Move auth logic from view to backend

.gitignore

@@ -2,3 +2,4 @@ __pycache__/
 .env
 .vscode/
 .Pipfile.lock
+*client_secret.json*

backend/users/backend.py

@@ -1,17 +1,38 @@
+from django.conf import settings
 from django.contrib.auth.backends import ModelBackend
+from google.auth.transport import requests
+from google.oauth2 import id_token
+from google_auth_oauthlib.flow import Flow
 
+from .mail import send_validation_mail
 from .models import User
 
 
 class OAuthAuthenticationBackend(ModelBackend):
     """
-    Authentication backend to allow authenticating users against a
-    Microsoft ADFS server with an authorization code.
+    Authentication backend to allow user use Google to login.
     """
 
     def authenticate(self, request, username=None, password=None, **kwargs):
-        if kwargs.get('id_info'):
-            user = self.get_google_oauth_user(kwargs.get('id_info'))
+        state = kwargs.get('oauth_state')
+        flow = Flow.from_client_secrets_file(
+            f'{settings.ROOT_DIR}/backend/client_secret.json',
+            scopes=None,
+            redirect_uri=request.build_absolute_uri('/users/google-callback/'),
+        )
+
+        # Use the authorization response to get tokens
+        flow.fetch_token(authorization_response=request.build_absolute_uri(), state=state)
+
+        # Use the id_token to get user information
+        token = flow.credentials.id_token
+        request_google_oauth = requests.Request()
+        id_info = id_token.verify_oauth2_token(
+            token,
+            request_google_oauth,
+        )
+
+        user = self.get_google_oauth_user(id_info)
         return user
 
     def get_google_oauth_user(self, id_info):
@@ -24,5 +45,6 @@ def get_google_oauth_user(self, id_info):
             user = User.objects.get(email=data['email'])
         except User.DoesNotExist:
             user = User.objects.create(**data)
+            send_validation_mail(email=data['email'])
 
         return user

backend/users/mail.py

@@ -30,4 +30,5 @@ def send_validation_mail(email: str):
             recipient_list,
             html_message=f'{message}<br><a href={url}{token}>{url}{token}</a>',
         )
+        print(f'Email sent successfully to {recipient_list} !')
         return ({'title': 'Success', 'detail': 'Validation email sent.'},)

backend/users/views.py

@@ -5,8 +5,6 @@
 from django.shortcuts import redirect
 from django.utils import timezone
 from django.utils.http import url_has_allowed_host_and_scheme
-from google.auth.transport import requests
-from google.oauth2 import id_token
 from google_auth_oauthlib.flow import Flow
 from rest_framework import generics, permissions, status
 from rest_framework.decorators import action
@@ -26,11 +24,20 @@ class OAuthViewset(GenericViewSet):
     @action(detail=False, methods=['get'], url_path='google-login')
     def google_login(self, request):
         # Set up the Google OAuth2.0 flow
-        flow = Flow.from_client_secrets_file(
-            f'{settings.ROOT_DIR}/backend/client_secret.json',
-            scopes=['openid', 'profile', 'email'],
-            redirect_uri=request.build_absolute_uri('/users/google-callback/'),
-        )
+        try:
+            flow = Flow.from_client_secrets_file(
+                f'{settings.ROOT_DIR}/backend/client_secret.json',
+                scopes=['openid', 'profile', 'email'],
+                redirect_uri=request.build_absolute_uri('/users/google-callback/'),
+            )
+        except FileNotFoundError:
+            return Response(
+                {
+                    'title': 'Error',
+                    'Detail': 'Google login is currently disabled due'
+                    + 'to missing client secrets on the host server.',
+                },
+            )
 
         authorization_url, state = flow.authorization_url(prompt='consent')
         # Store the state so the callback can verify the response.
@@ -42,25 +49,7 @@ def google_callback(self, request):  # pragma: no cover
         # Get the state from the session to verify the response.
         state = request.session.get('oauth_state')
 
-        flow = Flow.from_client_secrets_file(
-            f'{settings.ROOT_DIR}/backend/client_secret.json',
-            scopes=None,
-            redirect_uri=request.build_absolute_uri('/users/google-callback/'),
-        )
-
-        # Use the authorization response to get tokens
-        flow.fetch_token(authorization_response=request.build_absolute_uri(), state=state)
-
-        # Use the id_token to get user information
-        token = flow.credentials.id_token
-        request_google_oauth = requests.Request()
-        id_info = id_token.verify_oauth2_token(
-            token,
-            request_google_oauth,
-        )
-
-        user = authenticate(request=request, id_info=id_info)
-
+        user = authenticate(request=request, oauth_state=state)
         if user:
             if user.is_active:
                 login(request, user)