#   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 . import accounting
from . import ledger
from .config import config
from .model import *

import calendar
from datetime import datetime, timedelta
from decimal import Decimal
import flask
import itertools

app = flask.Flask(__name__, template_folder='jinja2')

@app.route('/')
def index():
	date = datetime.now()
	pstart = ledger.financial_year(date)
	
	return flask.render_template('index.html', date=date, pstart=pstart)

def make_period(pstart, date, compare, cmp_period):
	pstarts = []
	dates = []
	labels = []
	
	for i in range(0, compare + 1):
		if cmp_period == 'year':
			date2 = date.replace(year=date.year - i)
			pstarts.append(pstart.replace(year=pstart.year - i))
			dates.append(date2)
			labels.append(date2.strftime('%Y'))
		elif cmp_period == 'month':
			pstart2 = pstart
			date2 = date
			
			for _ in range(i):
				# Go backward one month
				pstart2 = pstart2.replace(day=1) - timedelta(days=1)
				date2 = date2.replace(day=1) - timedelta(days=1)
			
			pstart2 = pstart2.replace(day=pstart.day)
			
			# Is this the last day of the month?
			is_last = calendar.monthrange(date.year, date.month)[1] == date.day
			if is_last:
				date2 = date2.replace(day=calendar.monthrange(date2.year, date2.month)[1])
			else:
				if date.day > calendar.monthrange(date.year, date.month)[1]:
					date2 = date2.replace(day=calendar.monthrange(date2.year, date2.month)[1])
				else:
					date2 = date2.replace(day=date.day)
			
			pstarts.append(pstart2)
			dates.append(date2)
			labels.append(date2.strftime('%b %Y'))
	
	return pstarts, dates, labels

def describe_period(date_end, date_beg):
	if date_end == (date_beg.replace(year=date_beg.year + 1) - timedelta(days=1)):
		return 'year ended {}'.format(date_end.strftime('%d %B %Y'))
	elif date_beg == ledger.financial_year(date_end):
		return 'financial year to {}'.format(date_end.strftime('%d %B %Y'))
	else:
		return 'period from {} to {}'.format(date_beg.strftime('%d %B %Y'), date_end.strftime('%d %B %Y'))

@app.route('/trial')
def trial():
	date = datetime.strptime(flask.request.args['date'], '%Y-%m-%d')
	pstart = datetime.strptime(flask.request.args['pstart'], '%Y-%m-%d')
	compare = int(flask.request.args.get('compare', '0'))
	cmp_period = flask.request.args.get('cmpperiod', 'year')
	cash = flask.request.args.get('cash', False)
	
	if compare == 0:
		# Get trial balance
		l = ledger.raw_transactions_at_date(date)
		report_commodity = l.get_commodity(config['report_commodity'])
		if cash:
			l = accounting.ledger_to_cash(l, report_commodity)
		trial_balance = accounting.trial_balance(l, date, pstart, report_commodity)
		
		total_dr = Amount(0, report_commodity)
		total_cr = Amount(0, report_commodity)
		
		for account in l.accounts.values():
			# Display in "cost basis" as we have already accounted for unrealised gains
			balance = trial_balance.get_balance(account).exchange(report_commodity, True)
			if balance > 0:
				total_dr += balance
			else:
				total_cr -= balance
		
		# Identify which accounts have transactions
		accounts = sorted(l.accounts.values(), key=lambda a: a.name)
		trial_balance.trn_accounts = [a for a in accounts if any(p.account == a for t in l.transactions for p in t.postings if t.date >= pstart and t.date <= date)]
		
		return flask.render_template('trial.html', date=date, pstart=pstart, trial_balance=trial_balance, accounts=accounts, total_dr=total_dr, total_cr=total_cr, report_commodity=report_commodity)
	else:
		# Get multiple trial balances for comparison
		pstarts, dates, labels = make_period(pstart, date, compare, cmp_period)
		
		l = ledger.raw_transactions_at_date(date)
		report_commodity = l.get_commodity(config['report_commodity'])
		if cash:
			l = accounting.ledger_to_cash(l, report_commodity)
		trial_balances = [accounting.trial_balance(l.clone(), d, p, report_commodity, label=lbl) for d, p, lbl in zip(dates, pstarts, labels)]
		
		# Identify which accounts have transactions in which periods
		accounts = sorted(l.accounts.values(), key=lambda a: a.name)
		for trial_balance in trial_balances:
			trial_balance.trn_accounts = [a for a in accounts if any(p.account == a for t in l.transactions for p in t.postings if t.date >= trial_balance.pstart and t.date <= trial_balance.date)]
		
		# Delete accounts with always no transactions
		for account in accounts[:]:
			if not any(account in b.trn_accounts for b in trial_balances):
				accounts.remove(account)
		
		return flask.render_template('trial_multiple.html', trial_balances=trial_balances, accounts=accounts, report_commodity=report_commodity, cash=cash)

@app.route('/balance')
def balance():
	date = datetime.strptime(flask.request.args['date'], '%Y-%m-%d')
	pstart = datetime.strptime(flask.request.args['pstart'], '%Y-%m-%d')
	compare = int(flask.request.args.get('compare', '0'))
	cmp_period = flask.request.args.get('cmpperiod', 'year')
	cash = flask.request.args.get('cash', False)
	
	pstarts, dates, labels = make_period(pstart, date, compare, cmp_period)
	
	l = ledger.raw_transactions_at_date(date)
	report_commodity = l.get_commodity(config['report_commodity'])
	if cash:
		l = accounting.ledger_to_cash(l, report_commodity)
	balance_sheets = [accounting.balance_sheet(accounting.trial_balance(l.clone(), d, p, report_commodity, label=lbl)) for d, p, lbl in zip(dates, pstarts, labels)]
	
	# Delete accounts with always zero balances
	accounts = list(l.accounts.values())
	for account in accounts[:]:
		if all(b.get_balance(account).exchange(report_commodity, True).near_zero and b.get_total(account).exchange(report_commodity, True).near_zero for b in balance_sheets):
			accounts.remove(account)
	
	return flask.render_template('balance.html', ledger=l, balance_sheets=balance_sheets, accounts=accounts, config=config, report_commodity=report_commodity, cash=cash)

@app.route('/pandl')
def pandl():
	date_beg = datetime.strptime(flask.request.args['date_beg'], '%Y-%m-%d')
	date_end = datetime.strptime(flask.request.args['date_end'], '%Y-%m-%d')
	compare = int(flask.request.args.get('compare', '0'))
	cmp_period = flask.request.args.get('cmpperiod', 'year')
	cash = flask.request.args.get('cash', False)
	scope = flask.request.args.get('scope', 'pandl')
	
	dates_beg, dates_end, labels = make_period(date_beg, date_end, compare, cmp_period)
	
	l = ledger.raw_transactions_at_date(date_end)
	report_commodity = l.get_commodity(config['report_commodity'])
	if cash:
		l = accounting.ledger_to_cash(l, report_commodity)
	pandls = [accounting.trial_balance(l.clone(), de, db, report_commodity, label=lbl) for de, db, lbl in zip(dates_end, dates_beg, labels)]
	
	# Process separate P&L accounts
	separate_pandls = []
	for separate_pandl_name in config['separate_pandl']:
		acc_income = l.get_account(config['income_account'] + ':' + separate_pandl_name)
		acc_expenses = l.get_account(config['expenses_account'] + ':' + separate_pandl_name)
		separate_pandls.append((acc_income, acc_expenses))
		
		# Unlink from parents so raw figures not counted in income/expense total
		acc_income.parent.children.remove(acc_income)
		acc_expenses.parent.children.remove(acc_expenses)
		
		# Add summary account
		for i, de, db in zip(range(compare + 1), dates_end, dates_beg):
			balance = (pandls[i].get_total(acc_income) + pandls[i].get_total(acc_expenses)).exchange(report_commodity, True)
			
			if balance <= 0: # Credit
				summary_account = l.get_account(config['income_account'] + ':' + separate_pandl_name + ' Profit')
			else:
				summary_account = l.get_account(config['expenses_account'] + ':' + separate_pandl_name + ' Loss')
			
			pandls[i].balances[summary_account.name] = pandls[i].get_balance(summary_account) + balance
	
	# Delete accounts with always zero balances
	accounts = list(l.accounts.values())
	for account in accounts[:]:
		if all(p.get_balance(account) == 0 and p.get_total(account) == 0 for p in pandls):
			accounts.remove(account)
	
	return flask.render_template('pandl.html', period=describe_period(date_end, date_beg), ledger=l, pandls=pandls, accounts=accounts, separate_pandls=separate_pandls, config=config, report_commodity=report_commodity, cash=cash, scope=scope)

@app.route('/cashflow')
def cashflow():
	date_beg = datetime.strptime(flask.request.args['date_beg'], '%Y-%m-%d')
	date_end = datetime.strptime(flask.request.args['date_end'], '%Y-%m-%d')
	compare = int(flask.request.args.get('compare', '0'))
	cmp_period = flask.request.args.get('cmpperiod', 'year')
	method = flask.request.args['method']
	
	dates_beg, dates_end, labels = make_period(date_beg, date_end, compare, cmp_period)
	
	l = ledger.raw_transactions_at_date(date_end)
	report_commodity = l.get_commodity(config['report_commodity'])
	
	cash_accounts = [a for a in l.accounts.values() if a.is_cash]
	
	# Calculate opening and closing cash
	opening_balances = []
	closing_balances = []
	cashflows = []
	profits = []
	for de, db, lbl in zip(dates_end, dates_beg, labels):
		tb = accounting.trial_balance(l.clone(), db - timedelta(days=1), db, report_commodity)
		opening_balances.append(sum((tb.get_balance(a) for a in cash_accounts), Balance()).exchange(report_commodity, True))
		
		tb = accounting.trial_balance(l.clone(), de, db, report_commodity)
		closing_balances.append(sum((tb.get_balance(a) for a in cash_accounts), Balance()).exchange(report_commodity, True))
		
		if method == 'direct':
			# Determine transactions affecting cash assets
			cashflows.append(accounting.account_flows(tb.ledger, de, db, cash_accounts, True, label=lbl))
		else:
			# Determine net profit (loss)
			profits.append(-(tb.get_total(tb.ledger.get_account(config['income_account'])) + tb.get_total(tb.ledger.get_account(config['expenses_account'])) + tb.get_total(tb.ledger.get_account(config['oci_account']))).exchange(report_commodity, True))
			
			# Determine transactions affecting equity, liabilities and non-cash assets
			noncash_accounts = [a for a in l.accounts.values() if a.is_equity or a.is_liability or (a.is_asset and not a.is_cash)]
			cashflows.append(accounting.account_flows(tb.ledger, de, db, noncash_accounts, False, label=lbl))
	
	# Delete accounts with always zero balances
	accounts = list(l.accounts.values())
	for account in accounts[:]:
		if all(p.get_balance(account) == 0 and p.get_total(account) == 0 for p in cashflows):
			accounts.remove(account)
	
	if method == 'direct':
		return flask.render_template('cashflow_direct.html', period=describe_period(date_end, date_beg), ledger=l, cashflows=cashflows, opening_balances=opening_balances, closing_balances=closing_balances, accounts=accounts, config=config, report_commodity=report_commodity)
	else:
		return flask.render_template('cashflow_indirect.html', period=describe_period(date_end, date_beg), ledger=l, cashflows=cashflows, profits=profits, opening_balances=opening_balances, closing_balances=closing_balances, accounts=accounts, config=config, report_commodity=report_commodity)

@app.route('/transactions')
def transactions():
	date_beg = datetime.strptime(flask.request.args['date_beg'], '%Y-%m-%d')
	date_end = datetime.strptime(flask.request.args['date_end'], '%Y-%m-%d')
	account = flask.request.args.get('account', None)
	cash = flask.request.args.get('cash', False)
	commodity = flask.request.args.get('commodity', False)
	
	# General ledger
	l = ledger.raw_transactions_at_date(date_end)
	report_commodity = l.get_commodity(config['report_commodity'])
	if cash:
		l = accounting.ledger_to_cash(l, report_commodity)
	
	# Unrealized gains
	l = accounting.trial_balance(l, date_end, date_beg, report_commodity).ledger
	
	if not account:
		# General Ledger
		transactions = [t for t in l.transactions if t.date <= date_end and t.date >= date_beg]
		
		total_dr = sum((p.amount for t in transactions for p in t.postings if p.amount > 0), Balance()).exchange(report_commodity, True)
		total_cr = sum((p.amount for t in transactions for p in t.postings if p.amount < 0), Balance()).exchange(report_commodity, True)
		
		return flask.render_template('transactions.html', date_beg=date_beg, date_end=date_end, period=describe_period(date_end, date_beg), account=None, ledger=l, transactions=transactions, total_dr=total_dr, total_cr=total_cr, report_commodity=report_commodity, cash=cash)
	elif commodity:
		# Account Transactions with commodity detail
		account = l.get_account(account)
		transactions = [t for t in l.transactions if t.date <= date_end and t.date >= date_beg and any(p.account == account for p in t.postings)]
		
		# Use trial_balance_raw because ledger is already adjusted for unrealised gains, etc.
		opening_balance = accounting.trial_balance_raw(l, date_beg - timedelta(days=1), date_beg).get_balance(account).clean()
		closing_balance = accounting.trial_balance_raw(l, date_end, date_beg).get_balance(account).clean()
		
		def matching_posting(transaction, amount):
			return next((p for p in transaction.postings if p.account == account and p.amount.commodity == amount.commodity), None)
		
		return flask.render_template('transactions_commodity.html', date_beg=date_beg, date_end=date_end, period=describe_period(date_end, date_beg), account=account, ledger=l, transactions=transactions, opening_balance=opening_balance, closing_balance=closing_balance, report_commodity=report_commodity, cash=cash, timedelta=timedelta, matching_posting=matching_posting)
	else:
		# Account Transactions
		account = l.get_account(account)
		transactions = [t.perspective_of(account) for t in l.transactions if t.date <= date_end and t.date >= date_beg and any(p.account == account for p in t.postings)]
		
		opening_balance = accounting.trial_balance_raw(l, date_beg - timedelta(days=1), date_beg).get_balance(account).exchange(report_commodity, True)
		closing_balance = accounting.trial_balance_raw(l, date_end, date_beg).get_balance(account).exchange(report_commodity, True)
		
		return flask.render_template('transactions.html', date_beg=date_beg, date_end=date_end, period=describe_period(date_end, date_beg), account=account, ledger=l, transactions=transactions, opening_balance=opening_balance, closing_balance=closing_balance, report_commodity=report_commodity, cash=cash, timedelta=timedelta)

@app.route('/transaction')
def transaction():
	date = datetime.strptime(flask.request.args['date'], '%Y-%m-%d')
	pstart = datetime.strptime(flask.request.args['pstart'], '%Y-%m-%d')
	uuid = flask.request.args['uuid']
	cash = flask.request.args.get('cash', False)
	commodity = flask.request.args.get('commodity', False)
	split = flask.request.args.get('split', False)
	
	# General ledger
	l = ledger.raw_transactions_at_date(None)
	report_commodity = l.get_commodity(config['report_commodity'])
	if cash:
		l = accounting.ledger_to_cash(l, report_commodity)
	
	l = accounting.trial_balance(l, date, pstart, report_commodity).ledger
	
	transaction = next((t for t in l.transactions if str(t.uuid) == uuid))
	
	if split:
		postings = transaction.split(report_commodity)
		transaction = Transaction(l, transaction.id, transaction.date, transaction.description, transaction.code, transaction.uuid)
		transaction.postings = [p for r in postings for p in r]
	
	if commodity:
		total_dr = sum((p.amount for p in transaction.postings if p.amount > 0), Balance()).clean()
		total_cr = sum((p.amount for p in transaction.postings if p.amount < 0), Balance()).clean()
		totals = itertools.zip_longest(total_dr.amounts, total_cr.amounts)
		return flask.render_template('transaction_commodity.html', ledger=l, transaction=transaction, totals=totals, total_dr=total_dr.exchange(report_commodity, True), total_cr=total_cr.exchange(report_commodity, True), report_commodity=report_commodity, cash=cash, split=split, date=date, pstart=pstart)
	else:
		total_dr = sum((p.amount for p in transaction.postings if p.amount > 0), Balance()).exchange(report_commodity, True)
		total_cr = sum((p.amount for p in transaction.postings if p.amount < 0), Balance()).exchange(report_commodity, True)
		return flask.render_template('transaction.html', ledger=l, transaction=transaction, total_dr=total_dr, total_cr=total_cr, report_commodity=report_commodity, cash=cash, split=split, date=date, pstart=pstart)

# Template filters

@app.template_filter('a')
def filter_amount(amt, link=None):
	if amt.near_zero:
		amt_str = '0.00'
		is_pos = True
	elif amt >= 0:
		amt_str = '{:,.2f}'.format(amt.amount).replace(',', '&#8239;') # Narrow no-break space
		is_pos = True
	else:
		amt_str = '{:,.2f}'.format(-amt.amount).replace(',', '&#8239;')
		is_pos = False
	
	if link:
		if is_pos:
			return flask.Markup('<a href="{}"><span title="{}">{}</span></a>&nbsp;'.format(link, amt.tostr(False), amt_str))
		else:
			return flask.Markup('<a href="{}"><span title="{}">({})</span></a>'.format(link, amt.tostr(False), amt_str))
	else:
		if is_pos:
			return flask.Markup('<span class="copyable-amount" title="{}">{}</span>&nbsp;'.format(amt.tostr(False), amt_str))
		else:
			return flask.Markup('<span class="copyable-amount" title="{}">({})</span>'.format(amt.tostr(False), amt_str))

@app.template_filter('b')
def filter_amount_positive(amt):
	return flask.Markup('<span class="copyable-amount" title="{}">{:,.2f}</span>'.format(amt.tostr(False), amt.amount).replace(',', '&#8239;'))

@app.template_filter('bc')
def filter_commodity_positive(amt):
	if amt.commodity.is_prefix:
		return flask.Markup('<span class="copyable-amount" title="{}">{}{}{:,.2f}</span>'.format(amt.tostr(False), amt.commodity.name, ' ' if amt.commodity.is_space else '', amt.amount).replace(',', '&#8239;'))
	else:
		return flask.Markup('<span class="copyable-amount" title="{}">{:,.2f}{}{}</span>'.format(amt.tostr(False), amt.amount, ' ' if amt.commodity.is_space else '', amt.commodity.name).replace(',', '&#8239;'))

@app.template_filter('bt')
def filter_commodity_table_positive(amt, show_price, link=None):
	result = []
	if amt.commodity.is_prefix:
		amt_str = filter_commodity_positive(amt)
		cur_str = ''
	else:
		amt_str = '{:,.2f}'.format(amt.amount).replace(',', '&#8239;')
		cur_str = amt.commodity.name
	
	amt_full = amt.tostr(False)
	
	result.append('<td style="text-align: right;"><a href="{}"><span class="copyable-amount" title="{}">{}</span></a></td>'.format(link, amt_full, amt_str) if link else '<td style="text-align: right;"><span class="copyable-amount" title="{}">{}</span></td>'.format(amt_full, amt_str))
	result.append('<td><span class="copyable-amount" title="{}">{}</span></td>'.format(amt_full, cur_str))
	
	if show_price:
		if amt.commodity.price:
			result.append('<td>{{{}}}</td>'.format(filter_commodity_positive(amt.commodity.price)))
		else:
			result.append('<td></td>')
	
	return flask.Markup(''.join(result))

# Debug views

@app.route('/debug/imbalances')
def debug_imbalances():
	date = datetime.strptime(flask.request.args['date'], '%Y-%m-%d')
	pstart = datetime.strptime(flask.request.args['pstart'], '%Y-%m-%d')
	cash = flask.request.args.get('cash', False)
	
	l = ledger.raw_transactions_at_date(date)
	report_commodity = l.get_commodity(config['report_commodity'])
	if cash:
		l = accounting.ledger_to_cash(l, report_commodity)
	
	transactions = [t for t in l.transactions if t.date <= date and t.date >= pstart and not sum((p.amount for p in t.postings), Balance()).exchange(report_commodity, True).near_zero]
	
	total_dr = sum((p.amount for t in transactions for p in t.postings if p.amount > 0), Balance()).exchange(report_commodity, True)
	total_cr = sum((p.amount for t in transactions for p in t.postings if p.amount < 0), Balance()).exchange(report_commodity, True)
	
	return flask.render_template('transactions.html', date=date, pstart=pstart, period=describe_period(date, pstart), account=None, ledger=l, transactions=transactions, total_dr=total_dr, total_cr=total_cr, report_commodity=report_commodity, cash=cash)

# Load extensions
for ext_name in config['extensions']:
	with open(ext_name, 'r') as f:
		exec(f.read())