#   DrCr: Web-based double-entry bookkeeping framework
#   Copyright (C) 2022–2023  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 redirect, render_template, request

from drcr.models import AccountConfiguration, Amount, Posting, Transaction
from drcr.database import db
from drcr.plugins import render_plugin_template
from drcr.webapp import app

from .models import CGTAsset, CGTCostAdjustment
from .reports import eofy_date, tax_summary_report

from datetime import datetime

@app.route('/tax/cgt-adjustments')
def cgt_adjustments():
	adjustments = db.session.scalars(db.select(CGTCostAdjustment)).all()
	return render_plugin_template('austax', 'cgt_adjustments.html', cgt_adjustments=adjustments)

@app.route('/tax/cgt-adjustments/new', methods=['GET', 'POST'])
def cgt_adjustment_new():
	if request.method == 'GET':
		return render_plugin_template('austax', 'cgt_adjustments_edit.html', adjustment=None)
	
	asset = Amount.parse(request.form['asset'])
	adjustment = CGTCostAdjustment(
		quantity=asset.quantity,
		commodity=asset.commodity,
		account=request.form['account'],
		acquisition_date=datetime.strptime(request.form['acquisition_date'], '%Y-%m-%d'),
		dt=datetime.strptime(request.form['dt'], '%Y-%m-%d'),
		description=request.form['description'],
		cost_adjustment=Amount.parse(request.form['cost_adjustment']).quantity
	)
	db.session.add(adjustment)
	db.session.commit()
	
	return redirect('/tax/cgt-adjustments')

@app.route('/tax/cgt-assets')
def cgt_assets():
	# Find all CGT asset accounts
	cgt_accounts = []
	account_configurations = AccountConfiguration.get_all_kinds()
	for account_name, kinds in account_configurations.items():
		if 'austax.cgtasset' in kinds:
			cgt_accounts.append(account_name)
	
	# Get all postings to CGT asset accounts
	cgt_postings = db.session.scalars(
		db.select(Posting)
		.where(Posting.account.in_(cgt_accounts))
		.join(Posting.transaction)
		.order_by(Transaction.dt)
	).all()
	
	# Process postings to determine final balances
	assets = []
	
	for posting in cgt_postings:
		if posting.quantity >= 0:
			assets.append(CGTAsset(posting.quantity, posting.commodity, posting.account, posting.transaction.dt))
		elif posting.quantity < 0:
			asset = next((a for a in assets if a.commodity == posting.commodity and a.account == posting.account), None)
			
			if asset is None:
				raise Exception('Attempted credit {} without preceding debit balance'.quantity(posting.amount()))
			if asset.quantity + posting.quantity < 0:
				raise Exception('Attempted credit {} with insufficient debit balance {}'.quantity(posting.amount(), asset.amount()))
			
			if asset.quantity + posting.quantity != 0:
				raise NotImplementedError('Partial disposal of CGT asset not implemented')
			
			asset.disposal_date = posting.transaction.dt
			
			# Calculate disposal value by searching for matching asset postings
			asset.disposal_value = Amount(0, '$')
			for other_posting in posting.transaction.postings:
				if posting != other_posting and 'drcr.asset' in account_configurations.get(other_posting.account, []):
					asset.disposal_value.quantity += other_posting.amount().as_cost().quantity
	
	# Process CGT adjustments
	for cost_adjustment in db.session.scalars(db.select(CGTCostAdjustment)).all():
		asset = next((a for a in assets if a.quantity == cost_adjustment.quantity and a.commodity == cost_adjustment.commodity and a.account == cost_adjustment.account and a.acquisition_date == cost_adjustment.acquisition_date), None)
		
		if asset is None:
			raise Exception('No matching CGT asset for {}'.format(repr(cost_adjustment.asset())))
		
		asset.cost_adjustments.append(cost_adjustment)
	
	return render_plugin_template('austax', 'cgt_assets.html', assets=assets, eofy_date=eofy_date())

@app.route('/tax/summary')
def tax_summary():
	report = tax_summary_report()
	return render_template('report.html', report=report)