// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.

((window) => {
  const add = Symbol("add");
  const signalAbort = Symbol("signalAbort");
  const remove = Symbol("remove");

  const illegalConstructorKey = Symbol("illegalConstructorKey");

  class AbortSignal extends EventTarget {
    #aborted = false;
    #abortAlgorithms = new Set();

    [add](algorithm) {
      this.#abortAlgorithms.add(algorithm);
    }

    [signalAbort]() {
      if (this.#aborted) {
        return;
      }
      this.#aborted = true;
      for (const algorithm of this.#abortAlgorithms) {
        algorithm();
      }
      this.#abortAlgorithms.clear();
      this.dispatchEvent(new Event("abort"));
    }

    [remove](algorithm) {
      this.#abortAlgorithms.delete(algorithm);
    }

    constructor(key) {
      if (key != illegalConstructorKey) {
        throw new TypeError("Illegal constructor.");
      }
      super();
      // HTML specification section 8.1.5.1
      let eventHandler = null;
      Object.defineProperty(this, "onabort", {
        get() {
          return eventHandler;
        },
        set(value) {
          if (eventHandler) {
            this.removeEventListener("abort", eventHandler);
          }
          eventHandler = value;
          if (typeof eventHandler === "function") {
            this.addEventListener("abort", value);
          }
        },
        configurable: true,
        enumerable: true,
      });
    }

    get aborted() {
      return Boolean(this.#aborted);
    }

    get [Symbol.toStringTag]() {
      return "AbortSignal";
    }
  }

  class AbortController {
    #signal = new AbortSignal(illegalConstructorKey);

    get signal() {
      return this.#signal;
    }

    abort() {
      this.#signal[signalAbort]();
    }

    get [Symbol.toStringTag]() {
      return "AbortController";
    }
  }

  window.AbortSignal = AbortSignal;
  window.AbortController = AbortController;
  window.__bootstrap = window.__bootstrap || {};
  window.__bootstrap.abortSignal = {
    add,
    signalAbort,
    remove,
  };
})(this);