/*  Title:      Pure/System/session.scala

     Author:     Makarius

     Options:    :folding=explicit:collapseFolds=1:

 Main Isabelle/Scala session, potentially with running prover process.

 */

 package isabelle

 import java.lang.System

 import scala.actors.TIMEOUT

 import scala.actors.Actor

 import scala.actors.Actor._

 object Session

 {

   /* file store */

   abstract class File_Store

   {

     def append(master_dir: String, path: Path): String

     def require(file: String): Unit

   }

   /* events */

   //{{{

   case object Global_Settings

   case object Perspective

   case object Assignment

   case class Commands_Changed(set: Set[Command])

   sealed abstract class Phase

   case object Inactive extends Phase

   case object Startup extends Phase  // transient

   case object Failed extends Phase

   case object Ready extends Phase

   case object Shutdown extends Phase  // transient

   //}}}

 }

 class Session(val file_store: Session.File_Store)

 {

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

   val input_delay = Time.seconds(0.3)  // user input (e.g. text edits, cursor movement)

   val output_delay = Time.seconds(0.1)  // prover output (markup, common messages)

   val update_delay = Time.seconds(0.5)  // GUI layout updates

   val load_delay = Time.seconds(0.5)  // file load operations (new buffers etc.)

   /* pervasive event buses */

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

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

   val assignments = new Event_Bus[Session.Assignment.type]

   val commands_changed = new Event_Bus[Session.Commands_Changed]

   val phase_changed = new Event_Bus[Session.Phase]

   val raw_messages = new Event_Bus[Isabelle_Process.Message]

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

   //{{{

   private case object Stop

   private val (_, command_change_buffer) =

     Simple_Thread.actor("command_change_buffer", daemon = true)

   {

     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 - System.currentTimeMillis()) max 0

       }

     def flush()

     {

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

       changed = Set()

       flush_time = None

     }

     def invoke()

     {

       val now = System.currentTimeMillis()

       flush_time match {

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

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

       }

     }

     var finished = false

     while (!finished) {

       receiveWithin(flush_timeout) {

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

         case TIMEOUT => flush()

         case Stop => finished = true; reply(())

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

       }

     }

   }

   //}}}

   /** main protocol actor **/

   /* global state */

   @volatile var verbose: Boolean = false

   @volatile private var loaded_theories: Set[String] = Set()

   @volatile private var syntax = new Outer_Syntax

   def current_syntax(): Outer_Syntax = syntax

   @volatile private var reverse_syslog = List[XML.Elem]()

   def syslog(): String = reverse_syslog.reverse.map(msg => XML.content(msg).mkString).mkString("\n")

   @volatile private var _phase: Session.Phase = Session.Inactive

   private def phase_=(new_phase: Session.Phase)

   {

     _phase = new_phase

     phase_changed.event(new_phase)

   }

   def phase = _phase

   def is_ready: Boolean = phase == Session.Ready

   private val global_state = new Volatile(Document.State.init)

   def current_state(): Document.State = global_state()

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

     global_state().snapshot(name, pending_edits)

   /* theory files */

   val thy_load = new Thy_Load

   {

     override def is_loaded(name: String): Boolean =

       loaded_theories.contains(name)

     override def check_thy(dir: Path, name: String): (String, Thy_Header) =

     {

       val file = Isabelle_System.platform_file(dir + Thy_Header.thy_path(name))

       if (!file.exists || !file.isFile) error("No such file: " + quote(file.toString))

       val text = Standard_System.read_file(file)

       val header = Thy_Header.read(text)

       (text, header)

     }

   }

   val thy_info = new Thy_Info(thy_load)

   def header_edit(name: String, master_dir: String,

     header: Document.Node_Header): Document.Edit_Text =

   {

     def norm_import(s: String): String =

     {

       val thy_name = Thy_Header.base_name(s)

       if (thy_load.is_loaded(thy_name)) thy_name

       else file_store.append(master_dir, Thy_Header.thy_path(Path.explode(s)))

     }

     def norm_use(s: String): String =

       file_store.append(master_dir, Path.explode(s))

     val header1: Document.Node_Header =

       header match {

         case Exn.Res(Thy_Header(thy_name, _, _))

         if (thy_load.is_loaded(thy_name)) =>

           Exn.Exn(ERROR("Attempt to update loaded theory " + quote(thy_name)))

         case _ => Document.Node.norm_header(norm_import, norm_use, header)

       }

     (name, Document.Node.Header(header1))

   }

   /* actor messages */

   private case class Start(timeout: Time, args: List[String])

   private case object Interrupt

   private case class Check_Loaded_Files(ask: List[String] => Boolean)

   private case class Init_Node(name: String, master_dir: String,

     header: Document.Node_Header, perspective: Text.Perspective, text: String)

   private case class Edit_Node(name: String, master_dir: String,

     header: Document.Node_Header, perspective: Text.Perspective, edits: List[Text.Edit])

   private case class Change_Node(

     name: String,

     doc_edits: List[Document.Edit_Command],

     previous: Document.Version,

     version: Document.Version)

   private val (_, session_actor) = Simple_Thread.actor("session_actor", daemon = true)

   {

     val this_actor = self

     var prover: Option[Isabelle_Process with Isar_Document] = None

     /* perspective */

     def update_perspective(name: String, text_perspective: Text.Perspective)

     {

       val previous = global_state().tip_version

       val (perspective, version) = Thy_Syntax.edit_perspective(previous, name, text_perspective)

       val text_edits: List[Document.Edit_Text] =

         List((name, Document.Node.Perspective(text_perspective)))

       val change =

         global_state.change_yield(

           _.continue_history(Future.value(previous), text_edits, Future.value(version)))

       val assignment = global_state().the_assignment(previous).check_finished

       global_state.change(_.define_version(version, assignment))

       global_state.change_yield(_.assign(version.id, Document.no_assign))

       prover.get.update_perspective(previous.id, version.id, name, perspective)

     }

     /* incoming edits */

     def handle_edits(name: String, master_dir: String,

         header: Document.Node_Header, edits: List[Document.Node.Edit[Text.Edit, Text.Perspective]])

     //{{{

     {

       val syntax = current_syntax()

       val previous = global_state().history.tip.version

       val text_edits = header_edit(name, master_dir, header) :: edits.map(edit => (name, edit))

       val result = Future.fork { Thy_Syntax.text_edits(syntax, previous.join, text_edits) }

       val change =

         global_state.change_yield(_.continue_history(previous, text_edits, result.map(_._2)))

       result.map {

         case (doc_edits, _) =>

           assignments.await { global_state().is_assigned(previous.get_finished) }

           this_actor ! Change_Node(name, doc_edits, previous.join, change.version.join)

       }

     }

     //}}}

     /* exec state assignment */

     def handle_assign(id: Document.Version_ID, assign: Document.Assign)

     //{{{

     {

       val cmds = global_state.change_yield(_.assign(id, assign))

       for (cmd <- cmds) command_change_buffer ! cmd

       assignments.event(Session.Assignment)

     }

     //}}}

     /* resulting changes */

     def handle_change(change: Change_Node)

     //{{{

     {

       val previous = change.previous

       val version = change.version

       val name = change.name

       val doc_edits = change.doc_edits

       def id_command(command: Command)

       {

         if (global_state().lookup_command(command.id).isEmpty) {

           global_state.change(_.define_command(command))

           prover.get.define_command(command.id, Symbol.encode(command.source))

         }

       }

       doc_edits foreach {

         case (_, edit) =>

           edit foreach { case (c1, c2) => c1 foreach id_command; c2 foreach id_command }

       }

       val assignment = global_state().the_assignment(previous).check_finished

       global_state.change(_.define_version(version, assignment))

       prover.get.update(previous.id, version.id, doc_edits)

     }

     //}}}

     /* prover results */

     def handle_result(result: Isabelle_Process.Result)

     //{{{

     {

       def bad_result(result: Isabelle_Process.Result)

       {

         if (verbose)

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

       }

       result.properties match {

         case Position.Id(state_id) if !result.is_raw =>

           try {

             val st = global_state.change_yield(_.accumulate(state_id, result.message))

             command_change_buffer ! st.command

           }

           catch {

             case _: Document.State.Fail => bad_result(result)

           }

         case Markup.Invoke_Scala(name, id) if result.is_raw =>

           Future.fork {

             val arg = XML.content(result.body).mkString

             val (tag, res) = Invoke_Scala.method(name, arg)

             prover.get.invoke_scala(id, tag, res)

           }

         case Markup.Cancel_Scala(id) =>

           System.err.println("cancel_scala " + id)  // FIXME cancel JVM task

         case _ =>

           if (result.is_syslog) {

             reverse_syslog ::= result.message

             if (result.is_ready) {

               // FIXME move to ML side (!?)

               syntax += ("hence", Keyword.PRF_ASM_GOAL, "then have")

               syntax += ("thus", Keyword.PRF_ASM_GOAL, "then show")

               phase = Session.Ready

             }

             else if (result.is_exit && phase == Session.Startup) phase = Session.Failed

             else if (result.is_exit) phase = Session.Inactive

           }

           else if (result.is_stdout) { }

           else if (result.is_status) {

             result.body match {

               case List(Isar_Document.Assign(id, assign)) =>

                 try { handle_assign(id, assign) }

                 catch { case _: Document.State.Fail => bad_result(result) }

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

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

               case List(Thy_Info.Loaded_Theory(name)) => loaded_theories += name

               case _ => bad_result(result)

             }

           }

           else bad_result(result)

       }

     }

     //}}}

     /* main loop */

     //{{{

     var finished = false

     while (!finished) {

       receive {

         case Start(timeout, args) if prover.isEmpty =>

           if (phase == Session.Inactive || phase == Session.Failed) {

             phase = Session.Startup

             prover = Some(new Isabelle_Process(timeout, this_actor, args:_*) with Isar_Document)

           }

         case Stop =>

           if (phase == Session.Ready) {

             global_state.change(_ => Document.State.init)  // FIXME event bus!?

             phase = Session.Shutdown

             prover.get.terminate

             prover = None

             phase = Session.Inactive

           }

           finished = true

           reply(())

         case Interrupt if prover.isDefined =>

           prover.get.interrupt

         case Check_Loaded_Files(ask) => // FIXME

         case Init_Node(name, master_dir, header, perspective, text) if prover.isDefined =>

           // FIXME compare with existing node

           handle_edits(name, master_dir, header,

             List(Document.Node.Clear(),

               Document.Node.Edits(List(Text.Edit.insert(0, text))),

               Document.Node.Perspective(perspective)))

           reply(())

         case Edit_Node(name, master_dir, header, perspective, text_edits) if prover.isDefined =>

           if (text_edits.isEmpty && global_state().tip_stable &&

               perspective.range.stop <= global_state().last_exec_offset(name))

             update_perspective(name, perspective)

           else

             handle_edits(name, master_dir, header,

               List(Document.Node.Edits(text_edits), Document.Node.Perspective(perspective)))

           reply(())

         case change: Change_Node if prover.isDefined =>

           handle_change(change)

         case input: Isabelle_Process.Input =>

           raw_messages.event(input)

         case result: Isabelle_Process.Result =>

           handle_result(result)

           raw_messages.event(result)

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

       }

     }

     //}}}

   }

   /* actions */

   def start(timeout: Time, args: List[String]) { session_actor ! Start(timeout, args) }

   def stop() { command_change_buffer !? Stop; session_actor !? Stop }

   def interrupt() { session_actor ! Interrupt }

   def check_loaded_files(ask: List[String] => Boolean)

   {

     session_actor ! Check_Loaded_Files(ask)

   }

   // FIXME simplify signature

   def init_node(name: String, master_dir: String,

     header: Document.Node_Header, perspective: Text.Perspective, text: String)

   { session_actor !? Init_Node(name, master_dir, header, perspective, text) }

   // FIXME simplify signature

   def edit_node(name: String, master_dir: String, header: Document.Node_Header,

     perspective: Text.Perspective, edits: List[Text.Edit])

   { session_actor !? Edit_Node(name, master_dir, header, perspective, edits) }

 }