PICARD-2886: If MB server OAuth2 logout fails, show a dialog box

Offer the user the options to retry the request, cancel or remove locally
stored credentials anyway. This prevents the user being unable to
remove local credentials and being stuck with broken credentials due to
some technical error.

picard/ui/options/general.py

@@ -28,7 +28,10 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
 
-from PyQt5 import QtCore
+from PyQt5 import (
+    QtCore,
+    QtWidgets,
+)
 
 from picard.config import (
     BoolOption,
@@ -173,7 +176,27 @@ def logout(self):
         self.tagger.mb_logout(self.on_logout_finished)
 
     def on_logout_finished(self, successful, error_msg=None):
-        self.update_login_logout(error_msg)
+        if not successful:
+            msg = QtWidgets.QMessageBox(self)
+            msg.setIcon(QtWidgets.QMessageBox.Icon.Warning)
+            msg.setWindowTitle(_("Logout error"))
+            msg.setText(_(
+                "A server error occurred while revoking access to the MusicBrainz server: %s\n"
+                "\n"
+                "Remove locally stored credentials anyway?"
+            ) % error_msg)
+            msg.setStandardButtons(
+                QtWidgets.QMessageBox.StandardButton.Yes
+                | QtWidgets.QMessageBox.StandardButton.No
+                | QtWidgets.QMessageBox.StandardButton.Retry)
+            result = msg.exec()
+            if result == QtWidgets.QMessageBox.StandardButton.Yes:
+                oauth_manager = self.tagger.webservice.oauth_manager
+                oauth_manager.forget_access_token()
+                oauth_manager.forget_refresh_token()
+            elif result == QtWidgets.QMessageBox.StandardButton.Retry:
+                self.logout()
+        self.update_login_logout()
 
     def restore_defaults(self):
         super().restore_defaults()