Google Authentication and Fetching Emails using Django

"""Django's command-line utility for administrative tasks."""
import os
import sys

def main():
    """Run administrative tasks."""
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'gfg_auth_project.settings')
    try:
        from django.core.management import execute_from_command_line
    except ImportError as exc:
        raise ImportError(
            "Couldn't import Django. Are you sure it's installed and "
            "available on your PYTHONPATH environment variable? Did you "
            "forget to activate a virtual environment?"
        ) from exc
    os.environ['OAUTHLIB_INSECURE_TRANSPORT'] = '1'  # Allow HTTP for OAuth (development only)    
    execute_from_command_line(sys.argv)

if __name__ == '__main__':
    main()

from django.shortcuts import render, redirect
import os
import json
from django.urls import reverse
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build
from django.shortcuts import redirect
from django.http import HttpResponse
from django.conf import settings
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import Flow


# Google OAuth2 client ID and secret
CLIENT_SECRETS_FILE = os.path.join(settings.BASE_DIR, 'credentials.json')
SCOPES = ['https://www.googleapis.com/auth/gmail.readonly']

REDIRECT_URI = 'http://localhost:8000/google/callback/'


def home(request):
    return HttpResponse("Welcome! <a href='/google/login/'>Login with Google</a>")

def google_login(request):
    flow = InstalledAppFlow.from_client_secrets_file(CLIENT_SECRETS_FILE, SCOPES)
    flow.redirect_uri = 'http://localhost:8000/google/callback/'

    authorization_url, state = flow.authorization_url(access_type='offline', prompt='consent')

    # Store the state in the session for later use
    request.session['state'] = state

    return redirect(authorization_url)


def google_callback(request):
    flow = Flow.from_client_secrets_file(
        CLIENT_SECRETS_FILE,
        scopes=SCOPES,
        redirect_uri=REDIRECT_URI,
    )
    flow.fetch_token(authorization_response=request.build_absolute_uri())

    credentials = flow.credentials
    service = build('gmail', 'v1', credentials=credentials)

    # Fetch messages
    result = service.users().messages().list(userId='me', maxResults=5).execute()
    messages = result.get('messages', [])

    email_data = []
    for msg in messages:
        msg_detail = service.users().messages().get(userId='me', id=msg['id']).execute()
        headers = msg_detail['payload'].get('headers', [])
        subject = next((h['value'] for h in headers if h['name'] == 'Subject'), 'No Subject')
        sender = next((h['value'] for h in headers if h['name'] == 'From'), 'Unknown')
        snippet = msg_detail.get('snippet', '')
        email_data.append({
            'subject': subject,
            'sender': sender,
            'snippet': snippet,
        })
    return render(request, 'emails.html', {'emails': email_data})

def fetch_emails(request):
    creds = None
    if os.path.exists('token.json'):
        creds = Credentials.from_authorized_user_file('token.json', SCOPES)

    if not creds or not creds.valid:
        return HttpResponse("No valid credentials. Please log in first.")
    service = build('gmail', 'v1', credentials=creds)

    try:
        results = service.users().messages().list(userId='me', maxResults=5).execute()
        messages = results.get('messages', [])

        email_subjects = []
        if not messages:
            email_subjects.append('No messages found.')
        else:
            for message in messages:
                msg = service.users().messages().get(userId='me', id=message['id']).execute()
                snippet = msg.get('snippet', '(No snippet)')
                email_subjects.append(snippet)
        return HttpResponse('<br><br>'.join(email_subjects))
    except Exception as e:
        return HttpResponse(f"An error occurred: {str(e)}")

from django.urls import path
from . import views

urlpatterns = [
    path('', views.home, name='home'),
    path('google/login/', views.google_login, name='google_login'),
    path('google/callback/', views.google_callback, name='google_callback'),
    path('google/emails/', views.fetch_emails, name='fetch_emails'),
]

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('gfg_auth_app.urls')),
]