module Recurso
  module Resource

    def self.included(base)
      base.has_many :permissions, as: :resource, dependent: :destroy, class_name: Recurso::Config.instance.default_permission_class_name
      base.has_one  :permission_policy, as: :resource, autosave: true
      base.belongs_to :itself, class_name: base.to_s, foreign_key: :id, required: false

      def base.relevant_associations
        relevant_association_names.map(&method(:reflect_on_association))
      end

      def base.relevant_association_names
        [:itself]
      end
    end

    def policy_type
      permission_policy&.policy_type
    end

    def policy_type=(value)
      if permission_policy
        permission_policy.policy_type = value
      else
        build_permission_policy(policy_type: value)
      end
    end

    def policy_class
      "#{self.class}Policy".constantize
    rescue NameError
      Recurso::ResourcePolicy
    end

    def relevant_policy_type
      (relevant_resources.map(&:policy_type).detect(&:present?) || :open).to_sym
    end

    def relevant_resources
      @relevant_resources ||= self.class.relevant_association_names.map(&method(:public_send)).compact.uniq
    end

    def relevant_levels_for(action)
      [
        Recurso::Config.instance.levels_for_action[action],
        (Recurso::Config.instance.default_level if default_can?(action))
      ].flatten.compact
    end

    private

    def default_can?(action)
      Recurso::Config.instance.actions_for_default[relevant_policy_type].include?(action)
    end
  end
end