Introduction

Santander.API: ASP.net Core WebAPI project. This is the start up project comprising of 2 controllers.
- HealthCheck - This provides an endpoint for checking health of the API.
- Story: - This provides an endpoint for retrieving the story details of the n best stories. n is a passed parameter specified by the user (as per provided specification).
Santander.API.Common: Contain interfaces and POCO's
Santander.API.HackerNews: Contain the Hacker Rank specific code.
- HackerNewsBestStoryTransformer
  - This converts the Hacker Rank Best Story model into the required format, as returned by the Story API.
- HackerNewsApiClient
  - This calls the Hacker News API to obtain the Story Ids (ranked by score) and the details of each specific story.
- HackerNewsProcessor
  - This wraps the API calls to HackerNewsApiClient and manages the flow / business rules. Story data is cached in this class (see Assumptions) and throttling of the calls to the Hacker News API is achieve via the Bulkhead feature of the Polly Nuget

Usage

The story controller exposes an endpoint called BestStories and expects an integer parameter, which specifies the how many top stories to return. The endpoint is a GET and can be called like this:

https://localhost:7282/Story/BestStories?topNStories=2

The returned JSON for the above request would be as per below:

[
  {
    "title": "OpenTF announces fork of Terraform",
    "uri": "https://opentf.org/announcement",
    "postedBy": "cube2222",
    "time": "2023-08-25T14:56:48+00:00",
    "score": 1679,
    "commentCount": 483
  },
  {
    "title": "Factorio: Space Age",
    "uri": "https://factorio.com/blog/post/fff-373",
    "postedBy": "haunter",
    "time": "2023-08-25T11:50:20+00:00",
    "score": 1423,
    "commentCount": 353
  }
]

If the topNStories parameter is not a valid integer > 0 then an empty array will be returned:

Appsettings

Within appsettings there is a StoryApiConfig section comprising of the following:

Item	Description
BaseUrl	Stores the base URL of the (Hacker News) Story API (https://hacker-news.firebaseio.com)
BestStoriesEndPoint	Hacker News endpoint to obtain best stories (/v0/beststories.json)
StoryEndPoint	Hacker News endpoint to obtain each story detail (/v0/item/{0}.json)
ConnectionTimeout	Limit (in seconds) when connecting to Hacker News API
MaxHTTPParallelization	Value indicating how many concurrent requests will be used when calling the Hacker News API (this value is used by the Polly Bulkhead.
CacheTimeout	Value indicating how many seconds to cache story data for. If the value is omitted or a value that is 0 or less is specified, then no caching will occur.
ThreadCount	Value indicating how many separate threads will be used to obtain the story information. For example if this is set to 10 and a user requests the top 100 stories, then 10 threads will be fired, each thread requesting details of 10 stories each.
--	--

Assumptions

The following assumptions have been made:

The story ids returned from https://hacker-news.firebaseio.com/v0/beststories.json are in descending order of score.
The stories' scores do not change change so frequently (perhaps every 30mins), thus caching of the best story ids and story data provides a suitable balance between service efficacy and data accuracy. Cache duration can be amended or be disabled.
Timestamps provided in the payload via the https://hacker-news.firebaseio.com/v0/item/123.json end point is UTC.

Future Enhancements / Changes

Add benchmarking to provide a view of how long the API is taking to obtain and return story data.
Implement logging to disk (serilog for example)
Implement Common error handler
Unit tests
Possibly implement a distributed cache

Misc.