SKY MODULE - button widgets for calculator
<!-- TODO(ianh): implement accessibility handling once the ax service exists -->

<script>
  class AbstractButton extends Element {
    constructor (hostModule) {
      super(hostModule);
      let selector = new SelectorQuery('.dynamic');
      this.addEventListener('pointer-down', (event) => {
        selector.findAll(this.shadowRoot).every((element) => element.setAttribute('clicked'));
        // TODO(ianh): track the pointer; if it leaves the button, cancel the click
        // TOOD(ianh): if the pointer doesn't leave the button before being released, then fire some event on ourselves
        module.application.document.addEventListener('pointer-up', function upHandler (event) {
          module.application.document.removeEventListener('pointer-up', upHandler);
          selector.findAll(this.shadowRoot).every((element) => element.removeAttribute('clicked'));
        });
      });
    }
  }
</script>

<template id="threed-button-shadow-tree">
 <style>
  /* TODO(ianh): make this shrink-wrap the contents */
  div { border: solid 1px; }
  #a { border-color: #666666 #333333 #333333 #666666; }
  #b { border-color: #EEEEEE #666666 #666666 #EEEEEE; }
  #c { border-color: #EEEEEE #666666 #666666 #EEEEEE; }
  #d { border-color: #EEEEEE #999999 #999999 #EEEEEE; padding: 2px 0 0 0; background: #DDDDDD; color: black; text-align: center; }
  #a[clicked] { border-color: #666666 #333333 #333333 #666666; width: 6em; }
  #b[clicked] { border-color: #666666 #DDDDDD #DDDDDD #666666; border-width: 1px 0 0 1px; }
  #c[clicked] { border-color: #666666 #DDDDDD #DDDDDD #666666; border-width: 1px 0 0 1px; }
  #d[clicked] { border-color: #999999 #DDDDDD #DDDDDD #999999; padding: 4px 0 0 2px; }
 </style>
 <div class="dynamic" id="a">
  <div class="dynamic" id="b">
   <div class="dynamic" id="c">
    <div class="dynamic" id="d">
     <content/>
    </div>
   </div>
  </div>
 </div>
</template>

<template id="flat-button-shadow-tree">
 <style>
  div { background: green; color: yellow; }
  div[clicked] { background: yellow; color: green; }
 </style>
 <div class=dynamic>
  <content/>
 </div>
</template>

<script>
 module.exports = {
   ThreeDButtonElement: module.registerElement(
     class extends AbstractButton {
       static get tagName() { return 'graybutton'; }
       static get shadow() { return true; }
       constructor (hostModule) {
         super(hostModule);
         this.shadowRoot.append(module.document.findId('threed-button-shadow-tree').cloneNode(true));
       }
     }
   ),
   FlatButtonElement: module.registerElement(
     class extends AbstractButton {
       static get tagName() { return 'flatbutton'; }
       static get shadow() { return true; }
       constructor (hostModule) {
         super(hostModule);
         this.shadowRoot.append(module.document.findId('flat-shadow-tree').cloneNode(true));
       }
     }
   ),
 };
</script>