module Scrivito

#
# @api private
#
class ModelLibrary
  attr_reader :custom_pages, :custom_widgets, :custom_paths

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

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

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

  #
  # Lists available page models.
  #
  # @api private
  # @see Scrivito.models
  # @return [Scrivito::ClassCollection] available page classes
  #
  def pages
    @pages ||= load_models('page', Scrivito::BasicObj)
  end

  #
  # Lists available widget models.
  #
  # @api private
  # @see Scrivito.models
  # @return [Scrivito::ClassCollection] available widget classes
  #
  def widgets
    @widgets ||= load_models('widget', Scrivito::BasicWidget)
  end

  #
  # Lists available paths to scan for models.
  #
  # @api private
  # @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 load_models(type, base_class)
    model_classes = load_models_from_paths(type, base_class) + load_custom_models(type, base_class)
    ClassCollection.new(model_classes.compact)
  end

  def load_models_from_paths(type, base_class)
    paths.map { |path| load_models_from_path(type, path, base_class) }.flatten
  end

  def load_models_from_path(type, path, base_class)
    Dir["#{path}/**/*_#{type}.rb"].map do |file_path|
      load_model(file_path.gsub(path, '').gsub('.rb', '').classify, base_class)
    end
  end

  def load_model(class_name, base_class)
    model_class = class_name.constantize
    model_class if model_class.ancestors.include?(base_class)
  rescue NameError
  end

  def load_custom_models(type, base_class)
    send("custom_#{type}s").map do |class_name|
      load_model(class_name, base_class)
    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 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