class ActiveSupport::TimeZone

def self.find_tzinfo(name)
  TZInfo::TimezoneProxy.new(MAPPING[name] || name)
end

def self.seconds_to_utc_offset(seconds, colon = true)
  format = colon ? UTC_OFFSET_WITH_COLON : UTC_OFFSET_WITHOUT_COLON
  sign = (seconds < 0 ? '-' : '+')
  hours = seconds.abs / 3600
  minutes = (seconds.abs % 3600) / 60
  format % [sign, hours, minutes]
end

def <=>(zone)
  return unless zone.respond_to? :utc_offset
  result = (utc_offset <=> zone.utc_offset)
  result = (name <=> zone.name) if result == 0
  result
end

def =~(re)
  re === name || re === MAPPING[name]
end

def [](arg)
  case arg
    when String
    begin
      lazy_zones_map[arg] ||= lookup(arg).tap { |tz| tz.utc_offset }
    rescue TZInfo::InvalidTimezoneIdentifier
      nil
    end
    when Numeric, ActiveSupport::Duration
      arg *= 3600 if arg.abs <= 13
      all.find { |z| z.utc_offset == arg.to_i }
    else
      raise ArgumentError, "invalid argument to TimeZone[]: #{arg.inspect}"
  end
end

def all
  @zones ||= zones_map.values.sort
end

def at(secs)
  Time.at(secs).utc.in_time_zone(self)
end

def formatted_offset(colon=true, alternate_utc_string = nil)
  utc_offset == 0 && alternate_utc_string || self.class.seconds_to_utc_offset(utc_offset, colon)
end

def initialize(name, utc_offset = nil, tzinfo = nil)
  self.class.send(:require_tzinfo)
  @name = name
  @utc_offset = utc_offset
  @tzinfo = tzinfo || TimeZone.find_tzinfo(name)
  @current_period = nil
end

def lazy_zones_map
  require_tzinfo
  @lazy_zones_map ||= Hash.new do |hash, place|
    hash[place] = create(place) if MAPPING.has_key?(place)
  end
end

def local(*args)
  time = Time.utc(*args)
  ActiveSupport::TimeWithZone.new(nil, self, time)
end

def local_to_utc(time, dst=true)
  tzinfo.local_to_utc(time, dst)
end

def lookup(name)
  (tzinfo = find_tzinfo(name)) && create(tzinfo.name.freeze)
end

def new(name)
  self[name]
end

def now
  time_now.utc.in_time_zone(self)
end

def parse(str, now=now())
  parts = Date._parse(str, false)
  return if parts.empty?
  time = Time.new(
    parts.fetch(:year, now.year),
    parts.fetch(:mon, now.month),
    parts.fetch(:mday, now.day),
    parts.fetch(:hour, 0),
    parts.fetch(:min, 0),
    parts.fetch(:sec, 0) + parts.fetch(:sec_fraction, 0),
    parts.fetch(:offset, 0)
  )
  if parts[:offset]
    TimeWithZone.new(time.utc, self)
  else
    TimeWithZone.new(nil, self, time)
  end
end

def period_for_local(time, dst=true)
  tzinfo.period_for_local(time, dst)
end

def period_for_utc(time)
  tzinfo.period_for_utc(time)
end

def require_tzinfo
  require 'tzinfo' unless defined?(::TZInfo)
rescue LoadError
  $stderr.puts "You don't have tzinfo installed in your application. Please add it to your Gemfile and run bundle install"
  raise
end

def time_now
  Time.now
end

def to_s
  "(GMT#{formatted_offset}) #{name}"
end

def today
  tzinfo.now.to_date
end

def us_zones
  @us_zones ||= all.find_all { |z| z.name =~ /US|Arizona|Indiana|Hawaii|Alaska/ }
end

def utc_offset
  if @utc_offset
    @utc_offset
  else
    @current_period ||= tzinfo.try(:current_period)
    @current_period.try(:utc_offset)
  end
end

def utc_to_local(time)
  tzinfo.utc_to_local(time)
end

def zones_map
  @zones_map ||= begin
    new_zones_names = MAPPING.keys - lazy_zones_map.keys
    new_zones       = Hash[new_zones_names.map { |place| [place, create(place)] }]
    lazy_zones_map.merge(new_zones)
  end
end