feathersjs/feathers

import { RealTimeConnection } from '@feathersjs/feathers'
import { Channel } from './base'

function collectConnections(children: Channel[]) {
  const mappings = new WeakMap<RealTimeConnection, any>()
  const connections: RealTimeConnection[] = []

  children.forEach((channel) => {
    channel.connections.forEach((connection) => {
      if (!mappings.has(connection)) {
        connections.push(connection)
        mappings.set(connection, channel.data)
      }
    })
  })

  return { connections, mappings }
}

export class CombinedChannel extends Channel {
  children: Channel[]
  mappings: WeakMap<RealTimeConnection, any>

  constructor(children: Channel[], data: any = null) {
    const { mappings, connections } = collectConnections(children)

    super(connections, data)

    this.children = children
    this.mappings = mappings
  }

  refresh() {
    const collected = collectConnections(this.children)

    return Object.assign(this, collected)
  }

  leave(...connections: RealTimeConnection[]) {
    return this.callChildren('leave', connections)
  }

  join(...connections: RealTimeConnection[]) {
    return this.callChildren('join', connections)
  }

  dataFor(connection: RealTimeConnection) {
    return this.mappings.get(connection)
  }

  private callChildren(method: string, connections: RealTimeConnection[]) {
    this.children.forEach((child: any) => child[method](...connections))
    this.refresh()

    return this
  }
}