#   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 hashlib
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):
	if date is None:
		return run_ledger(*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

csv.register_dialect('ledger', doublequote=False, escapechar='\\', strict=True)

RE_COMMODITY1 = re.compile(r'([0123456789.,-]+)( *)(.+)')
RE_COMMODITY2 = re.compile(r'(.+?)( *)([0123456789.,-]+)')

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-'):
		# Commodity follows number
		result = RE_COMMODITY1.match(amount_str)
		amount_num = Decimal(result.group(1).replace(',', ''))
		commodity = Commodity(result.group(3).strip('"'), False, len(result.group(2)) > 0)
	else:
		# Commodity precedes number
		result = RE_COMMODITY2.match(amount_str)
		amount_num = Decimal(result.group(3).replace(',', ''))
		commodity = Commodity(result.group(1).strip('"'), True, len(result.group(2)) > 0)
	
	if price_str:
		commodity.price = parse_amount(price_str)
	
	return Amount(amount_num, commodity)

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(), dialect='ledger')
	for date_str, commodity, price_str in reader:
		prices.append((datetime.strptime(date_str, '%Y-%m-%d'), commodity.strip('"'), 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(parent.code)),%(quoted(payee)),%(quoted(account)),%(quoted(display_amount)),%(quoted(comment)),%(quoted(state)),%(quoted(note))\n')
	
	uuids = set()
	
	reader = csv.reader(output.splitlines(True), dialect='ledger')
	for trn_id, date_str, code, payee, account_str, amount_str, comment, state_str, note_str in reader:
		if not ledger.transactions or trn_id != ledger.transactions[-1].id:
			if trn_id in uuids:
				digest = hashlib.sha256()
				digest.update(trn_id.encode('utf-8'))
				digest.update(date_str.encode('utf-8'))
				digest.update(payee.encode('utf-8'))
				uuid = digest.hexdigest()
			else:
				uuid = trn_id
			
			metadata = {}
			for line in note_str.splitlines():
				line = line.strip()
				if ': ' in line:
					metadata[line.split(': ')[0]] = line.split(': ')[1].strip()
			
			transaction = Transaction(ledger, trn_id, datetime.strptime(date_str, '%Y-%m-%d'), payee, code, uuid, metadata)
			ledger.transactions.append(transaction)
			
			uuids.add(uuid)
		else:
			# Transaction ID matches: continuation of previous transaction
			transaction = ledger.transactions[-1]
		
		if ';' in comment:
			comment = comment[comment.index(';')+1:].strip()
		
		amount = parse_amount(amount_str)
		posting = Posting(transaction, ledger.get_account(account_str), amount, comment=comment, state=Posting.State(int(state_str)))
		transaction.postings.append(posting)
		
		if amount.commodity.name not in ledger.commodities:
			ledger.commodities[amount.commodity.name] = amount.commodity.strip_price()
	
	ledger.transactions.sort(key=lambda t: t.date)
	
	return ledger