main.py

from fastapi import FastAPI, HTTPException
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel, EmailStr
from redis import Redis
from rq import Queue
import jwt
import os
from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail
from pydantic import parse_obj_as
import firebase_admin
from firebase_admin import credentials
from firebase_admin import firestore

INVALID_IDENTIFIER = 'Please, check identifier.'
INVALID_JWT = 'Of course! You shall not pass!'

JWT_SECRET = os.environ.get('JWT_SECRET')

app = FastAPI()

redis_conn = Redis()
magic_link_queue = Queue('send_magic_links', connection=redis_conn)

class MagicLink(BaseModel):
    identifier: EmailStr
    payload: dict


def confirm_identifier(magic: MagicLink):
    encoded = jwt.encode(jsonable_encoder(magic.dict()), JWT_SECRET, algorithm='HS256').decode('utf-8')
    print(f'Payload enconded to JWT: {encoded}')
    print(f'sending confirmation to: {magic.identifier}')
    
    message = Mail(
        from_email = os.environ.get('SENDGRID_SENDER'),
        to_emails = magic.identifier,
        subject = 'Are you a bot?',
        html_content = f'<a href="http://127.0.0.1:8000/validate/?token={encoded}">Confirm you are human or a super smart bot: </a>'
    )
    
    try:
        sg = SendGridAPIClient(os.environ.get('SENDGRID_API_KEY'))
        response = sg.send(message)
        print(response.status_code)
        print(response.body)
        print(response.headers)
    
    except Exception as e:
        print(e.body)

    return magic.payload


@app.get('/validate/', status_code=204)
def validate(token: str):    
    try:        
        magic_link = parse_obj_as(
            MagicLink, 
            jwt.decode(token, JWT_SECRET, algorithms=['HS256'])
        )

        cred = credentials.Certificate('./serviceAccountKey.json')
        firebase_admin.initialize_app(cred)
        db = firestore.client()

        doc_ref = db.collection('users').document(magic_link.identifier)
        doc_ref.set(magic_link.payload)
    
    except Exception as e:
        print(e)
        error_detail = jsonable_encoder({
            'message': INVALID_JWT
        })
        
        raise HTTPException(status_code=400, detail=error_detail)
        

@app.post('/send/', status_code=204)
def send(magic: MagicLink):
    magic_link_queue.enqueue(confirm_identifier, magic)