/*  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, IOException}

object IsabelleProcess {

  /* results */

  object Kind extends Enumeration {

    //{{{ values and codes

    // internal system notification

    val SYSTEM = Value("SYSTEM")

    // Posix channels/events

    val STDIN = Value("STDIN")

    val STDOUT = Value("STDOUT")

    val SIGNAL = Value("SIGNAL")

    val EXIT = Value("EXIT")

    // Isabelle messages

    val INIT = Value("INIT")

    val STATUS = Value("STATUS")

    val WRITELN = Value("WRITELN")

    val PRIORITY = Value("PRIORITY")

    val TRACING = Value("TRACING")

    val WARNING = Value("WARNING")

    val ERROR = Value("ERROR")

    val DEBUG = Value("DEBUG")

    // messages codes

    val code = Map(

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

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

      ('C' : Int) -> Kind.WRITELN,

      ('D' : Int) -> Kind.PRIORITY,

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

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

      ('G' : Int) -> Kind.ERROR,

      ('H' : Int) -> Kind.DEBUG,

      ('0' : Int) -> Kind.SYSTEM,

      ('1' : Int) -> Kind.STDIN,

      ('2' : Int) -> Kind.STDOUT,

      ('3' : Int) -> Kind.SIGNAL,

      ('4' : Int) -> Kind.EXIT)

    // message markup

    val markup = Map(

      Kind.INIT -> Markup.INIT,

      Kind.STATUS -> Markup.STATUS,

      Kind.WRITELN -> Markup.WRITELN,

      Kind.PRIORITY -> Markup.PRIORITY,

      Kind.TRACING -> Markup.TRACING,

      Kind.WARNING -> Markup.WARNING,

      Kind.ERROR -> Markup.ERROR,

      Kind.DEBUG -> Markup.DEBUG,

      Kind.SYSTEM -> Markup.SYSTEM,

      Kind.STDIN -> Markup.STDIN,

      Kind.STDOUT -> Markup.STDOUT,

      Kind.SIGNAL -> Markup.SIGNAL,

      Kind.EXIT -> Markup.EXIT)

    //}}}

    def is_raw(kind: Value) =

      kind == STDOUT

    def is_control(kind: Value) =

      kind == SYSTEM ||

      kind == SIGNAL ||

      kind == EXIT

    def is_system(kind: Value) =

      kind == SYSTEM ||

      kind == STDIN ||

      kind == SIGNAL ||

      kind == EXIT ||

      kind == STATUS

  }

  class Result(val kind: Kind.Value, val props: List[(String, String)], val result: String) {

    override def toString = {

      val trees = YXML.parse_body_failsafe(result)

      val res =

        if (kind == Kind.STATUS) trees.map(_.toString).mkString

        else trees.flatMap(XML.content(_).mkString).mkString

      if (props.isEmpty)

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

      else

        kind.toString + " " +

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

    }

    def is_raw = Kind.is_raw(kind)

    def is_control = Kind.is_control(kind)

    def is_system = Kind.is_system(kind)

  }

  def parse_message(isabelle_system: IsabelleSystem, result: Result) =

  {

    XML.Elem(Markup.MESSAGE, (Markup.CLASS, Kind.markup(result.kind)) :: result.props,

      YXML.parse_body_failsafe(isabelle_system.symbols.decode(result.result)))

  }

}

class IsabelleProcess(isabelle_system: IsabelleSystem,

  results: EventBus[IsabelleProcess.Result], args: String*)

{

  import IsabelleProcess._

  /* demo constructor */

  def this(args: String*) =

    this(new IsabelleSystem, new EventBus[IsabelleProcess.Result] + Console.println, args: _*)

  /* process information */

  @volatile private var proc: Process = null

  @volatile private var closing = false

  @volatile private var pid: String = null

  @volatile private var the_session: String = null

  def session = the_session

  /* results */

  def parse_message(result: Result): XML.Tree =

    IsabelleProcess.parse_message(isabelle_system, result)

  private val result_queue = new LinkedBlockingQueue[Result]

  private def put_result(kind: Kind.Value, props: List[(String, String)], result: String)

  {

    if (kind == Kind.INIT) {

      val map = Map(props: _*)

      if (map.isDefinedAt(Markup.PID)) pid = map(Markup.PID)

      if (map.isDefinedAt(Markup.SESSION)) the_session = map(Markup.SESSION)

    }

    result_queue.put(new Result(kind, props, result))

  }

  private class ResultThread extends Thread("isabelle: results") {

    override def run() = {

      var finished = false

      while (!finished) {

        val result =

          try { result_queue.take }

          catch { case _: NullPointerException => null }

        if (result != null) {

          results.event(result)

          if (result.kind == Kind.EXIT) finished = true

        }

        else finished = true

      }

    }

  }

  /* signals */

  def interrupt() = synchronized {

    if (proc == null) error("Cannot interrupt Isabelle: no process")

    if (pid == null) put_result(Kind.SYSTEM, Nil, "Cannot interrupt: unknown pid")

    else {

      try {

        if (isabelle_system.execute(true, "kill", "-INT", pid).waitFor == 0)

          put_result(Kind.SIGNAL, Nil, "INT")

        else

          put_result(Kind.SYSTEM, Nil, "Cannot interrupt: kill command failed")

      }

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

    }

  }

  def kill() = synchronized {

    if (proc == 0) error("Cannot kill Isabelle: no process")

    else {

      try_close()

      Thread.sleep(500)

      put_result(Kind.SIGNAL, Nil, "KILL")

      proc.destroy

      proc = null

      pid = null

    }

  }

  /* output being piped into the process */

  private val output = new LinkedBlockingQueue[String]

  private def output_raw(text: String) = synchronized {

    if (proc == null) error("Cannot output to Isabelle: no process")

    if (closing) error("Cannot output to Isabelle: already closing")

    output.put(text)

  }

  def output_sync(text: String) =

    output_raw(" \\<^sync>\n; " + text + " \\<^sync>;\n")

  def command(text: String) =

    output_sync("Isabelle.command " + IsabelleSyntax.encode_string(text))

  def command(props: List[(String, String)], text: String) =

    output_sync("Isabelle.command " + IsabelleSyntax.encode_properties(props) + " " +

      IsabelleSyntax.encode_string(text))

  def ML(text: String) =

    output_sync("ML_val " + IsabelleSyntax.encode_string(text))

  def close() = synchronized {    // FIXME watchdog/timeout

    output_raw("\u0000")

    closing = true

  }

  def try_close() = synchronized {

    if (proc != null && !closing) {

      try { close() }

      catch { case _: RuntimeException => }

    }

  }

  /* stdin */

  private class StdinThread(out_stream: OutputStream) extends Thread("isabelle: stdin") {

    override def run() = {

      val writer = new BufferedWriter(new OutputStreamWriter(out_stream, isabelle_system.charset))

      var finished = false

      while (!finished) {

        try {

          //{{{

          val s = output.take

          if (s == "\u0000") {

            writer.close

            finished = true

          }

          else {

            put_result(Kind.STDIN, Nil, s)

            writer.write(s)

            writer.flush

          }

          //}}}

        }

        catch {

          case e: IOException => put_result(Kind.SYSTEM, Nil, "Stdin thread: " + e.getMessage)

        }

      }

      put_result(Kind.SYSTEM, Nil, "Stdin thread terminated")

    }

  }

  /* stdout */

  private class StdoutThread(in_stream: InputStream) extends Thread("isabelle: stdout") {

    override def run() = {

      val reader = new BufferedReader(new InputStreamReader(in_stream, isabelle_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(Kind.STDOUT, Nil, result.toString)

            result.length = 0

          }

          else {

            reader.close

            finished = true

            try_close()

          }

          //}}}

        }

        catch {

          case e: IOException => put_result(Kind.SYSTEM, Nil, "Stdout thread: " + e.getMessage)

        }

      }

      put_result(Kind.SYSTEM, Nil, "Stdout thread terminated")

    }

  }

  /* messages */

  private class MessageThread(fifo: String) extends Thread("isabelle: messages") {

    override def run() = {

      val reader = isabelle_system.fifo_reader(fifo)

      var kind: Kind.Value = null

      var props: List[(String, String)] = Nil

      var result = new StringBuilder

      var finished = false

      while (!finished) {

        try {

          if (kind == null) {

            //{{{ Char mode -- resync

            var c = -1

            do {

              c = reader.read

              if (c >= 0 && c != 2) result.append(c.asInstanceOf[Char])

            } while (c >= 0 && c != 2)

            if (result.length > 0) {

              put_result(Kind.SYSTEM, Nil, "Malformed message:\n" + result.toString)

              result.length = 0

            }

            if (c < 0) {

              reader.close

              finished = true

              try_close()

            }

            else {

              c = reader.read

              if (Kind.code.isDefinedAt(c)) kind = Kind.code(c)

              else kind = null

            }

            //}}}

          }

          else {

            //{{{ Line mode

            val line = reader.readLine

            if (line == null) {

              reader.close

              finished = true

              try_close()

            }

            else {

              val len = line.length

              // property

              if (line.endsWith("\u0002,")) {

                val i = line.indexOf('=')

                if (i > 0) {

                  val name = line.substring(0, i)

                  val value = line.substring(i + 1, len - 2)

                  props = (name, value) :: props

                }

              }

              // last text line

              else if (line.endsWith("\u0002.")) {

                result.append(line.substring(0, len - 2))

                put_result(kind, props.reverse, result.toString)

                kind = null

                props = Nil

                result.length = 0

              }

              // text line

              else {

                result.append(line)

                result.append('\n')

              }

            }

            //}}}

          }

        }

        catch {

          case e: IOException => put_result(Kind.SYSTEM, Nil, "Message thread: " + e.getMessage)

        }

      }

      put_result(Kind.SYSTEM, Nil, "Message thread terminated")

    }

  }

  /** main **/

  {

    /* isabelle version */

    {

      val (msg, rc) = isabelle_system.isabelle_tool("version")

      if (rc != 0) error("Version check failed -- bad Isabelle installation:\n" + msg)

      put_result(Kind.SYSTEM, Nil, msg)

    }

    /* messages */

    val message_fifo = isabelle_system.mk_fifo()

    def rm_fifo() = isabelle_system.rm_fifo(message_fifo)

    val message_thread = new MessageThread(message_fifo)

    message_thread.start

    new ResultThread().start

    /* exec process */

    try {

      val cmdline =

        List(isabelle_system.getenv_strict("ISABELLE_PROCESS"), "-W", message_fifo) ++ args

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

    }

    catch {

      case e: IOException =>

        rm_fifo()

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

    }

    /* stdin/stdout */

    new StdinThread(proc.getOutputStream).start

    new StdoutThread(proc.getInputStream).start

    /* exit */

    new Thread("isabelle: exit") {

      override def run() = {

        val rc = proc.waitFor()

        Thread.sleep(300)

        put_result(Kind.SYSTEM, Nil, "Exit thread terminated")

        put_result(Kind.EXIT, Nil, Integer.toString(rc))

        rm_fifo()

      }

    }.start

  }

}