andrer0cha / cash-register

Cash Register

Description

This project aims to reproduce a simple cash register that supports business rules like buy-one-get-one-free when adding a product to cart.

Current suported rules

1. Buy X get Y free - Buy X products and get Y items of same product.
2. Buy X or more items and pays a fixed price per item.
3. Buy X or more items and receives a discount in percentage per item.

Usage instructions

This app was develop on top of a modular Sinatra application and has the following requirements:

ruby 3.2.2 and bundler 2.4.22

To run the app, after installing the requirements, one can simply:

1. Clone the repository
2. Navigate to project's folder
3. Run bundle to install dependencies
4. Run bundle exec rake db:create && bundle exec rake db:migrate to setup databases
5. Run bundle exec rake db:seed to populate the database with initial data
6. Start the server/application by running bundle exec rackup config.ru

To interact with the app, we should use it as an API, we can use Postman to make requests and check the responses

Available Routes

• GET /products - index of all products in the DB
• GET /cart - Current User's cart items
• PATCH /cart/add_product - Add product to Current User's cart

  Request body:
  {
    "product_id": <id_of_product_to_add>,
    "qty_to_add": <units_to_be_added>
  }
  

• DELETE /cart/clean_cart - Remove all products from current user's cart
• DELETE /cart/remove_product - Remove specific product from current user's cart

  Request body:
  {
    "product_id": <id_of_product_to_delete>,
    "qty_to_delete": <units_to_be_removed_from_cart>
  }
  

How to create a rule

Currently, all the rules are created in the db/seeds.rb file, but the architecture is simple and flexible enough to allow it to be created from an endpoint (to be created). The rules database has the following columns:

• trigger_product_id: (Integer that stores the value of the product that will trigger the rule - it allows empty values for rules that check for any product in the cart)
• trigger_amount: (Decimal that stores the value amount that will trigger the rule)
• trigger_amount_type: (String that stores the type of the trigger amount, it can be 'unit', 'cents' or 'percentage')
• trigger_amount_operator: (String that stores the logical operator that the rule will use to compare and see if it should be triggered, it allows:
  • 'GTE' (>=)
  • 'LTE' (<=)
  • 'EQ' (==)
  • 'LT' (<)
  • 'GT' (>)
• rule_type_id: (Integer that stores the id of the RuleType record that the rule belongs_to
• target_product_id: (Integer that stores the value of the product that will be the target of the rule - will be added to the card or will receive a discount)
• target_amount: (Decimal that stores the value amount for the target item - discount to be given, units to add, price to set, etc.)
• target_amount_type: (String that stores the type of the target amount, it can be 'unit', 'cents' or 'percentage')

Database Diagram

Possible Next steps

1. Revert the rules when removing product from cart
2. Fix endpoint responses to follow API patterns properly
3. Improve specs
4. Add User Interface / Front-end
5. Improve support for different RuleTypes