// networklayer.cc for the assignment 2.
// Last modified 4/Sep/2006 Ahmet Sekercioglu

#include <map>
#include <omnetpp.h>
#include "packet_m.h"


class NetworkLayer : public cSimpleModule
{
  private:
    int myAddress;
    bool router;

    typedef std::map<int,int> RoutingTable; // destaddr --> port
    RoutingTable rtable;

  protected:
    virtual void initialize();
    virtual void handleMessage(cMessage *msg);
    virtual void finish();
};

Define_Module(NetworkLayer);

void NetworkLayer::initialize()
{
  myAddress = parentModule()->par("address");

  WATCH(myAddress);

  // Am I part of a router or not?
  if (strcmp("router", parentModule()->name()) == 0) {
    router = true;
  } else {
    router = false;
  }
}

void NetworkLayer::handleMessage(cMessage *msg)
{
  Packet *pk = check_and_cast<Packet *>(msg);
  int destAddr = pk->getDestAddr();
  
  if (destAddr == myAddress) {
    if (router) { // Routers don't have an application layer.
      ev << "Packet discarded: " << pk->name() << endl;
      delete pk;
    } else {
      ev << "Delivery of packet to higher layer: " << pk->name() << endl;
      send(pk,"localOut");
    }
    return;
  }
  
  RoutingTable::iterator it = rtable.find(destAddr);

  if (it == rtable.end()) {
    ev << "Address " << destAddr << " unreachable, discarding packet " << pk->name() << endl;
    delete pk;
    return;
  }

  if (pk->getSrcAddr() == -1) {
    // Application layer has forwarded this packet to the network layer.
    char pkname[40];
    sprintf(pkname,"pk-%d-to-%d", myAddress, pk->getDestAddr());
    pk->setSrcAddr(myAddress); 
    pk->setName(pkname);
  } 
  int outGate = (*it).second;
  ev << simTime() << " Forwarding packet " << pk->name() << " on gate id = " << outGate << endl;
  pk->setHopCount(pk->getHopCount()+1);
  send(pk, outGate);
}


void NetworkLayer::finish()
{
  RoutingTable::iterator it;

  int dest_address = (*it).first;
  int outGateId = (*it).second;

  ev << parentModule()->fullName() << " final routing table:" << endl;
  ev << "  destination\tnext hop" << endl;
  ev << "    address" << endl;
  ev << "  -----------\t--------" << endl;
  for(it = rtable.begin(); it != rtable.end(); it++) {
    dest_address = (*it).first;
    outGateId = (*it).second; 
    // (Keep network diagram close-by if you get confused about the following
    // information, observing the connections on the diagram will help.)
    // We will now follow the path to find the nextHopModule.
    // 
    // OutGateId is the ID of the local gate connected to the
    // outputQueueModule.  serverModule services the
    // outputQueueModule.  serverModule is connected to the gate
    // connected to the nextHopModule towards the destination node
    // module.
    cGate *outGate = gate(outGateId);
    cModule *outputQueueModule = outGate->toGate()->ownerModule();
    cModule *serverModule = outputQueueModule->gate("out")->toGate()->ownerModule();
    cGate *parentModuleGate = serverModule->gate("out")->toGate();
    cModule *nextHopModule = parentModuleGate->toGate()->ownerModule();
    ev << "       " << dest_address << "\t" << nextHopModule->fullName() << endl;
  }
  ev << " " << endl;

}