smugglys/translatomatic

require 'i18n_data'

module Translatomatic
  # Represents a locale
  # @see https://en.wikipedia.org/wiki/Locale_(computer_software)
  class Locale
    # @return [String] ISO 639-1 language
    attr_reader :language

    # @return [String] ISO 15924 script
    attr_reader :script

    # @return [String] ISO 3166-1 alpha-2 country code
    attr_reader :region

    class << self
      # @return [Locale] The default locale
      attr_accessor :default

      # Parse the given tag
      # @param tag [String] A string representing a locale
      # @param validate [boolean] If true, return nil if the locale is invalid
      # @return [Locale] A locale object
      def parse(tag, validate = true)
        return nil if tag.nil?

        locale = tag
        unless tag.is_a?(Translatomatic::Locale)
          tag = tag.to_s.tr('_', '-')
          locale = new(tag)
        end
        validate && !locale.valid? ? nil : locale
      end

      # @return [Array<String>] A list of ISO 639-1 language codes
      def language_codes
        VALID_LANGUAGES
      end
    end

    # @return [Locale] create a new locale object
    def initialize(tag)
      data = ::I18n::Locale::Tag::Rfc4646.tag(tag)
      if data
        @language = data.language
        @script = data.script
        @region = data.region
      end
    end

    # @return true if language is a valid ISO 639-1 language
    def valid?
      VALID_LANGUAGES.include?(language)
    end

    # @return [String] Locale as a string
    def to_s
      [language, script, region].compact.join('-')
    end

    # @param other [Object] Another object
    # @return [boolean] true if the other object is a {Translatomatic::Locale}
    #   object and has equal language, script and region.
    def eql?(other)
      other.is_a?(Translatomatic::Locale) && other.hash == hash
    end

    # (see #eql?)
    def ==(other)
      eql?(other)
    end

    # @!visibility private
    def hash
      [language, script, region].hash
    end

    # list of 2 letter country codes
    VALID_LANGUAGES = ::I18nData.languages.keys.collect(&:downcase).sort.freeze
    private_constant :VALID_LANGUAGES

    begin
      # get default locale from the environment
      lang = (ENV['LANG'] || '').split(/\./)[0]
      self.default = parse(lang) || parse('en')
    end
  end
end