GODT-1984: Handle permanent message deletion

Only delete messages when unlabeled from trash/spam if they only exists
in All Mail and (spam or trash).

This patch also ports delete_from_trash.feature and use status rather
than fetch to count messages in a mailboxes.

internal/user/events.go

@@ -289,7 +289,9 @@ func (user *User) handleMessageEvents(ctx context.Context, messageEvents []litea
 			}
 
 		case liteapi.EventDelete:
-			return ErrNotImplemented
+			if err := user.handleDeleteMessageEvent(ctx, event); err != nil {
+				return fmt.Errorf("failed to handle delete message event: %w", err)
+			}
 		}
 	}
 
@@ -331,6 +333,20 @@ func (user *User) handleUpdateMessageEvent(_ context.Context, event liteapi.Mess
 	}, user.updateChLock)
 }
 
+func (user *User) handleDeleteMessageEvent(_ context.Context, event liteapi.MessageEvent) error { //nolint:unparam
+	return safe.RLockRet(func() error {
+		for _, updateCh := range user.updateCh {
+			update := imap.NewMessagesDeleted(
+				imap.MessageID(event.ID),
+			)
+
+			updateCh.Enqueue(update)
+		}
+
+		return nil
+	}, user.updateChLock)
+}
+
 func getMailboxName(label liteapi.Label) []string {
 	var name []string
 

internal/user/imap.go

@@ -311,7 +311,34 @@ func (conn *imapConnector) AddMessagesToMailbox(ctx context.Context, messageIDs
 
 // RemoveMessagesFromMailbox unlabels the given messages with the given label ID.
 func (conn *imapConnector) RemoveMessagesFromMailbox(ctx context.Context, messageIDs []imap.MessageID, mailboxID imap.MailboxID) error {
-	return conn.client.UnlabelMessages(ctx, mapTo[imap.MessageID, string](messageIDs), string(mailboxID))
+	if err := conn.client.UnlabelMessages(ctx, mapTo[imap.MessageID, string](messageIDs), string(mailboxID)); err != nil {
+		return err
+	}
+
+	if mailboxID == liteapi.SpamLabel || mailboxID == liteapi.TrashLabel {
+		// check if messages are only in Trash and AllMail before they are permanently deleted.
+		var messagesToDelete []string
+
+		// GODT-1993 - Update to more efficient method.
+		for _, messageID := range messageIDs {
+			m, err := conn.client.GetMessage(ctx, string(messageID))
+			if err != nil {
+				return fmt.Errorf("failed to get message info")
+			}
+
+			if len(m.LabelIDs) == 1 && m.LabelIDs[0] == liteapi.AllMailLabel {
+				messagesToDelete = append(messagesToDelete, m.ID)
+			}
+		}
+
+		if len(messagesToDelete) == 0 {
+			return nil
+		}
+
+		return conn.client.DeleteMessage(ctx, messagesToDelete...)
+	}
+
+	return nil
 }
 
 // MoveMessages removes the given messages from one label and adds them to the other label.