#!/usr/bin/env python3
"""
Contains authentication methods for the app.
"""
import os
import functools

from fido2.client import ClientData
from fido2.server import Fido2Server, RelyingParty
from fido2.ctap2 import AttestationObject, AuthenticatorData, \
	AttestedCredentialData
from fido2 import cbor
from flask import Blueprint, session, render_template, request, abort, \
	redirect, url_for, g
from passlib.hash import argon2

import config
import db

auth_views = Blueprint("auth_views", __name__)

rp = RelyingParty('steelbea.me', 'Juice')
server = Fido2Server(rp)


def auth_required(func):
	"""
	Wrapper for views which should be protected by authentication.
	"""
	@functools.wraps(func)
	def wrapper(*args, **kwargs):
		username = session.get('username')
		token = session.get('token')
		if not username or not token:
			return redirect(url_for('auth_views.login'))
	
		data = db.get_user(username)
		if not data:
			session.pop('username')
			return redirect(url_for('auth_views.login'))
		token_hash = data[2]
		if not token_hash:
			return redirect(url_for('auth_views.login'))

		if argon2.verify(token, token_hash):
			return func(*args, **kwargs)
		else:
			session.pop('token')
			return redirect(url_for('auth_views.login'))
	return wrapper


@auth_views.route('/api/register/begin', methods=['POST'])
def register_begin():
	if not config.registration_open:
		return "Registration is closed."

	username = session.get('username')
	if not username:
		return 'invalid'

	data = db.get_user(username)
	if not data:
		session.pop('username')
		return 'invalid'
	user_id = data[0]

	exist_cred = db.get_credentials(user_id)
	exist_cred = [AttestedCredentialData(cd[2]) for cd in exist_cred]

	registration_data, state = server.register_begin({
		'id': str(user_id).encode('utf8'),
		'name': username,
		'displayName': username,
	}, exist_cred, user_verification='discouraged')

	session['state'] = state
	return cbor.encode(registration_data)


@auth_views.route('/api/register/complete', methods=['POST'])
def register_complete():
	if not config.registration_open:
		return "Registration is closed."

	username = session.get('username')
	if not username:
		return 'invalid'

	data = db.get_user(username)
	if not data:
		session.pop('username')
		return 'invalid'
	user_id = data[0]

	data = cbor.decode(request.get_data())
	client_data = ClientData(data['clientDataJSON'])
	att_obj = AttestationObject(data['attestationObject'])

	auth_data = server.register_complete(
		session.pop('state'),
		client_data,
		att_obj
	)

	db.set_credential(user_id, auth_data.credential_data)
	return cbor.encode({'status': 'OK'})


@auth_views.route('/api/authenticate/begin', methods=['POST'])
def authenticate_begin():
	username = session.get('username')
	if not username:
		return 'invalid'

	data = db.get_user(session['username'])
	if not data:
		session.pop('username')
		return 'invalid'
	user_id = data[0]

	credentials = db.get_credentials(user_id)
	credentials = [AttestedCredentialData(cd[2]) for cd in credentials]

	auth_data, state = server.authenticate_begin(credentials)
	session['state'] = state
	return cbor.encode(auth_data)


@auth_views.route('/api/authenticate/complete', methods=['POST'])
def authenticate_complete():
	username = session.get('username')
	if not username:
		return 'invalid'

	data = db.get_user(session['username'])
	if not data:
		session.pop('username')
		return 'invalid'
	user_id = data[0]

	credentials = db.get_credentials(user_id)
	credentials = [AttestedCredentialData(cd[2]) for cd in credentials]

	data = cbor.decode(request.get_data())
	credential_id = data['credentialId']
	client_data = ClientData(data['clientDataJSON'])
	auth_data = AuthenticatorData(data['authenticatorData'])
	signature = data['signature']

	server.authenticate_complete(
		session.pop('state'),
		credentials,
		credential_id,
		client_data,
		auth_data,
		signature
	)

	token = os.urandom(32)
	token_hash = argon2.hash(token)
	db.set_user_token(username, token_hash)
	session['token'] = token

	return cbor.encode({'status': 'OK'})


@auth_views.route('/register', methods=['GET', 'POST'])
def register():
	"""
	Registration page.
	"""
	if not config.registration_open:
		return "Registration is closed."

	if request.method == 'GET':
		params = {
			'title': 'Register',
			'heading': 'Register an account',
			'form_url': url_for('auth_views.register'),
		}
		return render_template('auth.html', **params)

	username = request.form.get('username')
	
	if len(username) > 64:
		return "username too long"
	elif len(username) < 3:
		return "username too short"

	db.set_user(username) # TODO: handle username error
	session['username'] = username

	params = {
		'title': 'Register',
		'heading': 'Register your authenticator',
		'api_begin': url_for('auth_views.register_begin'),
		'api_complete': url_for('auth_views.register_complete'),
	}
	return render_template('auth_fido.html', **params)


@auth_views.route('/login', methods=['GET', 'POST'])
def login():
	"""
	Login page.
	"""
	if request.method == 'GET':
		params = {
			'title': 'Login',
			'heading': 'Login',
			'form_url': url_for('auth_views.login'),
		}
		return render_template('auth.html', **params)

	
	username = request.form.get('username')
	session['username'] = username

	params = {
		'title': 'Login',
		'heading': 'Login with your authenticator',
		'api_begin': url_for('auth_views.authenticate_begin'),
		'api_complete': url_for('auth_views.authenticate_complete'),
	}
	return render_template('auth_fido.html', **params)