/*  Title:      Pure/System/standard_system.scala

     Author:     Makarius

 Standard system operations, with basic Cygwin/Posix compatibility.

 */

 package isabelle

 import java.util.regex.Pattern

 import java.util.Locale

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

   BufferedInputStream, FileInputStream, BufferedReader, InputStreamReader,

   File, FileFilter, IOException}

 import scala.io.{Source, Codec}

 import scala.util.matching.Regex

 import scala.collection.mutable

 object Standard_System

 {

   val charset = "UTF-8"

   def codec(): Codec = Codec(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

   }

   /* basic file operations */

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

   {

     val file = File.createTempFile(prefix, null)

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

   }

   def read_file(file: File): String =

   {

     val buf = new StringBuilder(file.length.toInt)

     val reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), charset))

     var c = reader.read

     while (c != -1) {

       buf.append(c.toChar)

       c = reader.read

     }

     reader.close

     buf.toString

   }

   def write_file(file: File, text: CharSequence)

   {

     val writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset))

     try { writer.append(text) }

     finally { writer.close }

   }

   // FIXME handle (potentially cyclic) directory graph

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

   {

     val files = new mutable.ListBuffer[File]

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

     def find_entry(entry: File)

     {

       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: File, 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)

     try { proc.start }

     catch { case e: IOException => error(e.getMessage) }

   }

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

   {

     proc.getOutputStream.close

     val output = Source.fromInputStream(proc.getInputStream)(codec()).mkString  // FIXME

     val rc =

       try { proc.waitFor }

       finally {

         proc.getInputStream.close

         proc.getErrorStream.close

         proc.destroy

         Thread.interrupted

       }

     (output, rc)

   }

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

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

 }

 class Standard_System

 {

   val platform_root = if (Platform.is_windows) Cygwin.check_root() else "/"

   override def toString = platform_root

   /* 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 + ":" + File.separator)

             rest

           case Named_Root(root, rest) =>

             result_path ++= File.separator

             result_path ++= File.separator

             result_path ++= root

             rest

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

             result_path ++= platform_root

             path

           case path => path

         }

       for (p <- rest.split("/") if p != "") {

         val len = result_path.length

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

           result_path += File.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

   /* this_java executable */

   def this_java(): String =

   {

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

     val java_exe =

       if (Platform.is_windows) new File(java_home + "\\bin\\java.exe")

       else new File(java_home + "/bin/java")

     if (!java_exe.isFile) error("Expected this Java executable: " + java_exe.toString)

     posix_path(java_exe.getAbsolutePath)

   }

 }