class ActiveSupport::TimeWithZone

def +(other)
  if duration_of_variable_length?(other)
    method_missing(:+, other)
  else
    result = utc.acts_like?(:date) ? utc.since(other) : utc + other rescue utc.since(other)
    result.in_time_zone(time_zone)
  end
end

def -(other)
  if other.acts_like?(:time)
    to_time - other.to_time
  elsif duration_of_variable_length?(other)
    method_missing(:-, other)
  else
    result = utc.acts_like?(:date) ? utc.ago(other) : utc - other rescue utc.ago(other)
    result.in_time_zone(time_zone)
  end
end

def <=>(other)
  utc <=> other
end

def acts_like_time?
  true
end

def advance(options)
  # If we're advancing a value of variable length (i.e., years, weeks, months, days), advance from #time,
  # otherwise advance from #utc, for accuracy when moving across DST boundaries
  if options.values_at(:years, :weeks, :months, :days).any?
    method_missing(:advance, options)
  else
    utc.advance(options).in_time_zone(time_zone)
  end
end

def ago(other)
  since(-other)
end

def as_json(options = nil)
  if ActiveSupport::JSON::Encoding.use_standard_json_time_format
    xmlschema(ActiveSupport::JSON::Encoding.time_precision)
  else
    %(#{time.strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)})
  end
end

def between?(min, max)
  utc.between?(min, max)
end

def blank?
  false
end

def change(options)
  if options[:zone] && options[:offset]
    raise ArgumentError, "Can't change both :offset and :zone at the same time: #{options.inspect}"
  end
  new_time = time.change(options)
  if options[:zone]
    new_zone = ::Time.find_zone(options[:zone])
  elsif options[:offset]
    new_zone = ::Time.find_zone(new_time.utc_offset)
  end
  new_zone ||= time_zone
  periods = new_zone.periods_for_local(new_time)
  self.class.new(nil, new_zone, new_time, periods.include?(period) ? period : nil)
end

def dst?
  period.dst?
end

def duration_of_variable_length?(obj)
  ActiveSupport::Duration === obj && obj.variable?
end

def encode_with(coder) # :nodoc:
  coder.map = { "utc" => utc, "zone" => time_zone, "time" => time }
end

def eql?(other)
  other.eql?(utc)
end

def formatted_offset(colon = true, alternate_utc_string = nil)
  utc? && alternate_utc_string || TimeZone.seconds_to_utc_offset(utc_offset, colon)
end

def freeze
  # preload instance variables before freezing
  period; utc; time; to_datetime; to_time
  super
end

def future?
  utc.future?
end

def get_period_and_ensure_valid_local_time(period)
  # we don't want a Time.local instance enforcing its own DST rules as well,
  # so transfer time values to a utc constructor if necessary
  @time = transfer_time_values_to_utc_constructor(@time) unless @time.utc?
  begin
    period || @time_zone.period_for_local(@time)
  rescue ::TZInfo::PeriodNotFound
    # time is in the "spring forward" hour gap, so we're moving the time forward one hour and trying again
    @time += 1.hour
    retry
  end
end

def hash
  utc.hash
end

def httpdate
  utc.httpdate
end

def in_time_zone(new_zone = ::Time.zone)
  return self if time_zone == new_zone
  utc.in_time_zone(new_zone)
end

def incorporate_utc_offset(time, offset)
  if time.kind_of?(Date)
    time + Rational(offset, SECONDS_PER_DAY)
  else
    time + offset
  end
end

def init_with(coder) # :nodoc:
  initialize(coder["utc"], coder["zone"], coder["time"])
end

def initialize(utc_time, time_zone, local_time = nil, period = nil)
  @utc = utc_time ? transfer_time_values_to_utc_constructor(utc_time) : nil
  @time_zone, @time = time_zone, local_time
  @period = @utc ? period : get_period_and_ensure_valid_local_time(period)
end

def inspect
  "#{time.strftime('%a, %d %b %Y %H:%M:%S.%9N')} #{zone} #{formatted_offset}"
end

def is_a?(klass)
  klass == ::Time || super
end

def localtime(utc_offset = nil)
  utc.getlocal(utc_offset)
end

def marshal_dump
  [utc, time_zone.name, time]
end

def marshal_load(variables)
  initialize(variables[0].utc, ::Time.find_zone(variables[1]), variables[2].utc)
end

def method_missing(...)
  wrap_with_time_zone time.__send__(...)
rescue NoMethodError => e
  raise e, e.message.sub(time.inspect, inspect).sub("Time", "ActiveSupport::TimeWithZone"), e.backtrace
end

def past?
  utc.past?
end

def period
  @period ||= time_zone.period_for_utc(@utc)
end

def respond_to?(sym, include_priv = false)
  # ensure that we're not going to throw and rescue from NoMethodError in method_missing which is slow
  return false if sym.to_sym == :to_str
  super
end

def respond_to_missing?(sym, include_priv)
  return false if sym.to_sym == :acts_like_date?
  time.respond_to?(sym, include_priv)
end

def rfc2822
  to_fs(:rfc822)
end

def strftime(format)
  format = format.gsub(/((?:\A|[^%])(?:%%)*)%Z/, "\\1#{zone}")
  getlocal(utc_offset).strftime(format)
end

def time
  @time ||= incorporate_utc_offset(@utc, utc_offset)
end

def to_a
  [time.sec, time.min, time.hour, time.day, time.mon, time.year, time.wday, time.yday, dst?, zone]
end

def to_datetime
  @to_datetime ||= utc.to_datetime.new_offset(Rational(utc_offset, 86_400))
end

def to_f
  utc.to_f
end

def to_fs(format = :default)
  if format == :db
    utc.to_fs(format)
  elsif formatter = ::Time::DATE_FORMATS[format]
    formatter.respond_to?(:call) ? formatter.call(self).to_s : strftime(formatter)
  else
    # Change to to_s when deprecation is gone.
    "#{time.strftime("%Y-%m-%d %H:%M:%S")} #{formatted_offset(false, 'UTC')}"
  end
end

def to_i
  utc.to_i
end

def to_r
  utc.to_r
end

def to_s
  "#{time.strftime("%Y-%m-%d %H:%M:%S")} #{formatted_offset(false, 'UTC')}" # mimicking Ruby Time#to_s format
end

def to_time
  if preserve_timezone
    @to_time_with_instance_offset ||= getlocal(utc_offset)
  else
    @to_time_with_system_offset ||= getlocal
  end
end

def today?
  time.today?
end

def tomorrow?
  time.tomorrow?
end

def transfer_time_values_to_utc_constructor(time)
  # avoid creating another Time object if possible
  return time if time.instance_of?(::Time) && time.utc?
  ::Time.utc(time.year, time.month, time.day, time.hour, time.min, time.sec + time.subsec)
end

def utc
  @utc ||= incorporate_utc_offset(@time, -utc_offset)
end

def utc?
  zone == "UTC" || zone == "UCT"
end

def utc_offset
  period.observed_utc_offset
end

def wrap_with_time_zone(time)
  if time.acts_like?(:time)
    periods = time_zone.periods_for_local(time)
    self.class.new(nil, time_zone, time, periods.include?(period) ? period : nil)
  elsif time.is_a?(Range)
    wrap_with_time_zone(time.begin)..wrap_with_time_zone(time.end)
  else
    time
  end
end

def xmlschema(fraction_digits = 0)
  "#{time.strftime(PRECISIONS[fraction_digits.to_i])}#{formatted_offset(true, 'Z')}"
end

def yesterday?
  time.yesterday?
end

def zone
  period.abbreviation
end