/* global window, document */

(function () {
  'use strict';

  function initGalleryThumbs() {
    var imgs = document.querySelectorAll('div.luxtools-gallery img[data-thumb-src]');
    if (!imgs || !imgs.length) return;

    function loadThumb(img) {
      var src = img.getAttribute('data-thumb-src') || '';
      if (!src) return;
      if (img.getAttribute('data-thumb-loading') === '1') return;
      img.setAttribute('data-thumb-loading', '1');

      var pre = new window.Image();
      pre.onload = function () {
        img.src = src;
        img.removeAttribute('data-thumb-src');
        img.removeAttribute('data-thumb-loading');
      };
      pre.onerror = function () {
        img.removeAttribute('data-thumb-loading');
      };
      pre.src = src;
    }

    if ('IntersectionObserver' in window) {
      var io = new window.IntersectionObserver(function (entries) {
        entries.forEach(function (entry) {
          if (!entry.isIntersecting) return;
          loadThumb(entry.target);
          io.unobserve(entry.target);
        });
      }, { rootMargin: '200px' });

      imgs.forEach(function (img) { io.observe(img); });
    } else {
      // Fallback: load soon after initial render
      window.setTimeout(function () {
        imgs.forEach(loadThumb);
      }, 0);
    }
  }

  function getServiceUrl(el) {
    var url = el.getAttribute('data-service-url') || '';
    url = (url || '').trim();
    if (!url) return '';
    // strip trailing slashes
    return url.replace(/\/+$/, '');
  }

  function pingOpenViaImage(el, rawPath) {
    var baseUrl = getServiceUrl(el);
    if (!baseUrl) return;
    var url = baseUrl + '/open?path=' + encodeURIComponent(rawPath);

    // Fire-and-forget without CORS.
    try {
      var img = new window.Image();
      img.src = url;
    } catch (e) {
      // ignore
    }
  }

  function openViaService(el, rawPath) {
    var baseUrl = getServiceUrl(el);
    if (!baseUrl) return Promise.reject(new Error('No client service configured'));

    var headers = {
      'Content-Type': 'application/json'
    };

    return window.fetch(baseUrl + '/open', {
      method: 'POST',
      mode: 'cors',
      credentials: 'omit',
      headers: headers,
      body: JSON.stringify({ path: rawPath })
    }).then(function (res) {
      if (!res.ok) {
        return res.json().catch(function () { return null; }).then(function (body) {
          var msg = (body && body.message) ? body.message : ('HTTP ' + res.status);
          throw new Error(msg);
        });
      }
      return res.json().catch(function () { return { ok: true }; });
    });
  }

  function normalizeToFileUrl(path) {
    if (!path) return '';

    // already a file URL
    if (/^file:\/\//i.test(path)) return path;

    // UNC path: \\server\share\path
    if (/^\\\\/.test(path)) {
      var p = path.replace(/^\\\\/, '');
      p = p.replace(/\\/g, '/');
      return 'file://///' + p;
    }

    // Windows drive: C:\path\to\file
    if (/^[a-zA-Z]:\\/.test(path)) {
      var drive = path[0].toUpperCase();
      var rest = path.slice(2).replace(/\\/g, '/');
      return 'file:///' + drive + ':' + rest;
    }

    // POSIX absolute: /home/user/file
    if (path[0] === '/') {
      return 'file://' + path;
    }

    // Fall back to using the provided string.
    return path;
  }

  function onClick(event) {
    var el = event.target;
    if (!el || !el.classList || !el.classList.contains('luxtools-open')) return;

    var raw = el.getAttribute('data-path') || '';
    if (!raw) return;

    // Prefer local client service.
    openViaService(el, raw)
      .catch(function (err) {
        // If the browser blocks the request before it reaches localhost (mixed-content,
        // extensions, stricter CORS handling), fall back to a no-CORS GET ping.
        pingOpenViaImage(el, raw);

        // Fallback to old behavior (often blocked in modern browsers).
        var url = normalizeToFileUrl(raw);
        if (!url) return;
        console.warn('Local client service failed, falling back to file:// navigation:', err);
        try {
          window.open(url, '_blank', 'noopener');
        } catch (e) {
          try {
            window.location.href = url;
          } catch (e2) {
            console.error('Failed to open file URL:', e2);
          }
        }
      });
  }

  document.addEventListener('click', onClick, false);
  document.addEventListener('DOMContentLoaded', initGalleryThumbs, false);
})();