Select All Shenanigans

components.test\.js

import Component from "@glimmer/component";
import { action } from "@ember/object";
import { tracked } from "@glimmer/tracking";

export default class Test extends Component {
  @tracked selectedFiles = [];
  files = ["a", "b", "c"];

  @action
  handleFileToggle(file) {
    console.log(`Toggling file ${file}`);
    if (this.selectedFiles.includes(file)) {
      this.selectedFiles = this.selectedFiles.filter((f) => f !== file);
    } else {
      this.selectedFiles = [...this.selectedFiles, file];
    }
  }

  get areAllFilesSelected() {
    console.log("Running areAllFilesSelected getter");
    return this.selectedFiles.length === this.files.length;
  }

  get areSomeButNotAllFilesSelected() {
    console.log("Running areSomeButNotAllFilesSelected fn");
    return (
      this.selectedFiles.length > 0 &&
      this.selectedFiles.length !== this.files.length
    );
  }

  @action
  handleSelectAllChange(e) {
    console.log("handleSelectAllChange", e);
    e.preventDefault();

    if (!e.target.checked) {
      this.selectedFiles = [];
    } else {
      this.selectedFiles = [...this.files];
    }
  }
}

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

helpers.includes\.js

import { helper } from "@ember/component/helper";

export default helper(function ([needle, haystack]) {
  return needle.includes(haystack);
});

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>
<Test />
<br>
<br>

templates.components.test\.hbs

<label style="display: block;">
  Toggle ALL
  <Input 
    @type="checkbox" 
    @checked={{this.areAllFilesSelected}} 
    @indeterminate={{this.areSomeButNotAllFilesSelected}}
    {{on "change" this.handleSelectAllChange}} 
  />
</label>

<hr />

{{#each this.files as |file|}}
<label style="display: block;">
  Toggle {{file}}
  <Input 
  	@type="checkbox" 
    @checked={{includes this.selectedFiles file}}
    {{on "click" (fn this.handleFileToggle file)}} 
  />
</label>
{{/each}}

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}