server.js

const express = require("express");
const { v4: uuidv4 } = require("uuid");
const app = express();
const port = 3000;

/* const dataStructure = {
  ID: "9d451283-9e83-48eb-9c29-e7411f81eaf5",
  timestamp: new Date(),
  latitude: 51.494449497662984,
  longitude: -0.17357715798513457,
};
 */

function randLatitude() {
  //latitude coordinate must be between -90 and 90
  const max = 90;
  const min = -90;
  return (Math.random() * (max - min + 1) + min).toFixed(4);
}

function randLongitude() {
  // longitude coordinate must be between -180 and 180
  const max = 180;
  const min = -180;
  return (Math.random() * (max - min + 1) + min).toFixed(4);
}

function randData() {
  const dataObject = {
    ID: uuidv4(),
    timestamp: new Date().toISOString(),
    latitude: randLatitude(),
    longitude: randLongitude(),
  };
  console.log(dataObject);
}

// ----------------------------------------------------
/* Express App */

const initialEventsPerMinute = 30;
let sleepTimeMilliseconds = (60 / initialEventsPerMinute) * 1000;
let timer = null;

app.use(express.json());

// Bereitstellen der statischen Dateien (HTML, CSS, JS), die für die Darstellung der Webseite genutzt werden
app.use("/", express.static("www"));
app.use("/lib", express.static("node_modules"));

// Bereitstellen der Router
app.get("/api/start", (req, res) => {
  timer = setInterval(randData, sleepTimeMilliseconds);
  res.send("Starting to generate data");
});

app.get("/api/stop", (req, res) => {
  clearInterval(timer);
  timer = null;
  res.send("Stopping to generate data");
});

app.get("/api/config", (req, res) => {
  const configObj = {
    running: timer ? true : false,
    sleepTimeMilliseconds: sleepTimeMilliseconds,
  };
  res.send(configObj);
});

app.post("/api/config", function (req, res) {
  console.log("Request: " + "Method=" + req.method + ", URL=" + req.originalUrl);

  if (timer === null) {
    const eventsPerMinute = req.body.eventsPerMinute;
    sleepTimeMilliseconds = (60 / eventsPerMinute) * 1000;

    res.sendStatus(200);
  } else if (timer != null) {
    res.sendStatus(401);
  }
});

// Starten der App
app.listen(port, () => {
  console.log(`App listening at http://localhost:${port}`);
});