Nailgun CLI implementation **prototype** via Caseapp for Sailgun (Scala based client)

Cli.scala

package sailgun.caseapp

import _root_.caseapp.core.Parser
import _root_.caseapp.core.Messages
import _root_.caseapp.core.WithHelp

import java.io.PrintStream
import java.io.InputStream
import sailgun.protocol.Defaults
import sailgun.protocol.Streams
import sailgun.logging.SailgunLogger
import java.util.concurrent.atomic.AtomicBoolean
import sailgun.TcpClient

/**
  * An implementation of a CLI via case-app.
  *
  * Unfortunately, GraalVM Native Image doesn't correctly generate a native
  * image because of parsing errors and warnings generated by the use of macros
  * in case-app via Shapeless. For that reason, this class is left here but it's
  * not used by default, preferring a CLI implementation that requires no macros
  * and works with GraalVM Native Image.
  */
abstract class Cli(in: InputStream, out: PrintStream, err: PrintStream) {
  private implicit val cliParamsParser: Parser[CliParams] = Parser.generic
  private implicit val messagesParams =
    Messages.messages[CliParams].copy(appName = "nailgun", progName = "nailgun")
  private implicit val messagesParamsHelp = messagesParams.withHelp

  def exit(code: Int): Unit
  def run(args: Array[String]): Unit = {
    def errorAndExit(msg: String): Unit = { err.println(msg); exit(1) }
    cliParamsParser.withHelp.detailedParse(args) match {
      case Left(a) => errorAndExit(a)
      case Right((WithHelp(usage, help, result), remainingArgs, extraArgs)) =>
        if (usage) out.println(messagesParams.usageMessage)
        if (help)
          out.println("Type `--nailgun-help` to print help of nailgun CLI.")
        result match {
          case Left(parserError) => errorAndExit(parserError)
          case Right(params) =>
            if (params.nailgunShowVersion)
              out.println(s"Nailgun v${Defaults.Version}")
            if (params.nailgunHelp) {
              out.println(messagesParams.helpMessage)
              exit(0)
            } else {
              remainingArgs.headOption match {
                case None      => errorAndExit("Missing nailgun command to server!")
                case Some(cmd) =>
                  // Reconstruct arguments to pass them to the server correctly
                  val cmdArgs = {
                    val remaining0 = remainingArgs.tail
                    if (extraArgs.isEmpty) remaining0
                    else remaining0 ++ List("--") ++ extraArgs
                  }

                  val streams = Streams(in, out, err)
                  val client = TcpClient(params.nailgunServer, params.nailgunPort)
                  val logger = new SailgunLogger("log", out, isVerbose = params.verbose)
                  val code = client.run(
                    cmd,
                    cmdArgs.toArray,
                    Defaults.cwd,
                    Defaults.env,
                    streams,
                    logger,
                    new AtomicBoolean(false)
                  )

                  logger.debug(s"Return code is $code")
                  exit(code)
              }
            }
        }
    }
  }
}

object Cli extends Cli(System.in, System.out, System.err) {
  def main(args: Array[String]): Unit = run(args)
  override def exit(code: Int) = System.exit(code)
}

CliParams.scala

package sailgun.caseapp

import _root_.caseapp.{ExtraName, HelpMessage}
import sailgun.protocol.Defaults

final case class CliParams(
    nailgunServer: String = Defaults.Host,
    nailgunPort: Int = Defaults.Port,
    nailgunHelp: Boolean = false,
    verbose: Boolean = false,
    @ExtraName("--nailgun-showversion")
    nailgunShowVersion: Boolean = false
)