katdom13 / machine-prob-001

Full-stack Dev Exercise - Promo Microsite

Prerequisites:

Edit environment variable files

Backend env file

SECRET_KEY=django-insecure-_(w*%ktha#uiu51h_38v!jz-wtzu68=n)nd0kb-#3=6=d5imb@
DEBUG=True
ALLOWED_HOSTS=*

TWILIO_ACCOUNT_SID=<Your twilio account SID>
TWILIO_AUTH_TOKEN=<Your twilio auth token>
TWILIO_PHONE_NUMBER=<Your twilio phone number>

RECAPTCHA_SITE_KEY=<Your google recaptcha site key>
RECAPTCHA_SECRET_KEY=<Your google recaptcha secret key>

Frontend env file

NEXT_PUBLIC_RECAPTCHA_SITE_KEY=<Your google recaptcha site key>
RECAPTCHA_SECRET_KEY=<Your google recaptcha secret key>

Note: This repo has .env files for the sake of testing, I already took down the private keys, so if you want to run the app, you should supply your own keys.

Running the app

Via docker and docker-compose

docker-compose up

If there are any changes to the build file or the Dockerfiles, this command should be run prior to the app:

docker-compose build

If docker is not installed

To run the API server

cd backend
python manage.py runserver

Note: By default, the API server runs at port 8000

To run the UI:

cd frontend/scratchandwin
yarn start

If there are any changes to the UI, this command should be run prior:

yarn build

Note: By default, the UI runs at port 3000

Background

• An F&B client wanted to run a marketing-loyalty campaign wherein their packaged products will be distributed with a printed unique coupon code
• End-customers buying the packaged products may get this unique coupon code and will be able to get a chance to win prizes
• Client wanted a web interface where customers can redeem their coupon code
• Prize is fixed and does not vary per coupon
• Client shall provide a list of winning coupons

Data Modelling

Coupon Model

Model for a coupon object

Fields

• public_id

  UUID primary key

• code

  Required and Unique. 150 characters or fewer.

• is_claimed

  Boolean. Designates whether this has been claimed.

• created_at

  A datetime designating when the coupon was created. Is set to the current date/time by default when the coupon is created.

Promo Model

Model that represents an end-user or submission, hastily named Promo.

Fields

• coupon

  UUID one-to-one foreign key to a coupon object.

• mobile

  Required. Phone number of the end user.

• claimed_at

  A datetime designating when the coupon was claimed. Is set to the current date/time by default when the coupon is claimed.

• ip_address

  An IP address field that tracks an end-user IP address. Is set when a submission is made.

• user_agent

  A field that tracks an end-user's user agent. Is set when a submission is made.

A visual representation can be viewed at: https://dbdiagram.io/d/614a5347825b5b01460d18fb

Requirements

Redeem a Coupon Form page

Form data:

• coupon code = alphanumeric

• mobile number = mobile number, philippine numbers (639xxyyyzzzz)

  

Logic and Constraints:

• submitted coupon code will be validated against an existing database of coupons

  Example list

• valid coupons mean they exist in the database

• invalid coupon codes will be rejected

  

• valid coupon codes can only be claimed once

  

• a claimed coupon code is tied to a submission attempt entry

• a successful claim / redemption will get an SMS message

  

  The SMS messaging is implemented upon end-user entry:

    class Promo(models.Model):
      ...
       def save(self, *args, **kwargs):
        twilio_client.messages.create(
            body=f'You have successfully won a prize using coupon code: {self.coupon.code}. Please contact us to receive instructions to claim the prize.',
            from_=settings.TWILIO_PHONE_NUMBER,
            to=str(self.mobile)
        )
        return super().save(*args, **kwargs)
  

  Delivered Twilio message

  

  Note: Only verified numbers can receive messages from twilio. Since I am using a trial account, this app can only send messages to verified numbers.

• implement rate limit of attempts per IP-address

  

  Note: The rate limit for the app is 5 attempts per day for each IP address

    'DEFAULT_THROTTLE_CLASSES': [
        'rest_framework.throttling.AnonRateThrottle',
        'rest_framework.throttling.UserRateThrottle'
    ],
    'DEFAULT_THROTTLE_RATES': {
        'anon': '5/day',
        'user': '5/day'
    }
  

• use captcha also if possible to prevent bots

  

Data:

• coupons are hashed

  Coupons are hashed after creation:

    @receiver(post_save, sender=Coupon)
    def hash_coupon_code(sender, instance, created, **kwargs):
      # Hash coupon code upon creation
      if created:
          instance.code = hash_string(instance.code)
          instance.save()
  

  Example

  

• The following are logged: timestamp, mobile, coupon, ip address, user agent