import { Datastore , IServerAdapter } from "@lumino/datastore" ; import io , { Socket } from "socket.io-client" ; type TransactionHandler = ( transaction : Datastore . Transaction ) => void ; /**
 * A class that manages exchange of transactions with the collaboration server.
 *
 * Starts without the `onRemoteTransaction` set, but once it is we should connect
 * to the underlying socket. This is set when we create the Datastore for this adapter.
 */ export class CollaborationClient implements IServerAdapter { state : { label : "initial" ; } | { label : "connected" ; socket : typeof Socket ; } | { label : "disposed" ; } = { label : "initial" , } ; get isDisposed ( ) : boolean { return this . state . label === "disposed" ; } /**
     * Set by datastore when passed to it
     */ onUndo ! : ( ( transaction : Datastore . Transaction ) => void ) | null ; onRedo ! : ( ( transaction : Datastore . Transaction ) => void ) | null ; constructor ( private options ) { } broadcast ( transaction ) { if ( this . state . label !== "connected" ) { throw new Error ( "Cannot broadcast transactions before connected" ) ; } this . state . socket . emit ( "transaction" , transaction ) ; } undo ( ) { throw new Error ( "Method not implemented." ) ; } redo ( ) { throw new Error ( "Method not implemented." ) ; } set onRemoteTransaction ( onRemoteTransaction ) { if ( this . state . label !== "initial" ) { throw new Error ( "Can only set remote transaction function once, after creationg" ) ; } const socket = io ( this . options . url ) ; socket . on ( "transactions" , ( transactions ) => { transactions . map ( ( t ) => onRemoteTransaction ( t ) ) ; this . options . onLoad ( ) ; } ) ; socket . on ( "transaction" , ( t ) => onRemoteTransaction ( t ) ) ; this . state = { label : "connected" , socket , } ; } /**
     * Closes last socket and cleans up all observables.
     */ dispose ( ) { if ( this . state . label === "disposed" ) { return ; } if ( this . state . label === "connected" ) { this . state . socket . close ( ) ; } this . state = { label : "disposed" } ; } }