def parseArguments[T <: PipelineOptions: ClassTag]()

in scio-core/src/main/scala/com/spotify/scio/ScioContext.scala [323:383]
53 lines of code
10 McCabe index (conditional complexity)

  def parseArguments[T <: PipelineOptions: ClassTag](
    cmdlineArgs: Array[String],
    withValidation: Boolean = false
  ): (T, Args) = {
    val optClass = ScioUtil.classOf[T]
    PipelineOptionsFactory.register(optClass)

    // Extract --pattern of all registered derived types of PipelineOptions
    val registeredPatterns = for {
      cls <- PipelineOptionsFactory.getRegisteredOptions.asScala
      method <- cls.getMethods()
      name = method.getName
      str <-
        if (
          (!name.startsWith("get") && !name.startsWith("is")) ||
          method.getParameterTypes.nonEmpty || method.getReturnType == classOf[Unit]
        ) {
          None
        } else {
          Some(Introspector.decapitalize(name.substring(if (name.startsWith("is")) 2 else 3)))
        }
    } yield s"--$str($$|=)".r

    val patterns = registeredPatterns.toSet + "--help($$|=)".r

    // Split cmdlineArgs into 2 parts, optArgs for PipelineOptions and appArgs for Args
    val (optArgs, appArgs) =
      cmdlineArgs.partition(arg => patterns.exists(_.findFirstIn(arg).isDefined))

    val pipelineOpts = if (withValidation) {
      PipelineOptionsFactory.fromArgs(optArgs: _*).withValidation().as(optClass)
    } else {
      PipelineOptionsFactory.fromArgs(optArgs: _*).as(optClass)
    }

    val optionsFile = pipelineOpts.as(classOf[ScioOptions]).getOptionsFile
    if (optionsFile != null) {
      log.info(s"Appending options from $optionsFile")
      parseArguments(
        cmdlineArgs.filterNot(_.startsWith("--optionsFile=")) ++
          Source.fromFile(optionsFile).getLines()
      )
    } else {
      val args = Args(appArgs)
      if (appArgs.nonEmpty) {
        val argString = args.toString("", ", ", "")
        val sanitizedArgString =
          if (argString.length > appArgStringMaxLength) {
            log.warn("Truncating long app arguments")
            argString.substring(0, appArgStringMaxLength) + " [...]"
          } else {
            argString
          }

        pipelineOpts
          .as(classOf[ScioOptions])
          .setAppArguments(sanitizedArgString)
      }
      (pipelineOpts, args)
    }
  }