preseed/tampermonkey/backtohome.js

// ==UserScript==
// @name         Back to Home (39C3 Kiosk)
// @namespace    http://tampermonkey.net/
// @version      2025-12-18
// @description  Adds buttons to every website to return to home page and prompts on idle
// @author       You
// @match        *://*/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=google.com
// @grant        GM_addStyle
// ==/UserScript==

const target = "https://kiosk.39c3.by.vincent.mahn.ke/";
(function() {
    'use strict';

    // if the user is on target already or subdomain, do nothing
    if (window.location.href === target || window.location.href.startsWith(target + '/')) {
        return;
    }

    const btn = document.createElement('button');
    btn.textContent = 'Home';
    btn.style.cssText = '     all: unset; box-sizing: border-box; border: 2px solid #141414; background: #faf5f5; text-align: center; color: #141414;  position: fixed;    right: 10px;    bottom: 10px;    width: 60px;    height: 60px;    z-index: 2147483647;    padding-top: 6px;    border-radius: 60px;';
    btn.innerHTML = '<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="lucide lucide-house-icon lucide-house"><path d="M15 21v-8a1 1 0 0 0-1-1h-4a1 1 0 0 0-1 1v8"/><path d="M3 10a2 2 0 0 1 .709-1.528l7-6a2 2 0 0 1 2.582 0l7 6A2 2 0 0 1 21 10v9a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"/></svg>';
    btn.addEventListener('click', () => {
      window.location.href = target;
    });
    (document.body || document.documentElement).appendChild(btn);


    const IDLE_LIMIT_MS = 60_000;
    let idleTimer = null;
    let promptVisible = false;
    const PROMPT_LIMIT_MS = 30_000;
    let promptInterval = null;
    let promptTimeout = null;

    const modal = document.createElement('div');
    modal.id = 'idle-modal';
    modal.hidden = true;
    modal.style.cssText = `
      position: fixed;
      top: 50%;
      left: 50%;
      transform: translate(-50%, -50%);
      background-color: #141414 !important;
      border-radius: 0.385em;
      border: 2px solid #444;
      padding: 20px;
      z-index: 2147483647;
      box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    `;
    modal.innerHTML = `
      <h2>You seem to be idle</h2>
      <p>Do you want to stay on this page or go back to the home page?</p>
      <button id="idle-stay">Stay</button>
      <button id="idle-go">Go to Home</button>
      <p id="idle-countdown-msg" style="margin-top:8px">Auto return in <span id="idle-countdown">30</span>s</p>
    `;
    document.body.appendChild(modal);

    const backdrop = document.createElement('div');
    backdrop.id = 'idle-backdrop';
    backdrop.hidden = true;
    backdrop.style.cssText = `
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(0,0,0,0.5);
      z-index: 2147483646;
    `;
    document.body.appendChild(backdrop);

    const userEvents = [
      'mousemove',
      'mousedown',
      'keydown',
      'wheel',
      'touchstart',
      'scroll'
    ];

    function showPrompt() {
      promptVisible = true;
      modal.hidden = false;
      backdrop.hidden = false;

      // Clear any previous prompt timers
      if (promptInterval) { clearInterval(promptInterval); promptInterval = null; }
      if (promptTimeout) { clearTimeout(promptTimeout); promptTimeout = null; }

      // Wire button actions (once to avoid duplicates)
      const stayBtn = document.querySelector("#idle-stay");
      const goBtn = document.querySelector("#idle-go");

      if (stayBtn) {
        stayBtn.addEventListener("click", () => {
          hidePrompt();
          resetIdleTimer();
        }, { once: true });
      }

      if (goBtn) {
        goBtn.addEventListener("click", () => {
          window.location.href = target;
        }, { once: true });
      }

      // 30s countdown visible to the user
      let remaining = PROMPT_LIMIT_MS / 1000; // seconds
      const countdownEl = document.querySelector("#idle-countdown");
      if (countdownEl) countdownEl.textContent = String(remaining);

      promptInterval = setInterval(() => {
        remaining -= 1;
        if (remaining >= 0 && countdownEl) {
          countdownEl.textContent = String(remaining);
        }
      }, 1000);

      // Auto-go when expired
      promptTimeout = setTimeout(() => {
        const go = document.querySelector("#idle-go");
        if (go) {
          go.click();
        } else {
          window.location.href = target;
        }
      }, PROMPT_LIMIT_MS);
    }

    function hidePrompt() {
      promptVisible = false;
      modal.hidden = true;
      backdrop.hidden = true;
      if (promptInterval) { clearInterval(promptInterval); promptInterval = null; }
      if (promptTimeout) { clearTimeout(promptTimeout); promptTimeout = null; }
    }

    function onIdle() {
      showPrompt();
    }

    function resetIdleTimer() {
      if (promptVisible) return; // Don't auto-dismiss while prompt is visible
      if (idleTimer) clearTimeout(idleTimer);
      idleTimer = setTimeout(onIdle, IDLE_LIMIT_MS);
    }

    // Any user activity resets the timer
    userEvents.forEach(evt => {
      document.addEventListener(evt, resetIdleTimer, { passive: true });
    });

    // When returning to a visible tab, refresh the timer
    document.addEventListener('visibilitychange', () => {
      if (document.visibilityState === 'visible') {
        resetIdleTimer();
      }
    });

    // Actions

    // Kick things off
    resetIdleTimer();
})();