discourse/app/assets/javascripts/discourse/lib/show-modal.js.es6

export default (name, opts) => {
  opts = opts || {};

  if (opts.__type) {
    Ember.warn("showModal now takes `opts` as a second param instead of a model");
    opts = {model: opts};
  }

  const container = Discourse.__container__;

  // We use the container here because modals are like singletons
  // in Discourse. Only one can be shown with a particular state.
  const route = container.lookup('route:application');
  const modalController = route.controllerFor('modal');

  modalController.set('modalClass', null);

  const viewClass = container.lookupFactory('view:' + name);
  const controller = container.lookup('controller:' + name);
  if (viewClass) {
    route.render(name, { into: 'modal', outlet: 'modalBody' });
  } else {
    const templateName = Ember.String.dasherize(name);

    const renderArgs = { into: 'modal', outlet: 'modalBody', view: 'modal-body'};
    if (controller) { renderArgs.controller = name; }

    route.render('modal/' + templateName, renderArgs);
    if (opts.title) {
      modalController.set('title', I18n.t(opts.title));
    }
  }

  if (controller) {
    const model = opts.model;
    if (model) { controller.set('model', model); }
    if (controller.onShow) { controller.onShow(); }
    controller.set('flashMessage', null);
  }

  return controller;
};