message: Include both {new,originalRaw}Content in takeFailedMessageEdit

Greg points out that we'll need both values when restoring a failed
message edit: originalRawContent for the eventual edit-message
request (for prevContentSha256), and newContent to fill the
edit-message compose box, so the user can restore the edit session
to what it was before it failed.

Author: chrisbobbe

lib/model/message.dart

@@ -63,13 +63,18 @@ mixin MessageStore {
   ///
   /// Should only be called when there is a failed request,
   /// per [getEditMessageErrorStatus].
-  String takeFailedMessageEdit(int messageId);
+  ({String originalRawContent, String newContent}) takeFailedMessageEdit(int messageId);
 }
 
 class _EditMessageRequestStatus {
-  _EditMessageRequestStatus({required this.hasError, required this.newContent});
+  _EditMessageRequestStatus({
+    required this.hasError,
+    required this.originalRawContent,
+    required this.newContent,
+  });
 
   bool hasError;
+  final String originalRawContent;
   final String newContent;
 }
 
@@ -185,7 +190,7 @@ class MessageStoreImpl extends PerAccountStoreBase with MessageStore {
     }
 
     _editMessageRequests[messageId] = _EditMessageRequestStatus(
-      hasError: false, newContent: newContent);
+      hasError: false, originalRawContent: originalRawContent, newContent: newContent);
     _notifyMessageListViewsForOneMessage(messageId);
     try {
       await updateMessage(connection,
@@ -210,7 +215,7 @@ class MessageStoreImpl extends PerAccountStoreBase with MessageStore {
   }
 
   @override
-  String takeFailedMessageEdit(int messageId) {
+  ({String originalRawContent, String newContent}) takeFailedMessageEdit(int messageId) {
     final status = _editMessageRequests.remove(messageId);
     _notifyMessageListViewsForOneMessage(messageId);
     if (status == null) {
@@ -219,7 +224,10 @@ class MessageStoreImpl extends PerAccountStoreBase with MessageStore {
     if (!status.hasError) {
       throw StateError("called takeFailedMessageEdit, but edit hasn't failed");
     }
-    return status.newContent;
+    return (
+      originalRawContent: status.originalRawContent,
+      newContent: status.newContent
+    );
   }
 
   void handleUserTopicEvent(UserTopicEvent event) {

lib/model/store.dart

@@ -765,7 +765,7 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
       originalRawContent: originalRawContent, newContent: newContent);
   }
   @override
-  String takeFailedMessageEdit(int messageId) {
+  ({String originalRawContent, String newContent}) takeFailedMessageEdit(int messageId) {
     assert(!_disposed);
     return _messages.takeFailedMessageEdit(messageId);
   }

test/model/message_test.dart

@@ -252,7 +252,7 @@ void main() {
       check(store.getEditMessageErrorStatus(message.id)).isNotNull().isTrue();
       checkNotifiedOnce();
 
-      check(store.takeFailedMessageEdit(message.id)).equals('new content');
+      check(store.takeFailedMessageEdit(message.id).newContent).equals('new content');
       check(store.getEditMessageErrorStatus(message.id)).isNull();
       checkNotifiedOnce();
     }));
@@ -338,7 +338,7 @@ void main() {
       async.elapse(Duration(seconds: 1));
       check(store.getEditMessageErrorStatus(message.id)).isNotNull().isTrue();
       checkNotifiedOnce();
-      check(store.takeFailedMessageEdit(message.id)).equals('new content');
+      check(store.takeFailedMessageEdit(message.id).newContent).equals('new content');
       checkNotifiedOnce();
 
       await store.handleEvent(eg.updateMessageEditEvent(message)); // no error