circulation: Support self checkout by patrons

[sakshamarora1]

closes: CERNDocumentServer/cds-ils#839

[kpsherva]

Could you clarify why is this assignment needed?

[sakshamarora1]

Since, circulation is an extension it uses the circulation config and not the main config, so this is needed to get the value from the main config.

[kpsherva]

I wouldn't fit this variable under circulation because we are not bringing this change to the circulation module. The prefixes like CIRCULATION_ or ILS_ are meant to hint from which module the variable is coming from

[kpsherva]

to keep the config variables naming consistent:

Suggested change

	SELF_CHECKOUT_ENABLED = False
	ILS_SELF_CHECKOUT_ENABLED = False

[kpsherva]

well done for caring for flexibility of the configuration!
In this case it is a bit overkill though, because we already had the config:

ILS_VIEWS_PERMISSIONS_FACTORY = views_permissions_factory

[kpsherva]

just a reminder: we agreed to check if the action is performed by the librarian, not to pass the kwarg from the UI, since it is more reliable check.

[kpsherva]

for readability (check if the logic is correct ;) the point is to have less content heavy conditional statements to be able to understand the bussiness logic behind it easier:

Suggested change

	if (
	kwargs.get("self_checkout", False)
	and current_app.config.get("CIRCULATION_SELF_CHECKOUT_ENABLED", False)
	and patron_pid != current_user.id
	):
	self_checkout_enabled = current_app.config.get("CIRCULATION_SELF_CHECKOUT_ENABLED", False)
	is_librarian = .... check if librarian
	is_patron_current_user = patron_pid == current_user.id
	if self_checkout_enabled and (not is_librarian or not is_patron_current_user):