I'm trying to build a tool like SendGrid (jk) ;<
yet I'm trying to break it into manageable parts, ignoring all practices.

too lazy to write a commit message too motivated to write in readme: For now ...

A custom email sending service inspired by SendGrid, built with Node.js. This project handles email queuing, scheduling, templating, and delivery, with a focus on reliability and scalability.

• server.js
  Bootstrap file that initializes the Express server, worker manager, and Agenda scheduler.
• app.js
  Express application that defines API routes.

• config/mongodb.js: MongoDB connection setup.
• config/queue.js: Redis configuration for the Bull queue.
• config/smtp.js: SMTP server settings for email delivery.

• services/emailService.js: Core email sending functionality using Nodemailer.
• services/templateService.js: Renders email templates with EJS.
• views/email-templates/: Directory containing EJS templates (e.g., welcome.ejs).

• queues/emailQueue.js: Implementation of Bull queue for email jobs.
• queues/agendaSetup.js: Agenda scheduler for recurring and scheduled email tasks.
• jobs/emailJob.js: Processor for email sending jobs.

• workers/emailWorker.js: Worker thread that processes email jobs.
• workers/workerManager.js: Manages dynamic scaling of worker threads based on queue load.

• controllers/emailController.js: Handles immediate email sending requests.
• controllers/scheduledEmailController.js: Manages scheduled and recurring email requests.

• Queue-based Processing:
  Uses Bull (Redis-based queue) for asynchronous email sending.
• Scalable Architecture:
  Dynamic worker scaling based on queue size.
• Email Templates:
  EJS-based system for customizable email designs.
• Scheduled Emails:
  Supports one-time and recurring emails using Agenda.
• Graceful Shutdown:
  Properly terminates workers and connections.
• Error Handling:
  Implements retry mechanisms for failed email delivery.

• Database:
  MongoDB for managing scheduled jobs.
• Queue:
  Redis for handling the email sending queue.
• Email Transport:
  For now : Nodemailer configured with SMTP settings.
• Concurrency Control:
  Worker threads ensure parallel processing.
• Auto-scaling:
  Adjusts worker count based on the queue load.
• Templates:
  Dynamic rendering using EJS for email content.

┌─────────────┐     ┌─────────────┐     ┌───────────────┐
│ Express API │────▶│ Bull Queue  │────▶│ Worker Threads│
└─────────────┘     └─────────────┘     └───────────────┘
       │                   │                    │
       │                   │                    │
       ▼                   ▼                    ▼
┌─────────────┐     ┌─────────────┐     ┌───────────────┐
│   MongoDB   │     │    Redis    │     │   SMTP Server │
└─────────────┘     └─────────────┘     └───────────────┘
       ▲
       │
┌─────────────┐
│   Agenda    │
│  Scheduler  │
└─────────────┘

• Evaluate alternatives to Nodemailer, such as smtp-client, emailJs, or even implementing raw SMTP support.
• Introduce middleware components to improve request handling, security, and error processing.

make sure you have :

• Node.js (v16 or higher)

• MongoDB (running locally or accessible) refer to docs ps: Ctrl + click to open in another tab

• Redis (running locally or accessible) refer to docs ps: Ctrl + click to open in another tab

1. Clone the repository:

git clone https://github.com/Ayman-aa/noBrainerSendGrid.git
cd noBrainerSendGrid

2. Install dependencies:

npm install

3. Set up environment variables:

cp .example.env .env

4. Edit the .env file with your SMTP, Redis, and MongoDB configurations:

# SMTP Configuration (e.g., Gmail)
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=your_email
SMTP_PASS=your_password # Use an "App Password" if using Gmail
SMTP_SECURE=false  # true for port 465, false for 587
DEFAULT_FROM="No Reply <email@example.com>"

# Redis (required for Bull queue)
REDIS_HOST=127.0.0.1
REDIS_PORT=6379
# REDIS_PASSWORD=yourpassword (if applicable)

# MongoDB (required for Agenda scheduler)
MONGODB_URI=mongodb://localhost:27017/emailService #leave this as it is

# Server
PORT=3000

Start the server:

npm start

For development with auto-restart:

npm run dev

Sending an Email

curl -X POST http://localhost:3000/api/email/send \
  -H "Content-Type: application/json" \
  -d '{
    "to": "recipient@example.com",
    "subject": "Hello from noBrainerSendGrid",
    "body": "<h1>Hello!</h1><p>This is a test email.</p>"
  }'

Using a Template

curl -X POST http://localhost:3000/api/email/send \
  -H "Content-Type: application/json" \
  -d '{
    "to": "recipient@example.com",
    "subject": "Welcome to Our Service",
    "templateId": "welcome",
    "templateData": {
      "name": "John Doe",
      "docsUrl": "https://example.com/docs"
    }
  }'

Scheduling an Email

curl -X POST http://localhost:3000/api/email/schedule \
  -H "Content-Type: application/json" \
  -d '{
    "to": "recipient@example.com",
    "subject": "Reminder",
    "body": "<p>Don't forget your appointment!</p>",
    "scheduledTime": "2023-12-25T10:00:00.000Z"
  }'

Note: This is a custom implementation of an email delivery system and is not affiliated with SendGrid.