added email service using Nodemailer

Author: ericahan22

backend/.env.example

@@ -0,0 +1,4 @@
+MAILER_USER=your-email@gmail.com
+MAILER_REFRESH_TOKEN=your-refresh-token
+MAILER_CLIENT_SECRET=your-client-secret
+MAILER_CLIENT_ID=your-client-id

backend/examples/emailServiceExample.ts

@@ -0,0 +1,86 @@
+import nodemailerConfig from '../nodemailer.config';
+import EmailService from '../services/implementations/emailService';
+import IEmailService from '../services/interfaces/emailService';
+
+// Initialize the email service with optional display name
+const emailService: IEmailService = new EmailService(
+  nodemailerConfig,
+  'My App Name' // Optional: Display name that appears in the "From" field
+);
+
+// Example 1: Send a welcome email
+async function sendWelcomeEmail(userEmail: string, userName: string) {
+  const subject = 'Welcome to Our App!';
+  const htmlBody = `
+    <h1>Welcome, ${userName}!</h1>
+    <p>Thank you for joining our application.</p>
+    <p>We're excited to have you on board.</p>
+    <br>
+    <p>Best regards,<br>The Team</p>
+  `;
+
+  try {
+    await emailService.sendEmail(userEmail, subject, htmlBody);
+    console.log(`Welcome email sent successfully to ${userEmail}`);
+  } catch (error) {
+    console.error(`Failed to send welcome email: ${error}`);
+  }
+}
+
+// Example 2: Send a password reset email
+async function sendPasswordResetEmail(userEmail: string, resetLink: string) {
+  const subject = 'Password Reset Request';
+  const htmlBody = `
+    <h2>Password Reset</h2>
+    <p>We received a request to reset your password.</p>
+    <p>Click the link below to reset your password:</p>
+    <br>
+    <a href="${resetLink}" style="
+      background-color: #4CAF50;
+      color: white;
+      padding: 14px 20px;
+      text-decoration: none;
+      border-radius: 4px;
+      display: inline-block;
+    ">Reset Password</a>
+    <br><br>
+    <p><strong>This link will expire in 1 hour.</strong></p>
+    <p>If you didn't request this, please ignore this email.</p>
+  `;
+
+  try {
+    await emailService.sendEmail(userEmail, subject, htmlBody);
+    console.log(`Password reset email sent successfully to ${userEmail}`);
+  } catch (error) {
+    console.error(`Failed to send password reset email: ${error}`);
+  }
+}
+
+// Example 3: Send a notification email
+async function sendNotificationEmail(
+  userEmail: string,
+  notificationTitle: string,
+  notificationMessage: string
+) {
+  const subject = notificationTitle;
+  const htmlBody = `
+    <h2>${notificationTitle}</h2>
+    <p>${notificationMessage}</p>
+    <br>
+    <p>Best regards,<br>The Team</p>
+  `;
+
+  try {
+    await emailService.sendEmail(userEmail, subject, htmlBody);
+    console.log(`Notification email sent successfully to ${userEmail}`);
+  } catch (error) {
+    console.error(`Failed to send notification email: ${error}`);
+  }
+}
+
+// Example usage (uncomment to test):
+// sendWelcomeEmail("user@example.com", "John Doe");
+// sendPasswordResetEmail("user@example.com", "https://yourapp.com/reset?token=abc123");
+// sendNotificationEmail("user@example.com", "New Update", "Check out our new features!");
+
+export { sendWelcomeEmail, sendPasswordResetEmail, sendNotificationEmail };

backend/nodemailer.config.ts

@@ -0,0 +1,14 @@
+import { NodemailerConfig } from './types';
+
+const config: NodemailerConfig = {
+  service: 'gmail',
+  auth: {
+    type: 'OAuth2',
+    user: process.env.MAILER_USER ?? '',
+    clientId: process.env.MAILER_CLIENT_ID ?? '',
+    clientSecret: process.env.MAILER_CLIENT_SECRET ?? '',
+    refreshToken: process.env.MAILER_REFRESH_TOKEN ?? '',
+  },
+};
+
+export default config;

backend/package-lock.json

@@ -15,6 +15,7 @@
     "apollo-server-express": "^3.13.0",
     "dotenv": "^17.2.3",
     "express": "^4.18.2",
+    "nodemailer": "^8.0.1",
     "pg": "^8.18.0",
     "sequelize": "^6.37.7",
     "sequelize-typescript": "^2.1.6",
@@ -25,6 +26,7 @@
     "@types/dotenv": "^6.1.1",
     "@types/express": "^5.0.6",
     "@types/node": "^25.1.0",
+    "@types/nodemailer": "^7.0.9",
     "@types/pg": "^8.16.0",
     "@types/umzug": "^2.3.9",
     "@typescript-eslint/eslint-plugin": "^8.54.0",

backend/package.json

@@ -0,0 +1,37 @@
+import nodemailer, { Transporter } from 'nodemailer';
+import IEmailService from '../interfaces/emailService';
+import { NodemailerConfig } from '../../types';
+
+class EmailService implements IEmailService {
+  transporter: Transporter;
+
+  sender: string;
+
+  constructor(nodemailerConfig: NodemailerConfig, displayName?: string) {
+    this.transporter = nodemailer.createTransport(nodemailerConfig);
+    if (displayName) {
+      this.sender = `${displayName} <${nodemailerConfig.auth.user}>`;
+    } else {
+      this.sender = nodemailerConfig.auth.user;
+    }
+  }
+
+  async sendEmail(to: string, subject: string, htmlBody: string): Promise<void> {
+    const mailOptions = {
+      from: this.sender,
+      to,
+      subject,
+      html: htmlBody,
+    };
+
+    try {
+      await this.transporter.sendMail(mailOptions);
+    } catch (error: unknown) {
+      const errorMessage = error instanceof Error ? error.message : 'Unknown error';
+      console.error(`Failed to send email. Reason = ${errorMessage}`);
+      throw error;
+    }
+  }
+}
+
+export default EmailService;

backend/services/implementations/emailService.ts

@@ -0,0 +1,12 @@
+interface IEmailService {
+  /**
+   * Send email
+   * @param to recipient's email
+   * @param subject email subject
+   * @param htmlBody email body as html
+   * @throws Error if email was not sent successfully
+   */
+  sendEmail(to: string, subject: string, htmlBody: string): Promise<void>;
+}
+
+export default IEmailService;

backend/services/interfaces/emailService.ts

@@ -1,5 +1,8 @@
+import dotenv from 'dotenv';
 import express from 'express';
 
+dotenv.config();
+
 const app = express();
 const PORT = process.env.PORT || 3000;
 

backend/src/index.ts

@@ -12,3 +12,14 @@ export type CreateSampleDTO = {
   name: string;
   description: string;
 };
+
+export type NodemailerConfig = {
+  service: 'gmail';
+  auth: {
+    type: 'OAuth2';
+    user: string;
+    clientId: string;
+    clientSecret: string;
+    refreshToken: string;
+  };
+};