statiegeld_tokens - RevBank plugin for limiting return deposits
When using this plugin together with statiegeld, return deposits are limited to what users have previously paid. This is done by keeping track of tokens: when you buy something with a deposit, you receive a token, and when you return the empty container, you spend the token when getting your deposit back.
Tokens expire and are (currently) spent in FIFO order per type. The token type corresponds to the product_id of the matched addon.
The tokens are stored in a file called revbank.statiegeld which is not intended to be edited externally.
When checking out, return deposits are removed from the cart if the user does not have enough tokens for the transaction.
Users can choose to delete tokens by entering the void command before checking out. At the moment of writing, it is unclear whether this is actually useful for any practical use case.
Tokens expire only if ntpdate or systemd's datetimectl says the system time is synchronized. Else, new tokens made will never expire and existing tokens won't be processed for expiry.