Get timezone name from timezone offset like "GMT+03:00" => "Baghdad"

get_timezone.rb

# example get_timezone("GMT+03:00")
def get_timezone(offset)
  # return false if timezone not valid
  return false unless ActiveSupport::TimeZone.all.map(&:formatted_offset).include?(offset.gsub("GMT",""))

  # find zone name
  zone_name = ActiveSupport::TimeZone.all.map(&:to_s).select { |x| x.include?(offset) }.first.gsub("(#{offset}) ", "")

  # return false if zone_name not found
  return false unless zone_name.present?

  # return false if zone name not valid
  return false unless ActiveSupport::TimeZone[zone_name].present?

  # return zone name
  zone_name
end


# TESTES
## for test true in all zones
get_timezone("GMT+03:00") # "Baghdad"
get_timezone("GMT+05:30") # "Chennai"
ActiveSupport::TimeZone.all.map(&:formatted_offset).each { |z| get_timezone("GMT#{z}") }


# test for false
get_timezone("GMT+03:08")