require 'i18n/backend/pluralization'

module I18n
  module Backend
    class DiscourseI18n < I18n::Backend::Simple
      include I18n::Backend::Pluralization

      def initialize
        @overrides_enabled = true
      end

      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

      def reload!
        @overrides = {}
        super
      end

      def overrides_for(locale)
        @overrides ||= {}
        site_overrides = @overrides[RailsMultisite::ConnectionManagement.current_db] ||= {}

        return site_overrides[locale] if site_overrides[locale]
        locale_overrides = site_overrides[locale] = {}

        TranslationOverride.where(locale: locale).pluck(:translation_key, :value).each do |tuple|
          locale_overrides[tuple[0]] = tuple[1]
        end

        locale_overrides
      end

      # In some environments such as migrations we don't want to use overrides.
      # Use this to disable them over a block of ruby code
      def overrides_disabled
        @overrides_enabled = false
        yield
      ensure
        @overrides_enabled = true
      end

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

      def fallbacks(locale)
        [locale, SiteSetting.default_locale.to_sym, :en].uniq.compact
      end

      def translate(locale, key, options = {})
        (@overrides_enabled && overrides_for(locale)[key]) || super(locale, key, options)
      end

      def exists?(locale, key)
        fallbacks(locale).each do |fallback|
          begin
            return true if super(fallback, key)
          rescue I18n::InvalidLocale
            # we do nothing when the locale is invalid, as this is a fallback anyways.
          end
        end

        false
      end

    end
  end
end