module Spree
  module Permissions
    def method_missing(name, *args, &block)
      if name.to_s.starts_with?('can')
        can, action, subject, attribute = find_action_and_subject(name)

        Permissions.send(:define_method, name) do |current_ability, user|
          if attribute.nil?
            current_ability.send(can, action, subject)
          else
            current_ability.send(can, action, subject, attribute)
          end
        end
        send(name, args[0], args[1]) if self.respond_to?(name)
      else
        super
      end
    end
  
    define_method('default-permissions') do |current_ability, user|
      current_ability.can [:read, :update, :destroy], Spree.user_class do |resource|
        resource == user
      end
      
      current_ability.can [:read, :update], Spree::Order do |order, token|
        order.user == user || (order.guest_token && token == order.guest_token)
      end
      
      current_ability.can :create, Spree::Order
      current_ability.can :read, Spree::Address do |address|
        address.user == user
      end
      current_ability.can [:read], Spree::State
      current_ability.can [:read], Spree::Country

    end

    define_method('default-admin-permissions') do |current_ability, user|
      current_ability.can :admin, 'spree/admin/overview'
      current_ability.can :index, 'spree/admin/overview'
    end

    define_method('can-update-spree/users') do |current_ability, user|
      current_ability.can :update, Spree::User
      # The permission of cannot update role_ids was given to user so that no onw with this permission can change role of user.
      current_ability.cannot :update, Spree::User, :role_ids
    end

    define_method('can-create-spree/users') do |current_ability, user|
      current_ability.can :create, Spree::User
      current_ability.cannot :create, Spree::User, :role_ids
    end

    private
      def find_action_and_subject(name)
        can, action, subject, attribute = name.to_s.split('-')
 
        if subject == 'all'
          return can.to_sym, action.to_sym, subject.to_sym, attribute.try(:to_sym)
        elsif (subject_class = subject.classify.safe_constantize) && subject_class.ancestors.include?(ActiveRecord::Base)
          return can.to_sym, action.to_sym, subject_class, attribute.try(:to_sym)
        else
          return can.to_sym, action.to_sym, subject, attribute.try(:to_sym)
        end
      end
  end
end