/**
 * Office 文件预览处理器
 * 使用动态导入减小初始包体积
 */

// Excel 预览处理器
export async function previewExcel(file, container) {
  try {
    // 动态导入 xlsx 库
    const XLSX = await import('xlsx')

    // 读取文件
    const arrayBuffer = await file.arrayBuffer()
    const workbook = XLSX.read(arrayBuffer, { type: 'array' })

    // 获取第一个工作表
    const firstSheetName = workbook.SheetNames[0]
    const worksheet = workbook.Sheets[firstSheetName]

    // 转换为 HTML 表格
    const html = XLSX.utils.sheet_to_html(worksheet, {
      editable: false,
      header: '',
      footer: ''
    })

    // 渲染到容器
    container.innerHTML = `
      <div class="excel-preview">
        <div class="excel-sheet-info">
          <span class="sheet-name">📊 ${firstSheetName}</span>
          <span class="sheet-count">${workbook.SheetNames.length} 个工作表</span>
        </div>
        <div class="excel-table-wrapper">
          ${html}
        </div>
      </div>
      <style>
        .excel-preview {
          padding: 20px;
          height: 100%;
          overflow: auto;
        }
        .excel-sheet-info {
          display: flex;
          justify-content: space-between;
          align-items: center;
          padding: 8px 12px;
          background: var(--color-fill-2);
          border-radius: 6px;
          margin-bottom: 16px;
        }
        .sheet-name {
          font-weight: 600;
          font-size: 14px;
        }
        .sheet-count {
          font-size: 12px;
          color: var(--color-text-3);
        }
        .excel-table-wrapper {
          overflow: auto;
          border: 1px solid var(--color-border-2);
          border-radius: 6px;
        }
        .excel-table-wrapper table {
          width: 100%;
          border-collapse: collapse;
          font-size: 13px;
        }
        .excel-table-wrapper td,
        .excel-table-wrapper th {
          border: 1px solid var(--color-border-2);
          padding: 6px 10px;
          text-align: left;
          white-space: nowrap;
        }
        .excel-table-wrapper th {
          background: var(--color-fill-2);
          font-weight: 600;
          position: sticky;
          top: 0;
          z-index: 1;
        }
        .excel-table-wrapper tr:hover {
          background: var(--color-fill-1);
        }
      </style>
    `

    return { success: true }
  } catch (error) {
    console.error('Excel 预览失败:', error)
    return { success: false, error: error.message }
  }
}

// Word 预览处理器
export async function previewWord(file, container) {
  try {
    // 动态导入 mammoth 库
    const mammoth = await import('mammoth')

    // 读取文件并转换为 HTML
    const arrayBuffer = await file.arrayBuffer()
    const result = await mammoth.convertToHtml({ arrayBuffer })

    // 渲染到容器
    container.innerHTML = `
      <div class="word-preview">
        <div class="word-content">
          ${result.value}
        </div>
        ${result.messages.length > 0 ? `
          <div class="word-warnings">
            <details>
              <summary>转换警告 (${result.messages.length})</summary>
              <ul>
                ${result.messages.map(msg => `<li>${msg.message}</li>`).join('')}
              </ul>
            </details>
          </div>
        ` : ''}
      </div>
      <style>
        .word-preview {
          padding: 20px;
          height: 100%;
          overflow: auto;
        }
        .word-content {
          line-height: 1.6;
          color: var(--color-text-1);
        }
        .word-content h1,
        .word-content h2,
        .word-content h3,
        .word-content h4,
        .word-content h5,
        .word-content h6 {
          margin: 1em 0 0.5em;
          font-weight: 600;
        }
        .word-content h1 { font-size: 2em; }
        .word-content h2 { font-size: 1.5em; }
        .word-content h3 { font-size: 1.25em; }
        .word-content p {
          margin: 0.5em 0;
        }
        .word-content ul,
        .word-content ol {
          margin: 0.5em 0;
          padding-left: 2em;
        }
        .word-content table {
          border-collapse: collapse;
          width: 100%;
          margin: 1em 0;
        }
        .word-content td,
        .word-content th {
          border: 1px solid var(--color-border-2);
          padding: 6px 10px;
        }
        .word-content th {
          background: var(--color-fill-2);
          font-weight: 600;
        }
        .word-content img {
          max-width: 100%;
          height: auto;
        }
        .word-content a {
          color: rgb(var(--primary-6));
          text-decoration: none;
        }
        .word-content a:hover {
          text-decoration: underline;
        }
        .word-warnings {
          margin-top: 20px;
          padding: 12px;
          background: var(--color-warning-light-1);
          border: 1px solid var(--color-warning-3);
          border-radius: 6px;
          font-size: 12px;
        }
        .word-warnings summary {
          cursor: pointer;
          font-weight: 600;
        }
        .word-warnings ul {
          margin: 8px 0 0 20px;
        }
      </style>
    `

    return { success: true }
  } catch (error) {
    console.error('Word 预览失败:', error)
    return { success: false, error: error.message }
  }
}

// 判断是否为 Office 文件
export function isOfficeFile(fileName) {
  const ext = fileName?.toLowerCase()?.split('.').pop()
  return ['xlsx', 'xls', 'docx', 'doc'].includes(ext)
}

// 判断是否为 Excel 文件
export function isExcelFile(fileName) {
  const ext = fileName?.toLowerCase()?.split('.').pop()
  return ['xlsx', 'xls'].includes(ext)
}

// 判断是否为 Word 文件
export function isWordFile(fileName) {
  const ext = fileName?.toLowerCase()?.split('.').pop()
  return ['docx', 'doc'].includes(ext)
}