Booking Layer Test

The task from Booking Layer

Assumptions

These have been the assumptions while working on the test application.

Room (can be blocked or booked)
- id
- capacity (integer)
Booking (is a room reservation, that takes 1 capacity. So room with 4 capacity can be booked 4 times for same date)
- id
- room_id
- starts_at (date)
- ends_at (date)
Block (that’s not booking it’s just a indicator that room is not available then, same as booking one block takes only 1 capacity)-
- id
- room_id
- starts_at (date)
- ends_at (date)

Solution formulation

Steps I thought of and executed for solving the given problem:

Prepare the migrations for the required tables
Seed the data so that we can formulate a query. Even though the document states the feasibility the of the test-taker to create/edit models. To my understanding adding a table or a field should not be added unless really necessary.

Prepare necessary query

First Pass

Prepare query to filter bookings by given date/month/room_id

To prepare the monthly query for the first time i retrieved all the days and counted the booking start date and end date summed up the (inclusive)difference which was a not an efficent approach.

 $booking = Booking::where(function ($query) use ($startDate) {
     
     $query->whereMonth('starts_at', '<=', $startDate->month);
     
     $query->whereMonth('ends_at', '>=', $startDate->month);

})->get();

$allBookingDays = 0;

foreach ($booking as $allBookingDay) {
    
     $diff = Carbon::parse($allBookingDay->starts_at)->diffInDays(Carbon::parse($allBookingDay->ends_at)) + 1;
     
      $allBookingDays += $diff;
}

Prepare query to filter blocking by given date/month/room_id
Prepare query to calculate room capacity

Second Pass
- Improve the query to count the booking days
  - To improve the query I thought of delegating the task of calculation to database rather than the program itself, which came as:
```
  $this->getQuery(Booking::class)
      ->selectRaw(
          'sum(DATEDIFF(ADDDATE(ends_at, INTERVAL 1 DAY), starts_at))
              as days_between'
      )->whereRaw('month(starts_at) <= ? and month(ends_at) >= ?', [
          $month, $month,
      ])
      ->when(! empty($roomId), function ($query) use ($roomId) {
          return $query->whereIn('room_id', $roomId);
      });
```
  The above query helped me to get the exclusive interval if I swapped it for Booking, Block which gave the accurate results as above. Also the when method came handy here as we know the room_id os optional in requests.
- Third Pass:
  - Encaupaltion of necessary logic into place so that the controller does not get bloated
  - Refactoring and removing un-necessary code.

Libraries/Tools used

No any third party library other than the framework itself provides.
Uses php 8.1
Uses phpunit for testing and xDebug 3.0 for code coverage analysis.

Infrastructure

Docker is used to run the application, which encapsulates all the necessary services.

Installation

Run the following commands to set up the application, given that Docker is available in the host machine:

git clone https://github.com/ravisharmaa/booking-layer-test
docker-compose up -d

Running Tests

vendor/bin/phpunit:
For code coverage: vendor/bin/phpunit --coverage-text
Additionally a report can also be generated using the command vendor/bin/phpunit --coverage-html=reports

Usage of the project

The tests provide a basic overview of the application. Some steps can be done to see the application in action, which are.

To seed a basic data according to the document.
1. php artisan db:seed
2. Use the necessary routes to view the occupancy.

Decisions, tradeoffs and constraints

I have not used any form request validation or json resource to show the response.
I have not also validated the get request, lets say if the room_ids is a valid array or not and the date/month are valid or not.
I tried to use bindings but somehow it was not possible/working in some places.

Future Improvements.

It was a challenge. However, if I had to improve upon this:

I would work out to implement proper validation on places like Booking create, update, and get endpoints.
I would work on implementing proper bindings as it is a get request and there might be malicious attacks.
I would also work on using JsonResource to send the response.
More testing can also be done, to ensure applications integrity and behaviour.

ravisharmaa/booking-layer-test