import { EventEmitter } from "events";
import * as  net from "net";
import { assert } from "node-opcua-assert";

const port = 5678;
 
export class FakeServer extends EventEmitter {

    public port: number;
    public url: string;
    public tcpServer: net.Server;
    protected _serverSocket?: net.Socket;
    private _responses?: any[];

    constructor() {
        super();
        this.port = port;

        this.url = "opc.tcp://localhost:" + port;

        this.tcpServer = new net.Server();

        this._serverSocket = undefined;

        this.tcpServer.on("connection", (socket: net.Socket) => {
            assert(!this._serverSocket, " already connected");
            this._serverSocket = socket;

            this._serverSocket.on("data", (data: Buffer) => {
                const func = this.popResponse();
                if (func) {
                    func(this._serverSocket, data);
                }
            });
            this._serverSocket.on("err", (err: Error) => {
                // console.log(" @@@@ socket err ",err);
            });
            this._serverSocket.on("close", (err?: Error) => {
                // console.log(" @@@@ socket closed ",err);
            });
            this._serverSocket.on("end", (err?: Error) => {
                // console.log(" @@@@ socket end ",err);
                this.emit("end", err);
            });
        });
    }

    public initialize(done: () => void) {

        this.tcpServer.listen(this.port, () => {
            done();
        });
    }

    public shutdown(callback: (err?: Error) => void) {
        this.tcpServer.close(callback);
    }

    public popResponse() {
        if (!this._responses) {
            return null;
        }
        return this._responses.shift();
    }

    public pushResponse(func: any) {
        this._responses = this._responses || [];
        this._responses.push(func);
    }

}