@subhajit60/notification-engine

A powerful, extensible, and decorator-based notification engine for TypeScript applications.

Features

• Decorator Pattern: Easily add priority, timestamps, images, and custom metadata to notifications.
• Multiple Channels: Built-in support for Email, Telegram, and In-App notifications.
• Strategy Pattern: Decouple notification logic from delivery services (Nodemailer, Telegram Bots, etc.).
• Built-in Formatters: Beautifully formatted HTML emails and Telegram messages with customizable templates.
• Type-Safe: Full TypeScript support with consistent interfaces.

Installation

npm install @subhajit60/notification-engine

Basic Usage

1. Initialize Strategies

Define how your notifications are actually sent by providing "sender" functions to the built-in strategies.

import { 
    NotificationDispatcher, 
    SendEmailNotification, 
    SendTelegramMessage 
} from "@subhajit60/notification-engine";

// Example: Your custom mailer
const mailer = new MyMailer(); 
const myTelegramBot = new MyTelegramBot();

const dispatcher = new NotificationDispatcher({
    email: new SendEmailNotification(mailer.sendHtmlMail.bind(mailer)),
    telegram: new SendTelegramMessage(myTelegramBot.sendMessage.bind(myTelegramBot))
});

2. Build a Notification

Use the built-in builders to create common notification types.

import { buildEmailNotification } from "@subhajit60/notification-engine";

const notification = buildEmailNotification(
    'quiz',      // type
    'success',   // variant
    "Your quiz results are ready!", // message
    "Quiz Success" // title
);

3. Send the Notification

Dispatch the notification to a specific recipient.

await dispatcher.dispatch(notification, "[email protected]");

Advanced Usage: Decorators

You can manually compose notifications using decorators for maximum flexibility.

import { 
    SimpleNotification, 
    PriorityDecorator, 
    TimestampDecorator, 
    ChannelDecorator 
} from "@subhajit60/notification-engine";

let n = new SimpleNotification("alert", "warning", "System maintenance scheduled.");
n = new PriorityDecorator(n, "high");
n = new TimestampDecorator(n);
n = new ChannelDecorator(n, "email");

const payload = n.getContent();

Builders

| Builder | Purpose | |---------|---------| | buildEmailNotification | Creates a high-priority email notification with support for images. | | buildTelegramNotification | Creates a telegram notification with a timestamp and medium priority. | | buildQuizNotification | Standard quiz-related notification for in-app use. | | buildAnnouncementNotification | General announcement for in-app display. |

Strategy Interface

To implement custom delivery, simply extend INotificationStrategy:

import { INotificationStrategy, NotificationPayload } from "@subhajit60/notification-engine";

export class MyCustomStrategy extends INotificationStrategy {
    async send(notification: NotificationPayload, to: string) {
        // Your sending logic here
    }
}

License

ISC