/**
 * @license Copyright 2018 The Lighthouse Authors. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */

import {ProtocolMapping as CrdpMappings} from 'devtools-protocol/types/protocol-mapping.js';

type CrdpEvents = CrdpMappings.Events;
type CrdpCommands = CrdpMappings.Commands;

declare module Protocol {
  type TargetType = 'page' | 'iframe' | 'worker';

  /**
   * An intermediate type, used to create a record of all possible Crdp raw event
   * messages, keyed on method. e.g. {
   *   'Domain.method1Name': {method: 'Domain.method1Name', params: EventPayload1},
   *   'Domain.method2Name': {method: 'Domain.method2Name', params: EventPayload2},
   * }
   */
  type RawEventMessageRecord = {
    [K in keyof CrdpEvents]: {
      method: K,
      // Drop [] for `undefined` (so a JS value is valid).
      params: CrdpEvents[K] extends [] ? undefined: CrdpEvents[K][number]
      targetType: TargetType;
      // If sessionId is not set, it means the event was from the root target.
      sessionId?: string;
    };
  }

  /**
   * Union of raw (over the wire) message format of all possible Crdp events,
   * of the form `{method: 'Domain.event', params: eventPayload}`.
   */
  type RawEventMessage = RawEventMessageRecord[keyof RawEventMessageRecord];

  /**
   * Raw (over the wire) message format of all possible Crdp command responses.
   */
  type RawCommandMessage = {
    id: number;
    result: CrdpCommands[keyof CrdpCommands]['returnType'];
    error: {
      code: number,
      message: string
    };
  }

  /**
   * Raw (over the wire) message format of all possible Crdp events and command
   * responses.
   */
  type RawMessage = RawCommandMessage | RawEventMessage;

  /**
   * A more strictly-typed EventEmitter interface that checks the association
   * of event name and listener payload. TEventRecord should be a record mapping
   * event names to tuples that can contain zero or more items, which will
   * serve as the arguments to event listener callbacks.
   * Inspired by work from https://github.com/bterlson/strict-event-emitter-types.
   */
  type StrictEventEmitter<TEventRecord extends Record<keyof TEventRecord, unknown[]>> = {
    on<E extends keyof TEventRecord>(event: E, listener: (...args: TEventRecord[E]) => void): void;

    off<E extends keyof TEventRecord>(event: E, listener: Function): void;

    addListener<E extends keyof TEventRecord>(event: E, listener: (...args: TEventRecord[E]) => void): void;

    removeListener<E extends keyof TEventRecord>(event: E, listener: Function): void;

    removeAllListeners<E extends keyof TEventRecord>(event?: E): void;

    once<E extends keyof TEventRecord>(event: E, listener: (...args: TEventRecord[E]) => void): void;

    emit<E extends keyof TEventRecord>(event: E, ...request: TEventRecord[E]): void;

    listenerCount<E extends keyof TEventRecord>(event: E): number;
  }

  /**
   * A constructable StrictEventEmitter.
   */
  interface StrictEventEmitterClass<TEventRecord extends Record<keyof TEventRecord, unknown[]>> {
    new(): StrictEventEmitter<TEventRecord>;
  }
}

export default Protocol;