/*  Title:      Pure/System/isabelle_process.scala

     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

   {

     val message_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)

   }

   class Result(val message: XML.Elem)

   {

     def kind = message.markup.name

     def properties = message.markup.properties

     def body = message.body

     def is_init = kind == Markup.INIT

     def is_exit = kind == Markup.EXIT

     def is_stdout = kind == Markup.STDOUT

     def is_system = kind == Markup.SYSTEM

     def is_status = kind == Markup.STATUS

     def is_report = kind == Markup.REPORT

     def is_ready = Isar_Document.is_ready(message)

     def is_syslog = is_init || is_exit || is_system || is_ready

     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, timeout: Time, receiver: Actor, args: String*)

 {

   import Isabelle_Process._

   /* demo constructor */

   def this(args: String*) =

     this(Isabelle_System.default, Time.seconds(10),

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

   /* results */

   private def system_result(text: String)

   {

     receiver ! new Result(XML.Elem(Markup(Markup.SYSTEM, Nil), List(XML.Text(text))))

   }

   private val xml_cache = new XML.Cache(131071)

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

   {

     if (kind == Markup.INIT) rm_fifos()

     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))))

   }

   /* input actors */

   private case class Input_Text(text: String)

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

   private case object Close

   private def close(p: (Thread, Actor))

   {

     if (p != null && p._1.isAlive) {

       p._2 ! Close

       p._1.join

     }

   }

   @volatile private var standard_input: (Thread, Actor) = null

   @volatile private var command_input: (Thread, Actor) = null

   /** process manager **/

   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 val process =

     try {

       val cmdline =

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

       new system.Managed_Process(true, cmdline: _*)

     }

     catch { case e: IOException => rm_fifos(); throw(e) }

   val process_result =

     Simple_Thread.future("process_result") { process.join }

   private def terminate_process()

   {

     try { process.terminate }

     catch { case e: IOException => system_result("Failed to terminate Isabelle: " + e.getMessage) }

   }

   private val process_manager = Simple_Thread.fork("process_manager")

   {

     val (startup_failed, startup_output) =

     {

       val expired = System.currentTimeMillis() + timeout.ms

       val result = new StringBuilder(100)

       var finished: Option[Boolean] = None

       while (finished.isEmpty && System.currentTimeMillis() <= expired) {

         while (finished.isEmpty && process.stdout.ready) {

           val c = process.stdout.read

           if (c == 2) finished = Some(true)

           else result += c.toChar

         }

         if (process_result.is_finished) finished = Some(false)

         else Thread.sleep(10)

       }

       (finished.isEmpty || !finished.get, result.toString.trim)

     }

     system_result(startup_output)

     if (startup_failed) {

       put_result(Markup.EXIT, "Return code: 127")

       process.stdin.close

       Thread.sleep(300)

       terminate_process()

       process_result.join

     }

     else {

       // rendezvous

       val command_stream = system.fifo_output_stream(in_fifo)

       val message_stream = system.fifo_input_stream(out_fifo)

       standard_input = stdin_actor()

       val stdout = stdout_actor()

       command_input = input_actor(command_stream)

       val message = message_actor(message_stream)

       val rc = process_result.join

       system_result("process terminated")

       for ((thread, _) <- List(standard_input, stdout, command_input, message)) thread.join

       system_result("process_manager terminated")

       put_result(Markup.EXIT, "Return code: " + rc.toString)

     }

     rm_fifos()

   }

   /* management methods */

   def join() { process_manager.join() }

   def interrupt()

   {

     try { process.interrupt }

     catch { case e: IOException => system_result("Failed to interrupt Isabelle: " + e.getMessage) }

   }

   def terminate()

   {

     close()

     system_result("Terminating Isabelle process")

     terminate_process()

   }

   /** stream actors **/

   /* raw stdin */

   private def stdin_actor(): (Thread, Actor) =

   {

     val name = "standard_input"

     Simple_Thread.actor(name) {

       var finished = false

       while (!finished) {

         try {

           //{{{

           receive {

             case Input_Text(text) =>

               process.stdin.write(text)

               process.stdin.flush

             case Close =>

               process.stdin.close

               finished = true

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

           }

           //}}}

         }

         catch { case e: IOException => system_result(name + ": " + e.getMessage) }

       }

       system_result(name + " terminated")

     }

   }

   /* raw stdout */

   private def stdout_actor(): (Thread, Actor) =

   {

     val name = "standard_output"

     Simple_Thread.actor(name) {

       var result = new StringBuilder(100)

       var finished = false

       while (!finished) {

         try {

           //{{{

           var c = -1

           var done = false

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

             c = process.stdout.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 {

             process.stdout.close

             finished = true

           }

           //}}}

         }

         catch { case e: IOException => system_result(name + ": " + e.getMessage) }

       }

       system_result(name + " terminated")

     }

   }

   /* command input */

   private def input_actor(raw_stream: OutputStream): (Thread, Actor) =

   {

     val name = "command_input"

     Simple_Thread.actor(name) {

       val stream = new BufferedOutputStream(raw_stream)

       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 => system_result(name + ": " + e.getMessage) }

       }

       system_result(name + " terminated")

     }

   }

   /* message output */

   private def message_actor(stream: InputStream): (Thread, Actor) =

   {

     class EOF extends Exception

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

     val name = "message_output"

     Simple_Thread.actor(name) {

       val default_buffer = new Array[Byte](65536)

       var c = -1

       def read_chunk(): XML.Body =

       {

         //{{{

         // chunk size

         var n = 0

         c = stream.read

         if (c == -1) throw new EOF

         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)

           if (m != -1) i += m

         } while (m != -1 && 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.message_markup.isDefinedAt(name(0)) =>

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

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

           }

         }

         catch {

           case e: IOException => system_result("Cannot read message:\n" + e.getMessage)

           case e: Protocol_Error => system_result("Malformed message:\n" + e.getMessage)

           case _: EOF =>

         }

       } while (c != -1)

       stream.close

       system_result(name + " terminated")

     }

   }

   /** main methods **/

   def input_raw(text: String): Unit = standard_input._2 ! Input_Text(text)

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

     command_input._2 ! 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 = { close(command_input); close(standard_input) }

 }