(function (root, factory) {
  if (typeof module === 'object' && module.exports) {
    module.exports = factory(root);
    return;
  }

  root.MediaDisplay = factory(root);
  if (root.document) {
    root.document.addEventListener('DOMContentLoaded', function () {
      root.MediaDisplay.init(root.document);
    });
  }
})(typeof globalThis !== 'undefined' ? globalThis : window, function (root) {
  'use strict';

  function stringValue(value) {
    return value === undefined || value === null ? '' : String(value);
  }

  function escapeHtml(value) {
    return stringValue(value)
      .replace(/&/g, '&')
      .replace(/</g, '&lt;')
      .replace(/>/g, '&gt;')
      .replace(/"/g, '&quot;')
      .replace(/'/g, '&#39;');
  }

  function normalizeId(value) {
    var text;

    if (value === undefined || value === null || value === '') return '';
    if (typeof value === 'number' && !Number.isSafeInteger(value)) return '';
    text = String(value).trim();
    return /^[1-9][0-9]*$/.test(text) ? text : '';
  }

  function normalizeAccessUrl(value) {
    var url;

    try {
      url = new URL(stringValue(value).trim());
    } catch (error) {
      return '';
    }
    return url.protocol === 'https:' || url.protocol === 'http:' ? url.href : '';
  }

  function normalizeFileAccess(value) {
    var source = value || {};
    var accessUrl = normalizeAccessUrl(source.accessUrl);
    var fileId = normalizeId(source.fileId);
    var fileSize;
    var normalized;

    if (!accessUrl) return null;
    if (source.fileId !== undefined && source.fileId !== null && source.fileId !== '' && !fileId) return null;
    normalized = {
      fileId: fileId,
      fileName: stringValue(source.fileName).trim(),
      mediaType: stringValue(source.mediaType).trim().toLowerCase(),
      accessUrl: accessUrl,
      expiresAt: stringValue(source.expiresAt).trim()
    };
    fileSize = Number(source.fileSize);
    if (source.fileSize !== undefined && source.fileSize !== null && source.fileSize !== '' &&
        Number.isSafeInteger(fileSize) && fileSize >= 0) {
      normalized.fileSize = fileSize;
    }

    if (!normalized.fileId) delete normalized.fileId;
    if (!normalized.fileName) delete normalized.fileName;
    if (!normalized.mediaType) delete normalized.mediaType;
    if (!normalized.expiresAt) delete normalized.expiresAt;
    return normalized;
  }

  function normalizeFileList(values) {
    if (!Array.isArray(values)) return [];
    return values.map(normalizeFileAccess).filter(Boolean);
  }

  function classNames(base, value) {
    var additions = stringValue(value).split(/\s+/).filter(function (name) {
      return /^[a-zA-Z][a-zA-Z0-9_-]*$/.test(name);
    });

    return [base].concat(additions).join(' ');
  }

  function renderImage(value, options) {
    var file = normalizeFileAccess(value);
    var settings = options || {};
    var alt;
    var loading;
    var caption;

    if (!file) return '';
    alt = stringValue(settings.alt || file.fileName || '图片').trim();
    loading = settings.eager === true ? 'eager' : 'lazy';
    caption = stringValue(settings.caption).trim();
    return '<figure class="' + escapeHtml(classNames('media-frame', settings.className)) +
      '" data-media-kind="image"><button class="media-preview" type="button" data-media-preview-url="' +
      escapeHtml(file.accessUrl) + '" data-media-preview-alt="' + escapeHtml(alt) + '">' +
      '<img src="' + escapeHtml(file.accessUrl) + '" alt="' + escapeHtml(alt) +
      '" loading="' + loading + '" decoding="async" /></button>' +
      '<span class="media-fallback" hidden>图片暂时无法显示</span>' +
      (caption ? '<figcaption>' + escapeHtml(caption) + '</figcaption>' : '') + '</figure>';
  }

  function renderAvatar(value, options) {
    var file = normalizeFileAccess(value);
    var settings = options || {};
    var name = stringValue(settings.name || '用户').trim() || '用户';
    var initial = Array.from(name)[0] || '家';
    var classes = classNames('media-avatar', settings.className);

    if (!file) {
      return '<span class="' + escapeHtml(classes) + '" aria-label="' +
        escapeHtml(name + '的头像') + '">' + escapeHtml(initial) + '</span>';
    }
    return '<span class="' + escapeHtml(classes) + '"><img src="' + escapeHtml(file.accessUrl) +
      '" alt="' + escapeHtml(name + '的头像') + '" loading="lazy" decoding="async" />' +
      '<span class="media-avatar-fallback" aria-hidden="true">' + escapeHtml(initial) + '</span></span>';
  }

  function renderVideo(value, options) {
    var file = normalizeFileAccess(value);
    var settings = options || {};
    var poster = normalizeFileAccess(settings.posterFile);
    var title;

    if (!file) return '';
    title = stringValue(settings.title || file.fileName || '家族视频').trim();
    return '<figure class="' + escapeHtml(classNames('media-frame media-video', settings.className)) +
      '" data-media-kind="video"><video controls preload="metadata" src="' + escapeHtml(file.accessUrl) + '"' +
      (poster ? ' poster="' + escapeHtml(poster.accessUrl) + '"' : '') +
      ' aria-label="' + escapeHtml(title) + '"></video>' +
      '<span class="media-fallback" hidden>视频暂时无法播放</span>' +
      (settings.caption ? '<figcaption>' + escapeHtml(settings.caption) + '</figcaption>' : '') + '</figure>';
  }

  function mediaKind(file) {
    var type = stringValue(file && file.mediaType).toLowerCase();

    if (type.indexOf('image/') === 0) return 'image';
    if (type.indexOf('video/') === 0) return 'video';
    return 'file';
  }

  function renderDownload(file) {
    var label = file.fileName || '附件';

    return '<a class="media-download" href="' + escapeHtml(file.accessUrl) +
      '" target="_blank" rel="noopener noreferrer" download>下载 ' + escapeHtml(label) + '</a>';
  }

  function renderGallery(values, options) {
    var files = normalizeFileList(values);
    var settings = options || {};
    var label = stringValue(settings.label || '媒体附件').trim();
    var content;

    if (!files.length) return '';
    content = files.map(function (file) {
      var kind = mediaKind(file);

      if (kind === 'image') return renderImage(file, { alt: file.fileName || label });
      if (kind === 'video') return renderVideo(file, { title: file.fileName || label });
      return renderDownload(file);
    }).join('');
    return '<div class="' + escapeHtml(classNames('media-gallery', settings.className)) +
      '" role="group" aria-label="' + escapeHtml(label) + '">' + content + '</div>';
  }

  function ensurePreviewDialog(documentRef) {
    var dialog = documentRef.querySelector('[data-media-preview-dialog]');
    var close;

    if (dialog) return dialog;
    dialog = documentRef.createElement('dialog');
    dialog.className = 'media-dialog';
    dialog.setAttribute('data-media-preview-dialog', '');
    dialog.setAttribute('aria-label', '图片预览');
    dialog.innerHTML = '<button class="media-dialog-close" type="button" aria-label="关闭图片预览">关闭</button>' +
      '<img alt="" data-media-dialog-image />';
    documentRef.body.appendChild(dialog);
    close = dialog.querySelector('.media-dialog-close');
    close.addEventListener('click', function () {
      if (typeof dialog.close === 'function') dialog.close();
      else dialog.removeAttribute('open');
    });
    dialog.addEventListener('click', function (event) {
      if (event.target !== dialog) return;
      if (typeof dialog.close === 'function') dialog.close();
      else dialog.removeAttribute('open');
    });
    return dialog;
  }

  function init(documentRef) {
    if (!documentRef || documentRef.documentElement.getAttribute('data-media-display-ready') === 'true') return;
    documentRef.documentElement.setAttribute('data-media-display-ready', 'true');
    documentRef.addEventListener('error', function (event) {
      var target = event.target;
      var frame;
      var fallback;

      if (!target || !/^(IMG|VIDEO)$/.test(target.tagName)) return;
      frame = target.closest && target.closest('.media-frame, .media-avatar');
      if (!frame) return;
      frame.classList.add('is-media-error');
      target.hidden = true;
      fallback = frame.querySelector('.media-fallback, .media-avatar-fallback');
      if (fallback) fallback.hidden = false;
    }, true);
    documentRef.addEventListener('click', function (event) {
      var trigger = event.target.closest && event.target.closest('[data-media-preview-url]');
      var dialog;
      var image;
      var url;

      if (!trigger) return;
      url = normalizeAccessUrl(trigger.getAttribute('data-media-preview-url'));
      if (!url) return;
      dialog = ensurePreviewDialog(documentRef);
      image = dialog.querySelector('[data-media-dialog-image]');
      image.src = url;
      image.alt = trigger.getAttribute('data-media-preview-alt') || '图片预览';
      if (typeof dialog.showModal === 'function') dialog.showModal();
      else dialog.setAttribute('open', '');
    });
  }

  return {
    normalizeFileAccess: normalizeFileAccess,
    normalizeFileList: normalizeFileList,
    renderImage: renderImage,
    renderAvatar: renderAvatar,
    renderVideo: renderVideo,
    renderGallery: renderGallery,
    init: init
  };
});