lowcode-engine/packages/editor-core/src/event-bus.ts

import { IPublicApiEvent } from '@alilc/lowcode-types';
import { Logger } from '@alilc/lowcode-utils';
import EventEmitter from 'events';

const logger = new Logger({ level: 'warn', bizName: 'event-bus' });
const moduleLogger = new Logger({ level: 'warn', bizName: 'module-event-bus' });

export interface IEventBus extends IPublicApiEvent {
  removeListener(event: string | symbol, listener: (...args: any[]) => void): any;
  addListener(event: string | symbol, listener: (...args: any[]) => void): any;
  setMaxListeners(n: number): any;
  removeAllListeners(event?: string | symbol): any;
}

export class EventBus implements IEventBus {
  private readonly eventEmitter: EventEmitter;
  private readonly name?: string;

  /**
   * 内核触发的事件名
   */
  readonly names = [];

  constructor(emitter: EventEmitter, name?: string) {
    this.eventEmitter = emitter;
    this.name = name;
  }

  private getMsgPrefix(type: string): string {
    if (this.name && this.name.length > 0) {
      return `[${this.name}][event-${type}]`;
    } else {
      return `[*][event-${type}]`;
    }
  }

  private getLogger(): Logger {
    if (this.name && this.name.length > 0) {
      return moduleLogger;
    } else {
      return logger;
    }
  }

  /**
   * 监听事件
   * @param event 事件名称
   * @param listener 事件回调
   */
  on(event: string, listener: (...args: any[]) => void): () => void {
    this.eventEmitter.on(event, listener);
    this.getLogger().debug(`${this.getMsgPrefix('on')} ${event}`);
    return () => {
      this.off(event, listener);
    };
  }

  /**
   * 取消监听事件
   * @param event 事件名称
   * @param listener 事件回调
   */
  off(event: string, listener: (...args: any[]) => void) {
    this.eventEmitter.off(event, listener);
    this.getLogger().debug(`${this.getMsgPrefix('off')} ${event}`);
  }

  /**
   * 触发事件
   * @param event 事件名称
   * @param args 事件参数
   * @returns
   */
  emit(event: string, ...args: any[]) {
    this.eventEmitter.emit(event, ...args);
    this.getLogger().debug(`${this.getMsgPrefix('emit')} name: ${event}, args: `, ...args);
  }

  removeListener(event: string | symbol, listener: (...args: any[]) => void): any {
    return this.eventEmitter.removeListener(event, listener);
  }

  addListener(event: string | symbol, listener: (...args: any[]) => void): any {
    return this.eventEmitter.addListener(event, listener);
  }

  setMaxListeners(n: number): any {
    return this.eventEmitter.setMaxListeners(n);
  }
  removeAllListeners(event?: string | symbol): any {
    return this.eventEmitter.removeAllListeners(event);
  }
}

export const createModuleEventBus = (moduleName: string, maxListeners?: number): IEventBus => {
  const emitter = new EventEmitter();
  if (maxListeners) {
    emitter.setMaxListeners(maxListeners);
  }
  return new EventBus(emitter, moduleName);
};