Service Layer

import { randomBytes } from 'crypto';
 
export class WaitlistService {
  /**
   * Adds an email to the waitlist with the provided referral code and returns entry details.
   * If email already exists in the waitlist, it returns the existing entry details.
   */
  async addToWaitlist({ email, referredByCode }: { email: string; referredByCode?: string }) {
    // Find the signup record belonging to the provided referredByCode if exists
    const referredByRecord = referredByCode
      ? await prisma.waitlistSignUps.findFirst({ where: { referralCode: referredByCode } })
      : undefined;
 
    // Insert the new signup table if the email does not already exists in our waitlist
    const newReferralCode = this.generateReferralCode();
    const signUpRecord = await prisma.waitlistSignUps.upsert({
      where: { email },
      create: {
        email,
        referralCode: newReferralCode,
        referredById: referredByRecord?.id,
      },
      update: {}, // Do nothing if email already exists in the database
    });
 
    return {
      id: signUpRecord.id,
      referralCode: signUpRecord.referralCode,
      createdAt: signUpRecord.createdAt,
    };
  }
 
  /**
   * Generates a referral URL for the provided referral code.
   */
  getReferralUrl(referralCode: string) {
    const url = new URL(BASE_URL);
    url.pathname = REFERRAL_ENTRY_PATH;
    url.searchParams.set(REFERRAL_CODE_QUERY_KEY, referralCode);
    return url.toString();
  }
 
  /**
   * Generates an 8-character, URL-safe, cryptographically random referral code.
   */
  private generateReferralCode() {
    return randomBytes(8).toString('base64url');
  }
}

/**
 * The base URL of your client application.
 * This should be adjusted depending on the environment (e.g. http://localhost:3000).
 */
export const BASE_URL = 'https://example.com';
 
/**
 * The query key used to pass the referral code in the URL.
 * Example: https://example.com/signup?ref=abc123
 */
export const REFERRAL_CODE_QUERY_KEY = 'ref';
/**
 * The path where the referred users will land on in your website or app.
 * Example: /signup
 */
export const REFERRAL_ENTRY_PATH = '/';