(function (root, factory) {
  if (typeof module === 'object' && module.exports) {
    module.exports = factory(root);
    return;
  }
  root.AttachmentEditor = factory(root);
})(typeof globalThis !== 'undefined' ? globalThis : window, function (root) {
  'use strict';

  var editors = new Map();

  function normalizeFiles(files) {
    var seen = new Set();
    return (files || []).map(function (file) {
      var ossId = file && file.ossId;
      if ((typeof ossId === 'number' && !Number.isSafeInteger(ossId)) || !/^[1-9][0-9]*$/.test(String(ossId))) {
        throw new Error('原附件缺少有效的上传标识，暂不能保存，请刷新后重试');
      }
      return {
        ossId: String(ossId),
        fileName: String(file.fileName || '附件'),
        mediaType: String(file.mediaType || '').toLowerCase(),
        accessUrl: root.MediaDisplay ? (root.MediaDisplay.normalizeFileAccess(file) || {}).accessUrl || '' : ''
      };
    }).filter(function (file) {
      if (seen.has(file.ossId)) return false;
      seen.add(file.ossId);
      return true;
    });
  }

  function release(files) {
    files.forEach(function (file) {
      if (file.objectUrl) root.URL.revokeObjectURL(file.objectUrl);
    });
  }

  function getEditor(target) {
    if (typeof target === 'string') target = root.document.querySelector(target);
    return editors.get(target);
  }

  function sync(editor) {
    editor.target.value = editor.files.map(function (file) { return file.ossId; }).join(',');
    editor.preview.replaceChildren();
    editor.files.forEach(function (file) {
      var card = root.document.createElement('div');
      var url = file.objectUrl || file.accessUrl;
      var name = root.document.createElement('span');
      var remove = root.document.createElement('button');
      var media;
      card.className = 'attachment-edit-item';
      if (url && /^(image|video)(\/|$)/.test(file.mediaType)) {
        media = root.document.createElement(/^image/.test(file.mediaType) ? 'img' : 'video');
        media.src = url;
        if (media.tagName === 'IMG') media.alt = file.fileName;
        else { media.controls = true; media.preload = 'metadata'; }
        media.addEventListener('error', function () {
          media.hidden = true;
          name.textContent = file.fileName + '（预览不可用，附件仍保留）';
        });
        card.appendChild(media);
      }
      name.className = 'attachment-edit-name';
      name.textContent = file.fileName;
      card.appendChild(name);
      remove.type = 'button';
      remove.className = 'pill attachment-edit-remove';
      remove.textContent = '移除';
      remove.setAttribute('aria-label', '移除 ' + file.fileName);
      remove.disabled = editor.busy || editor.input.disabled;
      // 相册接口尚不支持可靠清空封面，仅允许替换。
      if (editor.input.hasAttribute('data-attachment-replace-only')) {
        remove.hidden = true;
      }
      remove.addEventListener('click', function () {
        if (editor.busy || editor.input.disabled) return;
        editor.files = editor.files.filter(function (existing) { return existing !== file; });
        release([file]);
        editor.cleared = true;
        sync(editor);
      });
      card.appendChild(remove);
      editor.preview.appendChild(card);
    });
    if (editor.status && !editor.busy) {
      editor.status.textContent = editor.files.length
        ? '已选择 ' + editor.files.length + ' 个文件；移除或替换将在保存后生效'
        : (editor.cleared ? '附件已移除，保存后生效' : '未选择文件');
    }
  }

  function init() {
    root.document.querySelectorAll('[data-attachment-editor]').forEach(function (input) {
      var target = root.document.querySelector(input.getAttribute('data-upload-target'));
      var preview;
      var editor;
      if (!target || editors.has(target)) return;
      preview = root.document.createElement('div');
      preview.className = 'attachment-edit-list';
      preview.setAttribute('aria-label', '已选择的附件');
      input.insertAdjacentElement('afterend', preview);
      editor = {
        target: target, input: input, preview: preview,
        status: root.document.querySelector(input.getAttribute('data-upload-status')),
        multiple: input.getAttribute('data-upload-multiple') === 'true',
        files: [], cleared: false, busy: false
      };
      editors.set(target, editor);
      new root.MutationObserver(function () {
        preview.querySelectorAll('button').forEach(function (button) { button.disabled = input.disabled || editor.busy; });
      }).observe(input, { attributes: true, attributeFilter: ['disabled'] });
    });
  }

  function setFiles(target, files) {
    init();
    var editor = getEditor(target);
    if (!editor) throw new Error('附件编辑控件未初始化');
    editor.invalid = true;
    var normalized = normalizeFiles(files);
    release(editor.files);
    editor.files = normalized;
    editor.cleared = false;
    editor.invalid = false;
    sync(editor);
  }

  function addUploaded(target, upload, file) {
    var editor = getEditor(target);
    if (!editor) return false;
    var attachment = normalizeFiles([{ ossId: upload.ossId, fileName: file.name, mediaType: file.type }])[0];
    if (editor.files.some(function (existing) { return existing.ossId === attachment.ossId; })) return true;
    attachment.objectUrl = root.URL.createObjectURL(file);
    if (!editor.multiple) { release(editor.files); editor.files = []; }
    editor.files.push(attachment);
    editor.cleared = false;
    sync(editor);
    return true;
  }

  function clear(target) {
    var editor = getEditor(target);
    if (!editor || editor.busy || editor.input.disabled) return;
    release(editor.files);
    editor.files = [];
    editor.cleared = true;
    sync(editor);
  }

  function readField(field) {
    var editor = getEditor(field);
    // nullable 单封面 PATCH：空值仅在用户主动移除时提交 null。
    if (editor && !editor.multiple && editor.cleared && !editor.files.length) return null;
    return field.value;
  }

  function setBusy(target, busy) {
    var editor = getEditor(target);
    if (!editor) return;
    editor.busy = busy;
    editor.preview.querySelectorAll('button').forEach(function (button) { button.disabled = busy || editor.input.disabled; });
  }

  if (root.document) {
    root.document.addEventListener('DOMContentLoaded', init);
    root.document.addEventListener('submit', function (event) {
      var pending = Array.from(editors.values()).some(function (editor) { return editor.input.form === event.target && editor.busy; });
      var invalid = Array.from(editors.values()).some(function (editor) { return editor.input.form === event.target && editor.invalid; });
      if (!pending && !invalid) return;
      event.preventDefault();
      event.stopImmediatePropagation();
      var status = event.target.querySelector('.upload-status');
      if (status) status.textContent = invalid ? '原附件读取不完整，请刷新后重试，暂不能保存' : '文件正在上传，请等待上传完成后再保存';
    }, true);
    root.addEventListener('pagehide', function (event) {
      if (!event.persisted) editors.forEach(function (editor) { release(editor.files); });
    });
  }

  return { init: init, normalizeFiles: normalizeFiles, setFiles: setFiles, addUploaded: addUploaded, clear: clear, readField: readField, setBusy: setBusy };
});