roadmap

1. write a parser for user messages such as /in [name] [amount] [details] and /out [name] [amount] [details] - DONE: src/grammar
2. attach metadata (datetime) to each message
3. write (append) to a ordered by datetime CSV file as double-entry bookkeeping registry
4. export CSV through HTTP URI e.g. https://fragal.eu/expenses/ (protected by auth or encrypted) - use NGINX for this
5. generate a readable report of expenses in a given period on query e.g. /report [daily|weekly|/montly|/yearly] or /r [d|w|m|y]
6. move from CSV to a SQLITE database for persistence, keeping functionality of point 4
7. add other functionalities such as setting limits for a period and alerting / memos