server.js

const http = require("http");

const PORT = 3000;
const HEADERS = {
  "Content-Type": "application/json",
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Methods": "OPTIONS, POST, GET",
  "Access-Control-Max-Age": 2592000,
};
const GET_ENDPOINT = "/ratp/ligne7/departures/courneuve";
const SERVER_START_MESSAGE = [
  `[START] Listening on ${PORT}`,
  `[ENDPOINT] ${GET_ENDPOINT}`,
].join("\n");
const LINE_HOUR_START = "06:30:00".split(":");
const LINE_HOUR_END = "00:30:00".split(":");

let departures = initDepartures();
let status = initStatus();

setInterval(() => {
  if (!isLineOpen()) {
    departures = [];
    status = "closed";
    return;
  }

  status = "open";
  for (const d of departures) {
    if (d.minutes === 0) {
      d.minutes = 7;
      continue;
    }
    d.minutes -= 1;
  }
}, seconds(60));

http
  .createServer(async (req, res) => {
    switch (req.url) {
      case GET_ENDPOINT:
        send(res, 200, { status, departures });
    }
  })
  .listen(PORT, "localhost", () => console.log(SERVER_START_MESSAGE));

function send(res, status, message) {
  res.writeHead(status, HEADERS);
  // console.log(message)
  res.end(JSON.stringify({ response: message }));
}

function isLineOpen() {
  const now = new Date(Date.now());
  const TODAY_START = new Date();
  const TODAY_END = new Date();
  TODAY_START.setHours(
    LINE_HOUR_START[0],
    LINE_HOUR_START[1],
    LINE_HOUR_START[2],
    0,
  );
  TODAY_END.setHours(LINE_HOUR_END[0], LINE_HOUR_END[1], LINE_HOUR_END[2], 0);

  if (now > TODAY_END && now < TODAY_START) {
    return false;
  } else {
    return true;
  }
}

function initStatus() {
  if (!isLineOpen) {
    return "closed";
  }
  return "open";
}

function initDepartures() {
  if (!isLineOpen) {
    return [];
  }
  return [
    { id: 1, minutes: 10 },
    { id: 2, minutes: 4 },
    { id: 3, minutes: 6 },
    { id: 4, minutes: 0 },
    { id: 5, minutes: 2 },
    { id: 6, minutes: 4 },
    { id: 7, minutes: 6 },
    { id: 8, minutes: 0 },
    { id: 9, minutes: 2 },
    { id: 10, minutes: 4 },
    { id: 11, minutes: 6 },
    { id: 12, minutes: 0 },
    { id: 13, minutes: 2 },
    { id: 14, minutes: 4 },
    { id: 15, minutes: 6 },
    { id: 16, minutes: 0 },
    { id: 17, minutes: 2 },
    { id: 18, minutes: 4 },
    { id: 19, minutes: 6 },
    { id: 20, minutes: 0 },
    { id: 21, minutes: 2 },
    { id: 22, minutes: 4 },
    { id: 23, minutes: 6 },
    { id: 24, minutes: 0 },
    { id: 25, minutes: 2 },
    { id: 26, minutes: 4 },
    { id: 27, minutes: 6 },
    { id: 28, minutes: 0 },
    { id: 29, minutes: 2 },
    { id: 30, minutes: 4 },
    { id: 31, minutes: 6 },
    { id: 32, minutes: 0 },
    { id: 33, minutes: 2 },
    { id: 34, minutes: 4 },
    { id: 35, minutes: 6 },
    { id: 36, minutes: 0 },
    { id: 37, minutes: 2 },
    { id: 38, minutes: 4 },
    { id: 39, minutes: 6 },
  ];
}

function seconds(count) {
  return count * 1000;
}