// vim: set ts=2 sw=2 et tw=80:

// Real code

const URL = 'https://usirooms.maggioni.xyz/schedule.html?name=';
const NOW = new Date();

const timeTable = {};

function roomStatus(room, callback) {
  return new Promise((resolve, _) => {
    const xhr = new XMLHttpRequest();
    xhr.addEventListener('load', () => {
      const parser = new DOMParser();
      const doc = parser.parseFromString(xhr.responseText, 'text/html');
      const lessons = doc.querySelectorAll(
        'table.rsContentTable div.rsAptSimple');
      const parsed = [];

      for (let lesson of lessons) {
        const time = lesson.querySelector('span[id$=lblOrario]');
        const start = new Date();
        start.setHours(parseInt(time.innerText.substring(1,3)));
        start.setMinutes(parseInt(time.innerText.substring(4,6)));
        start.setSeconds(0);

        const end = new Date();
        end.setHours(parseInt(time.innerText.substring(7,9)));
        end.setMinutes(parseInt(time.innerText.substring(10,12)));
        end.setSeconds(0);

        parsed.push({
          title: lesson.getAttribute('title').trim(),
          start: start,
          end: end
        });
      }

      let start = new Date();
      start.setHours(0);
      start.setMinutes(0);
      start.setSeconds(0);

      let s = start;

      let end = new Date();
      end.setHours(23);
      end.setMinutes(59);
      end.setSeconds(0);

      const holes = [];
      for (let i = 0; i <= parsed.length; i++) {
        const time = i == parsed.length ? end : parsed[i].start;
        if (time > s) {
          holes.push({title: "Unassigned", start: s, end: time});
        }
        if (time != end) {
          s = parsed[i].end;
        }
      }

      parsed.push(...holes);

      resolve(parsed);
    });
    xhr.open('GET', URL + room);
    xhr.send();
  });
}

const ROOMS = [
  'SI-003',
  'SI-015',
  'SI-004',
  'SI-006',
  'SI-013',
  'SI-007',
  'SI-008',
];

const ROOM_LIST = document.querySelector(".times");
const ROOM_TEMPLATE = document.getElementById("room");
const SLOT_TEMPLATE = document.getElementById("time-slot");
const FREE_SLOT_TEMPLATE = document.getElementById("time-free");

function getRoomNode() {
  return document.importNode(ROOM_TEMPLATE.content, true);
}

function formatTime(date) {
  const twoDigits = (n) => {
    return n < 10 ? "0" + n : n;
  }

  return twoDigits(date.getHours()) + ':' +
    twoDigits(date.getMinutes());
}

function colorRoom(roomTitle, node, time = NOW /* QuantumLeap */) {
  const data = timeTable[roomTitle];
  if (data == undefined) {
    return
  }

  const currentLecture = data.filter(d => d.start < time && d.end > time)[0] || null;
  const isFree = !!currentLecture && !!currentLecture.title &&
    currentLecture.title === "Overflow";
  console.log(roomTitle, isFree);
  const block = document.getElementById(roomTitle);

  block.className = block.className
    .replace(" room-in-use", "")
    .replace(" room-free", "")
    .replace(" room-unassigned", "");
  block.className += isFree ? " room-free" :
    currentLecture.title === "Unassigned" ? " room-unassigned" : " room-in-use";

  const title = isFree ? "Free (overflow)" : currentLecture.title;

  block.querySelector('p').innerHTML = title +
    "<br> (" + formatTime(currentLecture.start) + " - " +
    formatTime(currentLecture.end) + ")";
}

async function buildRoomMarkup(roomTitle) {
  const data = await roomStatus(roomTitle);
  const room = getRoomNode();
  const title = room.querySelector('.room-title');
  title.innerHTML = roomTitle;
  title.id = "schedule-" + roomTitle;
  const list = room.querySelector('.list');

  for (const d of data) {
    if (d.title === "Unassigned" || d.title === "Overflow") continue;
    const slot = document.importNode(SLOT_TEMPLATE.content, true);
    const title = slot.querySelector('.title');
    title.innerHTML = d.title;
    const start = slot.querySelector('.start');
    start.innerHTML = formatTime(d.start);
    const end = slot.querySelector('.end');
    end.innerHTML = formatTime(d.end);
    list.appendChild(slot);
  }

  timeTable[roomTitle] = data;
  colorRoom(roomTitle, room);

  if (data.length == 0) {
    list.appendChild(document.importNode(FREE_SLOT_TEMPLATE.content, true));
  }

  ROOM_LIST.appendChild(room);
}

function setTimePreview(date) {
  const timePreview = document.getElementById('timepreviewer');
  timePreview.innerText = "Time: " + formatTime(date);
}

function setupTimeMachine() {
  const slider = document.getElementById('timemachine');
  slider.min = 8 * 60 + 30;
  slider.max = 19 * 60 + 30;

  slider.addEventListener("input", (e) => {
    const date = new Date();
    date.setHours(0);
    date.setMinutes(slider.value);
    const node = getRoomNode();

    setTimePreview(date);

    ROOMS.forEach((roomTitle) => {
      colorRoom(roomTitle, node, date);
    });
  });

  const date = new Date();
  const mins = date.getHours() * 60 + date.getMinutes();
  slider.value = mins < slider.min ? slider.min :
    mins > slider.max ? slider.max : mins;
  setTimePreview(date);
}

// Thanks to Andrea Gallidabino and his mastery checks for this
Promise.all(ROOMS.map(buildRoomMarkup)).catch(console.error);

setupTimeMachine();