ledger-pyreport/ledger_pyreport/ledger.py

#   ledger-pyreport
#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
#
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU Affero General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU Affero General Public License for more details.
#
#   You should have received a copy of the GNU Affero General Public License
#   along with this program.  If not, see <https://www.gnu.org/licenses/>.

from .config import config
from .model import *

import csv
from datetime import datetime, timedelta
from decimal import Decimal
import re
import subprocess

# Helper commands to run Ledger

def run_ledger(*args):
	ledger_args = ['ledger', '--args-only', '--file', config['ledger_file'], '--date-format', '%Y-%m-%d', '--unround'] + config['ledger_args'] + list(args)
	proc = subprocess.Popen(ledger_args, encoding='utf-8', stdout=subprocess.PIPE, stderr=subprocess.PIPE)
	stdout, stderr = proc.communicate()
	
	if stderr:
		raise Exception(stderr)
	
	return stdout

def run_ledger_date(date, *args):
	return run_ledger('--end', (date + timedelta(days=1)).strftime('%Y-%m-%d'), *args)

# General financial logic

def financial_year(date):
	pstart = date.replace(day=1, month=7)
	if pstart > date:
		pstart = pstart.replace(year=pstart.year - 1)
	return pstart

# Ledger logic

def parse_amount(amount):
	if '{' in amount:
		amount_str = amount[:amount.index('{')].strip()
		price_str = amount[amount.index('{')+1:amount.index('}')].strip()
	else:
		amount_str = amount
		price_str = None
	
	if amount_str[0] in list('0123456789-'):
		# Currency follows number
		bits = amount_str.split()
		amount_num = Decimal(bits[0])
		currency = Currency(bits[1], False)
	else:
		# Currency precedes number
		currency = Currency(amount_str[0], True)
		amount_num = Decimal(amount_str[1:])
	
	if price_str:
		currency.price = parse_amount(price_str)
	
	return Amount(amount_num, currency)

def get_pricedb():
	output = run_ledger('prices', '--prices-format', '%(quoted(format_date(date))),%(quoted(display_account)),%(quoted(display_amount))\n')
	
	prices = []
	
	reader = csv.reader(output.splitlines())
	for date_str, currency, price_str in reader:
		prices.append((datetime.strptime(date_str, '%Y-%m-%d'), currency, parse_amount(price_str)))
	
	return prices

def raw_transactions_at_date(date):
	ledger = Ledger(date)
	ledger.prices = get_pricedb()
	
	output = run_ledger_date(date, 'csv', '--csv-format', '%(quoted(parent.id)),%(quoted(format_date(date))),%(quoted(payee)),%(quoted(account)),%(quoted(display_amount))\n')
	
	reader = csv.reader(output.splitlines())
	for trn_id, date_str, payee, account_str, amount_str in reader:
		if not ledger.transactions or trn_id != ledger.transactions[-1].id:
			transaction = Transaction(ledger, trn_id, datetime.strptime(date_str, '%Y-%m-%d'), payee)
			ledger.transactions.append(transaction)
		else:
			# Transaction ID matches: continuation of previous transaction
			transaction = ledger.transactions[-1]
		
		posting = Posting(transaction, ledger.get_account(account_str), parse_amount(amount_str))
		transaction.postings.append(posting)
	
	return ledger