DAB0mB/code-interview

Welcome to Vim!

These are instructions for your coding exercise. Please read them carefully and make sure to ask whatever question pops into your mind.

Goal

We would like to create a system for scheduling appointments with providers (doctors), which would able to:

• Search for providers to set up an appointment with.
• Select an appointment date from the search results & notifying the provider of the new appointment.
• Receive requests for adding, updating or deleting providers

Our system supports both synchronous queries and async queries. We use synchronous queries where possible, but sometimes when we rely on slow/unreliable external systems or when we need an event-based workflow we use an async system.

• The synchronous queries use REST APIs - one of which you will build.
• The asynchronous queries use a publish-subscribe (pub-sub) system based on “channels”. You will connect to this system as both a subscriber and a publisher. (bonus part)

What are we looking for?

• There is no “right” solution! As long as your code works, is readable and extensible- it’s great!
• You may use whatever external library you need.
• We’re looking for big picture stuff:
  • Is your code architecture clean?
  • Is it easy to add new functionality?
  • Is your code testable?
  • Is your code readable?
  • Does your code handle errors well?
  • Does your code have good logging?
• We’re not looking to find unimportant mistakes:
  • Don’t get stuck if you don’t understand the instructions. We will help you!
  • Don’t get stuck on silly syntax errors in libraries you have no experience with. We will help you!
  • Don’t get stuck on coding environment / bootstrapping issues. We will help you!
• We want you to be able to finish this exercise so we can talk about your solution.
• You are not expected to finish any bonus from part C. They are there if you happen to have enough time and to open up discussion points.
• You are not expected to use any specific framework or even any framework at all - work with what you like.
• We encourage you to execute each part of this exercise independently. For each part - read the instructions, make sure you understand them with your interviewer, implement the part, verify the tests pass and call your interviewer before moving on to the next part.

What’s a Provider?

A provider is a doctor. Its Object model looks like this:

{
    “name”: “Roland Deschain”, //Provider’s name
    “specialties”: [“Neurologist”, “Cardiologist”], //The provider’s specialties
    “availableDates”: [ //Available time slots for appointments
        {“from”:1548932400000,”to”:1548943200000},
        {“from”:1549000800000,”to”:1549031400000}
    ]
    “score”: 9.3 //Vim’s “secret sauce” - a provider’s score
}

We take the provider's name as unique, which we can differentiate between providers - you can rely on that when you think about data modeling.

Dates: The dates (all dates in our system) are formatted as Milliseconds since epoch (Which means that a date like this - 31/11/1990 16:30 is written like this - 660061800000 ). The dates are inclusive, meaning that if a provider has an availability of {"from":100, "to":200} then acceptable dates for an appointment would be: 150, 100, 200 but not 99, 201.

Scores: The scores are between 0 and 10.0

Datasource: For the purpose of this exercise, you will get a Provider list from a .json file and all reading/writing from/to it should be done in memory. Design your system in a way that supports millions of Providers, each with thousands of Specialties and AvailableDates, all in memory.

Exercise

Preparation and running the tests

• Make sure you have node.js, npm and git installed.
  • https://nodejs.org/en/download/
  • https://git-scm.com/downloads
• Clone this repository and create a new branch.
• The relevant folders for this part:
  • ./providers contains mock data
  • ./test contains the pre-written tests for your code
  • ./src will contain your answer
• Run npm install inside ./test.
• To run the tests for this part, you will need to have the server that you will implement running in the background.
  • Your server should be running on port 3500. You can change this in ./test/config.js.
  • In ./test execute npm run test.

Exercise

The goal of this part is to create a REST endpoint to allow users to set up appointments. Users look for a provider with a specific specialty (e.g ‘Neurologist’, ‘Cardiologist’) and with availability for a certain date. They should receive a list of providers ordered by relevance, and should be able to select one and set up an appointment with them.

Use the mock info under /providers/providers.json as your data source, but write your code such that it will be easy to switch this mock for an actual data source like a database / another HTTP endpoint.

• Create a REST server with the following endpoint: GET /appointments?specialty=<SPECIALTY>&date=<DATE>&minScore=<SCORE>

  • The results should take into account:
    • Threshold: They should only get providers whose scores are matching that threshold (inclusive, if minScore=9.0 then a provider with score 9.0 should be valid)
    • Specialty: They should only get providers that specialize in that specific specialty. Specialty is not case sensitive.
    • Availability: They should only get providers that are available in the specific time requested
    • Ordering: The providers should be ordered by score from highest to lowest
  • The endpoint should return an array of provider names according to the order defined above.
  • If there are no suitable providers the endpoint should return an empty array.
  • If the user gave bad parameters, like a missing specialty, or a bad date format (should be milliseconds since epoch), the server should return a 400 (BAD REQUEST) code.

• Create an endpoint to set up an appointment: POST /appointments BODY: { “name”: string, “date”: date }:

  • The server should validate that such an availability exists. If it doesn’t, the server should return 400 (BAD REQUEST).
  • If such an availability does exist, the server should return a 200 (OK) response to the client.
  • This endpoint does not actually change the providers data, they will be mutated in the bonus part ;).

Good luck from all of us at Vim!