Inventário da boutique

fibonacci = [0, 1, 1, 2, 3, 5, 8, 13]

fibonacci.count  { |number| number == 1 }   #=> 2
fibonacci.any?   { |number| number > 20 }   #=> false
fibonacci.none?  { |number| number > 20 }   #=> true
fibonacci.select { |number| number.odd? }   #=> [1, 1, 3, 5, 13]
fibonacci.all?   { |number| number < 20 }   #=> true
fibonacci.map    { |number| number * 2  }   #=> [0, 2, 2, 4, 6, 10, 16, 26]
fibonacci.select { |number| number >= 5 }   #=> [5, 8, 13]
fibonacci.find   { |number| number >= 6 }   #=> 8

# Some methods work with or without a block
fibonacci.sum  #=> 33
fibonacci.sum { |number| number * number }  #=> 273

# There are also methods to help with nested arrays:
animals = [ ['cat', 'bob'], ['horse', 'caris'], ['mouse', 'arya'] ]
animals.flatten  #=> ["cat", "bob", "horse", "caris", "mouse", "arya"]

pet_names = {cat: "bob", horse: "caris", mouse: "arya"}
pet_names.each { |animal, name| ... }

pet_names = {cat: "bob", horse: "caris", mouse: "arya"}
pet_names.map { |_, name| name }  #=> ["bob", "caris", "arya"]

pets = [
  { animal: "cats", names: ["bob", "fred", "sandra"] },
  { animal: "horses", names: ["caris", "black beard", "speedy"] },
  { animal: "mice", names: ["arya", "jerry"] }
]

pets.map { |pet|
  pet[:names].select { |name| name.length <= 5 }
}.flatten.sort
#=> ["arya", "bob", "caris", "fred", "jerry"]

Instruções

Você tem uma boutique de moda online. Sua grande liquidação anual está chegando, então você quer criar algumas funcionalidades para ajudar a fazer o levantamento do seu estoque e garantir que está tudo pronto.

Cada item do estoque é representado por um hash, e o estoque inteiro é um array desses hashes.

[
  {
    name: "White Shirt",
    price: 40,
    quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}
  },
  { ... }
]

1. Retornar uma lista com os nomes dos itens

Implemente BoutiqueInventory.item_names, que deve retornar uma lista com os nomes dos itens em ordem alfabética.

BoutiqueInventory.new([
  {price: 65.00, name: "Maxi Brown Dress", quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}},
  {price: 50.00, name: "Red Short Skirt", quantity_by_size: {}},
  {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
  {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
]).item_names

#=> ["Bamboo Socks Cats", "Black Short Skirt", "Maxi Brown Dress", "Red Short Skirt"]

2. Retornar os itens baratos

Implemente BoutiqueInventory.cheap, que deve retornar os itens que custam menos de $30.

BoutiqueInventory.new([
  {price: 65.00, name: "Maxi Brown Dress", quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}},
  {price: 50.00, name: "Red Short Skirt", quantity_by_size: {}},
  {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
  {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
]).cheap

# => [
#      {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
#      {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
#    ]

3. Retornar os itens sem estoque

Implemente BoutiqueInventory.out_of_stock, que deve retornar os itens que não têm estoque (quando quantity_by_size está vazio).

BoutiqueInventory.new([
  {price: 65.00, name: "Maxi Brown Dress", quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}},
  {price: 50.00, name: "Red Short Skirt", quantity_by_size: {}},
  {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
  {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
]).out_of_stock

#=> [{price: 50.00, name: "Red Short Skirt", quantity_by_size: {}}]

4. Retornar o estoque de um único item

Implemente BoutiqueInventory.stock_for_item(name) para retornar o estoque de um item pelo nome:

BoutiqueInventory.new([
  {price: 65.00, name: "Maxi Brown Dress", quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}},
  {price: 50.00, name: "Red Short Skirt", quantity_by_size: {}},
  {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
  {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
]).stock_for_item("Black Short Skirt")

#=> {s: 1, xl: 4}

5. Retornar o estoque total

Implemente BoutiqueInventory.total_stock para calcular a quantidade total de itens no seu depósito:

BoutiqueInventory.new([
  {price: 65.00, name: "Maxi Brown Dress", quantity_by_size: {s: 3, m: 7, l: 8, xl: 4}},
  {price: 50.00, name: "Red Short Skirt", quantity_by_size: {}},
  {price: 29.99, name: "Black Short Skirt", quantity_by_size: {s: 1, xl: 4}},
  {price: 20.00, name: "Bamboo Socks Cats", quantity_by_size: {s: 7, m: 2}}
]).total_stock

#=> 36