#   DrCr: Web-based double-entry bookkeeping framework
#   Copyright (C) 2022–2024  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 flask import abort, redirect, render_template, request, url_for

from .. import AMOUNT_DPS
from ..database import db
from ..models import Amount, Posting, Transaction, TrialBalancer, reporting_commodity
from ..webapp import all_accounts, all_transactions, app
from .models import BalanceAssertion
from ..statements.models import StatementLineReconciliation

from datetime import datetime

@app.route('/journal')
def journal():
	transactions = db.session.scalars(db.select(Transaction).options(db.selectinload(Transaction.postings)).order_by(Transaction.dt.desc(), Transaction.id.desc())).all()
	
	return render_template(
		'journal/journal.html',
		commodity_detail=request.args.get('commodity_detail', '0') == '1',
		transactions=transactions
	)

@app.route('/journal/new-transaction', methods=['GET', 'POST'])
def journal_new_transaction():
	if request.method == 'GET':
		return render_template('journal/journal_edit_transaction.html', transaction=None, all_accounts=all_accounts())
	
	# New transaction
	transaction = Transaction(
		dt=datetime.strptime(request.form['dt'], '%Y-%m-%d'),
		description=request.form['description'],
		postings=[]
	)
	
	for account, sign, amount_str in zip(request.form.getlist('account'), request.form.getlist('sign'), request.form.getlist('amount')):
		amount = Amount.parse(amount_str)
		if sign == 'cr':
			amount = -amount
		
		posting = Posting(
			account=account,
			quantity=amount.quantity,
			commodity=amount.commodity
		)
		transaction.postings.append(posting)
	
	transaction.assert_valid()
	
	db.session.add(transaction)
	db.session.commit()
	
	return redirect(request.form.get('referrer', '') or url_for('journal'))

@app.route('/journal/edit-transaction', methods=['GET', 'POST'])
def journal_edit_transaction():
	transaction = db.session.get(Transaction, request.args['id'])
	if not transaction:
		abort(404)
	
	if request.method == 'GET':
		return render_template('journal/journal_edit_transaction.html', transaction=transaction, all_accounts=all_accounts())
	
	if request.form.get('action', None) == 'delete':
		# Delete transaction
		db.session.delete(transaction)
		
		# Delete reconciliations if required
		for posting in transaction.postings:
			for reconciliation in StatementLineReconciliation.query.filter(StatementLineReconciliation.posting == posting):
				db.session.delete(reconciliation)
		
		db.session.commit()
		return redirect(request.form.get('referrer', '') or url_for('journal'))
	
	# Edit transaction
	transaction.dt = datetime.strptime(request.form['dt'], '%Y-%m-%d')
	transaction.description = request.form['description']
	
	new_postings = []
	for account, sign, amount_str in zip(request.form.getlist('account'), request.form.getlist('sign'), request.form.getlist('amount')):
		amount = Amount.parse(amount_str)
		if sign == 'cr':
			amount = -amount
		
		posting = Posting(
			account=account,
			quantity=amount.quantity,
			commodity=amount.commodity
		)
		new_postings.append(posting)
	
	# Fix up reconciliations
	for old_posting in transaction.postings:
		for reconciliation in StatementLineReconciliation.query.filter(StatementLineReconciliation.posting == old_posting):
			# See if there is a corresponding new posting
			new_posting = next((p for p in new_postings if p.account == old_posting.account and p.quantity == old_posting.quantity and p.commodity == old_posting.commodity), None)
			if new_posting is not None:
				# Match up reconciliation
				reconciliation.posting = new_posting
			else:
				# No matching reconciliation
				db.session.delete(reconciliation)
	
	transaction.postings = new_postings  # This queues the old postings for deletion
	transaction.assert_valid()
	
	db.session.commit()
	
	return redirect(request.form.get('referrer', '') or url_for('journal'))

@app.route('/balance-assertions')
def balance_assertions():
	assertions = db.session.scalars(db.select(BalanceAssertion).order_by(BalanceAssertion.dt.desc(), BalanceAssertion.id.desc())).all()
	
	# Check assertion status
	transactions = all_transactions()
	assertion_status = {}
	for assertion in assertions:
		# FIXME: This is very inefficient
		balancer = TrialBalancer()
		balancer.apply_transactions([t for t in transactions if t.dt <= assertion.dt])
		
		# TODO: Commodities
		if assertion.account in balancer.accounts and balancer.accounts[assertion.account].quantity == assertion.quantity:
			assertion_status[assertion] = True
		else:
			assertion_status[assertion] = False
	
	return render_template('journal/balance_assertions.html', assertions=assertions, assertion_status=assertion_status)

@app.route('/balance-assertions/new', methods=['GET', 'POST'])
def balance_assertions_new():
	if request.method == 'GET':
		return render_template('journal/balance_assertions_edit.html', assertion=None, all_accounts=all_accounts())
	
	quantity = round(float(request.form['amount']) * (10**AMOUNT_DPS))
	if request.form['sign'] == 'cr':
		quantity = -quantity
	
	# New balance assertion
	assertion = BalanceAssertion(
		dt=datetime.strptime(request.form['dt'], '%Y-%m-%d'),
		description=request.form['description'],
		account=request.form['account'],
		quantity=quantity,
		commodity=reporting_commodity()
	)
	db.session.add(assertion)
	db.session.commit()
	
	return redirect(url_for('balance_assertions'))

@app.route('/balance-assertions/edit', methods=['GET', 'POST'])
def balance_assertions_edit():
	assertion = db.session.get(BalanceAssertion, request.args['id'])
	if not assertion:
		abort(404)
	
	if request.method == 'GET':
		return render_template('journal/balance_assertions_edit.html', assertion=assertion, all_accounts=all_accounts())
	
	if request.form.get('action', None) == 'delete':
		# Delete balance assertion
		db.session.delete(assertion)
		db.session.commit()
		return redirect(request.form.get('referrer', '') or url_for('balance_assertions'))
	
	quantity = round(float(request.form['amount']) * (10**AMOUNT_DPS))
	if request.form['sign'] == 'cr':
		quantity = -quantity
	
	# Edit balance assertion
	assertion.dt = datetime.strptime(request.form['dt'], '%Y-%m-%d')
	assertion.description = request.form['description']
	assertion.account = request.form['account']
	assertion.quantity = quantity
	
	db.session.commit()
	
	return redirect(url_for('balance_assertions'))