require 'active_support/core_ext/time/zones'

class DateTime
  # Returns the simultaneous time in <tt>Time.zone</tt>.
  #
  #   Time.zone = 'Hawaii'             # => 'Hawaii'
  #   DateTime.new(2000).in_time_zone  # => Fri, 31 Dec 1999 14:00:00 HST -10:00
  #
  # This method is similar to Time#localtime, except that it uses <tt>Time.zone</tt> as the local zone
  # instead of the operating system's time zone.
  #
  # You can also pass in a TimeZone instance or string that identifies a TimeZone as an argument,
  # and the conversion will be based on that zone instead of <tt>Time.zone</tt>.
  #
  #   DateTime.new(2000).in_time_zone('Alaska')  # => Fri, 31 Dec 1999 15:00:00 AKST -09:00
  def in_time_zone(zone = ::Time.zone)
    return self unless zone

    ActiveSupport::TimeWithZone.new(utc? ? self : getutc, ::Time.find_zone!(zone))
  end
end