/*  Title:      Pure/System/isabelle_system.scala

    Author:     Makarius

Fundamental Isabelle system environment: quasi-static module with

optional init operation.

*/

package isabelle

import java.lang.System

import java.util.regex.Pattern

import java.util.Locale

import java.io.{InputStream, FileInputStream, OutputStream, FileOutputStream, File,

  BufferedReader, InputStreamReader, BufferedWriter, OutputStreamWriter, IOException}

import java.awt.{GraphicsEnvironment, Font}

import java.awt.font.TextAttribute

import scala.io.Source

import scala.util.matching.Regex

import scala.collection.mutable

object Isabelle_System

{

  /** implicit state **/

  private case class State(standard_system: Standard_System, settings: Map[String, String])

  @volatile private var _state: Option[State] = None

  private def check_state(): State =

  {

    if (_state.isEmpty) init()  // unsynchronized check

    _state.get

  }

  def standard_system: Standard_System = check_state().standard_system

  def settings: Map[String, String] = check_state().settings

  /*

    isabelle_home precedence:

      (1) this_isabelle_home as explicit argument

      (2) ISABELLE_HOME process environment variable (e.g. inherited from running isabelle tool)

      (3) isabelle.home system property (e.g. via JVM application boot process)

  */

  def init(this_isabelle_home: String = null) = synchronized {

    if (_state.isEmpty) {

      import scala.collection.JavaConversions._

      System.err.println("### Isabelle system initialization")

      val standard_system = new Standard_System

      val settings =

      {

        val env = Map(System.getenv.toList: _*) +

          ("THIS_JAVA" -> standard_system.this_java())

        val isabelle_home =

          if (this_isabelle_home != null) this_isabelle_home

          else

            env.get("ISABELLE_HOME") match {

              case None | Some("") =>

                val path = System.getProperty("isabelle.home")

                if (path == null || path == "") error("Unknown Isabelle home directory")

                else path

              case Some(path) => path

            }

          Standard_System.with_tmp_file("settings") { dump =>

              val shell_prefix =

                if (Platform.is_windows) List(standard_system.platform_root + "\\bin\\bash", "-l")

                else Nil

              val cmdline =

                shell_prefix ::: List(isabelle_home + "/bin/isabelle", "getenv", "-d", dump.toString)

              val (output, rc) = Standard_System.raw_exec(null, env, true, cmdline: _*)

              if (rc != 0) error(output)

              val entries =

                for (entry <- Source.fromFile(dump).mkString split "\0" if entry != "") yield {

                  val i = entry.indexOf('=')

                  if (i <= 0) (entry -> "")

                  else (entry.substring(0, i) -> entry.substring(i + 1))

                }

              Map(entries: _*) +

                ("HOME" -> System.getenv("HOME")) +

                ("PATH" -> System.getenv("PATH"))

            }

          }

      _state = Some(State(standard_system, settings))

    }

  }

  /* getenv */

  def getenv(name: String): String =

    settings.getOrElse(if (name == "HOME") "HOME_JVM" else name, "")

  def getenv_strict(name: String): String =

  {

    val value = getenv(name)

    if (value != "") value else error("Undefined environment variable: " + name)

  }

  /** file-system operations **/

  /* path specifications */

  def standard_path(path: Path): String = path.expand.implode

  def platform_path(path: Path): String = standard_system.jvm_path(standard_path(path))

  def platform_file(path: Path) = new File(platform_path(path))

  def posix_path(jvm_path: String): String = standard_system.posix_path(jvm_path)

  /* try_read */

  def try_read(paths: Seq[Path]): String =

  {

    val buf = new StringBuilder

    for {

      path <- paths

      file = platform_file(path) if file.isFile

      c <- (Source.fromFile(file) ++ Iterator.single('\n'))

    } buf.append(c)

    buf.toString

  }

  /* source files */

  private def try_file(file: File) = if (file.isFile) Some(file) else None

  def source_file(path: Path): Option[File] =

  {

    if (path.is_absolute || path.is_current)

      try_file(platform_file(path))

    else {

      val pure_file = platform_file(Path.explode("~~/src/Pure") + path)

      if (pure_file.isFile) Some(pure_file)

      else if (getenv("ML_SOURCES") != "")

        try_file(platform_file(Path.explode("$ML_SOURCES") + path))

      else None

    }

  }

  /** external processes **/

  /* plain execute */

  def execute(redirect: Boolean, args: String*): Process =

  {

    val cmdline =

      if (Platform.is_windows) List(standard_system.platform_root + "\\bin\\env.exe") ++ args

      else args

    Standard_System.raw_execute(null, settings, redirect, cmdline: _*)

  }

  /* managed process */

  class Managed_Process(redirect: Boolean, args: String*)

  {

    private val params =

      List(standard_path(Path.explode("~~/lib/scripts/process")), "group", "-", "no_script")

    private val proc = execute(redirect, (params ++ args):_*)

    // channels

    val stdin: BufferedWriter =

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

    val stdout: BufferedReader =

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

    val stderr: BufferedReader =

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

    // signals

    private val pid = stdout.readLine

    private def kill(signal: String): Boolean =

    {

      execute(true, "kill", "-" + signal, "-" + pid).waitFor

      execute(true, "kill", "-0", "-" + pid).waitFor == 0

    }

    private def multi_kill(signal: String): Boolean =

    {

      var running = true

      var count = 10

      while (running && count > 0) {

        if (kill(signal)) {

          Thread.sleep(100)

          count -= 1

        }

        else running = false

      }

      running

    }

    def interrupt() { multi_kill("INT") }

    def terminate() { multi_kill("INT") && multi_kill("TERM") && kill("KILL"); proc.destroy }

    // JVM shutdown hook

    private val shutdown_hook = new Thread { override def run = terminate() }

    try { Runtime.getRuntime.addShutdownHook(shutdown_hook) }

    catch { case _: IllegalStateException => }

    private def cleanup() =

      try { Runtime.getRuntime.removeShutdownHook(shutdown_hook) }

      catch { case _: IllegalStateException => }

    /* result */

    def join: Int = { val rc = proc.waitFor; cleanup(); rc }

  }

  /* bash */

  def bash(script: String): (String, String, Int) =

  {

    Standard_System.with_tmp_file("isabelle_script") { script_file =>

      Standard_System.write_file(script_file, script)

      val proc = new Managed_Process(false, "bash", posix_path(script_file.getPath))

      proc.stdin.close

      val stdout = Simple_Thread.future("bash_stdout") { Standard_System.slurp(proc.stdout) }

      val stderr = Simple_Thread.future("bash_stderr") { Standard_System.slurp(proc.stderr) }

      val rc =

        try { proc.join }

        catch { case e: InterruptedException => Thread.interrupted; proc.terminate; 130 }

      (stdout.join, stderr.join, rc)

    }

  }

  /* system tools */

  def isabelle_tool(name: String, args: String*): (String, Int) =

  {

    Path.split(getenv_strict("ISABELLE_TOOLS")).find { dir =>

      val file = platform_file(dir + Path.basic(name))

      try {

        file.isFile && file.canRead && file.canExecute &&

          !name.endsWith("~") && !name.endsWith(".orig")

      }

      catch { case _: SecurityException => false }

    } match {

      case Some(dir) =>

        val file = standard_path(dir + Path.basic(name))

        Standard_System.process_output(execute(true, (List(file) ++ args): _*))

      case None => ("Unknown Isabelle tool: " + name, 2)

    }

  }

  /* named pipes */

  private val next_fifo = new Counter

  def mk_fifo(): String =

  {

    val i = next_fifo()

    val script =

      "FIFO=\"/tmp/isabelle-fifo-${PPID}-$$" + i + "\"\n" +

      "echo -n \"$FIFO\"\n" +

      "mkfifo -m 600 \"$FIFO\"\n"

    val (out, err, rc) = bash(script)

    if (rc == 0) out else error(err.trim)

  }

  def rm_fifo(fifo: String): Boolean =

    (new File(standard_system.jvm_path(if (Platform.is_windows) fifo + ".lnk" else fifo))).delete

  def fifo_input_stream(fifo: String): InputStream =

  {

    if (Platform.is_windows) { // Cygwin fifo as Windows/Java input stream

      val proc = execute(false, standard_path(Path.explode("~~/lib/scripts/raw_dump")), fifo, "-")

      proc.getOutputStream.close

      proc.getErrorStream.close

      proc.getInputStream

    }

    else new FileInputStream(fifo)

  }

  def fifo_output_stream(fifo: String): OutputStream =

  {

    if (Platform.is_windows) { // Cygwin fifo as Windows/Java output stream

      val proc = execute(false, standard_path(Path.explode("~~/lib/scripts/raw_dump")), "-", fifo)

      proc.getInputStream.close

      proc.getErrorStream.close

      val out = proc.getOutputStream

      new OutputStream {

        override def close() { out.close(); proc.waitFor() }

        override def flush() { out.flush() }

        override def write(b: Array[Byte]) { out.write(b) }

        override def write(b: Array[Byte], off: Int, len: Int) { out.write(b, off, len) }

        override def write(b: Int) { out.write(b) }

      }

    }

    else new FileOutputStream(fifo)

  }

  /** Isabelle resources **/

  /* components */

  def components(): List[Path] =

    Path.split(getenv_strict("ISABELLE_COMPONENTS"))

  /* find logics */

  def find_logics(): List[String] =

  {

    val ml_ident = getenv_strict("ML_IDENTIFIER")

    val logics = new mutable.ListBuffer[String]

    for (dir <- Path.split(getenv_strict("ISABELLE_PATH"))) {

      val files = platform_file(dir + Path.explode(ml_ident)).listFiles()

      if (files != null) {

        for (file <- files if file.isFile) logics += file.getName

      }

    }

    logics.toList.sortWith(_ < _)

  }

  /* fonts */

  def get_font(family: String = "IsabelleText", size: Int = 1, bold: Boolean = false): Font =

    new Font(family, if (bold) Font.BOLD else Font.PLAIN, size)

  def install_fonts()

  {

    val ge = GraphicsEnvironment.getLocalGraphicsEnvironment()

    for (font <- Path.split(getenv_strict("ISABELLE_FONTS")))

      ge.registerFont(Font.createFont(Font.TRUETYPE_FONT, platform_file(font)))

  }

}