[feature] added the checkout resource

julioleitao · Mar 15, 2019 · cbb9f71 · cbb9f71
1 parent 044e43f
commit cbb9f71
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Showing 14 changed files with 373 additions and 4 deletions.
diff --git a/apps/store_core/lib/store_core/contexts/checkouts.ex b/apps/store_core/lib/store_core/contexts/checkouts.ex
@@ -0,0 +1,94 @@
+defmodule StoreCore.Checkouts do
+  alias StoreCore.Promotions
+  alias StoreCore.Products
+  alias StoreCore.CheckoutProduct
+
+  defp to_checkout_products(products) do
+    products = products
+    |> Enum.map(fn params ->
+      checkout_product =%CheckoutProduct{}
+      |> CheckoutProduct.changeset(params)
+
+      if checkout_product.valid?() do
+        CheckoutProduct.apply(checkout_product)
+      else
+        [:errors, checkout_product.errors]
+      end
+    end)
+
+    errors = Enum.filter(products, fn product ->
+      case product do
+        [:errors, errors] -> errors
+        _ -> false
+      end
+    end)
+
+    if length(errors) != 0 do
+      {:errors, errors}
+    else
+    {:ok, products}
+    end
+  end
+
+
+  def retrieve_products(products) do
+    products = Enum.map(products, fn checkout_product ->
+      case Products.get(checkout_product.id) do
+        {:ok, product} ->
+          Map.put(checkout_product, :price, product.price)
+        error -> error
+      end
+    end)
+
+    IO.puts "verifica em caso de erro"
+    Enum.filter(products, fn product ->
+      case product do
+        {:error, reason} -> true
+        _ -> false
+      end
+    end)
+    |> IO.inspect
+
+
+    {:ok, products}
+  end
+
+  def preview(products) do
+    with {:ok, products} <- to_checkout_products(products),
+    {:ok, products} <- retrieve_products(products) do
+      total =
+        products
+        |> Enum.reduce(0, fn product, acc ->
+          price =
+            product
+            |> promotion_descount
+
+          acc + price
+        end)
+
+      {:ok, [total: total, products: products]}
+    end
+  end
+
+  defp promotion_descount(product) do
+    if (Map.has_key?(product, :promotion_id) and product.promotion_id == nil) or
+         not Map.has_key?(product, :promotion_id) do
+      product.price * product.quantity
+    else
+      {:ok, promo} = Promotions.get(product.promotion_id)
+      descount_from(product, promo.name)
+    end
+  end
+
+  def descount_from(%{price: price, quantity: quantity}, "Pague 1 Leve 2") do
+    numberOfProductsNotIncluded = rem(quantity, 2)
+    quantity = div(quantity - numberOfProductsNotIncluded, 2)
+    price * (quantity + numberOfProductsNotIncluded)
+  end
+
+  def descount_from(%{price: price, quantity: quantity}, "3 por 10 reais") do
+    numberOfProductsNotIncluded = rem(quantity, 3)
+    quantity = div(quantity - numberOfProductsNotIncluded, 3)
+    10 * quantity + numberOfProductsNotIncluded * price
+  end
+end
diff --git a/apps/store_core/lib/store_core/contexts/promotions.ex b/apps/store_core/lib/store_core/contexts/promotions.ex
@@ -1,5 +1,22 @@
 defmodule StoreCore.Promotions do
   alias StoreCore.{Promotion, Repo}
 
-  def list, do: Promotion |> Repo.all
+  def list, do: Promotion |> Repo.all()
+
+  def get(id) do
+    case Repo.get(Promotion, id) do
+      nil -> {:error, :not_found}
+      promotion -> {:ok, promotion}
+    end
+  end
+
+  def filter_by_name(name) do
+    [promotion] =
+      list()
+      |> Enum.filter(fn promotion ->
+        promotion.name === name
+      end)
+
+    promotion
+  end
 end
diff --git a/apps/store_core/lib/store_core/schemas/checkout_product.ex b/apps/store_core/lib/store_core/schemas/checkout_product.ex
@@ -0,0 +1,21 @@
+defmodule StoreCore.CheckoutProduct do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  embedded_schema do
+    field :quantity, :integer
+    field :promotion_id, Ecto.UUID
+  end
+
+  @required [:id, :quantity]
+  @accepted [:promotion_id | @required]
+
+  def changeset(checkout_product, params \\ %{}) do
+    checkout_product
+    |> cast(params, @accepted)
+    |> validate_required(@required)
+  end
+
+  def apply(changeset), do: apply_changes(changeset)
+end
diff --git a/apps/store_core/lib/store_core/schemas/product.ex b/apps/store_core/lib/store_core/schemas/product.ex
@@ -8,15 +8,17 @@ defmodule StoreCore.Product do
   schema "products" do
     field :name, :string
     field :price, :integer
+    field :promotion_id, Ecto.UUID
 
     timestamps()
   end
 
   @required_params [:name, :price]
+  @accepted_params [:promotion_id | @required_params]
 
   def changeset(product, params \\ %{}) do
     product
-    |> cast(params, @required_params)
+    |> cast(params, @accepted_params)
     |> validate_required(@required_params)
   end
 end
diff --git a/apps/store_core/priv/repo/migrations/20190315041038_create_promotions.exs b/apps/store_core/priv/repo/migrations/20190315041038_create_promotions.exs
@@ -16,10 +16,14 @@ defmodule StoreCore.Repo.Migrations.CreatePromotions do
     flush()
 
     insert_promotions()
+
+    alter table(:products) do
+      add :promotion_id, references(:promotions, type: :uuid), null: true
+    end
   end
 
   defp insert_promotions() do
-    ["Pague 1 Leve 2", "3 Por 10 reais"]
+    ["Pague 1 Leve 2", "3 por 10 reais"]
     |> Enum.map(fn name ->
       %Promotion{name: name}
       |> Promotion.changeset()

diff --git a/apps/store_core/test/store_core/contexts/checkouts_test.exs b/apps/store_core/test/store_core/contexts/checkouts_test.exs
@@ -0,0 +1,123 @@
+defmodule StoreCore.CheckoutsTest do
+  use StoreCore.DataCase
+
+  alias StoreCore.{Checkouts, Product, Products, Promotions}
+
+  test "calculate a checkout without promo code" do
+    products =
+      [
+        %{name: "Lápis", price: 200, quantity: 1},
+        %{name: "Borracha", price: 100, quantity: 1}
+      ]
+      |> Enum.map(fn product ->
+        {:ok, created_product} = Products.create(product)
+
+        product = %{product | name: nil}
+        product = %{product | price: nil}
+        Map.put(product, :id, created_product.id)
+      end)
+
+    assert [total: 300, products: ^products] = Checkouts.preview(products)
+  end
+
+  describe "calculate Pague 1 Leve 2 with" do
+    test "with one group" do
+      total =
+        [
+          %{name: "Lápis", price: 200, quantity: 2, promotion_id: pague_1_leve_2()},
+          %{name: "Borracha", price: 100, quantity: 1}
+        ]
+        |> checkout_total
+
+      assert total === 300
+    end
+
+    test "with one group and one out from promotion" do
+      total =
+        [
+          %{name: "Lápis", price: 200, quantity: 3, promotion_id: pague_1_leve_2()},
+          %{name: "Borracha", price: 100, quantity: 1}
+        ]
+        |> checkout_total
+
+      assert total === 500
+    end
+
+    test "with many groups" do
+      total =
+        [
+          %{name: "Lápis", price: 200, quantity: 7, promotion_id: pague_1_leve_2()},
+          %{name: "Borracha", price: 150, quantity: 3, promotion_id: pague_1_leve_2()}
+        ]
+        |> checkout_total
+
+      assert total === 1100
+    end
+  end
+
+  describe "calculate 3 por 10 reais with" do
+    test "with one group" do
+      total =
+        [%{name: "Lápis", price: 200, quantity: 3, promotion_id: tres_por_10()}]
+        |> checkout_total
+
+      assert total === 10
+    end
+
+    test "with two groups" do
+      total =
+        [%{name: "Lápis", price: 200, quantity: 6, promotion_id: tres_por_10()}]
+        |> checkout_total
+
+      assert total === 20
+    end
+
+    test "with two groups and one out from promotion" do
+      total =
+        [%{name: "Lápis", price: 200, quantity: 7, promotion_id: tres_por_10()}]
+        |> checkout_total
+
+      assert total === 220
+    end
+  end
+
+  test "a mixed checkout" do
+    total =
+      [
+        # 700
+        %{name: "Ponta de lápis", price: 100, quantity: 7},
+        # 30
+        %{name: "Caixa de lápis", price: 650, quantity: 9, promotion_id: tres_por_10()},
+        # 300
+        %{name: "Borracha", price: 75, quantity: 7, promotion_id: pague_1_leve_2()},
+        # 320
+        %{name: "Pasta colegial", price: 300, quantity: 7, promotion_id: tres_por_10()},
+        # 200
+        %{name: "Caneta", price: 100, quantity: 3, promotion_id: pague_1_leve_2()},
+        # 1400
+        %{name: "Lápis", price: 200, quantity: 7}
+      ]
+      |> checkout_total
+
+    assert total === 700 + 30 + 300 + 320 + 200 + 1400
+  end
+
+  defp tres_por_10, do: Promotions.filter_by_name("3 por 10 reais").id
+
+  defp pague_1_leve_2, do: Promotions.filter_by_name("Pague 1 Leve 2").id
+
+  defp checkout_total(products) do
+    [total: total, products: _] =
+      products
+      |> Enum.map(fn product ->
+        {:ok, created_product} = Products.create(product)
+        # ensure that the price it is retrieved from the backend
+        product = %{product | name: nil}
+        product = %{product | price: nil}
+        Map.put(product, :id, created_product.id)
+      end)
+      |> Checkouts.preview()
+
+    total
+  end
+end
diff --git a/apps/store_core/test/store_core/contexts/promotions_test.exs b/apps/store_core/test/store_core/contexts/promotions_test.exs
@@ -6,4 +6,12 @@ defmodule StoreCore.PromotionsTest do
   test "list the default promotions" do
     assert length(Promotions.list()) === 2
   end
+
+  test "filter by name" do
+    name = "Pague 1 Leve 2"
+    promotion = Promotions.filter_by_name(name)
+
+    assert %{id: id, name: ^name} = promotion
+    assert promotion = Promotions.get(id)
+  end
 end
diff --git a/apps/store_web/lib/store_web/controllers/checkout_controller.ex b/apps/store_web/lib/store_web/controllers/checkout_controller.ex
@@ -0,0 +1,21 @@
+defmodule StoreWeb.CheckoutController do
+  use StoreWeb, :controller
+
+  alias StoreCore.Checkouts
+
+  action_fallback StoreWeb.FallbackController
+
+  def create(conn, %{"products" => products}) do
+    products = Enum.map(products, &convert_to_atom(&1))
+
+    with {:ok, checkout} <- Checkouts.preview(products) do
+      conn
+      |> put_status(:accepted)
+      |> render("show.json", checkout: checkout)
+    end
+  end
+
+  defp convert_to_atom(map) do
+    for {key, val} <- map, into: %{}, do: {String.to_atom(key), val}
+  end
+end
diff --git a/apps/store_web/lib/store_web/controllers/fallback_controller.ex b/apps/store_web/lib/store_web/controllers/fallback_controller.ex
@@ -12,6 +12,14 @@ defmodule StoreWeb.FallbackController do
     |> render("error.json", changeset: changeset)
   end
 
+  def call(conn, {:errors, errors}) do
+    conn
+    |> put_status(:unprocessable_entity)
+    |> put_view(StoreWeb.ChangesetView)
+    |> render("errors.json", errors: errors)
+  end
+
+
   def call(conn, {:error, :not_found}) do
     conn
     |> put_status(:not_found)

diff --git a/apps/store_web/lib/store_web/router.ex b/apps/store_web/lib/store_web/router.ex
@@ -10,5 +10,6 @@ defmodule StoreWeb.Router do
 
     resources "/products", ProductController, only: [:index, :create, :show, :update, :delete]
     get "/promotions", PromotionController, :index
+    post "/checkout", CheckoutController, :create
   end
 end
diff --git a/apps/store_web/lib/store_web/views/changeset_view.ex b/apps/store_web/lib/store_web/views/changeset_view.ex
@@ -5,6 +5,10 @@ defmodule StoreWeb.ChangesetView do
     Ecto.Changeset.traverse_errors(changeset, &translate_error/1)
   end
 
+  def render("errors.json", %{errors: errors}) do
+    %{errors: ["Invalid entity"]}
+  end
+
   def render("error.json", %{changeset: changeset}) do
     %{errors: translate_errors(changeset)}
   end

diff --git a/apps/store_web/lib/store_web/views/checkout_view.ex b/apps/store_web/lib/store_web/views/checkout_view.ex
@@ -0,0 +1,27 @@
+defmodule StoreWeb.CheckoutView do
+  use StoreWeb, :view
+
+  alias StoreWeb.CheckoutView
+
+  def render("show.json", %{checkout: checkout}) do
+    %{data: render_one(checkout, CheckoutView, "checkout.json")}
+  end
+
+  def render("checkout.json", %{checkout: [total: total, products: products]}) do
+    %{
+      total: total,
+      products: products_to_view(products)
+    }
+  end
+
+  defp products_to_view(products) do
+    products
+    |> Enum.map(fn product ->
+      %{
+        id: product.id,
+        price: product.price,
+        quantity: product.quantity
+      }
+    end)
+  end
+end