/*  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.zip.{ZipEntry, ZipInputStream}

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, FileFilter, IOException}

import java.nio.charset.Charset

import scala.io.{Source, 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: File): String = slurp(new FileInputStream(file))

  def write_file(file: File, text: CharSequence)

  {

    val writer =

      new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset))

    try { writer.append(text) }

    finally { writer.close }

  }

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

  {

    val file = File.createTempFile(prefix, null)

    file.deleteOnExit

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

  }

  // 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)

    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: File, env: Map[String, String], redirect: Boolean, args: String*)

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

  /* unpack zip archive -- platform file-system */

  def unzip(url: URL, root: File)

  {

    import scala.collection.JavaConversions._

    val buffer = new Array[Byte](4096)

    val zip_stream = new ZipInputStream(new BufferedInputStream(url.openStream))

    var entry: ZipEntry = null

    try {

      while ({ entry = zip_stream.getNextEntry; entry != null }) {

        val file = new File(root, entry.getName.replace('/', File.separatorChar))

        val dir = file.getParentFile

        if (dir != null && !dir.isDirectory && !dir.mkdirs)

          error("Failed to create directory: " + dir)

        var len = 0

        val out_stream = new BufferedOutputStream(new FileOutputStream(file))

        try {

          while ({ len = zip_stream.read(buffer); len != -1 })

            out_stream.write(buffer, 0, len)

        }

        finally { out_stream.close }

      }

    }

    finally { zip_stream.close }

  }

  /* unpack tar archive -- POSIX file-system */

  def posix_untar(url: URL, root: File, gunzip: Boolean = false,

    tar: String = "tar", gzip: String = "", progress: Int => Unit = _ => ()): String =

  {

    if (!root.isDirectory && !root.mkdirs)

      error("Failed to create root directory: " + root)

    val connection = url.openConnection

    val length = connection.getContentLength.toLong

    require(length >= 0L)

    val stream = new BufferedInputStream(connection.getInputStream)

    val progress_stream = new InputStream {

      private val total = length max 1L

      private var index = 0L

      private var percentage = 0L

      override def read(): Int =

      {

        val c = stream.read

        if (c != -1) {

          index += 100

          val p = index / total

          if (percentage != p) { percentage = p; progress(percentage.toInt) }

        }

        c

      }

      override def available(): Int = stream.available

      override def close() { stream.close }

    }

    val cmdline =

      List(tar, "-o", "-x", "-f-") :::

        (if (!gunzip) Nil else if (gzip == "") List("-z") else List("-I", gzip))

    val proc = raw_execute(root, null, false, cmdline:_*)

    val stdout = Simple_Thread.future("tar_stdout") { slurp(proc.getInputStream) }

    val stderr = Simple_Thread.future("tar_stderr") { slurp(proc.getErrorStream) }

    val stdin = new BufferedOutputStream(proc.getOutputStream)

    try {

      var c = -1

      val io_err =

        try { while ({ c = progress_stream.read; c != -1 }) stdin.write(c); false }

        catch { case e: IOException => true }

      stdin.close

      val rc = try { proc.waitFor } finally { Thread.interrupted }

      if (io_err || rc != 0) error(stderr.join.trim) else stdout.join

    }

    finally {

      progress_stream.close

      stdin.close

      proc.destroy

    }

  }

}

class Standard_System

{

  /* platform_root */

  val platform_root = if (Platform.is_windows) Cygwin.check_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) + ":" + 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 <- space_explode('/', rest) 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)

  }

}