Receipt Processor API

Overview

The Receipt Processing API is a RESTful service that processes receipts and calculates points based on predefined rules. It exposes two main APIs:

• POST /receipts/process: Submits a receipt for processing.
• GET /receipts/{id}/points: Retrieves the points awarded for a specific receipt.

Technology Stack

• Java 11+
• Spring Boot
• Maven
• Docker
• Postman (for API testing

Project Structure

src/
 └── main/
     └── java/
         └── com/receipt_processor/
             ├── controller/
             │   └── ReceiptController.java
             ├── service/
             │   └── PointsService.java
             ├── model/
             │   ├── Receipt.java
             │   ├── Item.java
             ├── dto/
             │   ├── ReceiptResponseDTO.java
             │   └── PointsResponseDTO.java
             ├── exception/
                 ├── ReceiptNotFoundException.java
                 ├── BadRequestException.java
                 └── InternalServerErrorException.java
                 └── GlobalExceptionHandler.java

API Flow and Interaction

• Post :

  • Request Handling

    • A POST request is sent to /receipts/process, received by ReceiptController.
    • The request body is validated based on the Receipt model.

  • Service Layer

    • The controller delegates the processing logic to PointsService.
    • A unique receipt ID (UUID) is generated and points are calculated based on:
      • Alphanumeric characters in the retailer name.
      • Total amount being a round number or divisible by 0.25.
      • Item description length and purchase time.
    • The receipt and calculated points are stored in memory.

  • Returning the Response

    • The receipt ID is returned to the client as part of a ReceiptResponseDTO with an HTTP 200 OK status.

• Get :

  • Request Handling

    • A GET request is sent to /receipts/{id}/points, received by ReceiptController.
    • The receipt ID is extracted from the URL and passed to the service layer.

  • Service Layer

    • The service attempts to retrieve the points using the receipt ID from the in-memory store.
    • If the receipt is found, the points are returned in a PointsResponseDTO.

  • Returning the Response

    • If the receipt ID is invalid or the receipt is not found, a ReceiptNotFoundException is thrown and caught by the GlobalExceptionHandler.

Error Handling

The API has robust error handling using Spring Boot’s @ControllerAdvice for global exception management.

Common Errors:

• 400 Bad Request: Returned when required fields are missing or have invalid formats.
• 404 Not Found: Returned when the receipt ID is not found.

How to run the program

Prerequisites

• Docker: Make sure Docker is installed and running.

Steps

• Clone the repository : git clone https://github.com/rakshith53/receipt-processor cd receipt-processor
• Build docker image : docker build -t receipt-processor .
• Run Docker Container: docker run -p 8080:8080 receipt-processor
• Access the application : The API will be running on http://localhost:8080. You can test the API endpoints using Postman or curl.

Example API calls

• Post:

  • Endpoint: /receipts/process

  curl -X POST http://localhost:8080/receipts/process \
    -H "Content-Type: application/json" \
    -d '{
          "retailer": "Target",
          "purchaseDate": "2022-01-01",
          "purchaseTime": "13:01",
          "items": [
            {"shortDescription": "Mountain Dew 12PK", "price": "6.49"}
          ],
          "total": "6.49"
        }'

• Get:

  • Endpoint : /receipts/{id}/points

  curl -X GET http://localhost:8080/receipts/{id}/points

Replace {id} with the actual receipt ID from the POST request.