/*  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, File => JFile}

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 = Text.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(Text.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 => Text.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 log = Logger.make(log_file)

      val channel = new Channel(System.in, System.out, log)

      val server = new Server(channel, options, text_length, logic, dirs, modes, log)

      // 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, No_Logger)

        channel.error_message(Exn.message(exn))

        throw(exn)

    }

  })

}

class Server(

  channel: Channel,

  options: Options,

  text_length: Text.Length = Text.Length.encoding(Server.default_text_length),

  session_name: String = Server.default_logic,

  session_dirs: List[Path] = Nil,

  modes: List[String] = Nil,

  log: Logger = No_Logger)

{

  /* prover session */

  private val session_ = Synchronized(None: Option[Session])

  def session: Session = session_.value getOrElse error("Server inactive")

  def resources: VSCode_Resources = session.resources.asInstanceOf[VSCode_Resources]

  def rendering_offset(node_pos: Line.Node_Position): Option[(VSCode_Rendering, Text.Offset)] =

    for {

      model <- resources.get_model(node_pos.name)

      rendering = model.rendering()

      offset <- model.doc.offset(node_pos.pos)

    } yield (rendering, offset)

  /* input from client or file-system */

  private val delay_input =

    Standard_Thread.delay_last(options.seconds("vscode_input_delay"))

    { resources.flush_input(session) }

  private val delay_load =

    Standard_Thread.delay_last(options.seconds("vscode_load_delay"))

    { if (resources.resolve_dependencies(session)) delay_input.invoke() }

  private val watcher =

    File_Watcher(sync_documents(_), options.seconds("vscode_load_delay"))

  private def sync_documents(changed: Set[JFile]): Unit =

    if (resources.sync_models(changed)) delay_input.invoke()

  private def update_document(uri: String, text: String)

  {

    resources.update_model(session, uri, text)

    delay_input.invoke()

  }

  private def close_document(uri: String)

  {

    resources.close_model(uri) match {

      case Some(model) =>

        model.register(watcher)

        sync_documents(Set(model.file))

      case None =>

    }

  }

  /* output to client */

  private val delay_output: Standard_Thread.Delay =

    Standard_Thread.delay_last(options.seconds("vscode_output_delay"))

    {

      if (session.current_state().stable_tip_version.isEmpty) delay_output.invoke()

      else resources.flush_output(channel)

    }

  private val prover_output =

    Session.Consumer[Session.Commands_Changed](getClass.getName) {

      case changed if changed.nodes.nonEmpty =>

        resources.update_output(changed.nodes.toList.map(_.node))

        delay_output.invoke()

      case _ =>

    }

  private val syslog =

    Session.Consumer[Prover.Message](getClass.getName) {

      case output: Prover.Output if output.is_syslog =>

        channel.log_writeln(XML.content(output.message))

      case _ =>

    }

  /* 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(options, text_length, content.loaded_theories,

              content.known_theories, content.syntax, log) {

            override def commit(change: Session.Change): Unit =

              if (change.deps_changed) delay_load.invoke()

          }

        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.commands_changed += prover_output

      session.all_messages += syslog

      session.start(receiver =>

        Isabelle_Process(options = options, logic = session_name, dirs = session_dirs,

          modes = modes, receiver = receiver))

      session_.change(_ => Some(session))

    }

  }

  def shutdown(id: Protocol.Id)

  {

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

    session_.change({

      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

              session.commands_changed -= prover_output

              session.all_messages -= syslog

              reply("")

            case _ =>

          }

        session.phase_changed += session_phase

        session.stop()

        delay_input.revoke()

        delay_output.revoke()

        watcher.shutdown()

        None

      case None =>

        reply("Prover inactive")

        None

    })

  }

  def exit() {

    log("\n")

    sys.exit(if (session_.value.isDefined) 1 else 0)

  }

  /* hover */

  def hover(id: Protocol.Id, node_pos: Line.Node_Position)

  {

    val result =

      for {

        (rendering, offset) <- rendering_offset(node_pos)

        info <- rendering.tooltip(Text.Range(offset, offset + 1))

      } yield {

        val doc = rendering.model.doc

        val range = doc.range(info.range)

        val s = Pretty.string_of(info.info, margin = rendering.tooltip_margin)

        (range, List("```\n" + s + "\n```"))  // FIXME proper content format

      }

    channel.write(Protocol.Hover.reply(id, result))

  }

  /* goto definition */

  def goto_definition(id: Protocol.Id, node_pos: Line.Node_Position)

  {

    val result =

      (for ((rendering, offset) <- rendering_offset(node_pos))

        yield rendering.hyperlinks(Text.Range(offset, offset + 1))) getOrElse Nil

    channel.write(Protocol.GotoDefinition.reply(id, result))

  }

  /* main loop */

  def start()

  {

    log("Server 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) =>

            close_document(uri)

          case Protocol.Hover(id, node_pos) => hover(id, node_pos)

          case Protocol.GotoDefinition(id, node_pos) => goto_definition(id, node_pos)

          case _ => log("### IGNORED")

        }

      }

      catch { case exn: Throwable => channel.log_error_message(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 => log("### TERMINATE")

      }

    }

    loop()

  }

}