discourse/app/assets/javascripts/admin/controllers/admin-email-preview-digest.js.es6

import EmailPreview from 'admin/models/email-preview';
import { popupAjaxError } from 'discourse/lib/ajax-error';

export default Ember.Controller.extend({
  username: null,
  lastSeen: null,

  emailEmpty: Ember.computed.empty('email'),
  sendEmailDisabled: Ember.computed.or('emailEmpty', 'sendingEmail'),
  showSendEmailForm: Ember.computed.notEmpty('model.html_content'),
  htmlEmpty: Ember.computed.empty('model.html_content'),

  actions: {
    refresh() {
      const model = this.get('model');

      this.set('loading', true);
      this.set('sentEmail', false);

      let username = this.get('username');
      if (!username) {
        username = this.currentUser.get('username');
        this.set('username', username);
      }

      EmailPreview.findDigest(username, this.get('lastSeen')).then(email => {
        model.setProperties(email.getProperties('html_content', 'text_content'));
        this.set('loading', false);
      });
    },

    toggleShowHtml() {
      this.toggleProperty('showHtml');
    },

    sendEmail() {
      this.set('sendingEmail', true);
      this.set('sentEmail', false);

      EmailPreview.sendDigest(this.get('username'), this.get('lastSeen'), this.get('email')).then(result => {
        if (result.errors) {
          bootbox.alert(result.errors);
        } else {
          this.set('sentEmail', true);
        }
      }).catch(popupAjaxError).finally(() => {
        this.set('sendingEmail', false);
      });
    }
  }

});