import Stream._
import java.io.{ InputStream, EOFException }
import java.net.{ InetAddress, InetSocketAddress, Socket }
import scala.xml.{XML, Node, NodeSeq}

class EbusDefinition(val ebusXmlFile: String) {
  val xml = XML.loadFile(ebusXmlFile)

  def packetFromCommandId(primaryCommand: Char, secondaryCommand: Char): NodeSeq = {
    val packet = (xml \ "packets" \ "packet").filter(n =>
      n.attribute("primary").get.text.toInt == primaryCommand &&
						     n.attribute("secondary").get.text.toInt == secondaryCommand)
    packet
  }
}

abstract class EbusField(val name : String, val offset : Int);
class Data2c(override val name: String, override val offset : Int) extends EbusField(name, offset) {
}

object EbusField {
    def getFields(ebusDefinition : EbusDefinition, primaryCommand: Char, secondaryCommand: Char): List[EbusField] = {
      val packetDef = ebusDefinition.packetFromCommandId(primaryCommand, secondaryCommand)
      for (fieldDef <- (packetDef \ "fields").head.child) {
	App.println(buildField(fieldDef))
      }
      null
    }
  def buildField(field :Node) : Option[EbusField] = {
    if (field.label == "data2c") {
      val name = field.attribute("name").get.text
      val offset = field.attribute("offset").get.text.toInt
      return Some(new Data2c(name, offset))
    }
    return None
  }
}

class EbusL2Packet(val source: Char,
		   val destination: Char,
		   val primaryCommand: Char,
		   val secondaryCommand: Char,
		   val payloadLength: Char,
		   val payload: List[Char],
		   val crc: Char,
		   val rawLength: Int) {
  val length = 6 + payload.size

  override def toString: String = {
    val p = if (payload.size == 0)
      ""
	    else
	      payload.map(a => "%02x".format(a.toInt)).
    reduceLeft((a: Any, b: String) => a + " " + b)

    "L2Packet: d=%02x pC=%02x sC=%02x pL=%02x crc=%02x p=%s".format(
      destination.toInt, primaryCommand.toInt, secondaryCommand.toInt, payloadLength.toInt,
      crc.toInt, p.toString)
  }

  /**
   * Die CRC-Prüfsumme wird vom jeweiligen Sender über der expandierten Bytesendefolge mit dem
   * Generatorpolynom X8 +X7 + X4 + X3 + X +1 gebildet und als letztes Byte der Nachricht,
   * sofern notwendig, sogar expandiert gesendet.
   *
   * Generatorpol. 11001101
   */
  def calcCrc: Char = {
    //val foo = payload.reduce((a, b) => ((a.intValue + b.intValue) % 256).toChar)
    //val sum = destination + primaryCommand + secondaryCommand + payloadLength + foo

    val crc = 1 + 1
    1
  }
}

object EbusL2Packet {
  /**
   * Wird von {@link EbusReader} mit einer Streamposition aufgerufen.
   * Ausgehend von dieser Position wird versucht ein Paket aufzubauen,
   * und anschliesend die Checksumme geprüft.
   * Im Erfolgsfall wird eine EbusL2Packet-Instanz als Option zurückgegen,
   * sonst None
   */
  def apply(stream: Stream[Int]): Option[EbusL2Packet] = {
    try {
      var rawLength = 0
      val source = stream.apply(0).toChar
      val destination = stream.apply(1).toChar
      val primaryCommand = stream.apply(2).toChar
      val secondaryCommand = stream.apply(3).toChar
      val payloadLength = stream.apply(4).toChar
      rawLength = 5

      // Maximale payload Grösse = 16 Byte
      if (payloadLength > 16) {
	println("Erkannte payload Groesse zu gross: %d".format(payloadLength.toInt))
	return None
      }
      var payload = List[Char]()
      for (i <- 0 until payloadLength) {
        var it = stream.apply(rawLength).toChar
        rawLength += 1
        // Handle escape sequences
        // "eBUS  Spezifikation Physikalische Schicht – OSI 1 
        // Verbindungsschicht – OSI 2   V.1.3.1" auf Seite 8
        if (it == 0xa9.toChar) {
          val itNext = stream.apply(rawLength).toChar
          rawLength += 1
          if (itNext == 0x00.toChar) {
            it = 0xa9.toChar
          } else if (itNext == 0x01.toChar) {
            it = 0xaa.toChar
          } else {
            App.println("Ignore escape sequence 0xa9 0x%02x".format(itNext))
            rawLength -= 1
          }
        }
	payload = payload :+ it
      }
      val crc = stream.apply(5 + payloadLength).toChar
      val ack = stream.apply(6 + payloadLength).toChar
      if (ack != 0x00.toChar) {
	println("Fehlerhaftes ACK")
	return None
      }
      rawLength += 2
      
      if (stream.apply(6+payloadLength).toChar == 0xaa.toChar) {
	// Broadcast oder Master-Master
	return Some(new EbusL2Packet(source, destination,
				     primaryCommand, secondaryCommand,
				     payloadLength, payload, crc, rawLength))
      } else {
	// Master-Slave
      }
    } catch {
      case exc: IndexOutOfBoundsException => {
        App.println(exc.toString)
        exc.printStackTrace
        return None
      }
    }
  }
}

object EbusReader {
  def apply(streamI: Stream[Int]) : EbusL2Packet = {
    var stream = streamI
    while (true) {
      // Überspringe Synchronisationszeichen
      //stream = stream.dropWhile(v => v.toChar == 0xaa.toChar)
      // Überspringe solange nicht mindestens 6 Zeichen ohne 0xaa vorkommen
      while (stream.take(6).filter({v :Int => v.toChar == 0xaa.toChar}).size > 0) {
//	println("skip")
	stream = stream.drop(1)
      }

      EbusL2Packet(stream) match {
        case Some(packet) => {
          return packet
        }
        case None => {
          // Es konnte kein Paket eingelesen werden
          // verschiebe die Anfangsposition um ein Byte
          stream = stream.drop(1)
          App.println("skip 1 byte")
        }
      }
    }
    null
  }
}

object EbusL7Packet {
  def apply(l2packet : EbusL2Packet, ebusDefinition : EbusDefinition)
  : Option[EbusL7Packet] = {
    val packetDef = ebusDefinition.packetFromCommandId(
      l2packet.primaryCommand, l2packet.secondaryCommand)

    if (packetDef.isEmpty)
      return None
    else
      return Some(new EbusL7Packet(l2packet, packetDef))
  }
}

class EbusL7Packet(val l2packet : EbusL2Packet, val packetDefinition : NodeSeq) {
  def name : String = {
    packetDefinition.map({p :Node => p.attributes.apply("name")}).mkString
  }

  override def toString : String = {
    "EbusL7: name=%s".format(name)
  }
}

object App {
  val ebusDefinition = new EbusDefinition("/home/yvesf/vcs/ebus/ebus/ebus-xml/ebus.xml")
  var source: InputStream = null
  
  def println(msg : Any) {
    Predef.println("[ebus] " + msg.toString)
  }

  def main(args: Array[String]): Unit = {
    if (args.size == 1 && args(0) == "-") {
      println("Use stdin as source")
      source = System.in
    } else if (args.size == 2) {
      val addr = InetAddress.getByName(args(0))
      val sockAddr = new InetSocketAddress(addr, args(1).toInt)
      val s = new Socket()
      s.connect(sockAddr)
      println("Connected to %s %d".format(args(0), args(1).toInt))
      source = s.getInputStream
    } else if (args.size == 3 && args(0) == "dump") {
      val addr = InetAddress.getByName(args(1))
      val sockAddr = new InetSocketAddress(addr, args(2).toInt)
      val s = new Socket()
      s.connect(sockAddr)
      System.err.println("Connected to %s %d".format(args(1), args(2).toInt))
      while (true) {
        val v = s.getInputStream.read
        if (v == -1) {
	  println("Fehler: las -1")
          System.exit(1)
	}
        print(v.toChar)
      }
    } else {
      println("Missing Arguments")
      println(" -")
      println("    Read from stdin")
      println("HOST PORT")
      println("    Read from TCP Server")
      println("dump HOST PORT")
      println("    Dump TCP-Stream")
      System.exit(1)
    }

    val read = (() => {
      val value = source.read
      if (value == -1)
        throw new EOFException("End of File reached (read returned -1)")
      value
    })

      var stream: Stream[Int] = Stream.continually(read())
    
    while (true) {
      EbusReader(stream) match {
        case l2packet : EbusL2Packet => {
	  EbusL7Packet(l2packet, ebusDefinition) match {
	    case Some(l7packet) => {
	      println(l7packet)
	    }
	    case _ => {}
	  }
	  println(l2packet)
	  // Spule den Stream zur naechstmoeglichen Paketposition
	  stream = stream.drop(l2packet.rawLength)
        }
        case null => {
          println("null")
	  System.exit(1)
        }
      }
    }
    println("exiting")
    source.close
  }
}