NaturalCycles/nodejs-lib

import { Writable } from 'node:stream'
import { DeferredPromise } from '@naturalcycles/js-lib'
import { TransformOptions } from '../stream.model'

export interface WritableVoidOptions extends TransformOptions {
  /**
   * If set - it will be Resolved when the Stream is done (after final.cb)
   */
  streamDone?: DeferredPromise
}

/**
 * Use as a "null-terminator" of stream.pipeline.
 * It consumes the stream as quickly as possible without doing anything.
 * Put it in the end of your pipeline in case it ends with Transform that needs a consumer.
 */
export function writableVoid(opt: WritableVoidOptions = {}): Writable {
  return new Writable({
    objectMode: true,
    ...opt,
    write(chunk, _, cb) {
      cb()
    },
    final(cb) {
      cb()
      opt.streamDone?.resolve()
    },
  })
}