// lib/filePreview.ts：由 lib/utils.ts 按职责拆分（实现未改）
import { getToken } from '/@/utils/auth/index';
import type { AttachedFile } from '/@/views/ventAI/manageAssistent/types/resource';
import { isImageFile, isPdfFile, isWordFile, isExcelFile } from './fileIcon';

export const fetchPreviewFile = async (url: string, filename: string): Promise<AttachedFile | null> => {
  const resp = await fetch(url, { headers: { 'X-Access-Token': getToken() } });
  if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
  const ext = filename.split('.').pop()?.toLowerCase() || '';
  const mimeMap: Record<string, string> = {
    md: 'text/markdown',
    txt: 'text/plain',
    json: 'application/json',
    xml: 'text/xml',
    yaml: 'text/yaml',
    yml: 'text/yaml',
    csv: 'text/csv',
    // .dxf 是明文，按文本取回后由预览面板本地解析渲染
    dxf: 'text/plain',
  };
  const id = `report-${url}`;
  const uploadTime = new Date().toISOString();

  if (mimeMap[ext]) {
    const content = await resp.text();
    return { id, name: filename, size: content.length, type: mimeMap[ext], content, uploadTime };
  }
  if (isWordFile(filename) || isExcelFile(filename)) {
    const arrayBuffer = await resp.arrayBuffer();
    return { id, name: filename, size: arrayBuffer.byteLength, type: 'application/octet-stream', arrayBuffer, uploadTime };
  }
  if (isImageFile(filename) || isPdfFile(filename)) {
    const blob = await resp.blob();
    const dataUrl = await new Promise<string>((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = () => resolve(reader.result as string);
      reader.onerror = () => reject(reader.error);
      reader.readAsDataURL(blob);
    });
    return { id, name: filename, size: blob.size, type: blob.type, preview: dataUrl, uploadTime };
  }
  return null;
};