/*  Title:      Pure/Tools/isabelle_process.ML

    ID:         $Id$

    Author:     Makarius

    Options:    :folding=explicit:collapseFolds=1:

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

*/

package isabelle

import java.util.Properties

import java.util.concurrent.LinkedBlockingQueue

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

import isabelle.{Symbol, XML}

object IsabelleProcess {

  /* results */

  object Kind extends Enumeration {

    //{{{ values

    // Posix channels/events

    val STDIN = Value("STDIN")

    val STDOUT = Value("STDOUT")

    val STDERR = Value("STDERR")

    val SIGNAL = Value("SIGNAL")

    val EXIT = Value("EXIT")

    // Isabelle messages

    val WRITELN = Value("WRITELN")

    val PRIORITY = Value("PRIORITY")

    val TRACING = Value("TRACING")

    val WARNING = Value("WARNING")

    val ERROR = Value("ERROR")

    val DEBUG = Value("DEBUG")

    val PROMPT = Value("PROMPT")

    val INIT = Value("INIT")

    val STATUS = Value("STATUS")

    // internal system notification

    val SYSTEM = Value("SYSTEM")

    //}}}

    def is_raw(kind: Value) =

      kind == STDOUT ||

      kind == STDERR

    def is_control(kind: Value) =

      kind == SIGNAL ||

      kind == EXIT ||

      kind == SYSTEM

    def is_system(kind: Value) =

      kind == STDIN ||

      kind == SIGNAL ||

      kind == EXIT ||

      kind == PROMPT ||

      kind == STATUS ||

      kind == SYSTEM

  }

  class Result(val kind: Kind.Value, val props: Properties, val result: String) {

    override def toString = {

      val res = XML.content(YXML.parse_failsafe(result)).mkString("")

      if (props == null) kind.toString + " [[" + res + "]]"

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

    }

    def is_raw() = Kind.is_raw(kind)

    def is_control() = Kind.is_control(kind)

    def is_system() = Kind.is_system(kind)

  }

}

class IsabelleProcess(args: String*) {

  import IsabelleProcess._

  /* process information */

  private var proc: Process = null

  private var closing = false

  private var pid: String = null

  private var the_session: String = null

  def session() = the_session

  /* symbols */

  val symbols = new Symbol.Interpretation

  def decode_result(result: Result) = YXML.parse_failsafe(symbols.decode(result.result))

  /* results */

  private val results = new LinkedBlockingQueue[Result]

  private def put_result(kind: Kind.Value, props: Properties, result: String) {

    if (kind == Kind.INIT && props != null) {

      pid = props.getProperty(Markup.PID)

      the_session = props.getProperty(Markup.SESSION)

    }

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

  }

  def get_result() = results.take

  def try_result() = {

    val res = results.poll

    if (res != null) Some(res) else None

  }

  /* signals */

  def interrupt() = synchronized {

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

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

    else {

      try {

        if (IsabelleSystem.exec(List("kill", "-INT", pid)).waitFor == 0)

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

        else

          put_result(Kind.SYSTEM, null, "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, null, "KILL")

      proc.destroy

      proc = null

      pid = null

    }

  }

  /* output being piped into the process */

  private val output = new LinkedBlockingQueue[String]

  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: Properties, 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(writer: BufferedWriter) extends Thread {

    override def run() = {

      var finished = false

      while (!finished) {

        try {

          //{{{

          val s = output.take

          if (s == "\u0000") {

            writer.close

            finished = true

          }

          else {

            put_result(Kind.STDIN, null, s)

            writer.write(s)

            writer.flush

          }

          //}}}

        }

        catch {

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

        }

      }

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

    }

  }

  /* stdout */

  private class StdoutThread(reader: BufferedReader) extends Thread {

    override def run() = {

      var kind = Kind.STDOUT

      var props: Properties = null

      var result = new StringBuilder

      var finished = false

      while (!finished) {

        try {

          if (kind == Kind.STDOUT) {

            //{{{ Char mode

            var c = -1

            var done = false

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

              c = reader.read

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

              else done = true

            }

            if (result.length > 0) {

              put_result(kind, null, result.toString)

              result.length = 0

            }

            if (c == -1) {

              reader.close

              finished = true

              try_close()

            }

            else if (c == 2) {

              reader.read match {

                case 'A' => kind = Kind.WRITELN

                case 'B' => kind = Kind.PRIORITY

                case 'C' => kind = Kind.TRACING

                case 'D' => kind = Kind.WARNING

                case 'E' => kind = Kind.ERROR

                case 'F' => kind = Kind.DEBUG

                case 'G' => kind = Kind.PROMPT

                case 'H' => kind = Kind.INIT

                case 'I' => kind = Kind.STATUS

                case _ => kind = Kind.STDOUT

              }

              props = 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)

                  if (props == null) props = new Properties

                  if (!props.containsKey(name)) props.setProperty(name, value)

                }

              }

              // last text line

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

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

                put_result(kind, props, result.toString)

                result.length = 0

                kind = Kind.STDOUT

              }

              // text line

              else {

                result.append(line)

                result.append('\n')

              }

            }

            //}}}

          }

        }

        catch {

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

        }

      }

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

    }

  }

  /* stderr */

  private class StderrThread(reader: BufferedReader) extends Thread {

    override def run() = {

      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.STDERR, null, result.toString)

            result.length = 0

          }

          else {

            reader.close

            finished = true

            try_close()

          }

          //}}}

        }

        catch {

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

        }

      }

      put_result(Kind.SYSTEM, null, "Stderr thread terminated")

    }

  }

  /* exit */

  private class ExitThread extends Thread {

    override def run() = {

      val rc = proc.waitFor()

      Thread.sleep(300)

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

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

    }

  }

  /** main **/

  {

    /* exec process */

    try {

      proc = IsabelleSystem.exec(List(

        IsabelleSystem.getenv_strict("ISABELLE_HOME") + "/bin/isabelle-process", "-W") ++ args)

    }

    catch {

      case e: IOException => error("Failed to execute Isabelle process: " + e.getMessage)

    }

    /* control process via threads */

    val charset = "UTF-8"

    new StdinThread(new BufferedWriter(new OutputStreamWriter(proc.getOutputStream, charset))).start

    new StdoutThread(new BufferedReader(new InputStreamReader(proc.getInputStream, charset))).start

    new StderrThread(new BufferedReader(new InputStreamReader(proc.getErrorStream, charset))).start

    new ExitThread().start

  }

}