/*  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,

      ('H' : Int) -> Markup.DEBUG)

    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: List[XML.Tree])

  {

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

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

    xml_cache.cache_tree(XML.Elem(Markup(kind, props), body))((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 **/

  case class Input_Text(text: String)

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

  case object Close

  /* raw stdin */

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

    Library.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 =

    Library.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, raw_stream: OutputStream): Actor =

    Library.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 => 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, stream: InputStream): Actor =

    Library.thread_actor(name) {

      val default_buffer = new Array[Byte](65536)

      var c = -1

      def read_chunk(): List[XML.Tree] =

      {

        //{{{

        // 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 */

  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) }

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

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

  private val command_input = input_actor("command_input", system.fifo_output_stream(in_fifo))

  message_actor("message_output", system.fifo_input_stream(out_fifo))

  /* exit process */

  Library.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

}