hook note_is_being_flushed

I created multiple add-ons which want to transform a note before it is
being saved. For example, one add-on trim it, and remove useless line
break which arrived by accident.

Another add-on want to compile LaTeX as soon as the note is done, and
warn the user if LaTeX can't be compiled.

Having a hook in pre-flush would be useful here

pylib/anki/hooks.py

@@ -18,6 +18,7 @@ import decorator
 
 import anki
 from anki.cards import Card
+from anki.notes import Note
 
 # New hook/filter handling
 ##############################################################################
@@ -277,6 +278,32 @@ class _NoteTypeAddedHook:
 note_type_added = _NoteTypeAddedHook()
 
 
+class _NoteWillFlushHook:
+    """Allow to change a note before it is added/updated in the database."""
+
+    _hooks: List[Callable[[Note], None]] = []
+
+    def append(self, cb: Callable[[Note], None]) -> None:
+        """(note: Note)"""
+        self._hooks.append(cb)
+
+    def remove(self, cb: Callable[[Note], None]) -> None:
+        if cb in self._hooks:
+            self._hooks.remove(cb)
+
+    def __call__(self, note: Note) -> None:
+        for hook in self._hooks:
+            try:
+                hook(note)
+            except:
+                # if the hook fails, remove it
+                self._hooks.remove(hook)
+                raise
+
+
+note_will_flush = _NoteWillFlushHook()
+
+
 class _NotesWillBeDeletedHook:
     _hooks: List[Callable[["anki.storage._Collection", List[int]], None]] = []
 

pylib/anki/notes.py

@@ -6,6 +6,7 @@ from __future__ import annotations
 from typing import Any, Dict, List, Optional, Tuple
 
 import anki  # pylint: disable=unused-import
+from anki import hooks
 from anki.models import Field, NoteType
 from anki.utils import (
     fieldChecksum,
@@ -202,6 +203,7 @@ insert or replace into notes values (?,?,?,?,?,?,?,?,?,?,?)""",
     ##################################################
 
     def _preFlush(self) -> None:
+        hooks.note_will_flush(self)
         # have we been added yet?
         self.newlyAdded = not self.col.db.scalar(
             "select 1 from cards where nid = ?", self.id

pylib/tools/genhooks.py

@@ -67,6 +67,11 @@ hooks = [
         Your add-on can check filter_name to decide whether it should modify
         field_text or not before returning it.""",
     ),
+    Hook(
+        name="note_will_flush",
+        args=["note: Note"],
+        doc="Allow to change a note before it is added/updated in the database.",
+    ),
     Hook(
         name="card_did_render",
         args=[