let stream;
async function main() {
    const uri = "mongodb://127.0.0.1:26000/";
    const client = new MongoClient(uri, { useNewUrlParser: true });
    
    try {
        await client.connect()
    } catch (err) {
        console.error("failed to connect to MongoDB")
    }
    stream = client.watch([], {
    // let stream = client.db("realm").collection("blogs").watch(watchPipeline, {
        fullDocument: "updateLookup"
    });

    stream.on("change", onStreamChangeEvent);
    stream.on("close", onStreamClose);
    stream.on("end", onStreamEnd);
    stream.on("error", onStreamError);
}

function onStreamChangeEvent(rawEvent: object) {
    console.log(rawEvent);
};

function onStreamClose() {
    console.warn("MongoDB stream closed.");
};

function onStreamEnd() {
    console.warn("MongoDB stream ended.");
};

function onStreamError(err) {
    console.error("MongoDB stream encountered error:");
    console.error(err.stack);

    stream.close();
};


main();

console.log("Now watching events.")

const cursor = this.cursor;
return cursor.close(err => {
  ['data', 'close', 'end', 'error'].forEach(event => cursor.removeAllListeners(event));
  delete this.cursor;

  if (callback) return callback(err);
  return this.promiseLibrary.resolve();
});