lib/core_ext/time_zone.rb
require 'tzinfo'
require 'core_ext/object/blank'
require 'core_ext/object/try'
require 'concurrent/map'
module CoreExt
# The TimeZone class serves as a wrapper around TZInfo::Timezone instances.
# It allows us to do the following:
#
# * Limit the set of zones provided by TZInfo to a meaningful subset of 146
# zones.
# * Retrieve and display zones with a friendlier name
# (e.g., "Eastern Time (US & Canada)" instead of "America/New_York").
# * Lazily load TZInfo::Timezone instances only when they're needed.
# * Create CoreExt::TimeWithZone instances via TimeZone's +local+,
# +parse+, +at+ and +now+ methods.
#
# If you set <tt>config.time_zone</tt> in the Rails Application, you can
# access this TimeZone object via <tt>Time.zone</tt>:
#
# # application.rb:
# class Application < Rails::Application
# config.time_zone = 'Eastern Time (US & Canada)'
# end
#
# Time.zone # => #<CoreExt::TimeZone:0x514834...>
# Time.zone.name # => "Eastern Time (US & Canada)"
# Time.zone.now # => Sun, 18 May 2008 14:30:44 EDT -04:00
class TimeZone
# Keys are Rails TimeZone names, values are TZInfo identifiers.
MAPPING = {
"International Date Line West" => "Pacific/Midway",
"Midway Island" => "Pacific/Midway",
"American Samoa" => "Pacific/Pago_Pago",
"Hawaii" => "Pacific/Honolulu",
"Alaska" => "America/Juneau",
"Pacific Time (US & Canada)" => "America/Los_Angeles",
"Tijuana" => "America/Tijuana",
"Mountain Time (US & Canada)" => "America/Denver",
"Arizona" => "America/Phoenix",
"Chihuahua" => "America/Chihuahua",
"Mazatlan" => "America/Mazatlan",
"Central Time (US & Canada)" => "America/Chicago",
"Saskatchewan" => "America/Regina",
"Guadalajara" => "America/Mexico_City",
"Mexico City" => "America/Mexico_City",
"Monterrey" => "America/Monterrey",
"Central America" => "America/Guatemala",
"Eastern Time (US & Canada)" => "America/New_York",
"Indiana (East)" => "America/Indiana/Indianapolis",
"Bogota" => "America/Bogota",
"Lima" => "America/Lima",
"Quito" => "America/Lima",
"Atlantic Time (Canada)" => "America/Halifax",
"Caracas" => "America/Caracas",
"La Paz" => "America/La_Paz",
"Santiago" => "America/Santiago",
"Newfoundland" => "America/St_Johns",
"Brasilia" => "America/Sao_Paulo",
"Buenos Aires" => "America/Argentina/Buenos_Aires",
"Montevideo" => "America/Montevideo",
"Georgetown" => "America/Guyana",
"Greenland" => "America/Godthab",
"Mid-Atlantic" => "Atlantic/South_Georgia",
"Azores" => "Atlantic/Azores",
"Cape Verde Is." => "Atlantic/Cape_Verde",
"Dublin" => "Europe/Dublin",
"Edinburgh" => "Europe/London",
"Lisbon" => "Europe/Lisbon",
"London" => "Europe/London",
"Casablanca" => "Africa/Casablanca",
"Monrovia" => "Africa/Monrovia",
"UTC" => "Etc/UTC",
"Belgrade" => "Europe/Belgrade",
"Bratislava" => "Europe/Bratislava",
"Budapest" => "Europe/Budapest",
"Ljubljana" => "Europe/Ljubljana",
"Prague" => "Europe/Prague",
"Sarajevo" => "Europe/Sarajevo",
"Skopje" => "Europe/Skopje",
"Warsaw" => "Europe/Warsaw",
"Zagreb" => "Europe/Zagreb",
"Brussels" => "Europe/Brussels",
"Copenhagen" => "Europe/Copenhagen",
"Madrid" => "Europe/Madrid",
"Paris" => "Europe/Paris",
"Amsterdam" => "Europe/Amsterdam",
"Berlin" => "Europe/Berlin",
"Bern" => "Europe/Berlin",
"Rome" => "Europe/Rome",
"Stockholm" => "Europe/Stockholm",
"Vienna" => "Europe/Vienna",
"West Central Africa" => "Africa/Algiers",
"Bucharest" => "Europe/Bucharest",
"Cairo" => "Africa/Cairo",
"Helsinki" => "Europe/Helsinki",
"Kyiv" => "Europe/Kiev",
"Riga" => "Europe/Riga",
"Sofia" => "Europe/Sofia",
"Tallinn" => "Europe/Tallinn",
"Vilnius" => "Europe/Vilnius",
"Athens" => "Europe/Athens",
"Istanbul" => "Europe/Istanbul",
"Minsk" => "Europe/Minsk",
"Jerusalem" => "Asia/Jerusalem",
"Harare" => "Africa/Harare",
"Pretoria" => "Africa/Johannesburg",
"Kaliningrad" => "Europe/Kaliningrad",
"Moscow" => "Europe/Moscow",
"St. Petersburg" => "Europe/Moscow",
"Volgograd" => "Europe/Volgograd",
"Samara" => "Europe/Samara",
"Kuwait" => "Asia/Kuwait",
"Riyadh" => "Asia/Riyadh",
"Nairobi" => "Africa/Nairobi",
"Baghdad" => "Asia/Baghdad",
"Tehran" => "Asia/Tehran",
"Abu Dhabi" => "Asia/Muscat",
"Muscat" => "Asia/Muscat",
"Baku" => "Asia/Baku",
"Tbilisi" => "Asia/Tbilisi",
"Yerevan" => "Asia/Yerevan",
"Kabul" => "Asia/Kabul",
"Ekaterinburg" => "Asia/Yekaterinburg",
"Islamabad" => "Asia/Karachi",
"Karachi" => "Asia/Karachi",
"Tashkent" => "Asia/Tashkent",
"Chennai" => "Asia/Kolkata",
"Kolkata" => "Asia/Kolkata",
"Mumbai" => "Asia/Kolkata",
"New Delhi" => "Asia/Kolkata",
"Kathmandu" => "Asia/Kathmandu",
"Astana" => "Asia/Dhaka",
"Dhaka" => "Asia/Dhaka",
"Sri Jayawardenepura" => "Asia/Colombo",
"Almaty" => "Asia/Almaty",
"Novosibirsk" => "Asia/Novosibirsk",
"Rangoon" => "Asia/Rangoon",
"Bangkok" => "Asia/Bangkok",
"Hanoi" => "Asia/Bangkok",
"Jakarta" => "Asia/Jakarta",
"Krasnoyarsk" => "Asia/Krasnoyarsk",
"Beijing" => "Asia/Shanghai",
"Chongqing" => "Asia/Chongqing",
"Hong Kong" => "Asia/Hong_Kong",
"Urumqi" => "Asia/Urumqi",
"Kuala Lumpur" => "Asia/Kuala_Lumpur",
"Singapore" => "Asia/Singapore",
"Taipei" => "Asia/Taipei",
"Perth" => "Australia/Perth",
"Irkutsk" => "Asia/Irkutsk",
"Ulaanbaatar" => "Asia/Ulaanbaatar",
"Seoul" => "Asia/Seoul",
"Osaka" => "Asia/Tokyo",
"Sapporo" => "Asia/Tokyo",
"Tokyo" => "Asia/Tokyo",
"Yakutsk" => "Asia/Yakutsk",
"Darwin" => "Australia/Darwin",
"Adelaide" => "Australia/Adelaide",
"Canberra" => "Australia/Melbourne",
"Melbourne" => "Australia/Melbourne",
"Sydney" => "Australia/Sydney",
"Brisbane" => "Australia/Brisbane",
"Hobart" => "Australia/Hobart",
"Vladivostok" => "Asia/Vladivostok",
"Guam" => "Pacific/Guam",
"Port Moresby" => "Pacific/Port_Moresby",
"Magadan" => "Asia/Magadan",
"Srednekolymsk" => "Asia/Srednekolymsk",
"Solomon Is." => "Pacific/Guadalcanal",
"New Caledonia" => "Pacific/Noumea",
"Fiji" => "Pacific/Fiji",
"Kamchatka" => "Asia/Kamchatka",
"Marshall Is." => "Pacific/Majuro",
"Auckland" => "Pacific/Auckland",
"Wellington" => "Pacific/Auckland",
"Nuku'alofa" => "Pacific/Tongatapu",
"Tokelau Is." => "Pacific/Fakaofo",
"Chatham Is." => "Pacific/Chatham",
"Samoa" => "Pacific/Apia"
}
UTC_OFFSET_WITH_COLON = '%s%02d:%02d'
UTC_OFFSET_WITHOUT_COLON = UTC_OFFSET_WITH_COLON.tr(':', '')
@lazy_zones_map = Concurrent::Map.new
class << self
# Assumes self represents an offset from UTC in seconds (as returned from
# Time#utc_offset) and turns this into an +HH:MM formatted string.
#
# CoreExt::TimeZone.seconds_to_utc_offset(-21_600) # => "-06:00"
def 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 find_tzinfo(name)
TZInfo::Timezone.new(MAPPING[name] || name)
end
alias_method :create, :new
# Returns a TimeZone instance with the given name, or +nil+ if no
# such TimeZone instance exists. (This exists to support the use of
# this class with the +composed_of+ macro.)
def new(name)
self[name]
end
# Returns an array of all TimeZone objects. There are multiple
# TimeZone objects per time zone, in many cases, to make it easier
# for users to find their own time zone.
def all
@zones ||= zones_map.values.sort
end
# Locate a specific time zone object. If the argument is a string, it
# is interpreted to mean the name of the timezone to locate. If it is a
# numeric value it is either the hour offset, or the second offset, of the
# timezone to find. (The first one with that offset will be returned.)
# Returns +nil+ if no such time zone is known to the system.
def [](arg)
case arg
when String
begin
@lazy_zones_map[arg] ||= create(arg)
rescue TZInfo::InvalidTimezoneIdentifier
nil
end
when Numeric, CoreExt::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
# A convenience method for returning a collection of TimeZone objects
# for time zones in the USA.
def us_zones
@us_zones ||= all.find_all { |z| z.name =~ /US|Arizona|Indiana|Hawaii|Alaska/ }
end
private
def zones_map
@zones_map ||= begin
MAPPING.each_key {|place| self[place]} # load all the zones
@lazy_zones_map
end
end
end
include Comparable
attr_reader :name
attr_reader :tzinfo
# Create a new TimeZone object with the given name and offset. The
# offset is the number of seconds that this time zone is offset from UTC
# (GMT). Seconds were chosen as the offset unit because that is the unit
# that Ruby uses to represent time zone offsets (see Time#utc_offset).
def initialize(name, utc_offset = nil, tzinfo = nil)
@name = name
@utc_offset = utc_offset
@tzinfo = tzinfo || TimeZone.find_tzinfo(name)
@current_period = nil
end
# Returns the offset of this time zone from UTC in seconds.
def utc_offset
if @utc_offset
@utc_offset
else
@current_period ||= tzinfo.current_period if tzinfo
@current_period.utc_offset if @current_period
end
end
# Returns a formatted string of the offset from UTC, or an alternative
# string if the time zone is already UTC.
#
# zone = CoreExt::TimeZone['Central Time (US & Canada)']
# zone.formatted_offset # => "-06:00"
# zone.formatted_offset(false) # => "-0600"
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
# Compare this time zone to the parameter. The two are compared first on
# their offsets, and then by name.
def <=>(zone)
return unless zone.respond_to? :utc_offset
result = (utc_offset <=> zone.utc_offset)
result = (name <=> zone.name) if result == 0
result
end
# Compare #name and TZInfo identifier to a supplied regexp, returning +true+
# if a match is found.
def =~(re)
re === name || re === MAPPING[name]
end
# Returns a textual representation of this time zone.
def to_s
"(GMT#{formatted_offset}) #{name}"
end
# Method for creating new CoreExt::TimeWithZone instance in time zone
# of +self+ from given values.
#
# Time.zone = 'Hawaii' # => "Hawaii"
# Time.zone.local(2007, 2, 1, 15, 30, 45) # => Thu, 01 Feb 2007 15:30:45 HST -10:00
def local(*args)
time = Time.utc(*args)
CoreExt::TimeWithZone.new(nil, self, time)
end
# Method for creating new CoreExt::TimeWithZone instance in time zone
# of +self+ from number of seconds since the Unix epoch.
#
# Time.zone = 'Hawaii' # => "Hawaii"
# Time.utc(2000).to_f # => 946684800.0
# Time.zone.at(946684800.0) # => Fri, 31 Dec 1999 14:00:00 HST -10:00
def at(secs)
Time.at(secs).utc.in_time_zone(self)
end
# Method for creating new CoreExt::TimeWithZone instance in time zone
# of +self+ from parsed string.
#
# Time.zone = 'Hawaii' # => "Hawaii"
# Time.zone.parse('1999-12-31 14:00:00') # => Fri, 31 Dec 1999 14:00:00 HST -10:00
#
# If upper components are missing from the string, they are supplied from
# TimeZone#now:
#
# Time.zone.now # => Fri, 31 Dec 1999 14:00:00 HST -10:00
# Time.zone.parse('22:30:00') # => Fri, 31 Dec 1999 22:30:00 HST -10:00
#
# However, if the date component is not provided, but any other upper
# components are supplied, then the day of the month defaults to 1:
#
# Time.zone.parse('Mar 2000') # => Wed, 01 Mar 2000 00:00:00 HST -10:00
def parse(str, now=now())
parts_to_time(Date._parse(str, false), now)
end
# Parses +str+ according to +format+ and returns an CoreExt::TimeWithZone.
#
# Assumes that +str+ is a time in the time zone +self+,
# unless +format+ includes an explicit time zone.
# (This is the same behavior as +parse+.)
# In either case, the returned TimeWithZone has the timezone of +self+.
#
# Time.zone = 'Hawaii' # => "Hawaii"
# Time.zone.strptime('1999-12-31 14:00:00', '%Y-%m-%d %H:%M:%S') # => Fri, 31 Dec 1999 14:00:00 HST -10:00
#
# If upper components are missing from the string, they are supplied from
# TimeZone#now:
#
# Time.zone.now # => Fri, 31 Dec 1999 14:00:00 HST -10:00
# Time.zone.strptime('22:30:00', '%H:%M:%S') # => Fri, 31 Dec 1999 22:30:00 HST -10:00
#
# However, if the date component is not provided, but any other upper
# components are supplied, then the day of the month defaults to 1:
#
# Time.zone.strptime('Mar 2000', '%b %Y') # => Wed, 01 Mar 2000 00:00:00 HST -10:00
def strptime(str, format, now=now())
parts_to_time(DateTime._strptime(str, format), now)
end
# Returns an CoreExt::TimeWithZone instance representing the current
# time in the time zone represented by +self+.
#
# Time.zone = 'Hawaii' # => "Hawaii"
# Time.zone.now # => Wed, 23 Jan 2008 20:24:27 HST -10:00
def now
time_now.utc.in_time_zone(self)
end
# Returns the current date in this time zone.
def today
tzinfo.now.to_date
end
# Returns the next date in this time zone.
def tomorrow
today + 1
end
# Returns the previous date in this time zone.
def yesterday
today - 1
end
# Adjust the given time to the simultaneous time in the time zone
# represented by +self+. Returns a Time.utc() instance -- if you want an
# CoreExt::TimeWithZone instance, use Time#in_time_zone() instead.
def utc_to_local(time)
tzinfo.utc_to_local(time)
end
# Adjust the given time to the simultaneous time in UTC. Returns a
# Time.utc() instance.
def local_to_utc(time, dst=true)
tzinfo.local_to_utc(time, dst)
end
# Available so that TimeZone instances respond like TZInfo::Timezone
# instances.
def period_for_utc(time)
tzinfo.period_for_utc(time)
end
# Available so that TimeZone instances respond like TZInfo::Timezone
# instances.
# https://github.com/tzinfo/tzinfo/issues/32
def period_for_local(time, dst=true)
tzinfo.period_for_local(time, dst) { |results| results.first }
end
def periods_for_local(time) #:nodoc:
tzinfo.periods_for_local(time)
end
def init_with(coder) #:nodoc:
initialize(coder['name'])
end
def encode_with(coder) #:nodoc:
coder.tag ="!ruby/object:#{self.class}"
coder.map = { 'name' => tzinfo.name }
end
private
def parts_to_time(parts, now)
return if parts.empty?
time = Time.new(
parts.fetch(:year, now.year),
parts.fetch(:mon, now.month),
parts.fetch(:mday, parts[:year] || parts[:mon] ? 1 : 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 time_now
Time.now
end
end
end