(function () {
  'use strict';

  // ── Track setIntervals so navigation can clear them ───────────────────────
  const _origSetInterval  = window.setInterval.bind(window);
  const _origClearInterval = window.clearInterval.bind(window);
  let _intervals = [];

  window.setInterval = function (fn, ms, ...args) {
    const id = _origSetInterval(fn, ms, ...args);
    _intervals.push(id);
    return id;
  };

  function clearTrackedIntervals() {
    _intervals.forEach(id => _origClearInterval(id));
    _intervals = [];
  }

  // ── Cleanup state left behind by the outgoing page ────────────────────────
  function cleanupPage() {
    clearTrackedIntervals();

    // DataTables 2.x
    if (window.DataTable) {
      try { DataTable.tables({ api: true }).destroy(); } catch (_) {}
    }

    // Dropzone
    if (window.Dropzone) {
      try { [...Dropzone.instances].forEach(dz => dz.destroy()); } catch (_) {}
    }

    // Bootstrap modals – hide any open one and remove leftover backdrops
    document.querySelectorAll('.modal.show').forEach(el => {
      try { bootstrap.Modal.getInstance(el)?.hide(); } catch (_) {}
    });
    document.querySelectorAll('.modal-backdrop').forEach(el => el.remove());
    document.body.classList.remove('modal-open');
    document.body.style.removeProperty('padding-right');
  }

  function swapPageModals(doc) {
    document.querySelectorAll('[data-ajax-modal="true"]').forEach(el => el.remove());
    doc.querySelectorAll('body > .modal').forEach(old => {
      const wrapper = document.createElement('div');
      wrapper.innerHTML = old.outerHTML;
      const modal = wrapper.firstElementChild;
      if (!modal) return;
      modal.setAttribute('data-ajax-modal', 'true');
      document.body.appendChild(modal);
    });
  }

  // ── Per-page inline <style> management ───────────────────────────────────
  const STYLE_ID = 'ajax-page-style';
  function setPageStyles(cssText) {
    let tag = document.getElementById(STYLE_ID);
    if (!cssText) { tag?.remove(); return; }
    if (!tag) {
      tag = document.createElement('style');
      tag.id = STYLE_ID;
      document.head.appendChild(tag);
    }
    tag.textContent = cssText;
  }

  // ── Load external <script src> tags not already on the page ──────────────
  const _loadedSrcs = new Set(
    [...document.querySelectorAll('script[src]')].map(s => s.src)
  );

  function loadScript(src) {
    const abs = new URL(src, location.href).href;
    if (_loadedSrcs.has(abs)) return Promise.resolve();
    _loadedSrcs.add(abs);
    return new Promise((resolve, reject) => {
      const s = document.createElement('script');
      s.src = src;
      s.onload = resolve;
      s.onerror = reject;
      document.head.appendChild(s);
    });
  }

  // ── Load external <link rel="stylesheet"> tags not already on the page ───
  const _loadedHrefs = new Set(
    [...document.querySelectorAll('link[rel="stylesheet"]')].map(l => l.href)
  );

  function loadStylesheet(href) {
    const abs = new URL(href, location.href).href;
    if (_loadedHrefs.has(abs)) return Promise.resolve();
    _loadedHrefs.add(abs);
    return new Promise((resolve, reject) => {
      const l = document.createElement('link');
      l.rel = 'stylesheet';
      l.href = href;
      l.onload = resolve;
      l.onerror = reject;
      document.head.appendChild(l);
    });
  }

  // ── Re-execute inline scripts from the fetched document ──────────────────
  function runInlineScripts(doc) {
    doc.querySelectorAll('body script:not([src])').forEach(old => {
      const code = old.textContent;

      // Wrap in an IIFE so top-level `let`/`const` are function-scoped and
      // don't collide with bindings from a previous visit to the same page.
      // Then re-expose every named function declaration to `window` so that
      // inline onclick="foo()" handlers continue to resolve them globally.
      const funcNames = [
        ...code.matchAll(/^\s*(?:async\s+)?function\s+(\w+)\s*\(/gm),
      ].map(m => m[1]);

      const expose = funcNames
        .map(n => `try{window.${n}=${n};}catch(_){}`)
        .join('\n');

      const s = document.createElement('script');
      s.textContent = `(function(){\n${code}\n${expose}\n})();`;
      document.head.appendChild(s);
      s.remove();
    });
  }

  // ── Update which nav link is highlighted as active ────────────────────────
  function setActiveNav(filename) {
    document.querySelectorAll('.nav-link-custom, .bottom-nav a').forEach(el => {
      const hf = (el.getAttribute('href') || '').split('/').pop();
      el.classList.toggle('active', hf === filename);
    });
  }

  // ── Core AJAX navigation ──────────────────────────────────────────────────
  let _navigating = false;

  async function navigateTo(href) {
    if (_navigating) return;
    _navigating = true;

    const mainInner = document.querySelector('.main-inner');
    if (!mainInner) { window.location.href = href; return; }

    // Dim content while loading
    mainInner.style.transition = 'opacity 0.12s';
    mainInner.style.opacity = '0.35';

    try {
      const r = await fetch(href, { redirect: 'manual' });
      if (r.type === 'opaqueredirect') { window.location.reload(); return; }
      if (!r.ok) { window.location.href = href; return; }

      const text = await r.text();
      const doc = new DOMParser().parseFromString(text, 'text/html');

      // Load any external libs/styles the new page needs that aren't already loaded.
      // Scripts must load sequentially (order matters: e.g. jQuery before DataTables).
      // Stylesheets have no dependency order so can load in parallel.
      for (const s of doc.querySelectorAll('script[src]')) {
        await loadScript(s.getAttribute('src'));
      }
      await Promise.all(
        [...doc.querySelectorAll('link[rel="stylesheet"]')].map(l => loadStylesheet(l.getAttribute('href')))
      );

      // Swap page-specific inline styles
      const styles = [...doc.head.querySelectorAll('style')].map(s => s.textContent).join('\n');
      setPageStyles(styles || null);

      // Cleanup outgoing page, then inject new content
      cleanupPage();
      mainInner.innerHTML = doc.querySelector('.main-inner')?.innerHTML ?? '';
      swapPageModals(doc);
      document.title = doc.title;

      const filename = href.split('/').pop();
      setActiveNav(filename);

      // Execute page scripts from the centralized app bundle when available.
      if (typeof window.__runPageScripts === 'function') {
        window.__runPageScripts(filename);
      } else {
        // Fallback for legacy pages that still carry inline scripts.
        runInlineScripts(doc);
      }

    } catch {
      // Fallback to hard navigation on any error
      window.location.href = href;
    } finally {
      mainInner.style.opacity = '1';
      _navigating = false;
    }
  }

  // ── Intercept all local .html link clicks ────────────────────────────────
  document.addEventListener('click', e => {
    const link = e.target.closest('a[href]');
    if (!link) return;
    const href = link.getAttribute('href');
    if (!href || href.startsWith('#') || href.includes('://') || !href.endsWith('.html')) return;
    e.preventDefault();
    navigateTo(href);
  }, true);

  // History API intentionally omitted — no pushState/popstate.

})();