discourse/app/assets/javascripts/admin/addon/controllers/admin-customize-themes.js

import Controller from "@ember/controller";
import { THEMES } from "admin/models/theme";
import discourseComputed from "discourse-common/utils/decorators";

export default Controller.extend({
  currentTab: THEMES,

  @discourseComputed("model", "model.@each.component")
  fullThemes(themes) {
    return themes.filter((t) => !t.get("component"));
  },

  @discourseComputed("model", "model.@each.component")
  childThemes(themes) {
    return themes.filter((t) => t.get("component"));
  },

  @discourseComputed("model.content")
  installedThemes(content) {
    return content || [];
  },
});