const { OPCUAClient , NodeCrawler} = require("node-opcua");
const async = require("async");
const util = require("util");

const client = OPCUAClient.create({
    endpoint_must_exist: false
});

// UA Automation Ansi Demo Server
const endpointUrl = "opc.tcp://localhost:48020";
const nodeToExplore = "ns=4;s=Demo.Massfolder_Dynamic";
const tree = {

}


function main(callback) {

    async.series([
        function (cb3) {

        client.connect(endpointUrl, function (err) {

            if (err) {
                console.log(" cannot connect to endpoint :", endpointUrl);
            } else {
                console.log("connected !");
            }
            cb3(err);

        });

        },
        function (cb3) {
        client.createSession(function (err, session) {
            if (err) {
                console.log("Failed to Create the Browse Session");
            }
            else {
                console.log("Browse Session Creates Session Successfully!");
                the_session = session;
            }
            cb3(err);
        });

        },
        function (cb3) {
        var crawler = new NodeCrawler(the_session);
        var nodeId = nodeToExplore
        console.log("Browsing Data in the server from "+ nodeToExplore.toString());
        crawler.read(nodeId, function (err, obj) {
            if (err) {
                console.log("Failed to Read Data");
            }
            else {
                console.log("Data read from PLC is Successful");
            }
            cb3(err);
        });

        crawler.on("browsed", function (element) {

            const parentNode = (element.parent && element.parent.$node )? element.parent.$node : tree;
            const key = element.browseName.toString() + " " +  element.nodeId.toString();
            // xxelement.nodeId.toString();
            if (!parentNode[key]) {
                parentNode[key] = {     };
             }
             const n = parentNode[key];
             element.$node = n;
             console.log("element name:" + element.browseName.toString());
        });
        }
    ],
        function (err) {
            console.log(util.inspect(tree,{ depth: 100}));

        if (err) {
            console.log("Failure in opcua browsing!", err);
            callback(err)
        } else {
            console.log("No Error :)");
            callback();
        }
        console.log("disconnected");
        client.disconnect(function () { });
        });
}
main((err)=>{
    console.log("done",err);
});