FastGPT/packages/service/common/file/gridfs/utils.ts

import { detectFileEncoding } from '@fastgpt/global/common/file/tools';
import { PassThrough } from 'stream';

export const gridFsStream2Buffer = (stream: NodeJS.ReadableStream) => {
  return new Promise<Buffer>((resolve, reject) => {
    let tmpBuffer: Buffer = Buffer.from([]);

    stream.on('data', (chunk) => {
      tmpBuffer = Buffer.concat([tmpBuffer, chunk]);
    });
    stream.on('end', () => {
      resolve(tmpBuffer);
    });
    stream.on('error', (err) => {
      reject(err);
    });
  });
};

export const stream2Encoding = async (stream: NodeJS.ReadableStream) => {
  const start = Date.now();
  const copyStream = stream.pipe(new PassThrough());

  /* get encoding */
  const buffer = await (() => {
    return new Promise<Buffer>((resolve, reject) => {
      let tmpBuffer: Buffer = Buffer.from([]);

      stream.on('data', (chunk) => {
        if (tmpBuffer.length < 200) {
          tmpBuffer = Buffer.concat([tmpBuffer, chunk]);

          if (tmpBuffer.length >= 200) {
            resolve(tmpBuffer);
          }
        }
      });
      stream.on('end', () => {
        resolve(tmpBuffer);
      });
      stream.on('error', (err) => {
        reject(err);
      });
    });
  })();

  const enc = detectFileEncoding(buffer);
  console.log('Get encoding time', Date.now() - start, enc);
  return {
    encoding: enc,
    stream: copyStream
  };
};