def effectiveUri()

in http-core/src/main/scala/org/apache/pekko/http/scaladsl/model/HttpMessage.scala [474:508]
35 lines of code
20 McCabe index (conditional complexity)

  def effectiveUri(
      uri: Uri, headers: immutable.Seq[HttpHeader], securedConnection: Boolean, defaultHostHeader: Host): Uri = {
    @tailrec def findHostAndWsUpgrade(it: Iterator[HttpHeader], host: OptionVal[Host] = OptionVal.None,
        wsUpgrade: Option[Boolean] = None): (OptionVal[Host], Boolean) =
      if (host.isDefined && wsUpgrade.isDefined || !it.hasNext)
        (host, wsUpgrade.contains(true))
      else
        it.next() match {
          case h: Host    => findHostAndWsUpgrade(it, OptionVal.Some(h), wsUpgrade)
          case u: Upgrade => findHostAndWsUpgrade(it, host, Some(u.hasWebSocket))
          case _          => findHostAndWsUpgrade(it, host, wsUpgrade)
        }
    val (hostHeader, isWebsocket) = findHostAndWsUpgrade(headers.iterator)
    if (uri.isRelative) {
      def fail(detail: String) =
        throw IllegalUriException(
          s"Cannot establish effective URI of request to `$uri`, request has a relative URI and $detail",
          "consider setting `pekko.http.server.default-host-header`")
      val Host(hostHeaderHost, hostHeaderPort) = hostHeader match {
        case OptionVal.None => if (defaultHostHeader.isEmpty) fail("is missing a `Host` header") else defaultHostHeader
        case OptionVal.Some(x) if x.isEmpty =>
          if (defaultHostHeader.isEmpty) fail("an empty `Host` header") else defaultHostHeader
        case OptionVal.Some(x) => x
      }
      val defaultScheme =
        if (isWebsocket) Uri.websocketScheme(securedConnection)
        else Uri.httpScheme(securedConnection)
      uri.toEffectiveRequestUri(hostHeaderHost, hostHeaderPort, defaultScheme)
    } else // http://tools.ietf.org/html/rfc7230#section-5.4
    if (hostHeader.isEmpty || uri.authority.isEmpty && hostHeader.get.isEmpty ||
      hostHeader.get.host.equalsIgnoreCase(uri.authority.host) && hostHeader.get.port == uri.authority.port) uri
    else throw IllegalUriException(
      s"'Host' header value of request to `$uri` doesn't match request target authority",
      s"Host header: $hostHeader\nrequest target authority: ${uri.authority}")
  }