feat: Display dummy event in timeline for sending files

For thumbnail generation, encrypting
and uploading it is not necessary
to block the UI. The given file
event should already be displayed
in the timeline. This placed it in
the UI and adds a additional
fileSendingStatus property so the
app can fetch the current status.

lib/src/event.dart

@@ -19,6 +19,7 @@
 import 'dart:convert';
 import 'dart:typed_data';
 
+import 'package:collection/collection.dart';
 import 'package:html/parser.dart';
 import 'package:http/http.dart' as http;
 
@@ -796,4 +797,19 @@ class Event extends MatrixEvent {
       return _countEmojiRegex.allMatches(plaintextBody).length;
     }
   }
+
+  /// If this event is in Status SENDING and it aims to send a file, then this
+  /// shows the status of the file sending.
+  FileSendingStatus? get fileSendingStatus {
+    final status = unsigned?.tryGet<String>(fileSendingStatusKey);
+    if (status == null) return null;
+    return FileSendingStatus.values.singleWhereOrNull(
+        (fileSendingStatus) => fileSendingStatus.name == status);
+  }
+}
+
+enum FileSendingStatus {
+  generatingThumbnail,
+  encrypting,
+  uploading,
 }

lib/src/room.dart

@@ -50,6 +50,9 @@ const Map<HistoryVisibility, String> _historyVisibilityMap = {
 const String messageSendingStatusKey =
     'com.famedly.famedlysdk.message_sending_status';
 
+const String fileSendingStatusKey =
+    'com.famedly.famedlysdk.file_sending_status';
+
 const String sortOrderKey = 'com.famedly.famedlysdk.sort_order';
 
 /// Represents a Matrix room.
@@ -687,25 +690,78 @@ class Room {
   ///
   /// In case [file] is a [MatrixImageFile], [thumbnail] is automatically
   /// computed unless it is explicitly provided.
+  /// Set [shrinkImageMaxDimension] to for example `1600` if you want to shrink
+  /// your image before sending. This is ignored if the File is not a
+  /// [MatrixImageFile].
   Future<Uri> sendFileEvent(
     MatrixFile file, {
     String? txid,
     Event? inReplyTo,
     String? editEventId,
     bool waitUntilSent = false,
+    int? shrinkImageMaxDimension,
     MatrixImageFile? thumbnail,
     Map<String, dynamic>? extraContent,
   }) async {
+    txid ??= client.generateUniqueTransactionId();
+
+    // Create a fake Event object as a placeholder for the uploading file:
+    final syncUpdate = SyncUpdate(
+      nextBatch: '',
+      rooms: RoomsUpdate(
+        join: {
+          id: JoinedRoomUpdate(
+            timeline: TimelineUpdate(
+              events: [
+                MatrixEvent(
+                  content: {
+                    'msgtype': file.msgType,
+                    'body': file.name,
+                    'filename': file.name,
+                  },
+                  type: EventTypes.Message,
+                  eventId: txid,
+                  senderId: client.userID!,
+                  originServerTs: DateTime.now(),
+                  unsigned: {
+                    messageSendingStatusKey: EventStatus.sending.intValue,
+                    'transaction_id': txid,
+                  },
+                ),
+              ],
+            ),
+          ),
+        },
+      ),
+    );
+
     MatrixFile uploadFile = file; // ignore: omit_local_variable_types
     // computing the thumbnail in case we can
-    thumbnail ??= (file is MatrixImageFile && encrypted
+    if (file is MatrixImageFile &&
-        ? await file.generateThumbnail(compute: client.runInBackground)
+        (thumbnail == null || shrinkImageMaxDimension != null)) {
-        : null);
+      syncUpdate.rooms!.join!.values.first.timeline!.events!.first
+              .unsigned![fileSendingStatusKey] =
+          FileSendingStatus.generatingThumbnail.name;
+      await _handleFakeSync(syncUpdate);
+      thumbnail ??=
+          await file.generateThumbnail(compute: client.runInBackground);
+      if (shrinkImageMaxDimension != null) {
+        file = await MatrixImageFile.shrink(
+          bytes: file.bytes,
+          name: file.name,
+          maxDimension: shrinkImageMaxDimension,
+        );
+      }
+    }
+
     MatrixFile? uploadThumbnail =
         thumbnail; // ignore: omit_local_variable_types
     EncryptedFile? encryptedFile;
     EncryptedFile? encryptedThumbnail;
     if (encrypted && client.fileEncryptionEnabled) {
+      syncUpdate.rooms!.join!.values.first.timeline!.events!.first
+          .unsigned![fileSendingStatusKey] = FileSendingStatus.encrypting.name;
+      await _handleFakeSync(syncUpdate);
       encryptedFile = await file.encrypt();
       uploadFile = encryptedFile.toMatrixFile();
 
@@ -717,6 +773,9 @@ class Room {
     Uri? uploadResp, thumbnailUploadResp;
 
     final timeoutDate = DateTime.now().add(client.sendTimelineEventTimeout);
+
+    syncUpdate.rooms!.join!.values.first.timeline!.events!.first
+        .unsigned![fileSendingStatusKey] = FileSendingStatus.uploading.name;
     while (uploadResp == null ||
         (uploadThumbnail != null && thumbnailUploadResp == null)) {
       try {
@@ -733,9 +792,15 @@ class Room {
               )
             : null;
       } on MatrixException catch (_) {
+        syncUpdate.rooms!.join!.values.first.timeline!.events!.first
+            .unsigned![messageSendingStatusKey] = EventStatus.error.intValue;
+        await _handleFakeSync(syncUpdate);
         rethrow;
       } catch (_) {
         if (DateTime.now().isAfter(timeoutDate)) {
+          syncUpdate.rooms!.join!.values.first.timeline!.events!.first
+              .unsigned![messageSendingStatusKey] = EventStatus.error.intValue;
+          await _handleFakeSync(syncUpdate);
           rethrow;
         }
         Logs().v('Send File into room failed. Try again...');