Henry Meds Coding Challenge

Initial Set Up

Unless otherwise noted, all commands should be run from the same directory as this README file, i.e., the root directory for this project.

NOTE: For MacOS, you need to use gmake instead of make for the commands below.

1. Install GNU make:

   • MacOS: https://formulae.brew.sh/formula/make
   • Windows: https://stackoverflow.com/q/32127524

2. Install Docker: https://docs.docker.com/get-docker/

3. Install asdf: https://asdf-vm.com/

4. Install the Ruby plugin for asdf: https://github.com/asdf-vm/asdf-ruby

5. Install language runtimes: asdf install

6. Set up app:

   1. bundle install
   2. ./bin/rails db:setup
   3. make build

7. To view all API routes, run: ./bin/rails routes | grep api

Running the Application

1. Start the database: make start

   • Run make stop to stop the database.

2. Start the webserver: ./bin/rails server

   • Use ctrl + c to stop when done.

Running Tests

1. Ensure the database is running: make start

2. Run: bundle exec rspec

Approach

The following outlines my thought process and approach for this problem. Before a line of code was written, this approach doc was used to brainstorm how to tackle this coding challenge.

As you can see, ideally we'd have a cron job or some such that runs and cleans up data for us; however, for the sake of simplicity, the shipped code just does the checks in real time.

---

Definitions

**unusable_slots: Any slot whose start or end time is in the non-inclusive time interval
of a reserved slot.

Base Namespace:
/api/v1/

/api/v1/providers/{id}/schedules 
  - GET: Display provider_time_slots for a provider
    - Params:
      - ?date="2023-08-01": Filter by date
    - Returns:
      - provider_time_slots.as_json where reserved == false and editable == true
  - POST: Create provider_time_slots for a provider:
    - Params:
      - start_time
      - end_time
    - Requirements:
      - Validate:
        - Does not overlap existing provider_time_slots start or end times
        - 5 min increments, i.e., start_time and end_time both end in 0 or 5
        - end_time - start_time >= 15 minutes (at least one usable slot)
      - Once validated, "slotify":
        - Create records in provider_time_slots for given time span in 15 min increments
    - Returns:
      - HTTP operation result (200, 400, etc.)
      
/api/v1/providers/{id}/appointments/{id}/reserve
  - POST: Reserve a slot:
    - Params:
      - appointment_id
      - client_id
    - Requirements:
      - Validate:
        - slot.reserved == false && slot.editable == true
        - slot.start_at >= 24.hours.from_now
      - Reserve
        - Set slot.editable == false
          - Set slot reserved and reserved_at
          - Create client_booking for slot and given client_id
        - Set slot.editable == true
        - For all **unusable_slots:
          - Set slot.editable == false
            - Set reserved and reserved_at
          - Set slot.editable == true
    - Returns:
      - client_booking_id on HTTP:200
    
/api/v1/providers/{id}/appointments/{id}/confirm
  - POST: Confirm a reserved slot:
    - Params:
      - client_booking_id
    - Requirements:
      - Bail unless slot.editable == true
      - Set client_booking.confirmed and confirmed_at
    - Returns:
      - HTTP operation result (200, 400, etc.)
   
---
      
Cron that runs every minute:
  - For client_bookings where confirmed == false
    - If client_booking.provider_time_slot.reserved_at > 30.minutes.ago
      - Set slot.editable = false
        - Change slot.reserved = false
        - Change slot.reserved_at = nil
        - Set the corresponding client_booking.expired == true
      - Set slot.editable = true
      - For all previously **unusable_slots, reset reserved and reserved_at

---

Database Outline:

  providers
    id

  clients
    id

  provider_time_slots
    id
    provider_id

    start_at
    end_at

    editable=true

    reserved=false
    reserved_at=nil

  client_bookings
    id
    client_id
    provider_time_slot_id

    expired=false

    confirmed=false
    confirmed_at=nil

Things to Note

• The tests are a bit lighter than I would like; this is a function of...

• This challenge took > 2 hours.

• You can see the state of my work at the 2 hour mark by searching the git commit history for 2-Hour Mark Commit.

• There were some tradeoffs made due to time, specifically:

  • The appointments controller is too fat. I'd move a lot of this logic into services.
  • Things could be cleaner; the TimeSlotValidator class is not as single-purpose as I would like.
  • Once again, this needs more tests. Basic functionality is operational, but I'm quite sure there are bugs around edge cases.