/**
 * Public STCW Learn install landing page (no student session required).
 * Install-first → success message → student login on BOOKER.
 *
 * beforeinstallprompt often fires before deferred scripts load; the install
 * blade registers an early head listener into window.__stcwLearnBip.
 */
(function () {
  'use strict';

  var STORAGE_INSTALLED = 'stcw_learn_pwa_installed_v1';
  var deferredPrompt = null;
  var swRegistered = false;
  var redirectTimer = null;

  function adoptEarlyPrompt() {
    if (window.__stcwLearnBip) {
      deferredPrompt = window.__stcwLearnBip;
      window.__stcwLearnBip = null;
    }
  }

  function swUrl() {
    var fromBody = document.body && document.body.getAttribute('data-student-sw-url');
    return fromBody || '/student/sw.js';
  }

  function loginUrl() {
    return (document.body && document.body.getAttribute('data-login-url'))
      || 'https://stcwbooker.com/userdashboard/';
  }

  function isStandalone() {
    return window.matchMedia('(display-mode: standalone)').matches
      || window.navigator.standalone === true;
  }

  function isIos() {
    var ua = navigator.userAgent || '';
    return /iPad|iPhone|iPod/.test(ua)
      || (navigator.platform === 'MacIntel' && navigator.maxTouchPoints > 1);
  }

  function isFirefox() {
    return /Firefox\//i.test(navigator.userAgent || '');
  }

  function isChromium() {
    var ua = navigator.userAgent || '';
    return /Chrome\//i.test(ua) || /Edg\//i.test(ua) || /CriOS\//i.test(ua);
  }

  function setStatus(text, tone) {
    var el = document.getElementById('studentPwaInstallHint');
    if (!el || !text) return;
    el.textContent = text;
    el.setAttribute('data-tone', tone || 'info');
  }

  function markReadyIfPrompt() {
    adoptEarlyPrompt();
    if (!deferredPrompt) return;
    setStatus('Ready — tap Install Student App once to install.', 'ok');
    var btn = document.getElementById('studentPwaInstallBtn');
    if (btn) {
      btn.hidden = false;
      try { btn.focus(); } catch (err) { /* ignore */ }
    }
  }

  function markInstalled() {
    try { localStorage.setItem(STORAGE_INSTALLED, '1'); } catch (e) { /* ignore */ }
  }

  function showSuccessAndContinue() {
    markInstalled();
    var panel = document.getElementById('studentInstallPanel');
    var success = document.getElementById('studentInstallSuccess');
    if (panel) {
      panel.classList.add('is-hidden');
      panel.hidden = true;
    }
    if (success) {
      success.hidden = false;
      success.classList.add('is-visible');
    }
    var note = document.getElementById('studentInstallRedirectNote');
    var seconds = 3;
    function tick() {
      if (note) {
        note.textContent = seconds > 0
          ? ('Opening student login in ' + seconds + '…')
          : 'Opening student login…';
      }
      if (seconds <= 0) {
        window.location.href = loginUrl();
        return;
      }
      seconds -= 1;
      redirectTimer = window.setTimeout(tick, 1000);
    }
    tick();
  }

  function ensureServiceWorker() {
    if (!('serviceWorker' in navigator)) {
      setStatus('This browser cannot install PWAs. Open this page in Chrome or Edge on your phone.', 'warn');
      return Promise.resolve(null);
    }
    if (swRegistered) {
      return navigator.serviceWorker.ready.catch(function () { return null; });
    }
    swRegistered = true;
    return navigator.serviceWorker.register(swUrl(), { scope: '/student/' })
      .then(function () { return navigator.serviceWorker.ready; })
      .then(function (reg) {
        markReadyIfPrompt();
        if (!deferredPrompt && isChromium() && !isStandalone()) {
          setStatus(
            'Chrome can install this app. Tap the Install icon on the right of the address bar (monitor with ↓), or use menu (⋮) → Install page as app. On a phone, tap Install Student App after status says Ready.',
            'ok'
          );
        }
        return reg;
      })
      .catch(function () {
        swRegistered = false;
        setStatus('Could not register the app service worker. Reload over HTTPS and try again.', 'warn');
        return null;
      });
  }

  function guidanceForNoPrompt() {
    if (isStandalone()) {
      return 'Already running as the installed app. Continue to student login.';
    }
    if (isIos()) {
      return 'On iPhone/iPad: tap Share → Add to Home Screen, then open STCW Learn from your home screen.';
    }
    if (isFirefox()) {
      return 'Firefox cannot one-tap install. Open this page in Chrome or Edge on your phone, then tap Install once.';
    }
    if (isChromium()) {
      return 'Use the Install icon on the right of the address bar (monitor with ↓). That installs STCW Learn. Then open the app icon and sign in.';
    }
    return 'Use Chrome or Edge on Android for one-tap Install. On iPhone use Share → Add to Home Screen.';
  }

  function install() {
    adoptEarlyPrompt();
    setStatus('Checking install…', 'info');
    return ensureServiceWorker().then(function () {
      adoptEarlyPrompt();
      if (deferredPrompt) {
        var p = deferredPrompt;
        deferredPrompt = null;
        window.__stcwLearnBip = null;
        return p.prompt().then(function () {
          return p.userChoice;
        }).then(function (choice) {
          if (choice && choice.outcome === 'accepted') {
            setStatus('Installing…', 'ok');
            showSuccessAndContinue();
          } else {
            setStatus('Install was cancelled. Tap Install again, or use the address-bar Install icon.', 'warn');
          }
        }).catch(function () {
          setStatus(guidanceForNoPrompt(), 'warn');
        });
      }
      setStatus(guidanceForNoPrompt(), 'warn');
      return null;
    });
  }

  window.addEventListener('beforeinstallprompt', function (e) {
    e.preventDefault();
    deferredPrompt = e;
    window.__stcwLearnBip = e;
    markReadyIfPrompt();
  });

  window.addEventListener('appinstalled', function () {
    deferredPrompt = null;
    window.__stcwLearnBip = null;
    showSuccessAndContinue();
  });

  window.StudentLearnInstall = { install: install };

  function bind() {
    if (isStandalone()) {
      window.location.replace(loginUrl());
      return;
    }
    adoptEarlyPrompt();
    var btn = document.getElementById('studentPwaInstallBtn');
    if (btn && !btn.getAttribute('data-bound')) {
      btn.setAttribute('data-bound', '1');
      btn.addEventListener('click', function (e) {
        e.preventDefault();
        install();
      });
    }
    ensureServiceWorker();
    markReadyIfPrompt();
    if (deferredPrompt) {
      return;
    }
    if (isFirefox()) {
      setStatus('You are in Firefox. Open this page in Chrome or Edge on your phone, then tap Install once.', 'warn');
    } else if (isIos()) {
      setStatus('On iPhone: Share → Add to Home Screen, then open the STCW Learn icon.', 'info');
    } else {
      setStatus('Preparing install… If the address bar already shows an Install icon (monitor with ↓), click that. Or wait until status says Ready, then tap the blue button.', 'info');
    }
  }

  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', bind);
  } else {
    bind();
  }
})();