hook: history_line

I expect to use this hook to create an add-on which will simply remove
the ",,". By ignoring empty fields I expect to make this easier to
use.

qt/aqt/addcards.py

@@ -135,11 +135,14 @@ class AddCards(QDialog):
         m = QMenu(self)
         for nid in self.history:
             if self.mw.col.findNotes("nid:%s" % nid):
-                fields = self.mw.col.getNote(nid).fields
+                note = self.mw.col.getNote(nid)
+                fields = note.fields
                 txt = htmlToTextLine(", ".join(fields))
                 if len(txt) > 30:
                     txt = txt[:30] + "..."
-                a = m.addAction(_('Edit "%s"') % txt)
+                line = _('Edit "%s"') % txt
+                line = gui_hooks.addcards_will_add_history_entry(line, note)
+                a = m.addAction(line)
                 qconnect(a.triggered, lambda b, nid=nid: self.editHistory(nid))
             else:
                 a = m.addAction(_("(Note deleted)"))

qt/aqt/gui_hooks.py

@@ -149,6 +149,36 @@ class _AddCardsWillShowHistoryMenuHook:
 add_cards_will_show_history_menu = _AddCardsWillShowHistoryMenuHook()
 
 
+class _AddcardsWillAddHistoryEntryFilter:
+    """Allows changing the history line in the add-card window."""
+
+    _hooks: List[Callable[[str, "anki.notes.Note"], str]] = []
+
+    def append(self, cb: Callable[[str, "anki.notes.Note"], str]) -> None:
+        """(line: str, note: anki.notes.Note)"""
+        self._hooks.append(cb)
+
+    def remove(self, cb: Callable[[str, "anki.notes.Note"], str]) -> None:
+        if cb in self._hooks:
+            self._hooks.remove(cb)
+
+    def count(self) -> int:
+        return len(self._hooks)
+
+    def __call__(self, line: str, note: anki.notes.Note) -> str:
+        for filter in self._hooks:
+            try:
+                line = filter(line, note)
+            except:
+                # if the hook fails, remove it
+                self._hooks.remove(filter)
+                raise
+        return line
+
+
+addcards_will_add_history_entry = _AddcardsWillAddHistoryEntryFilter()
+
+
 class _AddonConfigEditorWillDisplayJsonFilter:
     """Allows changing the text of the json configuration before actually
         displaying it to the user. For example, you can replace "\n" by

qt/tools/genhooks_gui.py

@@ -485,6 +485,12 @@ hooks = [
         replace return the reason to reject. Otherwise return the
         input.""",
     ),
+    Hook(
+        name="addcards_will_add_history_entry",
+        args=["line: str", "note: anki.notes.Note"],
+        return_type="str",
+        doc="""Allows changing the history line in the add-card window.""",
+    ),
     # Editing
     ###################
     Hook(