ui: Move file picker invocation to the SendFiles bloc

lib/ui/bloc/conversation_bloc.dart

@@ -291,15 +291,8 @@ class ConversationBloc extends Bloc<ConversationEvent, ConversationState> {
   }
 
   Future<void> _onFileUploadRequested(FileUploadRequestedEvent event, Emitter<ConversationState> emit) async {
-    final result = await FilePicker.platform.pickFiles(type: FileType.image, allowMultiple: true);
-
-    if (result != null) {
     GetIt.I.get<SendFilesBloc>().add(
-        SendFilesPageRequestedEvent(
+      SendFilesPageRequestedEvent(state.conversation!.jid),
-          result.files.map((PlatformFile file) => file.path!).toList(),
-          state.conversation!.jid,
-        ),
     );
   }
-  }
 }

lib/ui/bloc/sendfiles_bloc.dart

@@ -19,14 +19,29 @@ class SendFilesBloc extends Bloc<SendFilesEvent, SendFilesState> {
     on<FileSendingRequestedEvent>(_onFileSendingRequested);
   }
 
+  /// Pick files. Returns either a list of paths to attach or null if the process has
+  /// been cancelled.
+  Future<List<String>?> _pickFiles() async {
+    // TODO(PapaTutuWawa): Allow multiple file types
+    final result = await FilePicker.platform.pickFiles(type: FileType.image, allowMultiple: true);
+
+    if (result == null) return null;
+
+    return result.files.map((PlatformFile file) => file.path!).toList();
+  }
+  
   Future<void> _sendFilesRequested(SendFilesPageRequestedEvent event, Emitter<SendFilesState> emit) async {
+    final files = await _pickFiles();
+    if (files == null) return;
+
     emit(
       state.copyWith(
-        files: event.files,
+        files: files,
         index: 0,
         conversationJid: event.jid,
       ),
     );
+
     GetIt.I.get<NavigationBloc>().add(
       PushedNamedEvent(
         const NavigationDestination(
@@ -41,19 +56,15 @@ class SendFilesBloc extends Bloc<SendFilesEvent, SendFilesState> {
   }
 
   Future<void> _onAddFilesRequested(AddFilesRequestedEvent event, Emitter<SendFilesState> emit) async {
-    final result = await FilePicker.platform.pickFiles(type: FileType.image, allowMultiple: true);
+    final files = await _pickFiles();
+    if (files == null) return;
 
-    if (result != null) {
     emit(
       state.copyWith(
-          files: List.from(state.files)
+        files: List.from(state.files)..addAll(files),
-            ..addAll(
-              result.files.map((PlatformFile file) => file.path!).toList(),
-            ),
       ),
     );
   }
-  }
 
   Future<void> _onFileSendingRequested(FileSendingRequestedEvent event, Emitter<SendFilesState> emitter) async {
     await MoxplatformPlugin.handler.getDataSender().sendData(

lib/ui/bloc/sendfiles_event.dart

@@ -4,8 +4,7 @@ abstract class SendFilesEvent {}
 
 class SendFilesPageRequestedEvent extends SendFilesEvent {
 
-  SendFilesPageRequestedEvent(this.files, this.jid);
+  SendFilesPageRequestedEvent(this.jid);
-  final List<String> files;
   final String jid;
 }