import datetime
import traceback
from urllib.parse import urljoin

from flask import current_app, flash
from flask_login import LoginManager
import jwt
import requests

from . import db

login_manager = LoginManager()

class User:
    def __init__(self, user, user_session):
        self.user = user
        self.user_session = user_session
        self.token = None

    def refresh_access_token(self):
        response = requests.post(urljoin(current_app.config['OAUTH_URL'], 'token'), data = {
            'grant_type': 'refresh_token',
            'client_id': current_app.config['OAUTH_CLIENT_ID'],
            'client_secret': current_app.config['OAUTH_CLIENT_SECRET'],
            'refresh_token': self.user_session.refresh_token,
        })
        if response.status_code != 200:
            flash('Failed to refresh authentication token (API call returned {} {})'.format(response.status_code, response.reason), 'error')
            return
        token = response.json()
        try:
            access_data = jwt.decode(token['access_token'], key = current_app.config['JWT_PUBLIC_KEY'], audience = current_app.config['OAUTH_CLIENT_ID'])
            refresh_data = jwt.decode(token['refresh_token'], key = current_app.config['JWT_PUBLIC_KEY'], audience = current_app.config['OAUTH_CLIENT_ID'])
        except jwt.InvalidTokenError as e:
            traceback.print_exc()
            flash('Failed to refresh authentication token (verification failed)', 'error')
            return
        with db.session_scope() as sess:
            self.user_session.access_token = token['access_token']
            self.user_session.refresh_token = token['refresh_token']
            self.user_session.updated = datetime.datetime.utcnow()
            sess.add(self.user_session)
        return True

    @property
    def is_authenticated(self):
        if self.user is None:
            return False
        if self.token:
            return True
        try:
            self.token = jwt.decode(self.user_session.access_token, key = current_app.config['JWT_PUBLIC_KEY'], audience = current_app.config['OAUTH_CLIENT_ID'])
        except jwt.ExpiredSignatureError:
            try:
                if not self.refresh_access_token():
                    return False
            except:
                traceback.print_exc()
                flash('Failed to refresh authentication token (unhandled error; contact an admin)', 'error')
                return False
        except jwt.InvalidTokenError:
            return False
        return True

    @property
    def is_active(self):
        return True

    @property
    def is_anonymous(self):
        return False

    def get_id(self):
        return '{}:{}'.format(self.user.id, self.user_session.id)

    def get_user_id(self):
        return self.user.id if self.is_authenticated else None

    @property
    def username(self):
        return self.user.username

@login_manager.user_loader
def load_user(user_id):
    user_id, session_id = map(int, user_id.split(':', 1))
    try:
        with db.session_scope() as sess:
            user, user_session = sess.query(db.User, db.UserSession).join(db.UserSession).filter(db.User.id == user_id, db.UserSession.id == session_id).one()
            return User(user, user_session)
    except:
        traceback.print_exc()
        return None