import type { Readable } from 'node:stream';

import BackPressureTransform from 'back-pressure-transform';

function getTransformedStream(stream: Readable): Readable {
  const transformedStream = new BackPressureTransform(
    // Transform callback.
    async (chunk) => {
      // Do something to chunk.
      // You can transform it, replace it, or discard it.

      return chunk;
    },

    // Final callback.
    async () => {
      // Return any extra data to go onto the end of the stream.

      return Buffer.from('All done!', 'utf8');
    }
  );

  stream.pipe(transformedStream.writable);

  // When one errors, propagate that to the other.
  stream.on('error', (err) => {
    if (!transformedStream.writable.destroyed) {
      transformedStream.writable.destroy(err);
    }
  });
  transformedStream.writable.on('error', (err) => {
    if (!stream.destroyed) {
      stream.destroy(err);
    }
  });

  return transformedStream.readable;
}