Class: Tilia::VObject::TimeZoneUtil

Inherits:
Object
  • Object
show all
Defined in:
lib/tilia/v_object/time_zone_util.rb

Overview

Time zone name translation.

This file translates well-known time zone names into “Olson database” time zone names.

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.map ⇒ Object

Returns the value of attribute map.



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# File 'lib/tilia/v_object/time_zone_util.rb', line 208

def map
  @map
end

.microsoft_exchange_map ⇒ Object

Returns the value of attribute microsoft_exchange_map.



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# File 'lib/tilia/v_object/time_zone_util.rb', line 209

def microsoft_exchange_map
  @microsoft_exchange_map
end

Class Method Details

.load_tz_maps ⇒ Object

This method will load in all the tz mapping information, if it’s not yet done.



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# File 'lib/tilia/v_object/time_zone_util.rb', line 197

def self.load_tz_maps
  return @map if @map

  @map = TimeZoneData::PhpZones.list
  @map.merge!(TimeZoneData::ExchangeZones.list)
  @map.merge!(TimeZoneData::LotusZones.list)
  @map.merge!(TimeZoneData::WindowsZones.list)
  @map
end

.time_zone(tzid, vcalendar = nil, fail_if_uncertain = false) ⇒ ActiveSupport::TimeZone

This method will try to find out the correct timezone for an iCalendar date-time value.

You must pass the contents of the TZID parameter, as well as the full calendar.

If the lookup fails, this method will return the default PHP timezone (as configured using date_default_timezone_set, or the date.timezone ini setting).

Alternatively, if fail_if_uncertain is set to true, it will throw an exception if we cannot accurately determine the timezone.

Parameters:

  • tzid (String)
  • vcalendar (Component) (defaults to: nil)

Returns:

  • (ActiveSupport::TimeZone) 


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# File 'lib/tilia/v_object/time_zone_util.rb', line 111

def self.time_zone(tzid, vcalendar = nil, fail_if_uncertain = false)
  # First we will just see if the tzid is a support timezone identifier.
  #
  # The only exception is if the timezone starts with (. This is to
  # handle cases where certain microsoft products generate timezone
  # identifiers that for instance look like:
  #
  # (GMT+01.00) Sarajevo/Warsaw/Zagreb
  #
  # Since PHP 5.5.10, the first bit will be used as the timezone and
  # this method will return just GMT+01:00. This is wrong, because it
  # doesn't take DST into account.

  unless tzid[0] == '('

    # PHP has a bug that logs PHP warnings even it shouldn't:
    # https://bugs.php.net/bug.php?id=67881
    #
    # That's why we're checking if we'll be able to successfull instantiate
    # \Date_time_zone before doing so. Otherwise we could simply instantiate
    # and catch the exception.
    return ActiveSupport::TimeZone.new(tzid) if ActiveSupport::TimeZone.new(tzid)
  end

  load_tz_maps

  # Next, we check if the tzid is somewhere in our tzid map.

  return ActiveSupport::TimeZone.new(@map[tzid]) if @map.key?(tzid)

  # Maybe the author was hyper-lazy and just included an offset. We
  # support it, but we aren't happy about it.
  matches = /^GMT(\+|-)([0-9]{4})$/.match(tzid)
  if matches

    # Note that the path in the source will never be taken from PHP 5.5.10
    # onwards. PHP 5.5.10 supports the "GMT+0100" style of format, so it
    # already gets returned early in this function. Once we drop support
    # for versions under PHP 5.5.10, this bit can be taken out of the
    # source.
    # @codeCoverageIgnoreStart
    return ActiveSupport::TimeZone.new("Etc/GMT#{matches[1]}#{matches[2][0..1].gsub(/^0+/, '')}")
    # @codeCoverageIgnoreEnd
  end

  if vcalendar
    # If that didn't work, we will scan VTIMEZONE objects
    vcalendar.select('VTIMEZONE').each do |vtimezone|
      next unless vtimezone['TZID'].to_s == tzid
      if vtimezone.key?('X-LIC-LOCATION')
        lic = vtimezone['X-LIC-LOCATION'].to_s

        # Libical generators may specify strings like
        # "SystemV/EST5EDT". For those we must remove the
        # SystemV part.
        lic = lic[8..-1] if lic[0...8] == 'SystemV/'

        return time_zone(lic, nil, fail_if_uncertain)
      end

      # Microsoft may add a magic number, which we also have an
      # answer for.
      next unless vtimezone.key?('X-MICROSOFT-CDO-TZID')
      cdo_id = vtimezone['X-MICROSOFT-CDO-TZID'].value.to_i

      # 2 can mean both Europe/Lisbon and Europe/Sarajevo.
      if cdo_id == 2 && vtimezone['TZID'].to_s.index('Sarajevo')
        return ActiveSupport::TimeZone.new('Europe/Sarajevo')
      end

      if @microsoft_exchange_map.key?(cdo_id)
        return ActiveSupport::TimeZone.new(@microsoft_exchange_map[cdo_id])
      end
    end
  end

  if fail_if_uncertain
    fail ArgumentError, "We were unable to determine the correct PHP timezone for tzid: #{tzid}"
  end

  # If we got all the way here, we default to UTC.
  Time.zone
end