/*  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

  {

    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 = 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, timeout: Int, receiver: Actor, args: String*)

{

  import Isabelle_Process._

  /* demo constructor */

  def this(args: String*) =

    this(new Isabelle_System, 10000,

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

  /* 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(a: Actor) { if (a != null) a ! Close }

  @volatile private var standard_input: Actor = null

  @volatile private var command_input: 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 proc =

    try {

      val cmdline =

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

      system.execute(true, cmdline: _*)

    }

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

  private val stdout_reader =

    new BufferedReader(new InputStreamReader(proc.getInputStream, Standard_System.charset))

  private val stdin_writer =

    new BufferedWriter(new OutputStreamWriter(proc.getOutputStream, Standard_System.charset))

  Simple_Thread.actor("process_manager") {

    val (startup_failed, startup_output) =

    {

      val expired = System.currentTimeMillis() + timeout

      val result = new StringBuilder(100)

      var finished = false

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

        while (!finished && stdout_reader.ready) {

          val c = stdout_reader.read

          if (c == 2) finished = true

          else result += c.toChar

        }

        Thread.sleep(10)

      }

      (!finished, result.toString)

    }

    if (startup_failed) {

      put_result(Markup.STDOUT, startup_output)

      put_result(Markup.EXIT, "127")

      stdin_writer.close

      Thread.sleep(300)  // FIXME !?

      proc.destroy  // FIXME reliable!?

    }

    else {

      put_result(Markup.SYSTEM, startup_output)

      standard_input = stdin_actor()

      stdout_actor()

      // rendezvous

      val command_stream = system.fifo_output_stream(in_fifo)

      val message_stream = system.fifo_input_stream(out_fifo)

      command_input = input_actor(command_stream)

      message_actor(message_stream)

      val rc = proc.waitFor()

      Thread.sleep(300)  // FIXME !?

      system_result("Isabelle process terminated")

      put_result(Markup.EXIT, rc.toString)

    }

    rm_fifos()

  }

  /* 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 (pid.isEmpty && kind == Markup.INIT) {

      rm_fifos()

      props.find(_._1 == Markup.PID).map(_._1) match {

        case None => system_result("Bad Isabelle process initialization: missing pid")

        case p => pid = p

      }

    }

    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 */

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

  def interrupt()

  {

    pid match {

      case None => system_result("Cannot interrupt Isabelle: unknowd pid")

      case Some(i) =>

        try {

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

            system_result("Interrupt Isabelle")

          else

            system_result("Cannot interrupt Isabelle: kill command failed")

        }

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

    }

  }

  def kill()

  {

    val running =

      try { proc.exitValue; false }

      catch { case e: java.lang.IllegalThreadStateException => true }

    if (running) {

      close()

      Thread.sleep(500)  // FIXME !?

      system_result("Kill Isabelle")

      proc.destroy

    }

  }

  /** stream actors **/

  /* raw stdin */

  private def stdin_actor(): Actor =

  {

    val name = "standard_input"

    Simple_Thread.actor(name) {

      var finished = false

      while (!finished) {

        try {

          //{{{

          receive {

            case Input_Text(text) =>

              stdin_writer.write(text)

              stdin_writer.flush

            case Close =>

              stdin_writer.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(): 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 || stdout_reader.ready)) {

            c = stdout_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 {

            stdout_reader.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): 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): 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)

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

}