/*  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,

    pending_output: Set[Document.Node.Name] = Set.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]

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

    for {

      model <- state.value.models.get(node_pos.name)

      rendering = model.rendering(options)

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

    } yield (rendering, offset)

  /* input from client */

  private val delay_input =

    Standard_Thread.delay_last(options.seconds("editor_input_delay")) {

      state.change(st =>

        {

          val changed = (for { entry <- st.models.iterator if entry._2.changed } yield entry).toList

          val edits = for { (_, model) <- changed; edit <- model.node_edits(resources) } yield edit

          session.update(Document.Blobs.empty, edits)

          st.copy(

            models = (st.models /: changed)({ case (ms, (uri, m)) => ms + (uri -> m.unchanged) }))

        })

    }

  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, text_length)

        st.copy(models = st.models + (uri -> model))

      })

    delay_input.invoke()

  }

  /* output to client */

  private val commands_changed =

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

      case changed =>

        state.change(st => st.copy(pending_output = st.pending_output ++ changed.nodes))

        delay_output.invoke()

    }

  private val delay_output =

    Standard_Thread.delay_last(options.seconds("editor_update_delay")) {

      state.change(st =>

        {

          val changed_iterator =

            for {

              node_name <- st.pending_output.iterator

              uri = node_name.node

              model <- st.models.get(uri)

              rendering = model.rendering(options)

              (diagnostics, model1) <- model.publish_diagnostics(rendering)

            } yield {

              channel.diagnostics(uri, rendering.diagnostics_output(diagnostics))

              (uri, model1)

            }

          st.copy(

            models = (st.models /: changed_iterator) { case (ms, (uri, m)) => ms + (uri -> m) },

            pending_output = Set.empty)

        })

    }

  /* 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.commands_changed += commands_changed

      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.commands_changed -= commands_changed

          session.stop()

          delay_input.revoke()

          delay_output.revoke()

          st.copy(session = None)

      })

  }

  def exit() {

    channel.log("\n")

    sys.exit(if (state.value.session.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, text_length)

        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()

  {

    channel.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) => channel.log("CLOSE " + uri)

          case Protocol.DidSaveTextDocument(uri) => channel.log("SAVE " + uri)

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

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

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

        }

      }

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

      }

    }

    loop()

  }

}