module Scrivito

#
# @api public
#
class ModelLibrary
  attr_reader :custom_pages, :custom_widgets, :custom_objs, :custom_paths

  def initialize
    @custom_pages   = []
    @custom_widgets = []
    @custom_objs    = []
    @custom_paths   = []
  end

  #
  # Clears model cache.
  #
  # @api public
  # @see Scrivito.models
  #
  def clear_cache
    @pages                = nil
    @widgets              = nil
    @objs                 = nil
    @paths                = nil
    @require_dependencies = nil
  end

  #
  # Configures which models Scrivito assumes as pages, widgets and objs.
  #
  # @api public
  # @see Scrivito.models
  #
  def define(&block)
    DSL.new(self).instance_eval(&block)
  end

  #
  # Lists available page models.
  #
  # @api public
  # @see Scrivito.models
  # @return [Scrivito::ClassCollection] available page classes
  #
  def pages
    @pages ||= build_class_collection { valid_page_classes }
  end

  #
  # Lists available widget models.
  #
  # @api public
  # @see Scrivito.models
  # @return [Scrivito::ClassCollection] available widget classes
  #
  def widgets
    @widgets ||= build_class_collection { valid_widget_classes }
  end

  #
  # Lists available CMS object models.
  #
  # @api public
  # @see Scrivito.models
  # @return [Scrivito::ClassCollection] available CMS object classes
  #
  def objs
    @objs ||= build_class_collection { BasicObj.descendants.select(&:name) }
  end

  #
  # Lists available paths to scan for models.
  #
  # @api public
  # @see Scrivito.models
  # @return [Array<String>] available paths to scan for models.
  #
  def paths
    @paths ||= (autoload_model_paths + custom_paths).map(&:to_s)
  end

  private

  def build_class_collection
    require_dependencies
    ClassCollection.new(yield)
  end

  def valid_widget_classes
    BasicWidget.descendants.select { |descendant| valid_widget_class?(descendant) }
  end

  def valid_widget_class?(model_class)
    model_class = model_class.to_s
    return true if custom_widgets.include?(model_class)

    model_class != 'Widget' && model_class.ends_with?('Widget')
  end

  def valid_page_classes
    BasicObj.descendants.select { |descendant| valid_page_class?(descendant) }
  end

  def valid_page_class?(model_class)
    model_class = model_class.to_s
    model_class.downcase.ends_with?('page') || custom_pages.include?(model_class)
  end

  def require_dependencies
    @require_dependencies ||= begin
      paths.each do |path|
        Dir["#{path}/**/*.rb"].sort.each do |file_path|
          begin
            require_dependency(file_path)
          rescue TypeError => e
            raise e if file_path.starts_with?(Rails.root.to_s)
          end
        end
      end
    end
  end

  def autoload_model_paths
    ActiveSupport::Dependencies.autoload_paths.select do |path|
      path.to_s.ends_with?('/app/models')
    end
  end

  class DSL < Struct.new(:model_library)
    def obj(*names)
      model_library.custom_objs.push(*names)
    end

    def page(*names)
      model_library.custom_pages.push(*names)
    end

    def widget(*names)
      model_library.custom_widgets.push(*names)
    end

    def paths
      model_library.custom_paths
    end
  end
end

end