Menu pluggability improvements.

Allow plugins to add items and sections at a given position in a
existing section.

Examples:

initializer 'plugin' do
  # create custom section with 2 custom items
  Menu::CustomLoader.register(
    Menu::Section.new(:spike, N_('Plugin'), 'fa fa-map-pin', [
      Menu::Item.new('plug1', N_('Test'), 'miq_report', {:feature => 'miq_report', :any => true}, '/plug'),
      Menu::Item.new('plug2', N_('Demo'), 'miq_report', {:feature => 'miq_report', :any => true}, '/demo')
    ])
  )

  # create custom item placed in an existing section 'vi' (Cloud Intel)
  Menu::CustomLoader.register(
    Menu::Item.new('plug3', N_('Plug Item'), 'miq_report', {:feature => 'miq_report', :any => true}, '/demo', :default, :vi)
  )

  # create custom section and place it before existing section 'compute' (Compute)
  Menu::CustomLoader.register(
    Menu::Section.new(:spike3, N_('Plugin 2'), 'fa fa-map-pin', [
      Menu::Item.new('plug4', N_('Demo'), 'miq_report', {:feature => 'miq_report', :any => true}, '/demo')
    ], :default, :compute)
  )

  # create custom section and place it inside an existing section 'compute' (Compute), before existing subsection 'clo' (Cloud)
  Menu::CustomLoader.register(
    # Struct.new(:id, :name, :icon, :items, :placement, :before, :type, :href, :parent_id
    Menu::Section.new(:spike3, N_('Nested section after'), 'fa fa-map-pin', [
      Menu::Item.new('plug5', N_('Test item'), 'miq_report', {:feature => 'miq_report', :any => true}, '/demo')
    ], :default, :clo, :default, nil, :compute)
  )
end

app/presenters/menu/item.rb

@@ -1,5 +1,5 @@
 module Menu
-  Item = Struct.new(:id, :name, :feature, :rbac_feature, :href, :type, :defaults) do
+  Item = Struct.new(:id, :name, :feature, :rbac_feature, :href, :type, :parent_id) do
     extend ActiveModel::Naming
 
     def self.base_class
@@ -10,7 +10,7 @@ def self.base_model
       model_name
     end
 
-    def initialize(an_id, a_name, features, rbac_feature, href, type = :default, defaults = nil)
+    def initialize(an_id, a_name, features, rbac_feature, href, type = :default, parent_id = nil)
       super
       @parent = nil
       @name = a_name.kind_of?(Proc) ? a_name : -> { a_name }

app/presenters/menu/manager.rb

@@ -74,23 +74,32 @@ def initialize
     def merge_sections(sections)
       sections.each do |section|
         position = nil
+
+        parent = if section.parent_id && @id_to_section.key?(section.parent_id)
+                   @id_to_section[section.parent_id].items
+                 else
+                   @menu
+                 end
+
         if section.before
-          position = @menu.index { |existing_section| existing_section.id == section.before }
+          position = parent.index { |existing_section| existing_section.id == section.before }
         end
 
         if position
-          @menu.insert(position, section)
+          parent.insert(position, section)
         else
-          @menu << section
+          parent << section
         end
       end
     end
 
     def merge_items(items)
       items.each do |item|
-        raise InvalidMenuDefinition, 'Invalid parent' unless @id_to_section.key?(item.parent)
-        @id_to_section[item.parent].items << item
-        item.parent = @id_to_section[item.parent]
+        parent = @id_to_section[item.parent_id]
+        raise InvalidMenuDefinition, 'Invalid parent' if parent.nil?
+
+        parent.items << item
+        item.parent = parent
       end
     end
 

app/presenters/menu/section.rb

@@ -1,5 +1,5 @@
 module Menu
-  Section = Struct.new(:id, :name, :icon, :items, :placement, :before, :type, :href) do
+  Section = Struct.new(:id, :name, :icon, :items, :placement, :before, :type, :href, :parent_id) do
     extend ActiveModel::Naming
 
     def self.base_class

app/presenters/menu/yaml_loader.rb

@@ -33,13 +33,15 @@ def create_custom_menu_item(properties)
         raise Menu::Manager::InvalidMenuDefinition,
               "incomplete definition -- missing #{property}" if properties[property].blank?
       end
-      item = Item.new(properties['id'],
-                            properties['name'],
-                            properties['feature'],
-                            rbac,
-                            properties['href'],
-                            item_type)
-      item.parent = properties['parent'].to_sym
+      item = Item.new(
+        properties['id'],
+        properties['name'],
+        properties['feature'],
+        rbac,
+        properties['href'],
+        item_type,
+        properties['parent'].to_sym
+      )
       item
     end