module ReactiveRuby
  module ServerRendering
    def self.context_instance_name
      return '@rhino_context' if RUBY_PLATFORM == 'java'
      '@v8_context'
    end

    def self.context_instance_for(context)
      context.instance_variable_get(context_instance_name)
    end

    class ContextualRenderer < React::ServerRendering::SprocketsRenderer
      def initialize(options = {})
        super(options)
        ComponentLoader.new(v8_context).load
      end

      def render(component_name, props, prerender_options)
        if prerender_options.is_a?(Hash)
          if v8_runtime? && prerender_options[:context_initializer]
            raise PrerenderError.new(component_name, props, "you must use 'therubyracer' with the prerender[:context] option") unless v8_runtime?
          else
            prerender_options[:context_initializer].call v8_context
            prerender_options = prerender_options[:static] ? :static : true
          end
        end

        super(component_name, props, prerender_options)
      end

      private

      def v8_runtime?
        ["(V8)", "therubyrhino (Rhino)"].include?(ExecJS.runtime.name)
      end

      def v8_context
        @v8_context ||= ReactiveRuby::ServerRendering.context_instance_for(@context)
      end
    end
  end
end