Extract UserUpdatePermissionBuilder

This commit moves the identical build_user_update_params method from
each of the three controllers into a class. I think this is an
improvement as it ensures that the business logic is defined in a
single place and can't drift out of sync.

The implementation of this method is currently covered by the
controller tests but in a subsequent commit I'll introduce some unit
tests for this class to help reduce the duplication in the controller
tests.

app/controllers/account/permissions_controller.rb

@@ -18,7 +18,12 @@ def edit
   def update
     authorize [:account, @application], :edit_permissions?
 
-    supported_permission_ids = build_user_update_params(current_user, @permissions.pluck(:id), update_params[:supported_permission_ids].map(&:to_i))
+    supported_permission_ids = UserUpdatePermissionBuilder.new(
+      user: current_user,
+      updatable_permission_ids: @permissions.pluck(:id),
+      selected_permission_ids: update_params[:supported_permission_ids].map(&:to_i),
+    ).build
+
     UserUpdate.new(current_user, { supported_permission_ids: }, current_user, user_ip_address).call
 
     flash[:application_id] = @application.id
@@ -38,12 +43,4 @@ def set_application
   def set_permissions
     @permissions = @application.sorted_supported_permissions_grantable_from_ui(include_signin: false)
   end
-
-  def build_user_update_params(user, updatable_permission_ids, selected_permission_ids)
-    permissions_user_has = user.supported_permissions.pluck(:id)
-    permissions_to_add = updatable_permission_ids.intersection(selected_permission_ids)
-    permissions_to_remove = updatable_permission_ids.difference(selected_permission_ids)
-
-    (permissions_user_has + permissions_to_add - permissions_to_remove).sort
-  end
 end

app/controllers/api_users/permissions_controller.rb

@@ -11,7 +11,12 @@ def edit
   def update
     authorize @api_user
 
-    supported_permission_ids = build_user_update_params(@api_user, @permissions.pluck(:id), update_params[:supported_permission_ids].map(&:to_i))
+    supported_permission_ids = UserUpdatePermissionBuilder.new(
+      user: @api_user,
+      updatable_permission_ids: @permissions.pluck(:id),
+      selected_permission_ids: update_params[:supported_permission_ids].map(&:to_i),
+    ).build
+
     UserUpdate.new(@api_user, { supported_permission_ids: }, current_user, user_ip_address).call
 
     flash[:application_id] = @application.id
@@ -35,12 +40,4 @@ def set_application
   def set_permissions
     @permissions = @application.sorted_supported_permissions_grantable_from_ui(include_signin: false)
   end
-
-  def build_user_update_params(user, updatable_permission_ids, selected_permission_ids)
-    permissions_user_has = user.supported_permissions.pluck(:id)
-    permissions_to_add = updatable_permission_ids.intersection(selected_permission_ids)
-    permissions_to_remove = updatable_permission_ids.difference(selected_permission_ids)
-
-    (permissions_user_has + permissions_to_add - permissions_to_remove).sort
-  end
 end

app/controllers/users/permissions_controller.rb

@@ -19,7 +19,12 @@ def edit
   def update
     authorize UserApplicationPermission.for(@user, @application)
 
-    supported_permission_ids = build_user_update_params(@user, @permissions.pluck(:id), update_params[:supported_permission_ids].map(&:to_i))
+    supported_permission_ids = UserUpdatePermissionBuilder.new(
+      user: @user,
+      updatable_permission_ids: @permissions.pluck(:id),
+      selected_permission_ids: update_params[:supported_permission_ids].map(&:to_i),
+    ).build
+
     UserUpdate.new(@user, { supported_permission_ids: }, current_user, user_ip_address).call
 
     flash[:application_id] = @application.id
@@ -43,12 +48,4 @@ def set_application
   def set_permissions
     @permissions = @application.sorted_supported_permissions_grantable_from_ui(include_signin: false)
   end
-
-  def build_user_update_params(user, updatable_permission_ids, selected_permission_ids)
-    permissions_user_has = user.supported_permissions.pluck(:id)
-    permissions_to_add = updatable_permission_ids.intersection(selected_permission_ids)
-    permissions_to_remove = updatable_permission_ids.difference(selected_permission_ids)
-
-    (permissions_user_has + permissions_to_add - permissions_to_remove).sort
-  end
 end

app/models/user_update_permission_builder.rb

@@ -0,0 +1,15 @@
+class UserUpdatePermissionBuilder
+  def initialize(user:, updatable_permission_ids:, selected_permission_ids:)
+    @user = user
+    @updatable_permission_ids = updatable_permission_ids
+    @selected_permission_ids = selected_permission_ids
+  end
+
+  def build
+    permissions_user_has = @user.supported_permissions.pluck(:id)
+    permissions_to_add = @updatable_permission_ids.intersection(@selected_permission_ids)
+    permissions_to_remove = @updatable_permission_ids.difference(@selected_permission_ids)
+
+    (permissions_user_has + permissions_to_add - permissions_to_remove).sort
+  end
+end