settings.rb in hanami-2.0.0.beta2

- old
+ new
@@ -1,23 +1,98 @@
 # frozen_string_literal: true
 
 require "dry/system/provider/source"
+require_relative "../constants"
+require_relative "../errors"
 
 module Hanami
   module Providers
+    # The settings provider loads and registers the "settings" component in app and slice
+    # containers.
+    #
+    # To register this provider with a slice container, you should use
+    # {.register_with_slice}, which will register the provider only if settings are
+    # defined for the slice.
+    #
+    # @see Slice::ClassMethods.prepare_container_providers
+    #
+    # @api private
+    # @since 2.0.0
     class Settings < Dry::System::Provider::Source
-      def self.for_slice(slice)
-        Class.new(self) do |klass|
-          klass.instance_variable_set(:@slice, slice)
+      class << self
+        # Registers the provider with the slice's container, but only if settings are
+        # defined for the slice.
+        def register_with_slice(slice)
+          return unless settings_defined?(slice)
+
+          slice.register_provider(:settings, source: with_slice(slice))
         end
+
+        # Creates a new subclass of the provider for the given slice.
+        #
+        # You must do this before registering the provider with a container. The provider
+        # uses the slice to locate the settings definition based on the slice's config.
+        def with_slice(slice)
+          Class.new(self) do |klass|
+            klass.instance_variable_set(:@slice, slice)
+          end
+        end
+
+        # Returns the slice for the provider
+        def slice
+          unless @slice
+            raise SliceLoadError, "a slice must be given to #{self} via `.with_slice(slice)`"
+          end
+
+          @slice
+        end
+
+        private
+
+        # Returns true if settings are defined for the slice.
+        #
+        # Settings are considered defined if a `Settings` class is already defined in the
+        # slice namespace, or a `config/settings.rb` exists under the slice root.
+        def settings_defined?(slice)
+          slice.namespace.const_defined?(SETTINGS_CLASS_NAME) ||
+            slice.root.join("#{SETTINGS_PATH}#{RB_EXT}").file?
+        end
       end
 
-      def self.slice
-        @slice || Hanami.app
+      def prepare
+        require_slice_settings unless slice_settings_class?
       end
 
       def start
-        register :settings, self.class.slice.settings
+        settings = slice_settings_class.new(slice.config.settings_store)
+
+        register :settings, settings
+      end
+
+      private
+
+      def slice
+        self.class.slice
+      end
+
+      def slice_settings_class?
+        slice.namespace.const_defined?(SETTINGS_CLASS_NAME)
+      end
+
+      def slice_settings_class
+        slice.namespace.const_get(SETTINGS_CLASS_NAME)
+      end
+
+      def require_slice_settings
+        require "hanami/settings"
+
+        slice_settings_require_path = File.join(slice.root, SETTINGS_PATH)
+
+        begin
+          require slice_settings_require_path
+        rescue LoadError => e
+          raise e unless e.path == slice_settings_require_path
+        end
       end
     end
   end
 end