"use strict";
  
  const HTMLElementImpl = require("./HTMLElement-impl").implementation;
  const MouseEvent = require("../generated/MouseEvent");
  const { domSymbolTree } = require("../helpers/internal-constants");
  const NODE_TYPE = require("../node-type");
  const { isLabelable, isDisabled } = require("../helpers/form-controls");
  const { fireAnEvent } = require("../helpers/events");
  
  function sendClickToAssociatedNode(node) {
    fireAnEvent("click", node, MouseEvent, {
      bubbles: true,
      cancelable: true,
      view: node.ownerDocument ? node.ownerDocument.defaultView : null,
      screenX: 0,
      screenY: 0,
      clientX: 0,
      clientY: 0,
      button: 0,
      detail: 1,
      relatedTarget: null
    });
  }
  
  class HTMLLabelElementImpl extends HTMLElementImpl {
    constructor(globalObject, args, privateData) {
      super(globalObject, args, privateData);
  
      this._hasActivationBehavior = true;
    }
  
    get control() {
      if (this.hasAttributeNS(null, "for")) {
        const forValue = this.getAttributeNS(null, "for");
        if (forValue === "") {
          return null;
        }
        const root = this.getRootNode({});
        for (const descendant of domSymbolTree.treeIterator(root)) {
          if (descendant.nodeType === NODE_TYPE.ELEMENT_NODE &&
            descendant.getAttributeNS(null, "id") === forValue) {
            return isLabelable(descendant) ? descendant : null;
          }
        }
        return null;
      }
      for (const descendant of domSymbolTree.treeIterator(this)) {
        if (isLabelable(descendant)) {
          return descendant;
        }
      }
      return null;
    }
  
    get form() {
      const node = this.control;
      if (node) {
        return node.form;
      }
      return null;
    }
  
    _activationBehavior() {
      const node = this.control;
      if (node && !isDisabled(node)) {
        sendClickToAssociatedNode(node);
      }
    }
  }
  
  module.exports = {
    implementation: HTMLLabelElementImpl
  };