/*  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()

       var system_mode = false

       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(default_logic) + """)

     -m MODE      add print mode for output

     -o OPTION    override Isabelle system OPTION (via NAME=VAL or NAME)

     -s           system build mode for session image

   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),

         "s" -> (_ => system_mode = true))

       val more_args = getopts(args)

       if (more_args.nonEmpty) getopts.usage()

       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, system_mode, 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,

   system_mode: Boolean = false,

   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 {

         if (!Build.build(options = options, build_heap = true, no_build = true,

               system_mode = system_mode, dirs = session_dirs, sessions = List(session_name)).ok)

         {

           val start_msg = "Build started for Isabelle/" + session_name + " ..."

           val fail_msg = "Session build failed -- prover process remains inactive!"

           val progress = channel.make_progress(verbose = true)

           progress.echo(start_msg); channel.writeln(start_msg)

           if (!Build.build(options = options, progress = progress, build_heap = true,

               system_mode = system_mode, dirs = session_dirs, sessions = List(session_name)).ok)

           {

             progress.echo(fail_msg); error(fail_msg)

           }

         }

         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()

   }

 }