import { EventBusSession, EventBus } from './eventBus';
import { sortBy } from 'lodash-es';
import { arrayLast } from '../index';

export class EventBusManager {
  private static instance?: EventBusManager;
  static getInstance(): EventBusManager {
    if (!this.instance) {
      this.instance = new EventBusManager();
    }
    return this.instance;
  }

  private eventBuses: { eventBus: EventBus; priority: number }[] = [];

  private tempEventBusMap = new Map<Symbol, EventBus>();

  private tempEventSessionMap = new Map<Symbol, EventBusSession>();

  registerEventBus(eventBus: EventBus, priority: number) {
    this.eventBuses.push({
      eventBus,
      priority,
    });
    this.eventBuses = sortBy(
      this.eventBuses,
      (item: { priority: any }) => item.priority,
    );
  }

  unregisterEventBus(eventBus: EventBus) {
    this.eventBuses = this.eventBuses.filter(
      item => item.eventBus !== eventBus,
    );
  }

  getActiveEventBus(): EventBus | undefined {
    const lastEventBus = arrayLast(this.eventBuses);
    return lastEventBus?.eventBus;
  }

  registerTempEventBus(key: Symbol, priority = 1, eventBus?: EventBus) {
    if (!this.tempEventBusMap.get(key)) {
      const tempEventBus = eventBus || new EventBus();
      this.registerEventBus(tempEventBus, priority);

      this.tempEventBusMap.set(key, tempEventBus);

      this.tempEventSessionMap.set(key, tempEventBus.getSession());
    }
    return this.tempEventBusMap.get(key);
  }

  unRegisterTempEventBus(key: Symbol) {
    const currentEventSession = this.tempEventSessionMap.get(key);
    currentEventSession?.clear();
    const currentEventBus = this.tempEventBusMap.get(key);
    if (currentEventBus) {
      this.unregisterEventBus(currentEventBus);
      this.tempEventSessionMap.delete(key);
      this.tempEventBusMap.delete(key);
    }
  }

  getTempEventBus(key: Symbol) {
    return this.tempEventBusMap.get(key);
  }

  getTempEventSession(key: Symbol) {
    if (!this.tempEventSessionMap.get(key)) {
      throw new Error(
        'please register tempEventBus before get tempEventBusSession',
      );
    }
    return this.tempEventSessionMap.get(key);
  }
}