Add in ability to dynamically load in deny_listed domains

lib/valid_email2/address.rb

@@ -89,7 +89,9 @@ def allow_listed?
     end
 
     def deny_listed?
-      valid? && domain_is_in?(ValidEmail2.deny_list)
+      valid? && (
+        DynamicOptionValues.domain_is_in?(:deny_list_function, address) || domain_is_in?(ValidEmail2.deny_list)
+      )
     end
 
     def valid_mx?

lib/valid_email2/dynamic_option_values.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal:true
+
+module ValidEmail2
+  class DynamicOptionValues
+    class << self
+      def deny_list_function
+        @deny_list_function ||= ->(_domain) { false }
+      end
+
+      def deny_list_function=(lambda_function)
+        return unless lambda_function.is_a?(Proc)
+        return unless lambda_function.arity == 1
+
+        @deny_list_function = lambda_function
+      end
+
+      def parse_option_for_additional_items(type, value)
+        return false unless respond_to?("#{type}_function=")
+
+        case value
+        when NilClass
+          return false
+        when TrueClass, FalseClass
+          return value
+        when Set, Array
+          self.deny_list_function = ->(domain) { value.include?(domain) }
+        when Proc
+          self.deny_list_function = value
+        else
+          return false
+        end
+
+        true
+      end
+
+      def domain_is_in?(type, address)
+        return false unless type.is_a?(Symbol)
+        return false unless respond_to?(type)
+        return false unless address.is_a?(Mail::Address)
+
+        downcase_domain = address.domain.downcase
+
+        send(type).call(downcase_domain)
+      end
+    end
+  end
+end

lib/valid_email2/email_validator.rb

@@ -1,4 +1,5 @@
 require "valid_email2/address"
+require "valid_email2/dynamic_option_values"
 require "active_model"
 require "active_model/validations"
 
@@ -41,6 +42,7 @@ def validate_each(record, attribute, value)
       end
 
       if options[:deny_list]
+        ValidEmail2::DynamicOptionValues.parse_option_for_additional_items(:deny_list, options[:deny_list])
         error(record, attribute) && return if addresses.any?(&:deny_listed?)
       end
 

spec/spec_helper.rb

@@ -21,3 +21,36 @@ def read_attribute_for_validation(key)
     @attributes[key]
   end
 end
+
+class TestDynamicDomainModel
+  def self.where(*); end
+
+  def self.column_names
+    [domain_attribute].compact
+  end
+
+  def self.exists?(hash)
+    value = hash[self.domain_attribute.to_sym]
+    return false if value.nil?
+
+    existng_array = self.domain_attribute_values
+    existng_array.include?(value)
+  end
+
+  def self.domain_attribute
+    @domain_attribute ||= "domain"
+  end
+
+  def self.domain_attribute_values
+    @domain_attribute_values ||= []
+  end
+
+  def self.domain_attribute=(new_domain_attribute)
+    @domain_attribute = new_domain_attribute
+    @domain_attribute_values = domain_attribute_values
+  end
+
+  def self.domain_attribute_values=(new_domain_attribute_values)
+    @domain_attribute_values = new_domain_attribute_values
+  end
+end

spec/valid_email2_spec.rb

@@ -59,6 +59,22 @@ class TestUserDisallowDenyListed < TestModel
   validates :email, 'valid_email_2/email': { deny_list: true }
 end
 
+class TestUserDisallowDenyListedWithDynamicArray < TestModel
+  validates :email, 'valid_email_2/email': { deny_list: proc { |domain| ["test-dynamic-array.com"].include?(domain) } }
+end
+
+class TestUserDisallowDenyListedWithDynamicSet < TestModel
+  validates :email, 'valid_email_2/email': { deny_list: proc { |domain| Set.new(["test-dynamic-set.com"]).include?(domain) } }
+end
+
+class TestUserDisallowDenyListedWithDynamicLambda < TestModel
+  validates :email, 'valid_email_2/email': { deny_list: ->(domain) { Set.new(["test-dynamic-lambda.com"]).include?(domain) } }
+end
+
+class TestUserDisallowDenyListedWithDynamicRailsModel < TestModel
+  validates :email, 'valid_email_2/email': { deny_list: ->(domain) { TestDynamicDomainModel.exists?(domain: domain) } }
+end
+
 class TestUserMessage < TestModel
   validates :email, 'valid_email_2/email': { message: "custom message" }
 end
@@ -262,6 +278,34 @@ def set_allow_list
       user = TestUserDisallowDenyListed.new(email: "[email protected]")
       expect(user.valid?).to be_falsey
     end
+
+    it "is invalid if the domain is deny-listed via a dynamic array option" do
+      user = TestUserDisallowDenyListedWithDynamicArray.new(email: "[email protected]")
+      expect(user.valid?).to be_falsy
+    end
+
+    it "is invalid if the domain is deny-listed via a dynamic set option" do
+      user = TestUserDisallowDenyListedWithDynamicSet.new(email: "[email protected]")
+      expect(user.valid?).to be_falsy
+    end
+
+    it "is invalid if the domain is deny-listed via a dynamic proc option" do
+      user = TestUserDisallowDenyListedWithDynamicLambda.new(email: "[email protected]")
+      expect(user.valid?).to be_falsy
+    end
+
+    it "is invalid if the domain is deny-listed via a dynamic rails model" do
+      invalid_dynamic_domain = "test-dynamic-rails-model.com"
+      TestDynamicDomainModel.domain_attribute_values = [invalid_dynamic_domain]
+      user = TestUserDisallowDenyListedWithDynamicRailsModel.new(email: "foo@#{invalid_dynamic_domain}")
+      expect(user.valid?).to be_falsy
+    end
+
+    it "is valid if the dynamic domain list does not include the email domain" do
+      TestDynamicDomainModel.domain_attribute_values = ["not-deny-listed.com"]
+      user = TestUserDisallowDenyListedWithDynamicRailsModel.new(email: "[email protected]")
+      expect(user.valid?).to be_truthy
+    end
   end
 
   describe "with mx validation" do