/*  Title:      Pure/System/standard_system.scala

     Module:     PIDE

     Author:     Makarius

 Standard system operations, with basic Cygwin/Posix compatibility.

 */

 package isabelle

 import java.lang.System

 import java.util.regex.Pattern

 import java.util.Locale

 import java.net.URL

 import java.io.{BufferedWriter, OutputStreamWriter, FileOutputStream, BufferedOutputStream,

   BufferedInputStream, InputStream, FileInputStream, BufferedReader, InputStreamReader,

   File => JFile, FileFilter, IOException}

 import java.nio.charset.Charset

 import java.util.zip.GZIPOutputStream

 import scala.io.Codec

 import scala.util.matching.Regex

 import scala.collection.mutable

 object Standard_System

 {

   /* UTF-8 charset */

   val charset_name: String = "UTF-8"

   val charset: Charset = Charset.forName(charset_name)

   def codec(): Codec = Codec(charset)

   def string_bytes(s: String): Array[Byte] = s.getBytes(charset)

   /* permissive UTF-8 decoding */

   // see also http://en.wikipedia.org/wiki/UTF-8#Description

   // overlong encodings enable byte-stuffing

   def decode_permissive_utf8(text: CharSequence): String =

   {

     val buf = new java.lang.StringBuilder(text.length)

     var code = -1

     var rest = 0

     def flush()

     {

       if (code != -1) {

         if (rest == 0 && Character.isValidCodePoint(code))

           buf.appendCodePoint(code)

         else buf.append('\uFFFD')

         code = -1

         rest = 0

       }

     }

     def init(x: Int, n: Int)

     {

       flush()

       code = x

       rest = n

     }

     def push(x: Int)

     {

       if (rest <= 0) init(x, -1)

       else {

         code <<= 6

         code += x

         rest -= 1

       }

     }

     for (i <- 0 until text.length) {

       val c = text.charAt(i)

       if (c < 128) { flush(); buf.append(c) }

       else if ((c & 0xC0) == 0x80) push(c & 0x3F)

       else if ((c & 0xE0) == 0xC0) init(c & 0x1F, 1)

       else if ((c & 0xF0) == 0xE0) init(c & 0x0F, 2)

       else if ((c & 0xF8) == 0xF0) init(c & 0x07, 3)

     }

     flush()

     buf.toString

   }

   private class Decode_Chars(decode: String => String,

     buffer: Array[Byte], start: Int, end: Int) extends CharSequence

   {

     def length: Int = end - start

     def charAt(i: Int): Char = (buffer(start + i).asInstanceOf[Int] & 0xFF).asInstanceOf[Char]

     def subSequence(i: Int, j: Int): CharSequence =

       new Decode_Chars(decode, buffer, start + i, start + j)

     // toString with adhoc decoding: abuse of CharSequence interface

     override def toString: String = decode(decode_permissive_utf8(this))

   }

   def decode_chars(decode: String => String,

     buffer: Array[Byte], start: Int, end: Int): CharSequence =

   {

     require(0 <= start && start <= end && end <= buffer.length)

     new Decode_Chars(decode, buffer, start, end)

   }

   /* basic file operations */

   def slurp(reader: BufferedReader): String =

   {

     val output = new StringBuilder(100)

     var c = -1

     while ({ c = reader.read; c != -1 }) output += c.toChar

     reader.close

     output.toString

   }

   def slurp(stream: InputStream): String =

     slurp(new BufferedReader(new InputStreamReader(stream, charset)))

   def read_file(file: JFile): String = slurp(new FileInputStream(file))

   def write_file(file: JFile, text: CharSequence, zip: Boolean = false)

   {

     val stream1 = new FileOutputStream(file)

     val stream2 = if (zip) new GZIPOutputStream(new BufferedOutputStream(stream1)) else stream1

     val writer = new BufferedWriter(new OutputStreamWriter(stream2, charset))

     try { writer.append(text) }

     finally { writer.close }

   }

   def eq_file(file1: JFile, file2: JFile): Boolean =

     file1.getCanonicalPath == file2.getCanonicalPath  // FIXME prefer java.nio.file.Files.isSameFile of Java 1.7

   def copy_file(src: JFile, dst: JFile) =

     if (!eq_file(src, dst)) {

       val in = new FileInputStream(src)

       try {

         val out = new FileOutputStream(dst)

         try {

           val buf = new Array[Byte](65536)

           var m = 0

           do {

             m = in.read(buf, 0, buf.length)

             if (m != -1) out.write(buf, 0, m)

           } while (m != -1)

         }

         finally { out.close }

       }

       finally { in.close }

     }

   def with_tmp_file[A](prefix: String)(body: JFile => A): A =

   {

     val file = JFile.createTempFile(prefix, null)

     file.deleteOnExit

     try { body(file) } finally { file.delete }

   }

   // FIXME handle (potentially cyclic) directory graph

   def find_files(start: JFile, ok: JFile => Boolean): List[JFile] =

   {

     val files = new mutable.ListBuffer[JFile]

     val filter = new FileFilter { def accept(entry: JFile) = entry.isDirectory || ok(entry) }

     def find_entry(entry: JFile)

     {

       if (ok(entry)) files += entry

       if (entry.isDirectory) entry.listFiles(filter).foreach(find_entry)

     }

     find_entry(start)

     files.toList

   }

   /* shell processes */

   def raw_execute(cwd: JFile, env: Map[String, String], redirect: Boolean, args: String*): Process =

   {

     val cmdline = new java.util.LinkedList[String]

     for (s <- args) cmdline.add(s)

     val proc = new ProcessBuilder(cmdline)

     if (cwd != null) proc.directory(cwd)

     if (env != null) {

       proc.environment.clear

       for ((x, y) <- env) proc.environment.put(x, y)

     }

     proc.redirectErrorStream(redirect)

     proc.start

   }

   def process_output(proc: Process): (String, Int) =

   {

     proc.getOutputStream.close

     val output = slurp(proc.getInputStream)

     val rc =

       try { proc.waitFor }

       finally {

         proc.getInputStream.close

         proc.getErrorStream.close

         proc.destroy

         Thread.interrupted

       }

     (output, rc)

   }

   def raw_exec(cwd: JFile, env: Map[String, String], redirect: Boolean, args: String*)

     : (String, Int) = process_output(raw_execute(cwd, env, redirect, args: _*))

   /* cygwin_root */

   def cygwin_root(): String =

   {

     val cygwin_root1 = System.getenv("CYGWIN_ROOT")

     val cygwin_root2 = System.getProperty("cygwin.root")

     val root =

       if (cygwin_root1 != null && cygwin_root1 != "") cygwin_root1

       else if (cygwin_root2 != null && cygwin_root2 != "") cygwin_root2

       else error("Bad Cygwin installation: unknown root")

     val root_file = new JFile(root)

     if (!new JFile(root_file, "bin\\bash.exe").isFile ||

         !new JFile(root_file, "bin\\env.exe").isFile ||

         !new JFile(root_file, "bin\\tar.exe").isFile)

       error("Bad Cygwin installation: " + quote(root))

     root

   }

 }

 class Standard_System

 {

   /* platform_root */

   val platform_root = if (Platform.is_windows) Standard_System.cygwin_root() else "/"

   /* jvm_path */

   private val Cygdrive = new Regex("/cygdrive/([a-zA-Z])($|/.*)")

   private val Named_Root = new Regex("//+([^/]*)(.*)")

   def jvm_path(posix_path: String): String =

     if (Platform.is_windows) {

       val result_path = new StringBuilder

       val rest =

         posix_path match {

           case Cygdrive(drive, rest) =>

             result_path ++= (drive.toUpperCase(Locale.ENGLISH) + ":" + JFile.separator)

             rest

           case Named_Root(root, rest) =>

             result_path ++= JFile.separator

             result_path ++= JFile.separator

             result_path ++= root

             rest

           case path if path.startsWith("/") =>

             result_path ++= platform_root

             path

           case path => path

         }

       for (p <- space_explode('/', rest) if p != "") {

         val len = result_path.length

         if (len > 0 && result_path(len - 1) != JFile.separatorChar)

           result_path += JFile.separatorChar

         result_path ++= p

       }

       result_path.toString

     }

     else posix_path

   /* posix_path */

   private val Platform_Root = new Regex("(?i)" +

     Pattern.quote(platform_root) + """(?:\\+|\z)(.*)""")

   private val Drive = new Regex("""([a-zA-Z]):\\*(.*)""")

   def posix_path(jvm_path: String): String =

     if (Platform.is_windows) {

       jvm_path.replace('/', '\\') match {

         case Platform_Root(rest) => "/" + rest.replace('\\', '/')

         case Drive(letter, rest) =>

           "/cygdrive/" + letter.toLowerCase(Locale.ENGLISH) +

             (if (rest == "") "" else "/" + rest.replace('\\', '/'))

         case path => path.replace('\\', '/')

       }

     }

     else jvm_path

   /* JDK home of running JVM */

   def this_jdk_home(): String =

   {

     val java_home = System.getProperty("java.home")

     val home = new JFile(java_home)

     val parent = home.getParent

     val jdk_home =

       if (home.getName == "jre" && parent != null &&

           (new JFile(new JFile(parent, "bin"), "javac")).exists) parent

       else java_home

     posix_path(jdk_home)

   }

 }