/*  Title:      Pure/General/sha1.scala

     Module:     PIDE

     Author:     Makarius

 Digest strings according to SHA-1 (see RFC 3174).

 */

 package isabelle

 import java.io.{File => JFile, FileInputStream}

 import java.security.MessageDigest

 object SHA1

 {

   sealed case class Digest(rep: String)

   {

     override def toString: String = rep

   }

   private def make_result(digest: MessageDigest): Digest =

   {

     val result = new StringBuilder

     for (b <- digest.digest()) {

       val i = b.asInstanceOf[Int] & 0xFF

       if (i < 16) result += '0'

       result ++= Integer.toHexString(i)

     }

     Digest(result.toString)

   }

   def digest(file: JFile): Digest =

   {

     val stream = new FileInputStream(file)

     val digest = MessageDigest.getInstance("SHA")

     val buf = new Array[Byte](65536)

     var m = 0

     try {

       do {

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

         if (m != -1) digest.update(buf, 0, m)

       } while (m != -1)

     }

     finally { stream.close }

     make_result(digest)

   }

   def digest(path: Path): Digest = digest(path.file)

   def digest(bytes: Array[Byte]): Digest =

   {

     val digest = MessageDigest.getInstance("SHA")

     digest.update(bytes)

     make_result(digest)

   }

   def digest(string: String): Digest = digest(Standard_System.string_bytes(string))

 }