vk_auth VIews

import requests

from django.shortcuts import render
from django.views.generic import TemplateView
from django.conf import settings
from django.urls import reverse
from django.shortcuts import redirect
from django.contrib.auth.models import User
from django.contrib.auth import login, logout
from django.db import transaction
from django.db import IntegrityError

from vk_auth.models import VkAuth
from vk.interface import VkApiInterface
from vk.exceptions import (AppException)


class AuthView(TemplateView):
    template_name = 'auth/index.html'

    def get(self, request, *args, **kwargs):
        context = {
            'vk_url': settings.VK_AUTH_URL,
            'client_id': settings.VK_APP_ID,
            'redirect_url': request.build_absolute_uri(reverse('verify_vk_auth'))
        }
        return self.render_to_response(context)


def create_or_authenticate_user(request):
    code = request.GET.get('code')
    auth_info = VkApiInterface.verify_user_auth(code, request.build_absolute_uri(reverse('verify_vk_auth')))
    access_token = auth_info['access_token']
    expires_in = auth_info['expires_in']
    user_id = auth_info['user_id']

    try:
        vk_auth = VkAuth.objects.get(user__username=user_id)
        vk_auth.vk_token = access_token
        vk_auth.expires_in = expires_in
        vk_auth.save()
        user_model = vk_auth.user
    except VkAuth.DoesNotExist:
        try:
            with transaction.atomic():
                user_model = User.objects.create(username=user_id, password=code)
                vk_auth = VkAuth.objects.create(user=user_model, vk_token=access_token, expires_in=expires_in)
        except IntegrityError as e:
            raise AppException(e)
    return user_model


def logout_view(request, *args, **kwargs):
    if request.user.is_authenticated:
        logout(request)
    return redirect('auth_index')


def verify_vk_auth(request, *args, **kwargs):
    try:
        user_model = create_or_authenticate_user(request)
        login(request, user_model)
        return redirect('index')
    except AppException as e:
        return render(request, 'error.html', {'error': getattr(e, 'inner_code'),
                                              'error_description': getattr(e, 'message')})