/*  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 =>

   {

     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) }

   })

   /* 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)

     }

     // FIXME handle error

     val content = Build.session_content(options, false, session_dirs, session_name)

     val resources =

       new VSCode_Resources(content.loaded_theories, content.known_theories, content.syntax)

     val session =

       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")

       }

     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()

   }

 }