module CanTango
  module Api
    module User
      module Ability
        def user_ability user, options = {}
          @current_ability ||= create_ability(user, ability_options.merge(options))
        end

        def current_ability user_type = :user
          user_ability get_ability_user(user_type)
        end

        protected

        include CanTango::Api::Common

        def get_ability_user user_type
          user_meth = :"current_#{user_type}"
          return AbilityUser.guest if !respond_to?(user_meth)

          user = send user_meth
          # test if current_xxx actually returns an account and not a user instance!
          # if so call the #user method on the account
          user = AbilityUser.resolve_user(user)
          # return guest user if user is nil
          user ? user : AbilityUser.guest
        end

        module AbilityUser
          def self.resolve_user obj
            return obj if AbilityUser.is_a_user?(obj)
            return obj.send(:user) if obj.respond_to? :user
            raise "no user object could be resolved via #{obj}. Please define a #user method for #{obj.class}"
          end

          def self.is_a_user? user
            ::CanTango.config.users.registered.include?(user.class.to_s.underscore.to_sym)
          end

          def self.guest
            user = CanTango.config.guest.user

            raise "You must set the guest_user to a Proc or lambda in CanTango.config" if !user
            user.respond_to?(:call) ? user.call : user
          end
        end

        include CanTango::Api::Options
      end
    end
  end
end