnown: false);
+      final room = Room(id: '!localpart:server.abc', client: await getClient());
+      final event = Event.fromJson({
+        'type': EventTypes.Message,
+        'content': {
+          'body': 'image',
+          'msgtype': 'm.image',
+          'url': 'mxc://example.org/newfile',
+          'info': {
+            'size': 5,
+          },
+        },
+        'event_id': '\$edit2',
+        'sender': '@alice:example.org',
+      }, room);
+
+      expect(
+          () async => await event.downloadAndDecryptAttachment(
+              downloadCallback: downloadCallback, fromLocalStoreOnly: true),
+          throwsA(anything));
+
+      expect(serverHits, 0);
+
+      await room.client.dispose(closeDatabase: true);
+    });
+
     test('emote detection', () async {
       var event = Event.fromJson({
         'type': EventTypes.Message,