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: Int, secondaryCommand: Int): 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: Int,
		   val destination: Int,
		   val primaryCommand: Int,
		   val secondaryCommand: Int,
		   val payloadLength: Int,
		   val payload: List[Int],
		   val crc: Int,
		   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: Int = {
    //val foo = payload.reduce((a, b) => ((a.intValue + b.intValue) % 256).toChar)
    //val sum = destination + primaryCommand + secondaryCommand + payloadLength + foo

    val crc = 1 + 1
    1
  }
}

class FakePacket(val length : Int);

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[Any] = {
    try {
      var rawLength = 0
      val source = stream(0)
      val destination = stream(1)
      val primaryCommand = stream(2)
      val secondaryCommand = stream(3)
      val payloadLength = stream(4)
      rawLength = 5

      println("source=0x%02x destination=0x%02x primaryCommand=0x%02x secondaryCommand=0x%02x payloadLength=0x%02x".format(
	source, destination, primaryCommand, secondaryCommand, payloadLength))

      // Maximale payload Grösse = 16 Byte
      if (payloadLength > 16) {
	println("Erkannte payload Groesse zu gross: %d".format(payloadLength))
	return None
      } else {
	println("Payload = " + payloadLength);
      }

      var payload = List[Int]()
      for (i <- 0 until payloadLength) {
        var it = stream(rawLength)
        rawLength += 1
        // Handle escape sequences
        // "eBUS  Spezifikation Physikalische Schicht – OSI 1 
        // Verbindungsschicht – OSI 2   V.1.3.1" auf Seite 8
        if (it == 0xa9) {
          val itNext = stream.apply(rawLength)
          rawLength += 1
          if (itNext == 0x00) {
            it = 0xa9
          } else if (itNext == 0x01) {
            it = 0xaa
          } else {
            App.println("Ignore escape sequence 0xa9 0x%02x".format(itNext))
            rawLength -= 1
          }
        }
	payload = payload :+ it
	println("Payload: " + payload.map((it) => "0x%02x".format(it)).foldLeft(""){(s1,s2) => s1+","+s2})
      }
      val crc = stream.apply(rawLength + 0)
      println("CRC=0x%x".format(crc))
      val ack = stream.apply(rawLength + 1)
      println("ACK=0x%02x".format(ack))
      if (destination == 0xfe) {
	// Broadcast
	if (ack != 0xaa) {
	  println("ACK Bei Broadcast Paket unerwertet nicht 0xaa sondern 0x%02x".format(ack))
	}
      } else {
	if (ack != 0x00) {
	  println("ACK unerwartet nicht 0x00 sondern 0x%02x".format(ack))
	}
      }
      rawLength += 0

      if (stream.apply(rawLength + 4) == 0xaa) {
	// Broadcast oder Master-Master
	return Some(new EbusL2Packet(source, destination,
				     primaryCommand, secondaryCommand,
				     payloadLength, payload, crc, rawLength))
      } else {
	// Master-Slave
	return Some(new FakePacket(rawLength))
      }
    } 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) {
      // Synchronisiere
      while (stream(0) != 0xaa && stream(1) != 0xaa) {
	stream = stream.drop(1)
      }
      // Überspringe Synchronisationszeichen
      while (stream(0).toChar == 0xaa) {
	stream = stream.drop(1)
      }

      EbusL2Packet(stream) match {
        case Some(packet : EbusL2Packet) => {
          return packet
        }
	case Some(packet : FakePacket)  => {
	  println("Fake paket - forward %d bytes".format(packet.length))
	  stream = stream.drop(packet.length)
	}
        case None => {
          // Es konnte kein Paket eingelesen werden
          // verschiebe die Anfangsposition um ein Byte
	  App.println("Paket konnte nicht gelesen werden, verschiebe start um 1 byte")
          stream = stream.drop(1)
        }
      }
    }
    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: read == -1")
          System.exit(1)
	}
	System.out.write(v)
      }
    } 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) {
      try {
	EbusReader(stream) match {
          case l2packet : EbusL2Packet => {
	    println("Read l2 packaet: " + l2packet);
	    /*
	     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)
		}
	}
      } catch {
	case exc : EOFException  => {
	  println("EOF")
	  source.close
	  exit(0)
	}
      }
    }
    println("exiting")
    source.close
  }
}

App.main(Array("-"))