feathersjs/feathers

import { EventEmitter } from 'events'
import { RealTimeConnection } from '@feathersjs/feathers'

export class Channel extends EventEmitter {
  connections: RealTimeConnection[]
  data: any

  constructor(connections: RealTimeConnection[] = [], data: any = null) {
    super()

    this.connections = connections
    this.data = data
  }

  get length() {
    return this.connections.length
  }

  leave(...connections: RealTimeConnection[]) {
    connections.forEach((current) => {
      if (typeof current === 'function') {
        const callback = current as (connection: RealTimeConnection) => boolean

        this.leave(...this.connections.filter(callback))
      } else {
        const index = this.connections.indexOf(current)

        if (index !== -1) {
          this.connections.splice(index, 1)
        }
      }
    })

    if (this.length === 0) {
      this.emit('empty')
    }

    return this
  }

  join(...connections: RealTimeConnection[]) {
    connections.forEach((connection) => {
      if (connection && this.connections.indexOf(connection) === -1) {
        this.connections.push(connection)
      }
    })

    return this
  }

  filter(fn: (connection: RealTimeConnection) => boolean) {
    return new Channel(this.connections.filter(fn), this.data)
  }

  send(data: any) {
    return new Channel(this.connections, data)
  }
}