the initial plan was to zero the creation time and leave the cards/facts there
until we have a chance to garbage collect them on a schema change, but such an
approach won't work with deck subscriptions
this means that content added earlier has a higher chance of appearing, but it
makes it consistent with sortCards(), and the user can sort manually if need
be
instead of completely resetting a card like we did in resetCards() in the
past, forgetCards() just puts the card back in the new queue and leaves the
factor and revlog alone. If users want to complete reset a card, they'll need to
export it.
reps should now be equal to the number of entries in the revlog, and only
exists so that we can order by review count in the browser efficiently
streak is no longer necessary as we have a learn queue now
The undo code was using triggers and a temporary table to write out all changed rows before making a change. This made for powerful undo/redo support, but had some problems:
- creating the tables and triggers wasn't cheap, especially on mobile devices
- likewise, every data modification required writing into two separate databases, almost doubling the amount of writes required
- it was possible to leave the DB in an inconsistent state if an undoable operation is followed by a non-undoable operation that references the undoable operation, and the user then rolls back the undoable operation.
To address these issues, we simplify undo by integrating it with the autosave changes:
- .save() can be passed a name to mark a rollback point. If the user undoes the change, any changes since the last save are lost
- autosaves happen every 5 minutes, and are pushed back on a .save(), so the maximum work a user can lose is 5 minutes.
- reviews are handled separately, so we can let the user undo multiple reviews at once
- if necessary, special cases could be added for other operations like marking
This means that if a user does two damaging operations in a row they won't be able to restore the first one, but such an event is both unlikely, and is also covered by the backups made each time a deck is opened.
