class ActiveSupport::TimeZone

def self.find_tzinfo(name)
  require 'active_support/tzinfo' unless defined?(::TZInfo)
  ::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)
  result = (utc_offset <=> zone.utc_offset)
  result = (name <=> zone.name) if result == 0
  result
end

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

def [](arg)
  case arg
    when String
    begin
      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)
  utc = Time.at(secs).utc rescue DateTime.civil(1970).since(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)
  begin
    require 'tzinfo'
  rescue LoadError => e
    $stderr.puts "You don't have tzinfo installed in your application. Please add it to your Gemfile and run bundle install"
    raise e
  end
  @name = name
  @utc_offset = utc_offset
  @tzinfo = tzinfo || TimeZone.find_tzinfo(name)
  @current_period = nil
end

def local(*args)
  time = Time.utc_time(*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)
  date_parts = Date._parse(str)
  return if date_parts.blank?
  time = Time.parse(str, now) rescue DateTime.parse(str)
  if date_parts[:offset].nil?
    ActiveSupport::TimeWithZone.new(nil, self, time)
  else
    time.in_time_zone(self)
  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 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 ||= Hash[MAPPING.map { |place, _| [place, create(place)] }]
end