import { EventEmitter } from "events" ; import { NodeCGIOCore } from "./index" ; import { NodeCG } from "nodecg-types/types/server" ; /**
 * A wrapper around a ServiceClient that has helper functions for setting up callbacks and
 * a function which just returns the current ServiceClient.
 * This class gets its client updates through the framework, namely using the  ServiceDependency . clientUpdateCallback .
  export class ServiceProvider < C > { private currentClient : C | undefined ; private em = new EventEmitter ( ) ; constructor ( ) { Object . defineProperty ( this , "currentClient" , { enumerable : false , writable : true } ) ; } return { C | undefined } getClient ( ) { return this . currentClient ; } param { ( client : C ) => void } handler onAvailable ( handler ) { this . em . on ( "set" , handler ) ; } param { ( ) => void } handler onUnavailable ( handler ) { this . em . on ( "unset" , handler ) ; } /**
     * Updates the client and calls all registered handlers of  onAvailable and  onUnavailable depending on
     * whether the passed client parameter was undefined or not.
     * This is only intended to be called by the framework and not by a bundle.
     *  param client updateClient ( client ) { this . currentClient = client ; this . em . emit ( client ? "set" : "unset" , client ) ; } } param { NodeCG } nodecg param { string } serviceType return { ServiceClientWrapper < C > | undefined } export function requireService < C > ( nodecg , serviceType ) { const core = nodecg . extensions [ "nodecg-io-core" ] as unknown as NodeCGIOCore | undefined ; if ( core === undefined ) { nodecg . log . error ( `nodecg-io-core isn't loaded! Can't require ${ serviceType } service for bundle ${ nodecg . bundleName }.` ) ; return ; } return core . requireService ( nodecg , serviceType ) ; }