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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.// Copyright Node.js contributors. All rights reserved. MIT License.
import {  ERR_EVENT_RECURSION,  ERR_INVALID_ARG_TYPE,  ERR_INVALID_THIS,  ERR_MISSING_ARGS,} from "./errors.ts";import { validateObject, validateString } from "./validators.mjs";import { emitWarning } from "../process.ts";import { nextTick } from "../_next_tick.ts";
import { customInspectSymbol, kEnumerableProperty } from "./util.mjs";import { inspect } from "../util.ts";
const kIsEventTarget = Symbol.for("nodejs.event_target");const kIsNodeEventTarget = Symbol("kIsNodeEventTarget");
import { EventEmitter } from "../events.ts";const {  kMaxEventTargetListeners,  kMaxEventTargetListenersWarned,} = EventEmitter;
const kEvents = Symbol("kEvents");const kIsBeingDispatched = Symbol("kIsBeingDispatched");const kStop = Symbol("kStop");const kTarget = Symbol("kTarget");const kHandlers = Symbol("khandlers");const kWeakHandler = Symbol("kWeak");
const kHybridDispatch = Symbol.for("nodejs.internal.kHybridDispatch");const kCreateEvent = Symbol("kCreateEvent");const kNewListener = Symbol("kNewListener");const kRemoveListener = Symbol("kRemoveListener");const kIsNodeStyleListener = Symbol("kIsNodeStyleListener");const kTrustEvent = Symbol("kTrustEvent");
const kType = Symbol("type");const kDefaultPrevented = Symbol("defaultPrevented");const kCancelable = Symbol("cancelable");const kTimestamp = Symbol("timestamp");const kBubbles = Symbol("bubbles");const kComposed = Symbol("composed");const kPropagationStopped = Symbol("propagationStopped");
function isEvent(value) {  return typeof value?.[kType] === "string";}
class Event extends globalThis.Event {  /**   * @param {string} type   * @param {{   *   bubbles?: boolean,   *   cancelable?: boolean,   *   composed?: boolean,   * }} [options]   */  constructor(type, options = null) {    super(type, options);    if (arguments.length === 0) {      throw new ERR_MISSING_ARGS("type");    }    validateObject(options, "options", {      allowArray: true,      allowFunction: true,      nullable: true,    });    const { cancelable, bubbles, composed } = { ...options };    this[kCancelable] = !!cancelable;    this[kBubbles] = !!bubbles;    this[kComposed] = !!composed;    this[kType] = `${type}`;    this[kDefaultPrevented] = false;    this[kTimestamp] = performance.now();    this[kPropagationStopped] = false;    this[kTarget] = null;    this[kIsBeingDispatched] = false;  }
  [customInspectSymbol](depth, options) {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    const name = this.constructor.name;    if (depth < 0) {      return name;    }
    const opts = Object.assign({}, options, {      depth: NumberIsInteger(options.depth) ? options.depth - 1 : options.depth,    });
    return `${name} ${      inspect({        type: this[kType],        defaultPrevented: this[kDefaultPrevented],        cancelable: this[kCancelable],        timeStamp: this[kTimestamp],      }, opts)    }`;  }
  stopImmediatePropagation() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    this[kStop] = true;  }
  preventDefault() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    this[kDefaultPrevented] = true;  }
  /**   * @type {EventTarget}   */  get target() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kTarget];  }
  /**   * @type {EventTarget}   */  get currentTarget() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kTarget];  }
  /**   * @type {EventTarget}   */  get srcElement() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kTarget];  }
  /**   * @type {string}   */  get type() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kType];  }
  /**   * @type {boolean}   */  get cancelable() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kCancelable];  }
  /**   * @type {boolean}   */  get defaultPrevented() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kCancelable] && this[kDefaultPrevented];  }
  /**   * @type {number}   */  get timeStamp() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kTimestamp];  }
  // The following are non-op and unused properties/methods from Web API Event.  // These are not supported in Node.js and are provided purely for  // API completeness.  /**   * @returns {EventTarget[]}   */  composedPath() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kIsBeingDispatched] ? [this[kTarget]] : [];  }
  /**   * @type {boolean}   */  get returnValue() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return !this.defaultPrevented;  }
  /**   * @type {boolean}   */  get bubbles() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kBubbles];  }
  /**   * @type {boolean}   */  get composed() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kComposed];  }
  /**   * @type {number}   */  get eventPhase() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kIsBeingDispatched] ? Event.AT_TARGET : Event.NONE;  }
  /**   * @type {boolean}   */  get cancelBubble() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    return this[kPropagationStopped];  }
  /**   * @type {boolean}   */  set cancelBubble(value) {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    if (value) {      this.stopPropagation();    }  }
  stopPropagation() {    if (!isEvent(this)) {      throw new ERR_INVALID_THIS("Event");    }    this[kPropagationStopped] = true;  }
  static NONE = 0;  static CAPTURING_PHASE = 1;  static AT_TARGET = 2;  static BUBBLING_PHASE = 3;}
Object.defineProperties(  Event.prototype,  {    [Symbol.toStringTag]: {      writable: true,      enumerable: false,      configurable: true,      value: "Event",    },    stopImmediatePropagation: kEnumerableProperty,    preventDefault: kEnumerableProperty,    target: kEnumerableProperty,    currentTarget: kEnumerableProperty,    srcElement: kEnumerableProperty,    type: kEnumerableProperty,    cancelable: kEnumerableProperty,    defaultPrevented: kEnumerableProperty,    timeStamp: kEnumerableProperty,    composedPath: kEnumerableProperty,    returnValue: kEnumerableProperty,    bubbles: kEnumerableProperty,    composed: kEnumerableProperty,    eventPhase: kEnumerableProperty,    cancelBubble: kEnumerableProperty,    stopPropagation: kEnumerableProperty,  },);
class NodeCustomEvent extends Event {  constructor(type, options) {    super(type, options);    if (options?.detail) {      this.detail = options.detail;    }  }}
// Weak listener cleanup// This has to be lazy for snapshots to worklet weakListenersState = null;// The resource needs to retain the callback so that it doesn't// get garbage collected now that it's weak.let objectToWeakListenerMap = null;function weakListeners() {  weakListenersState ??= new FinalizationRegistry(    (listener) => listener.remove(),  );  objectToWeakListenerMap ??= new WeakMap();  return { registry: weakListenersState, map: objectToWeakListenerMap };}
// The listeners for an EventTarget are maintained as a linked list.// Unfortunately, the way EventTarget is defined, listeners are accounted// using the tuple [handler,capture], and even if we don't actually make// use of capture or bubbling, in order to be spec compliant we have to// take on the additional complexity of supporting it. Fortunately, using// the linked list makes dispatching faster, even if adding/removing is// slower.class Listener {  constructor(    previous,    listener,    once,    capture,    passive,    isNodeStyleListener,    weak,  ) {    this.next = undefined;    if (previous !== undefined) {      previous.next = this;    }    this.previous = previous;    this.listener = listener;    // TODO(benjamingr) these 4 can be 'flags' to save 3 slots    this.once = once;    this.capture = capture;    this.passive = passive;    this.isNodeStyleListener = isNodeStyleListener;    this.removed = false;    this.weak = Boolean(weak); // Don't retain the object
    if (this.weak) {      this.callback = new WeakRef(listener);      weakListeners().registry.register(listener, this, this);      // Make the retainer retain the listener in a WeakMap      weakListeners().map.set(weak, listener);      this.listener = this.callback;    } else if (typeof listener === "function") {      this.callback = listener;      this.listener = listener;    } else {      this.callback = Function.prototype.bind.call(        listener.handleEvent,        listener,      );      this.listener = listener;    }  }
  same(listener, capture) {    const myListener = this.weak ? this.listener.deref() : this.listener;    return myListener === listener && this.capture === capture;  }
  remove() {    if (this.previous !== undefined) {      this.previous.next = this.next;    }    if (this.next !== undefined) {      this.next.previous = this.previous;    }    this.removed = true;    if (this.weak) {      weakListeners().registry.unregister(this);    }  }}
function initEventTarget(self) {  self[kEvents] = new Map();  self[kMaxEventTargetListeners] = EventEmitter.defaultMaxListeners;  self[kMaxEventTargetListenersWarned] = false;}
class EventTarget extends globalThis.EventTarget {  // Used in checking whether an object is an EventTarget. This is a well-known  // symbol as EventTarget may be used cross-realm.  // Ref: https://github.com/nodejs/node/pull/33661  static [kIsEventTarget] = true;
  constructor() {    super();    initEventTarget(this);  }
  [kNewListener](size, type, _listener, _once, _capture, _passive, _weak) {    if (      this[kMaxEventTargetListeners] > 0 &&      size > this[kMaxEventTargetListeners] &&      !this[kMaxEventTargetListenersWarned]    ) {      this[kMaxEventTargetListenersWarned] = true;      // No error code for this since it is a Warning      // eslint-disable-next-line no-restricted-syntax      const w = new Error(        "Possible EventTarget memory leak detected. " +          `${size} ${type} listeners ` +          `added to ${inspect(this, { depth: -1 })}. Use ` +          "events.setMaxListeners() to increase limit",      );      w.name = "MaxListenersExceededWarning";      w.target = this;      w.type = type;      w.count = size;      emitWarning(w);    }  }  [kRemoveListener](_size, _type, _listener, _capture) {}
  /**   * @callback EventTargetCallback   * @param {Event} event   */
  /**   * @typedef {{ handleEvent: EventTargetCallback }} EventListener   */
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @param {{   *   capture?: boolean,   *   once?: boolean,   *   passive?: boolean,   *   signal?: AbortSignal   * }} [options]   */  addEventListener(type, listener, options = {}) {    if (!isEventTarget(this)) {      throw new ERR_INVALID_THIS("EventTarget");    }    if (arguments.length < 2) {      throw new ERR_MISSING_ARGS("type", "listener");    }
    // We validateOptions before the shouldAddListeners check because the spec    // requires us to hit getters.    const {      once,      capture,      passive,      signal,      isNodeStyleListener,      weak,    } = validateEventListenerOptions(options);
    if (!shouldAddListener(listener)) {      // The DOM silently allows passing undefined as a second argument      // No error code for this since it is a Warning      // eslint-disable-next-line no-restricted-syntax      const w = new Error(        `addEventListener called with ${listener}` +          " which has no effect.",      );      w.name = "AddEventListenerArgumentTypeWarning";      w.target = this;      w.type = type;      emitWarning(w);      return;    }    type = String(type);
    if (signal) {      if (signal.aborted) {        return;      }      // TODO(benjamingr) make this weak somehow? ideally the signal would      // not prevent the event target from GC.      signal.addEventListener("abort", () => {        this.removeEventListener(type, listener, options);      }, { once: true, [kWeakHandler]: this });    }
    let root = this[kEvents].get(type);
    if (root === undefined) {      root = { size: 1, next: undefined };      // This is the first handler in our linked list.      new Listener(        root,        listener,        once,        capture,        passive,        isNodeStyleListener,        weak,      );      this[kNewListener](        root.size,        type,        listener,        once,        capture,        passive,        weak,      );      this[kEvents].set(type, root);      return;    }
    let handler = root.next;    let previous = root;
    // We have to walk the linked list to see if we have a match    while (handler !== undefined && !handler.same(listener, capture)) {      previous = handler;      handler = handler.next;    }
    if (handler !== undefined) { // Duplicate! Ignore      return;    }
    new Listener(      previous,      listener,      once,      capture,      passive,      isNodeStyleListener,      weak,    );    root.size++;    this[kNewListener](root.size, type, listener, once, capture, passive, weak);  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @param {{   *   capture?: boolean,   * }} [options]   */  removeEventListener(type, listener, options = {}) {    if (!isEventTarget(this)) {      throw new ERR_INVALID_THIS("EventTarget");    }    if (!shouldAddListener(listener)) {      return;    }
    type = String(type);    const capture = options?.capture === true;
    const root = this[kEvents].get(type);    if (root === undefined || root.next === undefined) {      return;    }
    let handler = root.next;    while (handler !== undefined) {      if (handler.same(listener, capture)) {        handler.remove();        root.size--;        if (root.size === 0) {          this[kEvents].delete(type);        }        this[kRemoveListener](root.size, type, listener, capture);        break;      }      handler = handler.next;    }  }
  /**   * @param {Event} event   */  dispatchEvent(event) {    if (!isEventTarget(this)) {      throw new ERR_INVALID_THIS("EventTarget");    }
    if (!(event instanceof globalThis.Event)) {      throw new ERR_INVALID_ARG_TYPE("event", "Event", event);    }
    if (event[kIsBeingDispatched]) {      throw new ERR_EVENT_RECURSION(event.type);    }
    this[kHybridDispatch](event, event.type, event);
    return event.defaultPrevented !== true;  }
  [kHybridDispatch](nodeValue, type, event) {    const createEvent = () => {      if (event === undefined) {        event = this[kCreateEvent](nodeValue, type);        event[kTarget] = this;        event[kIsBeingDispatched] = true;      }      return event;    };    if (event !== undefined) {      event[kTarget] = this;      event[kIsBeingDispatched] = true;    }
    const root = this[kEvents].get(type);    if (root === undefined || root.next === undefined) {      if (event !== undefined) {        event[kIsBeingDispatched] = false;      }      return true;    }
    let handler = root.next;    let next;
    while (      handler !== undefined &&      (handler.passive || event?.[kStop] !== true)    ) {      // Cache the next item in case this iteration removes the current one      next = handler.next;
      if (handler.removed) {        // Deal with the case an event is removed while event handlers are        // Being processed (removeEventListener called from a listener)        handler = next;        continue;      }      if (handler.once) {        handler.remove();        root.size--;        const { listener, capture } = handler;        this[kRemoveListener](root.size, type, listener, capture);      }
      try {        let arg;        if (handler.isNodeStyleListener) {          arg = nodeValue;        } else {          arg = createEvent();        }        const callback = handler.weak          ? handler.callback.deref()          : handler.callback;        let result;        if (callback) {          result = callback.call(this, arg);          if (!handler.isNodeStyleListener) {            arg[kIsBeingDispatched] = false;          }        }        if (result !== undefined && result !== null) {          addCatch(result);        }      } catch (err) {        emitUncaughtException(err);      }
      handler = next;    }
    if (event !== undefined) {      event[kIsBeingDispatched] = false;    }  }
  [kCreateEvent](nodeValue, type) {    return new NodeCustomEvent(type, { detail: nodeValue });  }  [customInspectSymbol](depth, options) {    if (!isEventTarget(this)) {      throw new ERR_INVALID_THIS("EventTarget");    }    const name = this.constructor.name;    if (depth < 0) {      return name;    }
    const opts = ObjectAssign({}, options, {      depth: Number.isInteger(options.depth)        ? options.depth - 1        : options.depth,    });
    return `${name} ${inspect({}, opts)}`;  }}
Object.defineProperties(EventTarget.prototype, {  addEventListener: kEnumerableProperty,  removeEventListener: kEnumerableProperty,  dispatchEvent: kEnumerableProperty,  [Symbol.toStringTag]: {    writable: true,    enumerable: false,    configurable: true,    value: "EventTarget",  },});
function initNodeEventTarget(self) {  initEventTarget(self);}
class NodeEventTarget extends EventTarget {  static [kIsNodeEventTarget] = true;  static defaultMaxListeners = 10;
  constructor() {    super();    initNodeEventTarget(this);  }
  /**   * @param {number} n   */  setMaxListeners(n) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    EventEmitter.setMaxListeners(n, this);  }
  /**   * @returns {number}   */  getMaxListeners() {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    return this[kMaxEventTargetListeners];  }
  /**   * @returns {string[]}   */  eventNames() {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    return Array.from(this[kEvents].keys());  }
  /**   * @param {string} [type]   * @returns {number}   */  listenerCount(type) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    const root = this[kEvents].get(String(type));    return root !== undefined ? root.size : 0;  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @param {{   *   capture?: boolean,   * }} [options]   * @returns {NodeEventTarget}   */  off(type, listener, options) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    this.removeEventListener(type, listener, options);    return this;  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @param {{   *   capture?: boolean,   * }} [options]   * @returns {NodeEventTarget}   */  removeListener(type, listener, options) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    this.removeEventListener(type, listener, options);    return this;  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @returns {NodeEventTarget}   */  on(type, listener) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    this.addEventListener(type, listener, { [kIsNodeStyleListener]: true });    return this;  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @returns {NodeEventTarget}   */  addListener(type, listener) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    this.addEventListener(type, listener, { [kIsNodeStyleListener]: true });    return this;  }
  /**   * @param {string} type   * @param {any} arg   * @returns {boolean}   */  emit(type, arg) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    validateString(type, "type");    const hadListeners = this.listenerCount(type) > 0;    this[kHybridDispatch](arg, type);    return hadListeners;  }
  /**   * @param {string} type   * @param {EventTargetCallback|EventListener} listener   * @returns {NodeEventTarget}   */  once(type, listener) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    this.addEventListener(type, listener, {      once: true,      [kIsNodeStyleListener]: true,    });    return this;  }
  /**   * @param {string} type   * @returns {NodeEventTarget}   */  removeAllListeners(type) {    if (!isNodeEventTarget(this)) {      throw new ERR_INVALID_THIS("NodeEventTarget");    }    if (type !== undefined) {      this[kEvents].delete(String(type));    } else {      this[kEvents].clear();    }
    return this;  }}
Object.defineProperties(NodeEventTarget.prototype, {  setMaxListeners: kEnumerableProperty,  getMaxListeners: kEnumerableProperty,  eventNames: kEnumerableProperty,  listenerCount: kEnumerableProperty,  off: kEnumerableProperty,  removeListener: kEnumerableProperty,  on: kEnumerableProperty,  addListener: kEnumerableProperty,  once: kEnumerableProperty,  emit: kEnumerableProperty,  removeAllListeners: kEnumerableProperty,});
// EventTarget API
function shouldAddListener(listener) {  if (    typeof listener === "function" ||    typeof listener?.handleEvent === "function"  ) {    return true;  }
  if (listener == null) {    return false;  }
  throw new ERR_INVALID_ARG_TYPE("listener", "EventListener", listener);}
function validateEventListenerOptions(options) {  if (typeof options === "boolean") {    return { capture: options };  }
  if (options === null) {    return {};  }  validateObject(options, "options", {    allowArray: true,    allowFunction: true,  });  return {    once: Boolean(options.once),    capture: Boolean(options.capture),    passive: Boolean(options.passive),    signal: options.signal,    weak: options[kWeakHandler],    isNodeStyleListener: Boolean(options[kIsNodeStyleListener]),  };}
function isEventTarget(obj) {  return obj instanceof globalThis.EventTarget;}
function isNodeEventTarget(obj) {  return obj?.constructor?.[kIsNodeEventTarget];}
function addCatch(promise) {  const then = promise.then;  if (typeof then === "function") {    then.call(promise, undefined, function (err) {      // The callback is called with nextTick to avoid a follow-up      // rejection from this promise.      emitUncaughtException(err);    });  }}
function emitUncaughtException(err) {  nextTick(() => {    throw err;  });}
function makeEventHandler(handler) {  // Event handlers are dispatched in the order they were first set  // See https://github.com/nodejs/node/pull/35949#issuecomment-722496598  function eventHandler(...args) {    if (typeof eventHandler.handler !== "function") {      return;    }    return Reflect.apply(eventHandler.handler, this, args);  }  eventHandler.handler = handler;  return eventHandler;}
function defineEventHandler(emitter, name) {  // 8.1.5.1 Event handlers - basically `on[eventName]` attributes  Object.defineProperty(emitter, `on${name}`, {    get() {      return this[kHandlers]?.get(name)?.handler ?? null;    },    set(value) {      if (!this[kHandlers]) {        this[kHandlers] = new Map();      }      let wrappedHandler = this[kHandlers]?.get(name);      if (wrappedHandler) {        if (typeof wrappedHandler.handler === "function") {          this[kEvents].get(name).size--;          const size = this[kEvents].get(name).size;          this[kRemoveListener](size, name, wrappedHandler.handler, false);        }        wrappedHandler.handler = value;        if (typeof wrappedHandler.handler === "function") {          this[kEvents].get(name).size++;          const size = this[kEvents].get(name).size;          this[kNewListener](size, name, value, false, false, false, false);        }      } else {        wrappedHandler = makeEventHandler(value);        this.addEventListener(name, wrappedHandler);      }      this[kHandlers].set(name, wrappedHandler);    },    configurable: true,    enumerable: true,  });}
const EventEmitterMixin = (Superclass) => {  class MixedEventEmitter extends Superclass {    constructor(...args) {      super(...args);      EventEmitter.call(this);    }  }  const protoProps = Object.getOwnPropertyDescriptors(EventEmitter.prototype);  delete protoProps.constructor;  Object.defineProperties(MixedEventEmitter.prototype, protoProps);  return MixedEventEmitter;};
export {  defineEventHandler,  Event,  EventEmitterMixin,  EventTarget,  initEventTarget,  initNodeEventTarget,  isEventTarget,  kCreateEvent,  kEvents,  kNewListener,  kRemoveListener,  kTrustEvent,  kWeakHandler,  NodeEventTarget,};
export default {  Event,  EventEmitterMixin,  EventTarget,  NodeEventTarget,  defineEventHandler,  initEventTarget,  initNodeEventTarget,  kCreateEvent,  kNewListener,  kTrustEvent,  kRemoveListener,  kEvents,  kWeakHandler,  isEventTarget,};