Payslips

Configuration and setup

Download this repository and run bundle install.
Start the server with shotgun
Open the URL 127.0.0.1:9393 in your browser and check that it is responding

The GET endpoint

A payroll is stored in the data/ directory that will serve as database. In order to load it, perform the following request with your favorite REST client:

GET 127.0.0.1:9393/v1/2018/12

It will return all the info.

The PUT endpoint

Perform the following request:

PUT 127.0.0.1:9393/v1/irpf-change

{"month": 12, "year": 2018, "irpf": 14}

If you git status now, you'll see the payroll stored in data/ has changed. Try the GET endpoint now to see the changes on the payroll.

Comments

I'm not fully confortable with the name of the URL for the PUT endpoint. Maybe I would have modelled it as a PATCH pointing to v1/2018/12 with only the irpf as body. Dunno, APIs are something I'm very willing to learn about.
I noticed there were rounding problems in a couple of payslips in the original dataset. I've decided to keep the amounts as ints and only change to float for representation matters.
I could have spent more time with treating errors (for instance, unexpected file format or arguments). I have implemented only the most obvious (0 <= months <= 12, etc).
In Payslip, I doubted between having redundant data (irpf, discount and net amounts) stored in the model or calculate them when needed. Since I had no performance constraints defined, I decided to go for not having redundancies. I'm not a fan of memoization either, so CPU cycles are not taken into consideration for this exercise.
I've tried to organize the code in directories to make it as clean as possible, using the IDD (Mancuso) approach of putting the system featues as actions.
I considered the option of doing the payroll/payslips immutable by making the apply_irpf! method return a copy instead of modifying the state. Since it is an entity, I saw no clear benefits on doing it.
I considered the idea of using a Value Object for the money, but since there is no currency involved I went for the simplest option.
One of the areas I spent more time with is the reading/writing of the payroll file. I wanted something that could be easy to read, and to change. So I came up with the Specification class in the repository.
After more than two years without writing Ruby I'm more rusty than I expected. Hope I haven't made big mistakes.
It's a simple exercise but I have had A LOT OF FUN doing this. Cheers!

Updates

08/02 I didn't like to work with ints so I've reconsidered. Now I'm using BigDecimal.
11/02 Use lock for writings to avoid concurrent writes and data corruption.

carlescliment / payslips