tab2ledger/tab

#!/usr/bin/env python3

import itertools
import sys
import os
import requests


ME       = os.getenv("TAB_ME")
TOKEN    = os.getenv("TAB_TOKEN")
BASE_URI = os.getenv("TAB_BASE_URI", default="https://tab.zeus.gent")

TAP_ACCOUNT  = os.getenv("LEDGER_TAP_ACCOUNT",  default="Expenses:Zeuskelder:Drinks and snacks")
FOOD_ACCOUNT = os.getenv("LEDGER_FOOD_ACCOUNT", default="Expenses:Zeuskelder:Food")

TAB2LEDGER_NAME    = "tab2ledger"
TAB2LEDGER_VERSION = "1.0"
TAB2LEDGER_URL     = "https://git.zeus.gent/midgard/tab2ledger"
USER_AGENT = os.getenv("TAB2LEDGER_USER_AGENT", default=f"{TAB2LEDGER_NAME} {TAB2LEDGER_VERSION} ({TAB2LEDGER_URL})")


def formatted_price(cents):
	return f"€ {cents / 100}"


def balance_assertion(balance):
	return \
		f"= {formatted_price(balance)}" \
		if balance is not None else ""


def formatted_transaction(transaction, me, balance_after=None):
	issuer = transaction["issuer"]
	debtor = transaction["debtor"]
	date   = transaction["time"][:10]
	amount = formatted_price(transaction["amount"])

	message = (
		transaction["message"].replace("1 ", "").replace(" and ", " en ")
		if issuer == "Tap" else
		transaction["message"]
	).strip()

	header = f"{date} {message}"

	assertion = balance_assertion(balance_after)

	if debtor == me:
		# If the issuer wasn't Tap, we assume the money we gave was for food – manual change to the
		# output required if it wasn't
		to_account = TAP_ACCOUNT if issuer == "Tap" else FOOD_ACCOUNT

		to_line   = f"{to_account}  {amount}"
		from_line = f"tab  {assertion}".rstrip()

	else:
		to_line   = f"tab  {amount} {assertion}"
		from_line = f"; {debtor}"


	return "\n".join([
		header,
		"\t" + to_line,
		"\t" + from_line
	])


def formatted_transactions(transactions, final_balance, me):
	all_but_last = itertools.islice(transactions, len(transactions) - 1)
	return [
		*(formatted_transaction(t, me) for t in all_but_last),
		formatted_transaction(transactions[-1], me, final_balance)
 ]


def main(me, token, file=sys.stdout):
	def get(path):
		return requests.get(
			f"{BASE_URI}{path}",
			headers={
				"Accept": "application/json", "Authorization": f"Token token={token}",
				"User-Agent": USER_AGENT
			}
		).json()

	balance      = get(f"/users/{me}")["balance"]
	transactions = get(f"/users/{me}/transactions")

	print(
		"\n\n".join(formatted_transactions(transactions, balance, me)),
		file=file
	)


if __name__ == "__main__":
	main(ME, TOKEN)