Added dependencies for API and VAPID implementation

.gitignore

@@ -1 +1,2 @@
 *~
+node_modules

package.json

@@ -7,8 +7,11 @@
     "node": ">= 18.12 <19"
   },
   "devDependencies": {
+    "@types/body-parser": "^1.19.2",
+    "@types/express": "^4.17.17",
     "@types/jest": "~29.5",
     "@types/node": "~18",
+    "@types/sqlite3": "^3.1.8",
     "@typescript-eslint/eslint-plugin": "~6.2",
     "@typescript-eslint/parser": "~6.2",
     "eslint": "~8.46",
@@ -36,7 +39,12 @@
   "author": "Jakub Synowiec <jsynowiec@users.noreply.github.com>",
   "license": "Apache-2.0",
   "dependencies": {
-    "tslib": "~2.6"
+    "body-parser": "^1.20.2",
+    "express": "^4.18.2",
+    "sqlite": "^5.0.1",
+    "sqlite3": "^5.1.6",
+    "tslib": "~2.6",
+    "web-push": "^3.6.4"
   },
   "volta": {
     "node": "18.12.1"

src/WebPushSender.ts

@@ -0,0 +1,81 @@
+import fetch from 'node-fetch';
+import * as crypto from 'crypto';
+import { ec as EC } from 'elliptic';
+
+class WebPushSender {
+  private ec = new EC('prime256v1');
+  private vapidPrivateKey: string;
+
+  constructor(vapidPrivateKey: string) {
+    this.vapidPrivateKey = vapidPrivateKey;
+  }
+
+  private generateECDHKeyPair() {
+    return this.ec.genKeyPair();
+  }
+
+  private deriveSharedSecret(senderKeys, receiverPublicKeyBase64: string) {
+    const receiverPublicKey = Buffer.from(receiverPublicKeyBase64, 'base64');
+    return senderKeys.derive(this.ec.keyFromPublic(receiverPublicKey).getPublic());
+  }
+
+  private generateContentEncryptionKeys(sharedSecret, authSecretBase64: string) {
+    const authSecret = Buffer.from(authSecretBase64, 'base64');
+    const info = Buffer.from('Content-Encoding: auth\0', 'utf8');
+    const prk = crypto.createHmac('sha256', authSecret).update(sharedSecret.toArray()).digest();
+    const context = crypto.createHmac('sha256', prk).update(info).digest();
+    const keyInfo = Buffer.from('Content-Encoding: aes128gcm\0', 'utf8');
+    return crypto.createHmac('sha256', context).update(keyInfo).digest().slice(0, 16);
+  }
+
+  private encryptPayload(contentEncryptionKey, payload: string) {
+    const nonce = Buffer.alloc(12);
+    const cipher = crypto.createCipheriv('aes-128-gcm', contentEncryptionKey, nonce);
+    return Buffer.concat([cipher.update(payload, 'utf8'), cipher.final()]);
+  }
+
+  private generateVapidToken(senderKeys, endpoint: string) {
+    const vapidPublicKey = senderKeys.getPublic().encode('hex');
+    const tokenPayload = {
+      aud: endpoint,
+      exp: Math.floor(Date.now() / 1000) + (24 * 60 * 60), // 24 hours
+      sub: 'mailto:your-email@example.com',
+    };
+    const encodedHeader = Buffer.from(JSON.stringify({ alg: 'ES256', typ: 'JWT' })).toString('base64');
+    const encodedPayload = Buffer.from(JSON.stringify(tokenPayload)).toString('base64');
+    const signature = this.ec.sign(encodedHeader + '.' + encodedPayload, this.vapidPrivateKey, 'base64');
+    const encodedSignature = signature.toDER('hex');
+    return `${encodedHeader}.${encodedPayload}.${encodedSignature}`;
+  }
+
+  public sendPushNotification(subscription, payload: string) {
+    const senderKeys = this.generateECDHKeyPair();
+    const sharedSecret = this.deriveSharedSecret(senderKeys, subscription.keys.p256dh);
+    const contentEncryptionKey = this.generateContentEncryptionKeys(sharedSecret, subscription.keys.auth);
+    const encryptedPayload = this.encryptPayload(contentEncryptionKey, payload);
+    const vapidToken = this.generateVapidToken(senderKeys, subscription.endpoint);
+
+    const headers = {
+      'Content-Encoding': 'aes128gcm',
+      'Authorization': `vapid t=${vapidToken}`,
+      'TTL': '60',
+    };
+
+    return fetch(subscription.endpoint, { method: 'POST', body: encryptedPayload, headers });
+  }
+}
+
+// Usage example
+const vapidPrivateKey = 'YOUR_PRIVATE_VAPID_KEY';
+const sender = new WebPushSender(vapidPrivateKey);
+const subscription = {
+  endpoint: 'https://example.pushservice.com/some-id',
+  keys: {
+    p256dh: 'BIPULBIpUL...',
+    auth: 'eHl6...',
+  },
+};
+
+sender.sendPushNotification(subscription, 'Your Push Payload Here')
+  .then(response => console.log('Push message sent successfully:', response))
+  .catch(error => console.error('Failed to send push message:', error));

src/main.ts

@@ -1,34 +1,72 @@
-/**
- * Some predefined delay values (in milliseconds).
- */
-export enum Delays {
-  Short = 500,
-  Medium = 2000,
-  Long = 5000,
+
+import express from 'express';
+import bodyParser from 'body-parser';
+import { Request, Response } from 'express';
+import sqlite3 from 'sqlite3';
+import { open } from 'sqlite';
+import { WebPushSender } from './WebPushSender'; // Import from previous example
+
+class PushService {
+  private app = express();
+  private db: any;
+  private sender: WebPushSender;
+
+  constructor(private port: number, private vapidPrivateKey: string) {
+    this.sender = new WebPushSender(vapidPrivateKey);
+    this.app.use(bodyParser.json());
+
+    open({ filename: './subscriptions.db', driver: sqlite3.Database }).then((db) => {
+      this.db = db;
+      this.db.run('CREATE TABLE IF NOT EXISTS subscriptions (p256dh TEXT PRIMARY KEY, endpoint TEXT, auth TEXT)');
+      this.setupRoutes();
+    });
+  }
+
+  private setupRoutes() {
+    this.app.post('/subscribe', this.handleSubscribe.bind(this));
+  }
+
+  private async handleSubscribe(req: Request, res: Response) {
+    const { endpoint, keys } = req.body;
+    const { p256dh, auth } = keys;
+
+    try {
+      await this.db.run('INSERT INTO subscriptions (p256dh, endpoint, auth) VALUES (?, ?, ?)', [p256dh, endpoint, auth]);
+      res.status(201).send('Subscription created successfully');
+    } catch (err) {
+      res.status(400).send('Failed to create subscription');
+    }
+  }
+
+  public async sendNotification(p256dh: string, payload: string) {
+    const row = await this.db.get('SELECT * FROM subscriptions WHERE p256dh = ?', [p256dh]);
+    if (row) {
+      const subscription = {
+        endpoint: row.endpoint,
+        keys: {
+          p256dh: row.p256dh,
+          auth: row.auth,
+        },
+      };
+
+      return this.sender.sendPushNotification(subscription, payload);
+    } else {
+      throw new Error('Subscription not found');
+    }
+  }
+
+  public start() {
+    this.app.listen(this.port, () => {
+      console.log(`Server running on http://localhost:${this.port}`);
+    });
+  }
 }
 
-/**
- * Returns a Promise<string> that resolves after a given time.
- *
- * @param {string} name - A name.
- * @param {number=} [delay=Delays.Medium] - A number of milliseconds to delay resolution of the Promise.
- * @returns {Promise<string>}
- */
-function delayedHello(
-  name: string,
-  delay: number = Delays.Medium,
-): Promise<string> {
-  return new Promise((resolve: (value?: string) => void) =>
-    setTimeout(() => resolve(`Hello, ${name}`), delay),
-  );
-}
+// Usage example
+const pushService = new PushService(3000, 'YOUR_PRIVATE_VAPID_KEY');
+pushService.start();
 
-// Please see the comment in the .eslintrc.json file about the suppressed rule!
-// Below is an example of how to use ESLint errors suppression. You can read more
-// at https://eslint.org/docs/latest/user-guide/configuring/rules#disabling-rules
-
-// eslint-disable-next-line @typescript-eslint/explicit-function-return-type
-export async function greeter(name: any) { // eslint-disable-line @typescript-eslint/no-explicit-any
-  // The name parameter should be of type string. Any is used only to trigger the rule.
-  return await delayedHello(name, Delays.Long);
-}
+// Example of sending a notification
+pushService.sendNotification('p256dh_value_here', 'Your Push Payload Here')
+  .then(() => console.log('Notification sent successfully'))
+  .catch((error) => console.error('Failed to send notification:', error));