/*  Title:      Pure/System/cygwin.scala

    Module:     PIDE

    Author:     Makarius

Accessing the Cygwin installation.

*/

package isabelle

import java.lang.System

import java.lang.reflect.Method

import java.io.File

import java.net.URL

import java.awt.Component

object Cygwin

{

  /* registry access */

  // Some black magic involving private WindowsPreferences from Sun, cf.

  // http://www.docjar.com/html/api/java/util/prefs/WindowsPreferences.java.html

  private val WindowsPreferences = Class.forName("java.util.prefs.WindowsPreferences")

  private val HKEY_CURRENT_USER = 0x80000001

  private val HKEY_LOCAL_MACHINE = 0x80000002

  private val KEY_READ = 0x20019

  private val NATIVE_HANDLE = 0

  private val ERROR_CODE = 1

  private def C_string(s: String): Array[Byte] =

    (s + "\0").getBytes("US-ASCII")

  private def J_string(bs: Array[Byte]): String =

    new String(bs, 0, bs.length - 1, "US-ASCII")

  private val INT = Integer.TYPE

  private val BYTES = (new Array[Byte](0)).getClass

  private def open_key(handle: Int, subkey: Array[Byte], mask: Int): Array[Int] =

  {

    val m = WindowsPreferences.getDeclaredMethod("WindowsRegOpenKey", INT, BYTES, INT)

    m.setAccessible(true)

    m.invoke(null, handle.asInstanceOf[Object], subkey.asInstanceOf[Object],

      mask.asInstanceOf[Object]).asInstanceOf[Array[Int]]

  }

  private def close_key(handle: Int): Int =

  {

    val m = WindowsPreferences.getDeclaredMethod("WindowsRegCloseKey", INT)

    m.setAccessible(true)

    m.invoke(null, handle.asInstanceOf[Object]).asInstanceOf[Int]

  }

  private def query(handle: Int, name: Array[Byte]) =

  {

    val m = WindowsPreferences.getDeclaredMethod("WindowsRegQueryValueEx", INT, BYTES)

    m.setAccessible(true)

    m.invoke(null, handle.asInstanceOf[Object], name.asInstanceOf[Object]).

      asInstanceOf[Array[Byte]]

  }

  def query_registry(sys: Boolean, path: String, name: String): Option[String] =

  {

    val handle = if (sys) HKEY_LOCAL_MACHINE else HKEY_CURRENT_USER

    val result = open_key(handle, C_string(path), KEY_READ)

    if (result(ERROR_CODE) != 0) None

    else {

      val res = query(result(NATIVE_HANDLE), C_string(name))

      if (res == null) None

      else Some(J_string(res))

    }

  }

  def query_registry(path: String, name: String): Option[String] =

    query_registry(false, path, name) orElse

      query_registry(true, path, name)

  /* Cygwin installation */

  private val CYGWIN_SETUP1 = "Software\\Cygwin\\setup"

  private val CYGWIN_SETUP2 = "Software\\Wow6432Node\\Cygwin\\setup"

  private def sanity_check(root: File)

  {

    if (!new File(root, "bin\\bash.exe").isFile ||

        !new File(root, "bin\\env.exe").isFile ||

        !new File(root, "bin\\tar.exe").isFile)

      error("Bad Cygwin installation: " + root.toString)

  }

  def check_root(): String =

  {

    val this_cygwin = System.getenv("THIS_CYGWIN")

    val root =

      if (this_cygwin != null && this_cygwin != "") this_cygwin

      else

        query_registry(CYGWIN_SETUP1, "rootdir") orElse

        query_registry(CYGWIN_SETUP2, "rootdir") getOrElse

        error("Failed to determine Cygwin installation -- version 1.7 required")

    sanity_check(new File(root))

    root

  }

  def setup(parent: Component, root: File)

  {

    if (!root.isDirectory && !root.mkdirs) error("Failed to create root directory: " + root)

    val download = new File(root, "download")

    if (!download.mkdir) error("Failed to create download directory: " + download)

    val setup_exe = new File(root, "setup.exe")

    try {

      Download.file(parent, "Downloading", new URL("http://www.cygwin.com/setup.exe"), setup_exe)

    }

    catch { case ERROR(_) => error("Failed to download Cygwin setup program") }

    val (_, rc) = Standard_System.raw_exec(root, null, true,

        setup_exe.toString, "-R", root.toString, "-l", download.toString,

          "-P", "libgmp3,make,perl,python", "-q", "-n")

    if (rc != 0) error("Cygwin setup failed!")

    sanity_check(root)

  }

}