Paymeter Backend Software Engineer Assessment

Deliverable

There is quite some flexibility in what can be delivered, just ensure the service:

• is a web service
• can run on Mac OS X or Linux (x86-64)
• is written in Java
• uses Spring Boot
• can make use of any existing open source libraries that don't directly address the problem statement (use your best judgement)

Send us:

• The full source code, including any code written which is not part of the normal program run (scripts, tests)
• Clear instructions on how to obtain and run the program
• Please provide any deliverables and instructions using a public Github (or similar) Repository as several people will need to inspect the solution

Evaluation

The point of the exercise is for us to see some of the code you wrote (and should be proud of). We will especially consider:

• Code organisation
• Quality
• Readability
• Actually solving the problem

Instructions

To run the application, run the following command in a terminal window:

# java 17 in host
./gradlew bootRun

# using docker
docker build -t app . && docker run -it -p 8080:8080 app

Check service is running:

curl http://localhost:8080

Execute the following command to test the application:

# java 17 in host
./gradlew test

# using docker
docker run --rm -u gradle -v "$PWD":/home/gradle/project -w /home/gradle/project gradle:8-jdk17 gradle test

Challenge

Our customers want to be sure they're properly charging the correct amount on their parkings. For this reason, we plan to create a new pricing calculation feature so they can test multiple scenarios. We have two customers with one parking each:

• Customer 1:

  • Parking id: P000123
  • Hourly price: 2€
  • Discounts
    • Max price per day: 15€

• Customer 2

  • Parking id: P000456
  • Hourly price: 3€
  • Discounts
    • Max price every 12 hours: 20€
    • First hour is free

Note:

• The price of a fraction of an hour is the same as a full hour
• If duration of the stay is less than one minute, parking is free
• There's no max time for a stay
• There's no limit of times that max price discount can be applied
• Max price discount starts counting when entering the parking

Requirements:

• Endpoint: POST /tickets/calculate
• Request:
  • Content type: JSON
  • Fields:
    • parkingId: string (required)
    • from: ISO 8601 timestamp string (required)
    • to: ISO 8601 timestamp string (optional, defaults to current time)
• Response:
  • Content type: JSON
  • Fields:
    • parkingId: string (required)
    • from: ISO 8601 timestamp string (required)
    • to: ISO 8601 timestamp string (required)
    • duration: integer (minutes)
    • price: string (integer amount + currency code, e.g. 2.35€ would be "235EUR")
  • Status codes:
    • 200 ok
    • 400 invalid request
    • 404 parking not found
    • 500 server error
    • (feel free to return any status codes needed)

Example usage:

curl -X POST http://localhost:8080/tickets/calculate \
  -H "Content-Type: application/json" \
  -d '{"parkingId":"P000123","from":"2024-02-27T09:00:00"}'