# this is heavily influenced by react-rails:
# https://github.com/reactjs/react-rails/blob/master/lib/react/server_rendering/exec_js_renderer.rb
class ExecJsRenderer
  JS_TEMPLATE = <<~JS
    var execJsGlobal = {};
    var self = self || this;
    var window = window || this;
  JS

  def initialize(js_code)
    @context = ExecJS.compile(JS_TEMPLATE + js_code)
  end

  def render(component_name, props)
    js_code = <<~JS
      (function() {
        var component = execJsGlobal["#{component_name}"];
        var sheet = new execJsGlobal.ServerStyleSheet();
        var element = execJsGlobal.React.createElement(component, #{props.to_json});
        var html = execJsGlobal.ReactDOMServer.renderToString(sheet.collectStyles(element));
        var styles = sheet.getStyleTags();
        return html + styles;
      })()
    JS
    @context.eval(js_code).html_safe
  end

  private

  def compose_js(js)
    <<~JS
    (function() {
      var result = #{js};
      return result;
    })()
    JS
  end
end