/*!
 * All material copyright ESRI, All Rights Reserved, unless otherwise specified.
 * See https://github.com/Esri/calcite-components/blob/master/LICENSE.md for details.
 * v1.0.0-beta.97
 */
import { Build } from '@stencil/core/internal/client/index.js';

/**
 * This utility ensures observers are created only for browser contexts.
 *
 * @param type - the type of observer to create
 * @param callback - the observer callback
 * @param options - the observer options
 */
function createObserver(type, callback, options) {
  if (!Build.isBrowser) {
    return undefined;
  }
  const Observer = getObserver(type);
  return new Observer(callback, options);
}
function getObserver(type) {
  // based on https://github.com/whatwg/dom/issues/126#issuecomment-1049814948
  class ExtendedMutationObserver extends window.MutationObserver {
    constructor(callback) {
      super(callback);
      this.observedEntry = [];
      this.callback = callback;
    }
    observe(target, options) {
      this.observedEntry.push({ target, options });
      return super.observe(target, options);
    }
    unobserve(target) {
      const newObservedEntries = this.observedEntry.filter((observed) => observed.target !== target);
      this.observedEntry = [];
      this.callback(super.takeRecords(), this);
      this.disconnect();
      newObservedEntries.forEach((observed) => this.observe(observed.target, observed.options));
    }
  }
  return (function () {
    return (type === "intersection"
      ? window.IntersectionObserver
      : type === "mutation"
        ? ExtendedMutationObserver
        : window.ResizeObserver);
  })();
}

export { createObserver as c };