/* Swipe/Keyboard navigation for Entry View
   - Respects localStorage 'swipeNavEnabled' (default ON)
   - Touch swipe on mobile, ArrowLeft/ArrowRight on keyboards
   - Edge protection and input-safe
*/
(function () {
  // Feature flag (client-side). Default ON.
  let swipeEnabled = true;
  try { swipeEnabled = (localStorage.getItem('swipeNavEnabled') !== 'false'); } catch (e) {}

  // Only attach if enabled
  if (!swipeEnabled) return;

  // Forms to submit for previous/next (your existing IDs)
  const prevForm = document.getElementById('navPrevForm');
  const nextForm = document.getElementById('navNextForm');

  // Create toast + hints lazily to keep HTML clean
  const toast = document.createElement('div');
  toast.id = 'toast-swipe-error';
  toast.style.cssText = [
    'position:fixed', 'left:50%', 'bottom:16px', 'transform:translateX(-50%)',
    'padding:10px 14px', 'border-radius:10px', 'background:#111827', 'color:#fff',
    'box-shadow:0 6px 20px rgba(0,0,0,.25)', 'opacity:0', 'pointer-events:none',
    'transition:opacity .25s', 'z-index:1200', 'font-size:14px'
  ].join(';');
  toast.textContent = "Can't navigate here.";
  document.body.appendChild(toast);

  function showToast() {
    toast.style.opacity = '1';
    setTimeout(() => { toast.style.opacity = '0'; }, 1200);
  }

  // Only show swipe hints on touch devices, once per session
  const isTouch = ('ontouchstart' in window) || (navigator.maxTouchPoints > 0);
  let hintL, hintR;
  if (isTouch) {
    try {
      if (!sessionStorage.getItem('swipeHintShown')) {
        sessionStorage.setItem('swipeHintShown', '1');

        const base = 'position:fixed;width:34px;height:34px;display:flex;align-items:center;justify-content:center;' +
                     'background:rgba(0,0,0,.35);color:#fff;border-radius:999px;box-shadow:0 6px 20px rgba(0,0,0,.25);' +
                     'z-index:1100;opacity:0;transform:scale(.9);transition:opacity .25s,transform .25s;top:45%';

        hintL = document.createElement('div');
        hintL.style.cssText = base + ';left:10px;';
        hintL.textContent = '‹';
        document.body.appendChild(hintL);

        hintR = document.createElement('div');
        hintR.style.cssText = base + ';right:10px;';
        hintR.textContent = '›';
        document.body.appendChild(hintR);

        setTimeout(() => { hintL.style.opacity = '1'; hintR.style.opacity = '1'; hintL.style.transform = 'scale(1)'; hintR.style.transform = 'scale(1)'; }, 300);
        setTimeout(() => { hintL.style.opacity = '0'; hintR.style.opacity = '0'; }, 2200);
      }
    } catch (e) {}
  }

  function navigate(dir) {
    try {
      if (dir < 0 && prevForm) { prevForm.submit(); return true; }
      if (dir > 0 && nextForm) { nextForm.submit(); return true; }
    } catch (e) {}
    showToast();
    return false;
  }

  // Keyboard shortcuts
  document.addEventListener('keydown', function (e) {
    if (!swipeEnabled) return;
    const tag = (e.target && e.target.tagName) || '';
    if (/INPUT|TEXTAREA|SELECT/.test(tag)) return;
    if (e.key === 'ArrowLeft') { e.preventDefault(); navigate(-1); }
    if (e.key === 'ArrowRight') { e.preventDefault(); navigate(1); }
  });

  // Touch swipe (edge-protected, vertical tolerance)
  if (isTouch) {
    let startX = 0, startY = 0, tracking = false;
    const EDGE = 20, THRESH = 40;
    const area = document.querySelector('main.page') || document.body;

    function isInteractive(el) {
      return !!(el.closest && el.closest('input, textarea, select, button, a, [contenteditable], .no-swipe'));
    }

    area.addEventListener('touchstart', function (e) {
      const t = e.touches[0];
      if (!t) return;
      if (isInteractive(e.target)) return;
      startX = t.clientX; startY = t.clientY; tracking = true;
    }, { passive: true });

    area.addEventListener('touchmove', function (e) {
      if (!tracking) return;
      const t = e.touches[0];
      if (!t) return;
      const dx = t.clientX - startX;
      const dy = t.clientY - startY;

      if (Math.abs(dx) > THRESH && Math.abs(dy) < 28) {
        // Edge-protection: avoid accidental from extreme edges
        if (startX < EDGE && dx > 0) { tracking = false; return; }
        if (startX > (window.innerWidth - EDGE) && dx < 0) { tracking = false; return; }
        e.preventDefault();
        navigate(dx > 0 ? -1 : 1);
        tracking = false;
      }
    }, { passive: false });

    area.addEventListener('touchend', function () { tracking = false; }, { passive: true });
  }
})();