example pusher with nestjs

pusher.service.ts

import * as Pusher from 'pusher'
import { Injectable } from '@nestjs/common'

@Injectable()
export class PusherService {
  private pusher = new Pusher({
    appId: process.env.PUSHER_APP_ID,
    key: process.env.PUSHER_APP_KEY,
    secret: process.env.PUSHER_APP_SECRET,
    cluster: process.env.PUSHER_APP_CLUSTER,
    useTLS: true
  })

  private isStringTooLong = (str: string): boolean => {
    return str.length > 10240 // 10kb
  }

  public async authenticate(
    socketId: string,
    channel: string
  ): Promise<Pusher.AuthResponse> {
    const presenceData = {
      user_id: socketId,
      user_info: {}
    }

    return this.pusher.authenticate(socketId, channel, presenceData)
  }

  public emitMessageToUser(
    channelName: string,
    eventName: string,
    data: any
  ): Promise<Response> {
    try {
      if (this.isStringTooLong(data)) {
        console.error(`The data content of events must be smaller than 10kB.`)
        return
      }

      return this.pusher.trigger(channelName, eventName, data)
    } catch (e) {
      console.error(e)
    }
  }

  public async getChannels(): Promise<string[]> {
    try {
      const response = await this.pusher.get({ path: '/channels' })
      if (response.status !== 200) {
        throw new Error(`Unexpected response status: ${response.status}`)
      }

      const { channels } = await response.json()
      if (channels) {
        return Object.keys(channels)
      }
    } catch (e) {
      console.error(`Error fetching channels: ${e.message}`)
      throw e
    }

    return []
  }
}