Add hook for initializing answer buttons

qt/aqt/gui_hooks.py

@@ -2079,6 +2079,52 @@ class _ReviewerDidShowQuestionHook:
 reviewer_did_show_question = _ReviewerDidShowQuestionHook()
 
 
+class _ReviewerWillInitAnswerButtonsFilter:
+    """Used to modify the answer buttons shown for a card.
+    """
+
+    _hooks: List[
+        Callable["aqt.reviewer.Reviewer", Card], Tuple[Tuple[int, str]]]
+    ] = []
+
+    def append(
+        self,
+        cb: Callable[
+            "aqt.reviewer.Reviewer", Card], Tuple[Tuple[int, str]]]
+        ],
+    ) -> None:
+        """(reviewer: aqt.reviewer.Reviewer, card: Card)"""
+        self._hooks.append(cb)
+
+    def remove(
+        self,
+        cb: Callable[
+            "aqt.reviewer.Reviewer", Card], Tuple[Tuple[int, str]]]
+        ],
+    ) -> None:
+        if cb in self._hooks:
+            self._hooks.remove(cb)
+
+    def count(self) -> int:
+        return len(self._hooks)
+
+    def __call__(
+        self, reviewer: aqt.reviewer.Reviewer, card: Card
+    ) -> Tuple[Tuple[int, str]]:
+        buttons_tuple = None
+        for filter in self._hooks:
+            try:
+                buttons_tuple = filter(reviewer, card)
+            except:
+                # if the hook fails, remove it
+                self._hooks.remove(filter)
+                raise
+        return buttons_tuple
+
+
+reviewer_will_init_answer_buttons = _ReviewerWillInitAnswerButtonsFilter()
+
+
 class _ReviewerWillAnswerCardFilter:
     """Used to modify the ease at which a card is rated or to bypass
         rating the card completely.

qt/aqt/reviewer.py

@@ -622,14 +622,18 @@ time = %(time)d;
             return 2
 
     def _answerButtonList(self) -> Sequence[Tuple[int, str]]:
-        l = ((1, _("Again")),)
-        cnt = self.mw.col.sched.answerButtons(self.card)
-        if cnt == 2:
-            return l + ((2, _("Good")),)
-        elif cnt == 3:
-            return l + ((2, _("Good")), (3, _("Easy")))
+        buttons_tuple = gui_hooks.reviewer_will_init_answer_buttons(self, self.card)
+        if buttons_tuple is not None:
+            return buttons_tuple
         else:
-            return l + ((2, _("Hard")), (3, _("Good")), (4, _("Easy")))
+            l = ((1, _("Again")),)
+            cnt = self.mw.col.sched.answerButtons(self.card)
+            if cnt == 2:
+                return l + ((2, _("Good")),)
+            elif cnt == 3:
+                return l + ((2, _("Good")), (3, _("Easy")))
+            else:
+                return l + ((2, _("Hard")), (3, _("Good")), (4, _("Easy")))
 
     def _answerButtons(self) -> str:
         default = self._defaultEase()

qt/tools/genhooks_gui.py

@@ -58,6 +58,17 @@ hooks = [
         legacy_hook="showAnswer",
         legacy_no_args=True,
     ),
+    Hook(
+        name="reviewer_will_init_answer_buttons",
+        args=["reviewer: aqt.reviewer.Reviewer", "card: Card"],
+        doc="""Used to modify list of answer buttons
+
+        Return a tuple of the form ((1, "Label1"), (2, "Label2"))
+
+        import _ from anki.lang to support translation, as
+           ((1, _("Label1)), ...)
+        """,
+    ),
     Hook(
         name="reviewer_will_answer_card",
         args=[