* sample of code points to detect unicode control characters commonly used in binary file
 * signatures.
 */
fun Buffer.isProbablyUtf8(): Boolean {
  try {
    val prefix = Buffer()
    val byteCount = size.coerceAtMost(64)
    copyTo(prefix, 0, byteCount)
    for (i in 0 until 16) {
      if (prefix.exhausted()) {
        break
      }
      val codePoint = prefix.readUtf8CodePoint()

        var closed = false

        override fun close() {
          closed = true
        }

        override fun read(
          sink: Buffer,
          byteCount: Long,
        ): Long {
          check(!closed)
          return data.read(sink, byteCount)
        }

        override fun timeout(): Timeout {
          return Timeout.NONE
        }
      }
    return source.buffer().asResponseBody(null, -1)

    assertThat(body.bytes()).isEqualTo(text)
  }
}

abstract class ForwardingSource(
  val delegate: Source,
) : Source {
  override fun read(
    sink: Buffer,
    byteCount: Long,
  ): Long = delegate.read(sink, byteCount)

  override fun timeout() = delegate.timeout()

  override fun close() = delegate.close()

  /** Used for tags and subidentifiers. */
  private fun writeVariableLengthLong(v: Long) {
    val sink = sink()
    val bitCount = 64 - java.lang.Long.numberOfLeadingZeros(v)
    val byteCount = (bitCount + 6) / 7
    for (shift in (byteCount - 1) * 7 downTo 0 step 7) {
      val lastBit = if (shift == 0) 0 else 0b1000_0000
      sink.writeByte(((v shr shift) and 0b0111_1111).toInt() or lastBit)
    }
  }

    headersBuilder.add(CHUNKED_BODY_HEADER)

    val bytesOut = Buffer()
    while (!body.exhausted()) {
      val chunkSize = minOf(body.size, maxChunkSize.toLong())
      bytesOut.writeHexadecimalUnsignedLong(chunkSize)
      bytesOut.writeUtf8("\r\n")
      bytesOut.write(body, chunkSize)
      bytesOut.writeUtf8("\r\n")
    }
    bytesOut.writeUtf8("0\r\n") // Last chunk. Trailers follow!
    this.body = bytesOut