src/service/notification_service.py

import os
import logging
import smtplib
import requests
from datetime import datetime
from email.message import EmailMessage
from src.repository.common import get_session
from src.repository.transaction_repo import fetch_transaction

from dotenv import load_dotenv

# Configure logging
logger = logging.getLogger(__name__)

# Load environment variables
load_dotenv()

SMTP_SERVER = os.getenv("SMTP_SERVER")
SMTP_PORT = os.getenv("SMTP_PORT")
SENDER_EMAIL = os.getenv("SENDER_EMAIL")
RECEIVER_EMAIL = os.getenv("RECEIVER_EMAIL")
SENDER_PASSWORD = os.getenv("SENDER_PASSWORD")
BREVO_API_KEY = os.getenv("BREVO_API_KEY")
B_USE_BREVO = os.getenv("USE_BREVO", "False").lower() == "true" and BREVO_API_KEY is not None

# ------------------------------------------------------------------------------

def send_notification(transaction_id: int):
    """
    Send a notification email when a transaction is detected as fraudulent.
    """
    logger.info("Sending notification email...")

    # Fetch the transaction details from the database
    with get_session() as session:
        transaction = fetch_transaction(session, transaction_id)
        
        if transaction is None:
            logger.error(f"Transaction {transaction_id} not found")
            return
        if transaction.fraud_details.notification_sent:
            logger.info(f"Notification already sent for transaction {transaction_id}")
            return
        
        if not B_USE_BREVO:
            _send_with_smtp_server(
                transaction_number=transaction.transaction_number,
                fraud_score=transaction.fraud_details.fraud_score,
                model_version=transaction.fraud_details.model_version,
            )
        else:
            # Alternatively, you can use Brevo (formerly Sendinblue) to send the email
            _send_with_brevo(
                transaction_number=transaction.transaction_number,
                fraud_score=transaction.fraud_details.fraud_score,
                model_version=transaction.fraud_details.model_version,
            )

        logger.info("Email sent!")

        # Update the transaction details in the database
        transaction.fraud_details.notification_sent = True
        transaction.fraud_details.notification_recipients = RECEIVER_EMAIL
        transaction.fraud_details.notification_datetime = datetime.now()
        session.commit()

def _build_notification_body(
        transaction_number: str,
        fraud_score: float,
        model_version: str,
    ) -> str:
    """
    Build the body of the notification email.
    """
    logger.debug("Building notification email body...")
    
    # Create the email body
    email_body = f"""<div>
    <h1>Fraud detected!</h1>
    <ul>
        <li>Transaction number: {transaction_number}</li>
        <li>Fraud score: {fraud_score}</li>
        <li>Model version: {model_version}</li>
    </ul>
    <p>Please check the transaction.</p>
    </div>"""
    
    return email_body

def _send_with_smtp_server(transaction_number: str,
                           fraud_score: float,
                           model_version: str):
    # Create the email
    email_body = _build_notification_body(
        transaction_number=transaction_number,
        fraud_score=fraud_score,
        model_version=model_version,
    )

    msg = EmailMessage()
    msg["Subject"] = "Fraud detected!"
    msg["From"] = SENDER_EMAIL
    msg["To"] = RECEIVER_EMAIL
    msg.set_content(email_body)

    # Send the email
    logger.debug(f"Connecting to SMTP server {SMTP_SERVER} using port {SMTP_PORT}...")
    with smtplib.SMTP(SMTP_SERVER, SMTP_PORT) as server:
        server.starttls()  # Secure the connection
        server.login(SENDER_EMAIL, SENDER_PASSWORD)
        server.send_message(msg)

def _send_with_brevo(transaction_number: str,
                     fraud_score: float,
                     model_version: str):
    url = "https://api.brevo.com/v3/smtp/email"

    email_body = _build_notification_body(
        transaction_number=transaction_number,
        fraud_score=fraud_score,
        model_version=model_version,
    )

    headers = {
        "accept": "application/json",
        "api-key": BREVO_API_KEY,
        "content-type": "application/json"
    }

    data = {
        "sender": {"name": "Fraud Detection Service", "email": SENDER_EMAIL},
        "to": [{"email": RECEIVER_EMAIL}],
        "subject": "Fraud detected!",
        "htmlContent": email_body,
    }

    response = requests.post(url, headers=headers, json=data)
    response.raise_for_status()