module LiquorTemplateLoader
  def self.namespace_to_params(pack, namespace)
    if namespace == :html
      scope     = pack.html_templates
      externals = [ :site, :request ]
    elsif namespace == :email
      scope     = pack.email_templates
      externals = [ :site, :subscription ]
    end

    [ scope, externals ]
  end

  def self.load(pack, namespace)
    manager = Liquor::Manager.new(import: [
      # Plugins
      Liquor::Pagination,
      FeedbackTag,
      EmailTag,

      # Core and plugin functions
      CoreFunctions,

      # Functions by model classes
      VideoFunctions,
      PostFunctions,
      MobileFunctions,
      EventFunctions,
      MarkupFunctions
    ])

    scope, scope_externals = namespace_to_params(pack, namespace)
    template_externals_map = scope.system_templates

    ActiveSupport::Notifications.instrument("load.liquor") do
      scope.includes(:site).turned_on.each do |template|
        name, body = template.name, template.body

        if manager.partial? name
          manager.register_partial name, body
        else
          ActiveSupport::Notifications.instrument("load_template.liquor", name: name) do
            if template_externals_map.include? name
              externals = scope_externals + template_externals_map[name]
            else
              externals = scope_externals
            end

            manager.register_template name, body, externals
          end
        end
      end
    end

    ActiveSupport::Notifications.instrument("compile.liquor") do
      manager.compile
    end

    manager
  end

  def self.try_load(pack, namespace)
    manager = load(pack, namespace)

    manager.errors
  end

  @cache            = {}
  @cache_timestamps = {}

  def self.load_with_caching(pack, namespace)
    cache_key = "#{pack.id}_#{namespace}"

    scope,          = namespace_to_params(pack, namespace)
    last_updated_at = scope.maximum('updated_at') || Time.now

    if !@cache_timestamps.has_key?(cache_key) ||
        @cache_timestamps[cache_key] < last_updated_at
      @cache[cache_key]            = load(pack, namespace)
      @cache_timestamps[cache_key] = last_updated_at
    end

    @cache[cache_key]
  end
end