# This patch performs 2 functions
#
# 1. It caches all translations which drastically improves
#    translation performance in an LRU cache
#
# 2. It patches I18n so it only loads the translations it needs
#    on demand
#
# This patch depends on the convention that locale yml files must be named [locale_name].yml

module I18n
  module Backend

    class Simple
      def available_locales
        # in case you are wondering this is:
        # Dir.glob( File.join(Rails.root, 'config', 'locales', 'client.*.yml') )
        #    .map {|x| x.split('.')[-2]}.sort
        LocaleSiteSetting.supported_locales.map(&:to_sym)
      end
    end

    module Base
      # force explicit loading
      def load_translations(*filenames)
        unless filenames.empty?
          filenames.flatten.each { |filename| load_file(filename) }
        end
      end

    end
  end
  # this accelerates translation a tiny bit (halves the time it takes)
  class << self
    alias_method :translate_no_cache, :translate
    alias_method :reload_no_cache!, :reload!
    LRU_CACHE_SIZE = 2000

    def reload!
      @loaded_locales = []
      @cache = nil
      reload_no_cache!
    end

    LOAD_MUTEX = Mutex.new
    def load_locale(locale)
      LOAD_MUTEX.synchronize do
        return if @loaded_locales.include?(config.locale)

        if @loaded_locales.empty?
          # load all rb files
          I18n.backend.load_translations(I18n.load_path.grep(/\.rb$/))
        end

        # load it
        I18n.backend.load_translations(I18n.load_path.grep Regexp.new("\\.#{locale}\\.yml$"))

        @loaded_locales << locale
      end
    end

    def translate(*args)
      @cache ||= LruRedux::ThreadSafeCache.new(LRU_CACHE_SIZE)
      found = true
      k = [args, config.locale, config.backend.object_id]
      t = @cache.fetch(k) { found = false }
      unless found
        load_locale(config.locale) unless @loaded_locales.include?(config.locale)
        begin
          t = translate_no_cache(*args)
        rescue MissingInterpolationArgument
          options = args.last.is_a?(Hash) ? args.pop.dup : {}
          options.merge!(locale: config.default_locale)
          key = args.shift
          t = translate_no_cache(key, options)
        ensure
          t = @cache[k] = t.freeze
        end
      end
      t
    end

    alias_method :t, :translate
  end
end