Application is written in Java 11 using Spring Boot and PostgreSQL database.

Easiest way to run this application is via Docker Compose. Dockerfile and docker-compose.yml files are prepared to build and run Java application and setup PostgreSQL database in docker containers.

Before starting application, to change default settings, please check .env file: application port, database properties and test data seeding option could be configured there. By default API port is set to 8080 and test data seeding on startup (ADD_TEST_DATA) is enabled.

To start application just run one of these commands in application directory:
docker-compose up or docker-compose up -d to start it in the background.

After build process two containers for API and DB will be started:

By default Swagger UI, where all endpoints are described and could be tested, can be accessed by these URLs:
http://localhost:8080
http://localhost:8080/swagger-ui/

OpenAPI documentation:
http://localhost:8080/v2/api-docs

Swagger UI screenshot with API endpoints:

On application start 3 tables will be created in the database and by default some test data will be added:

• products table - 6 test products.
• cart_rules table - 3 default rules from task description.
• cart_items table - no initial data.

After adding one of the products from products table to the cart POST /api/v1/cart/item, calculations will be performed based on cart rules from cart_rules table and response with cart summary will be sent back.

{
  "limitReached": false, // is price limit reached? some rules could add such limit for the cart 
  "sum": 11.41, // overall price for all items in the cart without a discount
  "discount": 1.59 // discount calculated based on defined rules
}

New cart rules and products could be added via certain endpoints.