ShoppingList

ShoppingList is a pure elixir handmade challenge proposed by Stone, with the purpose to fully distribute values from a given shopping list between the list's buyers.

In this service good pratices were used for code qualtity such as: Linter, Formatation, Tests Coverage, Github Flow (Merges, Pull requests), and functional programming paradigms

Index

• Index
• Installation
• Usage
• Tests

Installation

To use this service, you'll need Elixir installed on your machine or container.

Then, install the dependencies with the command:

 mix deps.get

And that's it... you're all set! 🎉

Usage

This service is written in pure Elixir, so in order to use it, you'll need to open your terminal inside the application's folder and type the following command to enter interative mode:

iex -S mix

After that, we'll start playing. 😊

First, you'll need to create the lists in which we'll work with. Which are the shopping list and the email list of our buyers. But first we'll start our app settings by using the start/0 function that will create the files in which will store our lists data.

• Note: if you want to erase all data from the lists, just use the start/0 function at any point and everything will be reinitialized

To do that, follow the example:

Starting the application and creating the shopping list

iex> Files.start
iex> ShoppingList.create_shopping_list(10, 100)

You should get a return like so:

{:ok, [%ShoppingItem{quantity: 10, unit_price: 100}]}

The crate_shopping_list/2 has the params:

• quantity: item quantity (integer)
• unit_price: price unit of the item (integer)

You can create as much shopping lists as you want, they will all be added to a single file and a single list, like the following:

iex> ShoppingList.create_shopping_list(10, 100)
iex> ShoppingList.create_shopping_list(1, 10)
iex> ShoppingList.create_shopping_list(2, 50)

And the return should be like this:

{:ok, [
  %ShoppingItem{quantity: 10, unit_price: 100}
  %ShoppingItem{quantity: 1, unit_price: 10}
  %ShoppingItem{quantity: 2, unit_price: 50}
]}

Creating the email list of the buyers

iex> EmailsList.create_emails_list("rick@mail.com")

Will return something like:

{:ok, [%EmailsList{email: "rick@mail.com"}]}

The crate_emails_list/1 contains the param:

• email: buyer email (string)

Such as the shopping list, you can create as much emails lists as you want, and it will also be added to a single list like below:

iex> EmailsList.create_emails_list("rick@mail.com")
iex> EmailsList.create_emails_list("ana@mail.com")
iex> EmailsList.create_emails_list("khaleesi@mail.com")

The return should be:

{:ok, [
  %EmailsList{email: "rick@mail.com"}
  %EmailsList{email: "ana@mail.com"}
  %EmailsList{email: "khaleesi@mail.com"}
]}

Emails list distributed equally not missing a single cent

After having our both lists, we can now generate our emails list with the values of the shopping list distributed equally except for one rule.

The rule is: if your shopping list's sum of values divided by the quantity of the items results in an infinite number, e.g. 100 / 3 = 0,33333333... , the values, in this case 33 cents, will be divided along the buyers, but the last buyer will receive the rest of the cents missing, in this case 32 + 1, so our distribution will be fully given not missing a single cent!

Let's see the examples of use with the function to generate the list get_shopping_list_distributed/0:

Generating list with sum not inifinite

ShoppingList.get_shopping_list_distributed

Remember we already created above three buyers with the shopping list's quantities of 10, 1 and 2 and unit prices of 100, 10 and 50.

So the result in this case will be:

{:ok,
 [
   %{"rick@mail.com" => 370},
   %{"ana@mail.com" => 370},
   %{"khaleesi@mail.com" => 370}
]}

Generating emails list distributed with infinite sums

Now if we add Lord Vader into this mess, we'll have to give him his equal part, plus the rest amount of the value so not a single cent will be missing!

EmailsList.create_emails_list("darthvader@mail.com")

Result

{:ok,
 [
   %EmailsList{email: "rick@mail.com"},
   %EmailsList{email: "ana@mail.com"},
   %EmailsList{email: "khaleesi@mail.com"},
   %EmailsList{email: "darthvader@mail.com"}
]}

Finally now, calling the list generating function, the final result shoud be:

{:ok,
 [
   %{"rick@mail.com" => 277},
   %{"ana@mail.com" => 277},
   %{"khaleesi@mail.com" => 277},
   %{"darthvader@mail.com" => 279}
]}

What can we do.. he's the boss! 🤷‍♂️

Tests

This application was 100% tested. So to check out the tests, run:

mix test

And to check coverage report, run:

mix coveralls.html