// ets_tracing: off

import * as CH from "../../Channel/index.js"
import * as C from "../core.js"

/**
 * Maps each element of this stream to another stream and returns the non-deterministic merge
 * of those streams, executing up to `n` inner streams concurrently. When a new stream is created
 * from an element of the source stream, the oldest executing stream is cancelled. Up to `bufferSize`
 * elements of the produced streams may be buffered in memory by this operator.
 */
export function chainParSwitch_<R, R1, E, E1, A, B>(
  self: C.Stream<R, E, A>,
  f: (a: A) => C.Stream<R1, E1, B>,
  n: number,
  bufferSize = 16
): C.Stream<R & R1, E | E1, B> {
  return new C.Stream(
    CH.mergeMap_(
      CH.concatMap_(self.channel, (_) => CH.writeChunk(_)),
      n,
      (_) => f(_).channel,
      bufferSize,
      "BufferSliding"
    )
  )
}

/**
 * Maps each element of this stream to another stream and returns the non-deterministic merge
 * of those streams, executing up to `n` inner streams concurrently. When a new stream is created
 * from an element of the source stream, the oldest executing stream is cancelled. Up to `bufferSize`
 * elements of the produced streams may be buffered in memory by this operator.
 *
 * @ets_data_first chainParSwitch_
 */
export function chainParSwitch<R1, E1, A, B>(
  f: (a: A) => C.Stream<R1, E1, B>,
  n: number,
  bufferSize = 16
) {
  return <R, E>(self: C.Stream<R, E, A>) => chainParSwitch_(self, f, n, bufferSize)
}