Allow creating custom vat rates

ecommerce/configuration.rb

@@ -13,10 +13,9 @@
 
 module Ecommerce
   class Configuration
-    def initialize(number_generator: nil, payment_gateway: nil, available_vat_rates: [])
+    def initialize(number_generator: nil, payment_gateway: nil)
       @number_generator = number_generator
       @payment_gateway = payment_gateway
-      @available_vat_rates = available_vat_rates
     end
 
     def call(event_store, command_bus)
@@ -37,7 +36,7 @@ def configure_bounded_contexts(event_store, command_bus)
         Payments::Configuration.new(@payment_gateway),
         Shipping::Configuration.new,
         Pricing::Configuration.new,
-        Taxes::Configuration.new(@available_vat_rates),
+        Taxes::Configuration.new,
         ProductCatalog::Configuration.new,
         Fulfillment::Configuration.new
       ].each { |c| c.call(event_store, command_bus) }

ecommerce/taxes/lib/taxes.rb

@@ -7,18 +7,10 @@
 
 module Taxes
   class Configuration
-    def self.available_vat_rates
-      @@available_vat_rates
-    end
-
-    def initialize(available_vat_rates = [])
-      @available_vat_rates = available_vat_rates
-    end
-
     def call(event_store, command_bus)
-      @@available_vat_rates = @available_vat_rates
       command_bus.register(SetVatRate, SetVatRateHandler.new(event_store))
       command_bus.register(DetermineVatRate, DetermineVatRateHandler.new(event_store))
+      command_bus.register(AddAvailableVatRate, AddAvailableVatRateHandler.new(event_store))
     end
   end
 end

ecommerce/taxes/lib/taxes/commands.rb

@@ -1,11 +1,16 @@
 module Taxes
   class SetVatRate < Infra::Command
     attribute :product_id, Infra::Types::UUID
-    attribute :vat_rate, Infra::Types::VatRate
+    attribute :vat_rate_code, Infra::Types::String
   end
 
   class DetermineVatRate < Infra::Command
     attribute :product_id, Infra::Types::UUID
     attribute :order_id, Infra::Types::UUID
   end
-end
+
+  class AddAvailableVatRate < Infra::Command
+    attribute :available_vat_rate_id, Infra::Types::UUID
+    attribute :vat_rate, Infra::Types::VatRate
+  end
+end

ecommerce/taxes/lib/taxes/events.rb

@@ -9,4 +9,9 @@ class VatRateDetermined < Infra::Event
     attribute :product_id, Infra::Types::UUID
     attribute :vat_rate, Infra::Types::VatRate
   end
-end
+
+  class AvailableVatRateAdded < Infra::Event
+    attribute :available_vat_rate_id, Infra::Types::UUID
+    attribute :vat_rate, Infra::Types::VatRate
+  end
+end

ecommerce/taxes/lib/taxes/product.rb

@@ -2,23 +2,16 @@ module Taxes
   class Product
     include AggregateRoot
 
-    VatRateNotApplicable = Class.new(StandardError)
-
     def initialize(id)
       @id = id
     end
 
     def set_vat_rate(vat_rate)
-      raise VatRateNotApplicable unless vat_rate_applicable?(vat_rate)
       apply(VatRateSet.new(data: { product_id: @id, vat_rate: vat_rate }))
     end
 
     private
 
-    def vat_rate_applicable?(vat_rate)
-      Configuration.available_vat_rates.include?(vat_rate)
-    end
-
     on(VatRateSet) { |_| }
   end
 end

ecommerce/taxes/lib/taxes/services.rb

@@ -1,12 +1,17 @@
 module Taxes
+  VatRateAlreadyExists = Class.new(StandardError)
+  VatRateNotApplicable = Class.new(StandardError)
   class SetVatRateHandler
     def initialize(event_store)
       @repository = Infra::AggregateRootRepository.new(event_store)
+      @catalog = VatRateCatalog.new(event_store)
     end
 
     def call(cmd)
+      vat_rate = @catalog.vat_rate_by_code(cmd.vat_rate_code)
+      raise VatRateNotApplicable unless vat_rate
       @repository.with_aggregate(Product, cmd.product_id) do |product|
-        product.set_vat_rate(cmd.vat_rate)
+        product.set_vat_rate(vat_rate)
       end
     end
   end
@@ -34,4 +39,34 @@ def stream_name(order_id)
       "Taxes::Order$#{order_id}"
     end
   end
-end
+
+  class AddAvailableVatRateHandler
+    def initialize(event_store)
+      @catalog = VatRateCatalog.new(event_store)
+      @event_store = event_store
+    end
+
+    def call(cmd)
+      raise VatRateAlreadyExists if catalog.vat_rate_by_code(cmd.vat_rate.code)
+
+      event_store.publish(available_vat_rate_added_event(cmd), stream_name: stream_name(cmd))
+    end
+
+    private
+
+    attr_reader :event_store, :catalog
+
+    def available_vat_rate_added_event(cmd)
+      AvailableVatRateAdded.new(
+        data: {
+          available_vat_rate_id: cmd.available_vat_rate_id,
+          vat_rate: cmd.vat_rate
+        }
+      )
+    end
+
+    def stream_name(cmd)
+      "Taxes::AvailableVatRate$#{cmd.vat_rate.code}"
+    end
+  end
+end

ecommerce/taxes/lib/taxes/vat_rate_catalog.rb

@@ -14,5 +14,15 @@ def vat_rate_for(product_id)
         &.data
         &.fetch(:vat_rate)
     end
+
+    def vat_rate_by_code(vat_rate_code)
+      @event_store
+        .read
+        .stream("Taxes::AvailableVatRate$#{vat_rate_code}")
+        .last
+        &.data
+        &.fetch(:vat_rate)
+        &.then { |vat_rate| Infra::Types::VatRate.new(vat_rate) }
+    end
   end
-end
+end

ecommerce/taxes/test/taxes_test.rb

@@ -3,51 +3,74 @@
 module Taxes
   class TaxesTest < Test
     def test_setting_available_vat_rate
+      vat_rate = Infra::Types::VatRate.new(code: "50", rate: 50)
+      add_available_vat_rate(vat_rate)
+
       product_id = SecureRandom.uuid
-      vat_rate_set = VatRateSet.new(data: { product_id: product_id, vat_rate: available_vat_rate })
+      vat_rate_set = VatRateSet.new(data: { product_id: product_id, vat_rate: vat_rate })
       assert_events("Taxes::Product$#{product_id}", vat_rate_set) do
-        set_vat_rate(product_id, available_vat_rate)
+        set_vat_rate(product_id, vat_rate.code)
       end
     end
 
     def test_setting_unavailable_vat_rate_should_raise_error
       product_id = SecureRandom.uuid
-      assert_raises(Product::VatRateNotApplicable) do
-        set_vat_rate(product_id, unavailable_vat_rate)
+      unavailable_vat_rate = Infra::Types::VatRate.new(code: "20", rate: 20)
+
+      assert_raises(Taxes::VatRateNotApplicable) do
+        set_vat_rate(product_id, unavailable_vat_rate.code)
       end
     end
 
     def test_determining_vat_rate
+      vat_rate = Infra::Types::VatRate.new(code: "50", rate: 50)
+      add_available_vat_rate(vat_rate)
+
       order_id = SecureRandom.uuid
       product_id = SecureRandom.uuid
       another_product_id = SecureRandom.uuid
 
-      set_vat_rate(product_id, available_vat_rate)
-      vat_rate_determined = VatRateDetermined.new(data: { order_id: order_id, product_id: product_id, vat_rate: available_vat_rate })
+      set_vat_rate(product_id, vat_rate.code)
+      vat_rate_determined = VatRateDetermined.new(data: { order_id: order_id, product_id: product_id, vat_rate: vat_rate })
       assert_events("Taxes::Order$#{order_id}", vat_rate_determined) do
-        determine_vat_rate(order_id, product_id, available_vat_rate)
+        determine_vat_rate(order_id, product_id, vat_rate)
       end
       assert_events("Taxes::Order$#{order_id}") do
-        determine_vat_rate(order_id, another_product_id, available_vat_rate)
+        determine_vat_rate(order_id, another_product_id, vat_rate)
+      end
+    end
+
+    def test_adding_available_vat_rate
+      available_vat_rate_id = SecureRandom.uuid
+      vat_rate = Infra::Types::VatRate.new(code: "50", rate: 50)
+      available_vat_rate_added = AvailableVatRateAdded.new(data: { available_vat_rate_id: available_vat_rate_id, vat_rate: vat_rate })
+
+      assert_events("Taxes::AvailableVatRate$#{vat_rate.code}", available_vat_rate_added) do
+        add_available_vat_rate(vat_rate, available_vat_rate_id)
+      end
+    end
+
+    def test_should_not_allow_for_double_registration
+      vat_rate = Infra::Types::VatRate.new(code: "50", rate: 50)
+      add_available_vat_rate(vat_rate)
+
+      assert_raises(VatRateAlreadyExists) do
+        add_available_vat_rate(vat_rate)
       end
     end
 
     private
 
-    def set_vat_rate(product_id, vat_rate)
-      run_command(SetVatRate.new(product_id: product_id, vat_rate: vat_rate))
+    def set_vat_rate(product_id, vat_rate_code)
+      run_command(SetVatRate.new(product_id: product_id, vat_rate_code: vat_rate_code))
     end
 
     def determine_vat_rate(order_id, product_id, vat_rate)
       run_command(DetermineVatRate.new(order_id: order_id, product_id: product_id, vat_rate: vat_rate))
     end
 
-    def available_vat_rate
-      Configuration.available_vat_rates.first
-    end
-
-    def unavailable_vat_rate
-      Infra::Types::VatRate.new(code: "50", rate: 50)
+    def add_available_vat_rate(vat_rate, available_vat_rate_id = SecureRandom.uuid)
+      run_command(AddAvailableVatRate.new(available_vat_rate_id: available_vat_rate_id, vat_rate: vat_rate))
     end
   end
 end

ecommerce/taxes/test/test_helper.rb

@@ -9,13 +9,7 @@ class Test < Infra::InMemoryTest
 
     def before_setup
       super
-      Configuration.new([dummy_vat_rate]).call(event_store, command_bus)
-    end
-
-    private
-
-    def dummy_vat_rate
-      Infra::Types::VatRate.new(code: "20", rate: 20)
+      Configuration.new.call(event_store, command_bus)
     end
   end
 end

ecommerce/taxes/test/vat_rate_catalog_test.rb

@@ -0,0 +1,30 @@
+require_relative "test_helper"
+
+module Taxes
+  class VatRateCatalogTest < Test
+    class VatRateByCodeTest < VatRateCatalogTest
+      def setup
+        @vat_rate = Infra::Types::VatRate.new(code: "50", rate: 50)
+        add_available_vat_rate(@vat_rate)
+      end
+
+      def test_returns_available_vat_rate
+        assert_equal @vat_rate, catalog.vat_rate_by_code("50")
+      end
+
+      def test_returns_nil_when_vat_rate_is_not_available
+        assert_nil catalog.vat_rate_by_code("60")
+      end
+    end
+
+    private
+
+    def catalog
+      VatRateCatalog.new(@event_store)
+    end
+
+    def add_available_vat_rate(vat_rate, available_vat_rate_id = SecureRandom.uuid)
+      run_command(AddAvailableVatRate.new(available_vat_rate_id: available_vat_rate_id, vat_rate: vat_rate))
+    end
+  end
+end

rails_application/app/controllers/available_vat_rates_controller.rb

@@ -0,0 +1,56 @@
+class AvailableVatRatesController < ApplicationController
+  class AvailableVatRateForm
+    include ActiveModel::Model
+    include ActiveModel::Validations
+
+    attr_reader :code, :rate
+
+    def initialize(params)
+      @code = params[:code]
+      @rate = params[:rate]
+    end
+
+    validates :code, presence: true
+    validates :rate, presence: true, numericality: { only_numeric: true, greater_than: 0 }
+  end
+
+  def new
+  end
+
+  def create
+    available_vat_rate_id = SecureRandom.uuid
+    available_vat_rate_form = AvailableVatRateForm.new(available_vat_rate_params)
+
+    unless available_vat_rate_form.valid?
+      return render "new", locals: { errors: available_vat_rate_form.errors }, status: :unprocessable_entity
+    end
+
+    add_available_vat_rate(available_vat_rate_form.code, available_vat_rate_form.rate, available_vat_rate_id)
+    rescue Taxes::VatRateAlreadyExists
+      flash.now[:notice] = "VAT rate already exists"
+      render "new", status: :unprocessable_entity
+    else
+    redirect_to available_vat_rates_path, notice: "VAT rate was successfully created"
+  end
+
+  def index
+    @available_vat_rates = VatRates::AvailableVatRate.all
+  end
+
+  private
+
+  def add_available_vat_rate(code, rate, available_vat_rate_id)
+    command_bus.(add_available_vat_rate_cmd(code, rate, available_vat_rate_id))
+  end
+
+  def add_available_vat_rate_cmd(code, rate, available_vat_rate_id)
+    Taxes::AddAvailableVatRate.new(
+      available_vat_rate_id: available_vat_rate_id,
+      vat_rate: Infra::Types::VatRate.new(code: code, rate: rate)
+    )
+  end
+
+  def available_vat_rate_params
+    params.permit(:code, :rate)
+  end
+end