Email Authentication — Email-Based Verification and Login Patterns

// Email verification flow
async function sendVerificationEmail(user) {
  const token = crypto.randomBytes(32).toString('hex');
  const expires = Date.now() + 24 * 60 * 60 * 1000;

  await redis.setex(`verify_email:${token}`, 86400, JSON.stringify({
    userId: user.id,
    newEmail: user.email,
    type: 'verification'
  }));

  const verifyUrl = `https://scanapp.com/verify-email?token=${token}`;

  await emailService.send({
    to: user.email,
    subject: 'Verify your ScanApp email',
    html: `
      <h2>Welcome to ScanApp!</h2>
      <p>Please verify your email by clicking the link below:</p>
      <a href="${verifyUrl}" style="padding:12px 24px; background:#2d6a9f; color:white;">
        Verify Email
      </a>
      <p>Link expires in 24 hours.</p>
    `
  });
}

// Magic link login
async function sendMagicLink(email) {
  const token = crypto.randomBytes(32).toString('hex');
  await redis.setex(`magic_link:${token}`, 900, email);

  const loginUrl = `https://scanapp.com/auth/magic-link?token=${token}`;

  await emailService.send({
    to: email,
    subject: 'Sign in to ScanApp',
    text: `Click to sign in: ${loginUrl}. Expires in 15 minutes.`
  });
}

// Email OTP
async function sendEmailOTP(email) {
  const code = Math.floor(100000 + Math.random() * 900000).toString();
  await redis.setex(`email_otp:${email}`, 300, code);

  await emailService.send({
    to: email,
    subject: 'Your ScanApp verification code',
    text: `Your verification code is: ${code}. Valid for 5 minutes.`
  });
}