/**
 * @license
 * Copyright 2022 Google Inc.
 * SPDX-License-Identifier: Apache-2.0
 */

import type {Protocol} from 'devtools-protocol';

import type {CDPSession} from '../api/CDPSession.js';
import type {EventEmitter, EventType} from '../common/EventEmitter.js';

import type {CdpTarget} from './Target.js';

/**
 * @internal
 */
export type TargetFactory = (
  targetInfo: Protocol.Target.TargetInfo,
  session?: CDPSession,
  parentSession?: CDPSession,
) => CdpTarget;

/**
 * @internal
 */
export const enum TargetManagerEvent {
  TargetDiscovered = 'targetDiscovered',
  TargetAvailable = 'targetAvailable',
  TargetGone = 'targetGone',
  /**
   * Emitted after a target has been initialized and whenever its URL changes.
   */
  TargetChanged = 'targetChanged',
}

/**
 * @internal
 */
export interface TargetManagerEvents extends Record<EventType, unknown> {
  [TargetManagerEvent.TargetAvailable]: CdpTarget;
  [TargetManagerEvent.TargetDiscovered]: Protocol.Target.TargetInfo;
  [TargetManagerEvent.TargetGone]: CdpTarget;
  [TargetManagerEvent.TargetChanged]: {
    target: CdpTarget;
    wasInitialized: true;
    previousURL: string;
  };
}

/**
 * TargetManager encapsulates all interactions with CDP targets and is
 * responsible for coordinating the configuration of targets with the rest of
 * Puppeteer. Code outside of this class should not subscribe `Target.*` events
 * and only use the TargetManager events.
 *
 * There are two implementations: one for Chrome that uses CDP's auto-attach
 * mechanism and one for Firefox because Firefox does not support auto-attach.
 *
 * @internal
 */
export interface TargetManager extends EventEmitter<TargetManagerEvents> {
  getAvailableTargets(): ReadonlyMap<string, CdpTarget>;
  getChildTargets(target: CdpTarget): ReadonlySet<CdpTarget>;
  initialize(): Promise<void>;
  dispose(): void;
}
