#+TITLE: Review Internals

* Implementation
Review is implemented by storing due cards in a global variable.  The
buffer the card is displayed in never leaves =org-mode=, [[https://github.com/abo-abo/hydra][abo-abo/hydra]]
is used to show review statistics (number of cards remaining, percent
again/hard/good/easy) and prompt for user actions.

1. jump to the file + id of the current card
2. set it up for review (i.e. hiding parts of the buffer)
3. open a hydra prompting to flip the card
4. flip the card or quit the review session
5. open a hydra prompting for a rating
6. rate the card or quit the review session
7. set the current card to the next card due
8. continue at 1.

If an error occurs during review, ~org-fc-review-quit~ can be used to
reset the current buffer and the review state.
* Display of Cards
Headlines are presented for review by hiding the all top level
headings before and after the one the heading to be reviewed is
located in.

This is done through the function ~org-fc-org-narrow-tree~.
~org-fc-show-all~ can be used to remove all overlays (i.e. reset the
display of the buffer).

All parent headings are shown but their body text (~section~) is
hidden.

If the file has a ~#+TITLE:~ keyword this is shown, too.

To hide the title during review (e.g. for a "Definition" flashcard),
add a ~:notitle:~ tag to the heading.

To hide the heading text of the current card during review, add a
~:noheading:~ tag.