/*  Title:      Pure/System/isabelle_process.ML

     Author:     Makarius

     Options:    :folding=explicit:collapseFolds=1:

 Isabelle process management -- always reactive due to multi-threaded I/O.

 */

 package isabelle

 import java.util.concurrent.LinkedBlockingQueue

 import java.io.{BufferedReader, BufferedWriter, InputStreamReader, OutputStreamWriter,

   InputStream, OutputStream, BufferedOutputStream, IOException}

 import scala.actors.Actor

 import Actor._

 object Isabelle_Process

 {

   /* results */

   object Kind {

     // message markup

     val markup = Map(

       ('A' : Int) -> Markup.INIT,

       ('B' : Int) -> Markup.STATUS,

       ('C' : Int) -> Markup.REPORT,

       ('D' : Int) -> Markup.WRITELN,

       ('E' : Int) -> Markup.TRACING,

       ('F' : Int) -> Markup.WARNING,

       ('G' : Int) -> Markup.ERROR)

     def is_raw(kind: String) =

       kind == Markup.STDOUT

     def is_control(kind: String) =

       kind == Markup.SYSTEM ||

       kind == Markup.SIGNAL ||

       kind == Markup.EXIT

     def is_system(kind: String) =

       kind == Markup.SYSTEM ||

       kind == Markup.INPUT ||

       kind == Markup.STDIN ||

       kind == Markup.SIGNAL ||

       kind == Markup.EXIT ||

       kind == Markup.STATUS

   }

   class Result(val message: XML.Elem)

   {

     def kind = message.markup.name

     def properties = message.markup.properties

     def body = message.body

     def is_raw = Kind.is_raw(kind)

     def is_control = Kind.is_control(kind)

     def is_system = Kind.is_system(kind)

     def is_status = kind == Markup.STATUS

     def is_report = kind == Markup.REPORT

     def is_ready = is_status && body == List(XML.Elem(Markup.Ready, Nil))

     override def toString: String =

     {

       val res =

         if (is_status || is_report) message.body.map(_.toString).mkString

         else Pretty.string_of(message.body)

       if (properties.isEmpty)

         kind.toString + " [[" + res + "]]"

       else

         kind.toString + " " +

           (for ((x, y) <- properties) yield x + "=" + y).mkString("{", ",", "}") + " [[" + res + "]]"

     }

   }

 }

 class Isabelle_Process(system: Isabelle_System, receiver: Actor, args: String*)

 {

   import Isabelle_Process._

   /* demo constructor */

   def this(args: String*) =

     this(new Isabelle_System,

       actor { loop { react { case res => Console.println(res) } } }, args: _*)

   /* process information */

   @volatile private var proc: Option[Process] = None

   @volatile private var pid: Option[String] = None

   /* results */

   private val xml_cache = new XML.Cache(131071)

   private def put_result(kind: String, props: List[(String, String)], body: XML.Body)

   {

     if (pid.isEmpty && kind == Markup.INIT)

       pid = props.find(_._1 == Markup.PID).map(_._1)

     val msg = XML.Elem(Markup(kind, props), Isar_Document.clean_message(body))

     xml_cache.cache_tree(msg)((message: XML.Tree) =>

       receiver ! new Result(message.asInstanceOf[XML.Elem]))

   }

   private def put_result(kind: String, text: String)

   {

     put_result(kind, Nil, List(XML.Text(system.symbols.decode(text))))

   }

   /* signals */

   def interrupt()

   {

     if (proc.isEmpty) put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: no process")

     else

       pid match {

         case None => put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: unknowd pid")

         case Some(i) =>

           try {

             if (system.execute(true, "kill", "-INT", i).waitFor == 0)

               put_result(Markup.SIGNAL, "INT")

             else

               put_result(Markup.SYSTEM, "Cannot interrupt Isabelle: kill command failed")

           }

           catch { case e: IOException => error("Cannot interrupt Isabelle: " + e.getMessage) }

       }

   }

   def kill()

   {

     proc match {

       case None => put_result(Markup.SYSTEM, "Cannot kill Isabelle: no process")

       case Some(p) =>

         close()

         Thread.sleep(500)  // FIXME !?

         put_result(Markup.SIGNAL, "KILL")

         p.destroy

         proc = None

         pid = None

     }

   }

   /** stream actors **/

   private val in_fifo = system.mk_fifo()

   private val out_fifo = system.mk_fifo()

   private def rm_fifos() = { system.rm_fifo(in_fifo); system.rm_fifo(out_fifo) }

   private case class Input_Text(text: String)

   private case class Input_Chunks(chunks: List[Array[Byte]])

   private case object Close

   /* raw stdin */

   private def stdin_actor(name: String, stream: OutputStream): Actor =

     Simple_Thread.actor(name) {

       val writer = new BufferedWriter(new OutputStreamWriter(stream, Standard_System.charset))

       var finished = false

       while (!finished) {

         try {

           //{{{

           receive {

             case Input_Text(text) =>

               // FIXME echo input?!

               writer.write(text)

               writer.flush

             case Close =>

               writer.close

               finished = true

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

           }

           //}}}

         }

         catch {

           case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)

         }

       }

       put_result(Markup.SYSTEM, name + " terminated")

     }

   /* raw stdout */

   private def stdout_actor(name: String, stream: InputStream): Actor =

     Simple_Thread.actor(name) {

       val reader = new BufferedReader(new InputStreamReader(stream, Standard_System.charset))

       var result = new StringBuilder(100)

       var finished = false

       while (!finished) {

         try {

           //{{{

           var c = -1

           var done = false

           while (!done && (result.length == 0 || reader.ready)) {

             c = reader.read

             if (c >= 0) result.append(c.asInstanceOf[Char])

             else done = true

           }

           if (result.length > 0) {

             put_result(Markup.STDOUT, result.toString)

             result.length = 0

           }

           else {

             reader.close

             finished = true

             close()

           }

           //}}}

         }

         catch {

           case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)

         }

       }

       put_result(Markup.SYSTEM, name + " terminated")

     }

   /* command input */

   private def input_actor(name: String): Actor =

     Simple_Thread.actor(name) {

       val stream = new BufferedOutputStream(system.fifo_output_stream(in_fifo))  // FIXME potentially blocking forever

       var finished = false

       while (!finished) {

         try {

           //{{{

           receive {

             case Input_Chunks(chunks) =>

               stream.write(Standard_System.string_bytes(

                   chunks.map(_.length).mkString("", ",", "\n")));

               chunks.foreach(stream.write(_));

               stream.flush

             case Close =>

               stream.close

               finished = true

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

           }

           //}}}

         }

         catch {

           case e: IOException => put_result(Markup.SYSTEM, name + ": " + e.getMessage)

         }

       }

       put_result(Markup.SYSTEM, name + " terminated")

     }

   /* message output */

   private class Protocol_Error(msg: String) extends Exception(msg)

   private def message_actor(name: String): Actor =

     Simple_Thread.actor(name) {

       val stream = system.fifo_input_stream(out_fifo)  // FIXME potentially blocking forever

       val default_buffer = new Array[Byte](65536)

       var c = -1

       def read_chunk(): XML.Body =

       {

         //{{{

         // chunk size

         var n = 0

         c = stream.read

         while (48 <= c && c <= 57) {

           n = 10 * n + (c - 48)

           c = stream.read

         }

         if (c != 10) throw new Protocol_Error("bad message chunk header")

         // chunk content

         val buf =

           if (n <= default_buffer.size) default_buffer

           else new Array[Byte](n)

         var i = 0

         var m = 0

         do {

           m = stream.read(buf, i, n - i)

           i += m

         } while (m > 0 && n > i)

         if (i != n) throw new Protocol_Error("bad message chunk content")

         YXML.parse_body_failsafe(YXML.decode_chars(system.symbols.decode, buf, 0, n))

         //}}}

       }

       do {

         try {

           val header = read_chunk()

           val body = read_chunk()

           header match {

             case List(XML.Elem(Markup(name, props), Nil))

                 if name.size == 1 && Kind.markup.isDefinedAt(name(0)) =>

               put_result(Kind.markup(name(0)), props, body)

             case _ => throw new Protocol_Error("bad header: " + header.toString)

           }

         }

         catch {

           case e: IOException =>

             put_result(Markup.SYSTEM, "Cannot read message:\n" + e.getMessage)

           case e: Protocol_Error =>

             put_result(Markup.SYSTEM, "Malformed message:\n" + e.getMessage)

         }

       } while (c != -1)

       stream.close

       close()

       put_result(Markup.SYSTEM, name + " terminated")

     }

   /** init **/

   /* exec process */

   try {

     val cmdline =

       List(system.getenv_strict("ISABELLE_PROCESS"), "-W", in_fifo + ":" + out_fifo) ++ args

     proc = Some(system.execute(true, cmdline: _*))

   }

   catch {

     case e: IOException =>

       rm_fifos()

       error("Failed to execute Isabelle process: " + e.getMessage)

   }

   /* I/O actors */

   private val command_input = input_actor("command_input")

   message_actor("message_output")

   private val standard_input = stdin_actor("standard_input", proc.get.getOutputStream)

   stdout_actor("standard_output", proc.get.getInputStream)

   /* exit process */

   Simple_Thread.actor("process_exit") {

     proc match {

       case None =>

       case Some(p) =>

         val rc = p.waitFor()

         Thread.sleep(300)  // FIXME property!?

         put_result(Markup.SYSTEM, "process_exit terminated")

         put_result(Markup.EXIT, rc.toString)

     }

     rm_fifos()

   }

   /** main methods **/

   def input_raw(text: String): Unit = standard_input ! Input_Text(text)

   def input_bytes(name: String, args: Array[Byte]*): Unit =

     command_input ! Input_Chunks(Standard_System.string_bytes(name) :: args.toList)

   def input(name: String, args: String*): Unit =

     input_bytes(name, args.map(Standard_System.string_bytes): _*)

   def close(): Unit = command_input ! Close

 }