Thank you for the opportunity to handle this code challenge. Before we get started, I am very well aware that this small asp.net core 3.1 web api project is NOT a match for a fully production ready payment gateway and it lacks the consideration around

• Failure Retrial Policies
• Scalable data storage
• Multiple Bank integration and different protocol requirements
• Fully auditable transaction events
• Tokenised card payment and digital wallets etc
• Multiple currency support and fee calculation

The solution is built using Visual Studio Professional 2019 Version 16.9.4

The gateway supports only GBP currency

It supports two operations

Request a card payment

HTTP POST : http://localhost:5000/payments

Request Headers :

• Content-Type : application/json
• Authorisation: test_key1

Payload:

{
    "expirymonth": 9,
    "expiryyear" : 2022,
    "number" : "1234 5678 9012 3452",
    "amount" : 111,
    "cvv" : "123",
    "currencycode": "GBP",
    "name" : "Mr Test"
}

Example Response:

{
    "id": "17e15e5b-edc1-4bb0-bce8-12a258004dc0",
    "success": true,
    "status": "fulfilled",
    "amount": 111,
    "currency": "GBP",
    "processedOn": "2021-05-13T13:56:06.9092883Z",
    "bankReference": "290e11c6-363f-4807-90c6-1bcca80730c4"
}

It returns the following Http status codes for various conditions

• 200 : For a successful response
• 401 : If the Authorisation header is not specified OR it is other than test_key1
• 400 : In case of request validation fails e.g. expiry month is not specified or outside the range of 1 and 12

Get card payment details

HTTP GET : http://localhost:5000/payments/17e15e5b-edc1-4bb0-bce8-12a258004dc0

Request Headers :

• Content-Type : application/json
• Authorisation: test_key1

Example Response:

{
    "id": "17e15e5b-edc1-4bb0-bce8-12a258004dc0",
    "cardDetail": {
        "number": "************3452",
        "expiryMonth": 9,
        "expiryYear": 2022,
        "currencyCode": "GBP",
        "name": "Mr Test"
    },
    "amount": 111,
    "merchantReference": null,
    "merchantId": "M_1111",
    "success": true,
    "status": "fulfilled",
    "bankReference": "290e11c6-363f-4807-90c6-1bcca80730c4",
    "bankDetails": "authorised",
    "requestedOn": "2021-05-13T13:56:06.9071733Z",
    "processedOn": "2021-05-13T13:56:06.9092883Z"
}