internal fun Regex.matchAtPolyfill(
  input: CharSequence,
  index: Int,
): MatchResult? {
  val candidate = find(input, index) ?: return null
  if (candidate.range.first != index) return null // Didn't match where it should have.
  return candidate
}

@JvmField
val EMPTY_BYTE_ARRAY: ByteArray = ByteArray(0)

/** Byte order marks. */
internal val UNICODE_BOMS =
  Options.of(
    // UTF-8.

            val string = reader.readUtf8String()
            return parseUtcTime(string)
          }

          override fun encode(
            writer: DerWriter,
            value: Long,
          ) {
            val string = formatUtcTime(value)
            return writer.writeUtf8(string)
          }
        },
    )

  @Throws(IOException::class)
  private fun cacheWritingResponse(
    cacheRequest: CacheRequest?,
    response: Response,
  ): Response {
    // Some apps return a null body; for compatibility we treat that like a null cache request.
    if (cacheRequest == null) return response
    val cacheBodyUnbuffered = cacheRequest.body()

    val source = response.body.source()
    val cacheBody = cacheBodyUnbuffered.buffer()

    if (":" in host) {
      "[$host]"
    } else {
      host
    }
  return if (includeDefaultPort || port != defaultPort(scheme)) {
    "$host:$port"
  } else {
    host
  }
}

/** Returns a [Locale.US] formatted [String]. */
internal fun format(
  format: String,
  vararg args: Any,
): String {
  return String.format(Locale.US, format, *args)
}

@Throws(IOException::class)

   * control this will return null. If there is more than a single task ready to execute immediately
   * this will start another thread to handle that work.
   */
  fun awaitTaskToRun(): Task? {
    lock.assertHeld()

    while (true) {
      if (readyQueues.isEmpty()) {
        return null // Nothing to do.
      }

      val now = backend.nanoTime()

    taskRunner.assertThreadHoldsLock()

    val index = serialTaskQueue.indexOfFirst { it.isReady() }
    if (index == -1) return null

    val nextTask = serialTaskQueue.removeAt(index)
    currentTask = nextTask
    contextSwitchCount++
    nextTask.start()
    return nextTask
  }

  private interface SerialTask {
    /** Returns true if this task is ready to start. */
    fun isReady() = true

  }

  private fun uppercase(original: RequestBody?): RequestBody {
    return object : RequestBody() {
      override fun contentType(): MediaType? {
        return original!!.contentType()
      }

      override fun contentLength(): Long {
        return original!!.contentLength()
      }

      override fun writeTo(sink: BufferedSink) {

        padding = 0
        if (flags and FLAG_END_HEADERS != 0) return -1L
        readContinuationHeader()
        // TODO: test case for empty continuation header?
      }

      val read = source.read(sink, minOf(byteCount, left.toLong()))
      if (read == -1L) return -1L
      left -= read.toInt()
      return read
    }

    override fun timeout(): Timeout = source.timeout()

 * [bytes] or [string]. Or stream the response with either [source], [byteStream], or [charStream].
 */
abstract class ResponseBody : Closeable {
  /** Multiple calls to [charStream] must return the same instance. */
  private var reader: Reader? = null

  abstract fun contentType(): MediaType?

  /**
   * Returns the number of bytes in that will returned by [bytes], or [byteStream], or -1 if

        } catch (expected: IOException) {
        }
      }
    thread.start()
    return thread
  }

  private fun newRequest(url: String): Request {
    return Request.Builder().url(url).build()
  }

  private fun newRequest(
    url: String,
    tag: String,
  ): Request {
    return Request.Builder().url(url).tag(tag).build()
  }