/*  Title:      Pure/System/session.scala

     Author:     Makarius

     Options:    :folding=explicit:collapseFolds=1:

 Isabelle session, potentially with running prover.

 */

 package isabelle

 import scala.actors.TIMEOUT

 import scala.actors.Actor

 import scala.actors.Actor._

 object Session

 {

   /* events */

   case object Global_Settings

   case object Perspective

   case class Commands_Changed(set: Set[Command])

   /* managed entities */

   trait Entity

   {

     val id: Document.ID

     def consume(message: XML.Tree, forward: Command => Unit): Unit

   }

 }

 class Session(system: Isabelle_System)

 {

   /* real time parameters */  // FIXME properties or settings (!?)

   // user input (e.g. text edits, cursor movement)

   val input_delay = 300

   // prover output (markup, common messages)

   val output_delay = 100

   // GUI layout updates

   val update_delay = 500

   /* pervasive event buses */

   val global_settings = new Event_Bus[Session.Global_Settings.type]

   val raw_results = new Event_Bus[Isabelle_Process.Result]

   val raw_output = new Event_Bus[Isabelle_Process.Result]

   val commands_changed = new Event_Bus[Session.Commands_Changed]

   val perspective = new Event_Bus[Session.Perspective.type]

   /* unique ids */

   private var id_count: Document.ID = 0

   def create_id(): Document.ID = synchronized {

     require(id_count > java.lang.Long.MIN_VALUE)

     id_count -= 1

     id_count

   }

   /** main actor **/

   @volatile private var syntax = new Outer_Syntax(system.symbols)

   def current_syntax: Outer_Syntax = syntax

   @volatile private var entities = Map[Document.ID, Session.Entity]()

   def lookup_entity(id: Document.ID): Option[Session.Entity] = entities.get(id)

   def lookup_command(id: Document.ID): Option[Command] =

     lookup_entity(id) match {

       case Some(cmd: Command) => Some(cmd)

       case _ => None

     }

   private case class Started(timeout: Int, args: List[String])

   private case object Stop

   private lazy val session_actor = actor {

     var prover: Isabelle_Process with Isar_Document = null

     def register(entity: Session.Entity) { entities += (entity.id -> entity) }

     var documents = Map[Document.Version_ID, Document]()

     def register_document(doc: Document) { documents += (doc.id -> doc) }

     register_document(Document.init)

     /* document changes */

     def handle_change(change: Document.Change)

     //{{{

     {

       require(change.parent.isDefined)

       val (node_edits, doc) = change.result.join

       val id_edits =

         node_edits map {

           case (name, None) => (name, None)

           case (name, Some(cmd_edits)) =>

             val chs =

               cmd_edits map {

                 case (c1, c2) =>

                   val id1 = c1.map(_.id)

                   val id2 =

                     c2 match {

                       case None => None

                       case Some(command) =>

                         if (!lookup_command(command.id).isDefined) {

                           register(command)

                           prover.define_command(command.id, system.symbols.encode(command.source))

                         }

                         Some(command.id)

                     }

                   (id1, id2)

               }

             (name -> Some(chs))

         }

       register_document(doc)

       prover.edit_document(change.parent.get.id, doc.id, id_edits)

     }

     //}}}

     /* prover results */

     def bad_result(result: Isabelle_Process.Result)

     {

       System.err.println("Ignoring prover result: " + result.message.toString)

     }

     def handle_result(result: Isabelle_Process.Result)

     //{{{

     {

       raw_results.event(result)

       val target_id: Option[Document.ID] = Position.get_id(result.properties)

       val target: Option[Session.Entity] =

         target_id match {

           case None => None

           case Some(id) => lookup_entity(id)

         }

       if (target.isDefined) target.get.consume(result.message, indicate_command_change)

       else if (result.is_status) {

         // global status message

         result.body match {

           // execution assignment

           case List(Isar_Document.Assign(edits)) if target_id.isDefined =>

             documents.get(target_id.get) match {

               case Some(doc) =>

                 val execs =

                   for {

                     Isar_Document.Edit(cmd_id, exec_id) <- edits

                     cmd <- lookup_command(cmd_id)

                   } yield {

                     val st = cmd.assign_exec(exec_id)  // FIXME session state

                     register(st)

                     (cmd, st)

                   }

                 doc.assign_execs(execs)  // FIXME session state

               case None => bad_result(result)

             }

           // keyword declarations

           case List(Keyword.Command_Decl(name, kind)) => syntax += (name, kind)

           case List(Keyword.Keyword_Decl(name)) => syntax += name

           case _ => if (!result.is_ready) bad_result(result)

         }

       }

       else if (result.kind == Markup.EXIT)

         prover = null

       else if (result.is_raw)

         raw_output.event(result)

       else if (!result.is_system)   // FIXME syslog (!?)

         bad_result(result)

     }

     //}}}

     /* prover startup */

     def startup_error(): String =

     {

       val buf = new StringBuilder

       while (

         receiveWithin(0) {

           case result: Isabelle_Process.Result =>

             if (result.is_raw) {

               for (text <- XML.content(result.message))

                 buf.append(text)

             }

             true

           case TIMEOUT => false

         }) {}

       buf.toString

     }

     def prover_startup(timeout: Int): Option[String] =

     {

       receiveWithin(timeout) {

         case result: Isabelle_Process.Result

           if result.kind == Markup.INIT =>

           while (receive {

             case result: Isabelle_Process.Result =>

               handle_result(result); !result.is_ready

             }) {}

           None

         case result: Isabelle_Process.Result

           if result.kind == Markup.EXIT =>

           Some(startup_error())

         case TIMEOUT =>  // FIXME clarify

           prover.kill; Some(startup_error())

       }

     }

     /* main loop */

     val xml_cache = new XML.Cache(131071)

     loop {

       react {

         case Started(timeout, args) =>

           if (prover == null) {

             prover = new Isabelle_Process(system, self, args:_*) with Isar_Document

             val origin = sender

             val opt_err = prover_startup(timeout)

             if (opt_err.isDefined) prover = null

             origin ! opt_err

           }

           else reply(None)

         case Stop =>  // FIXME clarify; synchronous

           if (prover != null) {

             prover.kill

             prover = null

           }

         case change: Document.Change if prover != null =>

           handle_change(change)

         case result: Isabelle_Process.Result =>

           handle_result(result.cache(xml_cache))

         case TIMEOUT =>  // FIXME clarify!

         case bad if prover != null =>

           System.err.println("session_actor: ignoring bad message " + bad)

       }

     }

   }

   /** buffered command changes (delay_first discipline) **/

   private lazy val command_change_buffer = actor

   //{{{

   {

     import scala.compat.Platform.currentTime

     var changed: Set[Command] = Set()

     var flush_time: Option[Long] = None

     def flush_timeout: Long =

       flush_time match {

         case None => 5000L

         case Some(time) => (time - currentTime) max 0

       }

     def flush()

     {

       if (!changed.isEmpty) commands_changed.event(Session.Commands_Changed(changed))

       changed = Set()

       flush_time = None

     }

     def invoke()

     {

       val now = currentTime

       flush_time match {

         case None => flush_time = Some(now + output_delay)

         case Some(time) => if (now >= time) flush()

       }

     }

     loop {

       reactWithin(flush_timeout) {

         case command: Command => changed += command; invoke()

         case TIMEOUT => flush()

         case bad => System.err.println("command_change_buffer: ignoring bad message " + bad)

       }

     }

   }

   //}}}

   def indicate_command_change(command: Command)

   {

     command_change_buffer ! command

   }

   /** editor history **/

   private case class Edit_Document(edits: List[Document.Node_Text_Edit])

   private val editor_history = new Actor

   {

     @volatile private var history = Document.Change.init

     def current_change(): Document.Change = history

     def act

     {

       loop {

         react {

           case Edit_Document(edits) =>

             val old_change = history

             val new_id = create_id()

             val result: isabelle.Future[(List[Document.Edit[Command]], Document)] =

               isabelle.Future.fork {

                 val old_doc = old_change.join_document

                 old_doc.await_assignment

                 Document.text_edits(Session.this, old_doc, new_id, edits)

               }

             val new_change = new Document.Change(new_id, Some(old_change), edits, result)

             history = new_change

             new_change.result.map(_ => session_actor ! new_change)

             reply(())

           case bad => System.err.println("editor_model: ignoring bad message " + bad)

         }

       }

     }

   }

   editor_history.start

   /** main methods **/

   def started(timeout: Int, args: List[String]): Option[String] =

     (session_actor !? Started(timeout, args)).asInstanceOf[Option[String]]

   def stop() { session_actor ! Stop }

   def snapshot(name: String, pending_edits: List[Text_Edit]): Document.Snapshot =

     editor_history.current_change().snapshot(name, pending_edits)

   def edit_document(edits: List[Document.Node_Text_Edit]) { editor_history !? Edit_Document(edits) }

 }