require 'active_support/concern'

module Tenzing
  module Localizer
    extend ActiveSupport::Concern

    included do
      before_filter :set_locale
      rescue_from I18n::InvalidLocale, with: :invalid_locale
    end

    def set_locale
      locale =  params[:lang]
      locale ||= session[:locale]
      locale ||= ((lang = request.env['HTTP_ACCEPT_LANGUAGE']) && lang[/^[a-z]{2}/])
      locale ||= I18n.default_locale

      I18n.locale = locale
      session[:locale] = I18n.locale
    end

    def invalid_locale(e)
      flash[:error] = e.message
      redirect_to root_url
    end

  end
end