E-commerce Checkout API: This is a simplified e-commerce API with a single endpoint for performing a checkout action. It calculates the total cost of a list of watches based on the provided watch IDs. Discounts are applied as per the specified catalog.

Setup To set up and run the application, follow these steps:

Prerequisites:

Install Visual Studio if not already installed.

Clone the Repository:

Clone this repository to your local machine using Git.

git clone https://github.com/h-pannu/ECommerceCheckout.git

Open the Project:

Open the project using Visual Studio.

Build and Run:

Build the project. Run the application using F5 or by pressing Ctrl + F5 in Visual Studio.

API Endpoint:

The API endpoint will be available at http://localhost:port/api/checkout by default.

Usage

Checkout API Endpoint To calculate the total price of a list of watches, make a POST request to the following endpoint:

URL: http://localhost:port/api/checkout

Method: POST

Headers:

Accept: application/json Content-Type: application/json Request Body:

Provide a list of watch IDs as strings in the request body. For example: ["001", "002", "001", "004", "003"]

Response:

The API will respond with the total price in JSON format, like this: { "price": 360 }

Approach I built this e-commerce checkout API using ASP.NET Core. Here's an overview of my approach:

Project Setup:

I created N-Tier architecture by creating Web Api project, Library project for Models, Library project for Services and xunit project to have seperation of concerns. I used dependency injection to inject checkout service into controller post method.

Data Model:

Created a Watch class to represent watches with properties for Watch ID, Watch Name, Unit Price, and Discount. Created a Discount class to represent Discount Id, DiscountQuantity, DiscountPrice

Checkout Controller:

Implemented a CheckoutController with a Checkout action. Injected checkout service interface to call CalculateTotalCost method.

This action calculates the total price based on the provided watch IDs, considering any discounts.

Discount Logic:

Implemented logic in the CalculateTotalCost Logic method to calculate the total price and apply discounts as specified in the requirements.

Testing:

Added unit tests to validate the API's functionality. Ensured the API returns the correct total price for different combinations of watches.

Documentation and Readme:

Documented the setup process and usage of the API in this README. Explained my approach, design decisions, and how I handled discount logic.

Improvements If I had more time, here are some improvements I would consider:

Error Handling:

Implement better error handling and provide meaningful error responses for edge cases or invalid input.

Authentication and Authorization:

Add authentication and authorization mechanisms to secure the API if it were to be used in a real e-commerce system.

Logging:

Implement logging to capture important events and exceptions for monitoring and debugging purposes.

Optimization:

Optimize the discount calculation logic for performance, especially if there is a large catalog.

API Versioning:

Consider adding versioning to the API to handle future changes or updates to the checkout logic.

More Testing:

Expand the test suite to cover additional scenarios and edge cases.

Containerization and Deployment:

Dockerize the application for easy deployment and consider deploying it to a cloud platform.