module Capybara
  module Node

    ##
    #
    # A {Capybara::Node::Base} represents either an element on a page through the subclass
    # {Capybara::Node::Element} or a document through {Capybara::Node::Document}.
    #
    # Both types of Node share the same methods, used for interacting with the
    # elements on the page. These methods are divided into three categories,
    # finders, actions and matchers. These are found in the modules
    # {Capybara::Node::Finders}, {Capybara::Node::Actions} and {Capybara::Node::Matchers}
    # respectively.
    #
    # A {Capybara::Session} exposes all methods from {Capybara::Node::Document} directly:
    #
    #     session = Capybara::Session.new(:rack_test, my_app)
    #     session.visit('/')
    #     session.fill_in('Foo', :with => 'Bar')    # from Capybara::Node::Actions
    #     bar = session.find('#bar')                # from Capybara::Node::Finders
    #     bar.select('Baz', :from => 'Quox')        # from Capybara::Node::Actions
    #     session.has_css?('#foobar')               # from Capybara::Node::Matchers
    #
    class Base
      attr_reader :session, :base, :parent

      include Capybara::Node::Finders
      include Capybara::Node::Actions
      include Capybara::Node::Matchers

      def initialize(session, base)
        @session = session
        @base = base
        @unsynchronized = false
      end

      # overridden in subclasses, e.g. Capybara::Node::Element
      def reload
        self
      end

      ##
      #
      # This method is Capybara's primary defence agains asynchronicity
      # problems. It works by attempting to run a given block of code until it
      # succeeds. The exact behaviour of this method depends on a number of
      # factors. Basically there are certain exceptions which, when raised
      # from the block, instead of bubbling up, are caught, and the block is
      # re-run.
      #
      # Certain drivers, such as RackTest, have no support for aynchronous
      # processes, these drivers run the block, and any error raised bubbles up
      # immediately. This allows faster turn around in the case where an
      # expectation fails.
      #
      # Only exceptions that are {Capybara::ElementNotFound} or any subclass
      # thereof cause the block to be rerun. Drivers may specify additional
      # exceptions which also cause reruns. This usually occurs when a node is
      # manipulated which no longer exists on the page. For example, the
      # Selenium driver specifies
      # `Selenium::WebDriver::Error::ObsoleteElementError`.
      #
      # As long as any of these exceptions are thrown, the block is re-run,
      # until a certain amount of time passes. The amount of time defaults to
      # {Capybara.default_wait_time} and can be overriden through the `seconds`
      # argument. This time is compared with the system time to see how much
      # time has passed. If the return value of {Time.now} is stubbed out,
      # Capybara will raise `Capybara::FrozenInTime`.
      #
      # @param [Integer] seconds          Number of seconds to retry this block
      # @return [Object]                  The result of the given block
      # @raise [Capybara::FrozenInTime]   If the return value of {Time.now} appears stuck
      #
      def synchronize(seconds=Capybara.default_wait_time)
        start_time = Time.now

        begin
          yield
        rescue => e
          raise e if @unsynchronized
          raise e unless driver.wait?
          raise e unless driver.invalid_element_errors.include?(e.class) || e.is_a?(Capybara::ElementNotFound)
          raise e if (Time.now - start_time) >= seconds
          sleep(0.05)
          raise Capybara::FrozenInTime, "time appears to be frozen, Capybara does not work with libraries which freeze time, consider using time travelling instead" if Time.now == start_time
          reload if Capybara.automatic_reload
          retry
        end
      end

      ##
      #
      # Within the given block, prevent synchronize from having any effect.
      #
      # This is an internal method which should not be called unless you are
      # absolutely sure of what you're doing.
      #
      # @api private
      # @return [Object]                  The result of the given block
      #
      def unsynchronized
        orig = @unsynchronized
        @unsynchronized = true
        yield
      ensure
        @unsynchronized = orig
      end

    protected

      def driver
        session.driver
      end
    end
  end
end