src/Tools/VSCode/src/server.scala

more explicit error;

/*  Title:      Tools/VSCode/src/server.scala
    Author:     Makarius

Server for VS Code Language Server Protocol 2.0, see also
https://github.com/Microsoft/language-server-protocol
https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md
*/

package isabelle.vscode


import isabelle._

import java.io.{PrintStream, OutputStream}

import scala.annotation.tailrec


object Server
{
  /* Isabelle tool wrapper */

  private val default_text_length = "UTF-16"
  private lazy val default_logic = Isabelle_System.getenv("ISABELLE_LOGIC")

  val isabelle_tool = Isabelle_Tool("vscode_server", "VSCode Language Server for PIDE", args =>
  {
    try {
      var log_file: Option[Path] = None
      var text_length = Length.encoding(default_text_length)
      var dirs: List[Path] = Nil
      var logic = default_logic
      var modes: List[String] = Nil
      var options = Options.init()

      def text_length_choice: String =
        commas(Length.encodings.map(
          { case (a, _) => if (a == default_text_length) a + " (default)" else a }))

      val getopts = Getopts("""
Usage: isabelle vscode_server [OPTIONS]

  Options are:
    -L FILE      enable logging on FILE
    -T LENGTH    text length encoding: """ + text_length_choice + """
    -d DIR       include session directory
    -l NAME      logic session name (default ISABELLE_LOGIC=""" + quote(logic) + """)
    -m MODE      add print mode for output
    -o OPTION    override Isabelle system OPTION (via NAME=VAL or NAME)

  Run the VSCode Language Server protocol (JSON RPC) over stdin/stdout.
""",
        "L:" -> (arg => log_file = Some(Path.explode(arg))),
        "T:" -> (arg => Length.encoding(arg)),
        "d:" -> (arg => dirs = dirs ::: List(Path.explode(arg))),
        "l:" -> (arg => logic = arg),
        "m:" -> (arg => modes = arg :: modes),
        "o:" -> (arg => options = options + arg))

      val more_args = getopts(args)
      if (more_args.nonEmpty) getopts.usage()

      if (!Build.build(options = options, build_heap = true, no_build = true,
            dirs = dirs, sessions = List(logic)).ok)
        error("Missing logic image " + quote(logic))

      val channel = new Channel(System.in, System.out, log_file)
      val server = new Server(channel, options, text_length, logic, dirs, modes)

      // prevent spurious garbage on the main protocol channel
      val orig_out = System.out
      try {
        System.setOut(new PrintStream(new OutputStream { def write(n: Int) {} }))
        server.start()
      }
      finally { System.setOut(orig_out) }
    }
    catch {
      case exn: Throwable =>
        val channel = new Channel(System.in, System.out, None)
        channel.error_message(Exn.message(exn))
        throw(exn)
    }
  })


  /* server state */

  sealed case class State(
    session: Option[Session] = None,
    models: Map[String, Document_Model] = Map.empty)
}

class Server(
  channel: Channel,
  options: Options,
  text_length: Length = Length.encoding(Server.default_text_length),
  session_name: String = Server.default_logic,
  session_dirs: List[Path] = Nil,
  modes: List[String] = Nil)
{
  /* server state */

  private val state = Synchronized(Server.State())

  def session: Session = state.value.session getOrElse error("Session inactive")
  def resources: VSCode_Resources = session.resources.asInstanceOf[VSCode_Resources]


  /* init and exit */

  def init(id: Protocol.Id)
  {
    def reply(err: String)
    {
      channel.write(Protocol.Initialize.reply(id, err))
      if (err == "")
        channel.writeln("Welcome to Isabelle/" + session_name + " (" + Distribution.version + ")")
      else channel.error_message(err)
    }

    val try_session =
      try {
        val content = Build.session_content(options, false, session_dirs, session_name)
        val resources =
          new VSCode_Resources(content.loaded_theories, content.known_theories, content.syntax)

        Some(new Session(resources) {
          override def output_delay = options.seconds("editor_output_delay")
          override def prune_delay = options.seconds("editor_prune_delay")
          override def syslog_limit = options.int("editor_syslog_limit")
          override def reparse_limit = options.int("editor_reparse_limit")
        })
      }
      catch { case ERROR(msg) => reply(msg); None }

    for (session <- try_session) {
      var session_phase: Session.Consumer[Session.Phase] = null
      session_phase =
        Session.Consumer(getClass.getName) {
          case Session.Ready =>
            session.phase_changed -= session_phase
            session.update_options(options)
            reply("")
          case Session.Failed =>
            session.phase_changed -= session_phase
            reply("Prover startup failed")
          case _ =>
        }
      session.phase_changed += session_phase

      session.start(receiver =>
        Isabelle_Process(options = options, logic = session_name, dirs = session_dirs,
          modes = modes, receiver = receiver))

      state.change(_.copy(session = Some(session)))
    }
  }

  def shutdown(id: Protocol.Id)
  {
    def reply(err: String): Unit = channel.write(Protocol.Shutdown.reply(id, err))

    state.change(st =>
      st.session match {
        case None => reply("Prover inactive"); st
        case Some(session) =>
          var session_phase: Session.Consumer[Session.Phase] = null
          session_phase =
            Session.Consumer(getClass.getName) {
              case Session.Inactive =>
                session.phase_changed -= session_phase
                reply("")
              case _ =>
            }
          session.phase_changed += session_phase
          session.stop()
          st.copy(session = None)
      })
  }

  def exit() { sys.exit(if (state.value.session.isDefined) 1 else 0) }


  /* document management */

  private val delay_flush =
    Standard_Thread.delay_last(options.seconds("editor_input_delay")) {
      state.change(st =>
        {
          val models = st.models
          val changed = (for { entry <- models.iterator if entry._2.changed } yield entry).toList
          val edits = for { (_, model) <- changed; edit <- model.node_edits } yield edit
          val models1 =
            (models /: changed)({ case (m, (uri, model)) => m + (uri -> model.unchanged) })

          session.update(Document.Blobs.empty, edits)
          st.copy(models = models1)
        })
    }

  def update_document(uri: String, text: String)
  {
    state.change(st =>
      {
        val node_name = resources.node_name(uri)
        val model = Document_Model(session, Line.Document(text), node_name)
        st.copy(models = st.models + (uri -> model))
      })
    delay_flush.invoke()
  }


  /* hover */

  def hover(id: Protocol.Id, uri: String, pos: Line.Position)
  {
    val result =
      for {
        model <- state.value.models.get(uri)
        rendering = model.rendering(options)
        offset <- model.doc.offset(pos, text_length)
        info <- rendering.tooltip(Text.Range(offset, offset + 1))
      } yield {
        val start = model.doc.position(info.range.start, text_length)
        val stop = model.doc.position(info.range.stop, text_length)
        val s = Pretty.string_of(info.info, margin = rendering.tooltip_margin)
        (Line.Range(start, stop), List("```\n" + s + "\n```"))  // FIXME proper content format
      }
    channel.write(Protocol.Hover.reply(id, result))
  }


  /* main loop */

  def start()
  {
    channel.log("\nServer started " + Date.now())

    def handle(json: JSON.T)
    {
      try {
        json match {
          case Protocol.Initialize(id) => init(id)
          case Protocol.Shutdown(id) => shutdown(id)
          case Protocol.Exit => exit()
          case Protocol.DidOpenTextDocument(uri, lang, version, text) =>
            update_document(uri, text)
          case Protocol.DidChangeTextDocument(uri, version, List(Protocol.TextDocumentContent(text))) =>
            update_document(uri, text)
          case Protocol.DidCloseTextDocument(uri) => channel.log("CLOSE " + uri)
          case Protocol.DidSaveTextDocument(uri) => channel.log("SAVE " + uri)
          case Protocol.Hover(id, uri, pos) => hover(id, uri, pos)
          case _ => channel.log("### IGNORED")
        }
      }
      catch { case exn: Throwable => channel.log("*** ERROR: " + Exn.message(exn)) }
    }

    @tailrec def loop()
    {
      channel.read() match {
        case Some(json) =>
          json match {
            case bulk: List[_] => bulk.foreach(handle(_))
            case _ => handle(json)
          }
          loop()
        case None => channel.log("### TERMINATE")
      }
    }
    loop()
  }
}