/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2011 Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Jaume Nin <jnin@cttc.es>
 *         Nicola Baldo <nbaldo@cttc.es>
 */

#include <ns3/epc-helper.h>
#include <ns3/log.h>
#include <ns3/inet-socket-address.h>
#include <ns3/mac48-address.h>
#include <ns3/epc-gtpu-tunnel-endpoint.h>
#include <ns3/eps-bearer.h>
#include <ns3/ipv4-address.h>
#include <ns3/internet-stack-helper.h>
#include <ns3/point-to-point-helper.h>
#include <ns3/packet-socket-helper.h>
#include <ns3/packet-socket-address.h>
#include <ns3/epc-enb-application.h>
#include <ns3/epc-sgw-pgw-application.h>


namespace ns3 {

NS_LOG_COMPONENT_DEFINE ("EpcHelper");

NS_OBJECT_ENSURE_REGISTERED (EpcHelper);

EpcHelper::EpcHelper () 
  : m_gtpuUdpPort (2152) // fixed by the standard
{
  NS_LOG_FUNCTION (this);

  // since we use point-to-point links for all S1-U links, 
  // we use a /30 subnet which can hold exactly two addresses 
  // (remember that net broadcast and null address are not valid)
  m_s1uIpv4AddressHelper.SetBase ("10.0.0.0", "255.255.255.252");

  // we use a /8 net for all UEs
  m_ueAddressHelper.SetBase ("7.0.0.0", "255.0.0.0");
  
  // create SgwPgwNode
  m_sgwPgw = CreateObject<Node> ();
  InternetStackHelper internet;
  internet.Install (m_sgwPgw);
  
  // create S1-U socket
  Ptr<Socket> sgwPgwS1uSocket = Socket::CreateSocket (m_sgwPgw, TypeId::LookupByName ("ns3::UdpSocketFactory"));
  int retval = sgwPgwS1uSocket->Bind (InetSocketAddress (Ipv4Address::GetAny (), m_gtpuUdpPort));
  NS_ASSERT (retval == 0);

  // create TUN device implementing tunneling of user data over GTP-U/UDP/IP 
  Ptr<VirtualNetDevice> tunDevice = CreateObject<VirtualNetDevice> ();

  // yes we need this
  tunDevice->SetAddress (Mac48Address::Allocate ()); 

  m_sgwPgw->AddDevice (tunDevice);
  NetDeviceContainer tunDeviceContainer;
  tunDeviceContainer.Add (tunDevice);
  
  // the TUN device is on the same subnet as the UEs, so when a packet
  // addressed to an UE arrives at the intenet to the WAN interface of
  // the PGW it will be forwarded to the TUN device. 
  Ipv4InterfaceContainer tunDeviceIpv4IfContainer = m_ueAddressHelper.Assign (tunDeviceContainer);  

  // create EpcSgwPgwApplication
  m_sgwPgwApp = CreateObject<EpcSgwPgwApplication> (tunDevice, sgwPgwS1uSocket);
  m_sgwPgw->AddApplication (m_sgwPgwApp);
  
  // connect SgwPgwApplication and virtual net device for tunneling
  tunDevice->SetSendCallback (MakeCallback (&EpcSgwPgwApplication::RecvFromTunDevice, m_sgwPgwApp));

}

EpcHelper::~EpcHelper ()
{
  NS_LOG_FUNCTION (this);
}

TypeId
EpcHelper::GetTypeId (void)
{
  static TypeId tid = TypeId ("ns3::EpcHelper")
    .SetParent<Object> ()
    .AddConstructor<EpcHelper> ()
    .AddAttribute ("S1uLinkDataRate", 
                   "The data rate to be used for the next S1-U link to be created",
                   DataRateValue (DataRate ("10Gb/s")),
                   MakeDataRateAccessor (&EpcHelper::m_s1uLinkDataRate),
                   MakeDataRateChecker ())
    .AddAttribute ("S1uLinkDelay", 
                   "The delay to be used for the next S1-U link to be created",
                   TimeValue (Seconds (0)),
                   MakeTimeAccessor (&EpcHelper::m_s1uLinkDelay),
                   MakeTimeChecker ())
    .AddAttribute ("S1uLinkMtu", 
                   "The MTU of the next S1-U link to be created. Note that, because of the additional GTP/UDP/IP tunneling overhead, you need a MTU larger than the end-to-end MTU that you want to support.",
                   UintegerValue (2000),
                   MakeUintegerAccessor (&EpcHelper::m_s1uLinkMtu),
                   MakeUintegerChecker<uint16_t> ())
  ;
  return tid;
}


void
EpcHelper::AddEnb (Ptr<Node> enb, Ptr<NetDevice> lteEnbNetDevice)
{
  NS_LOG_FUNCTION (this << enb << lteEnbNetDevice);

  NS_ASSERT (enb == lteEnbNetDevice->GetNode ());

  // add an IPv4 stack to the previously created eNB
  InternetStackHelper internet;
  internet.Install (enb);
  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after node creation: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());

  // create a point to point link between the new eNB and the SGW with
  // the corresponding new NetDevices on each side  
  NodeContainer enbSgwNodes;
  enbSgwNodes.Add (m_sgwPgw);
  enbSgwNodes.Add (enb);
  PointToPointHelper p2ph;
  p2ph.SetDeviceAttribute ("DataRate", DataRateValue (m_s1uLinkDataRate));
  p2ph.SetDeviceAttribute ("Mtu", UintegerValue (m_s1uLinkMtu));
  p2ph.SetChannelAttribute ("Delay", TimeValue (m_s1uLinkDelay));  
  NetDeviceContainer enbSgwDevices = p2ph.Install (enb, m_sgwPgw);
  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after installing p2p dev: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());  
  Ptr<NetDevice> enbDev = enbSgwDevices.Get (0);
  Ptr<NetDevice> sgwDev = enbSgwDevices.Get (1);
  m_s1uIpv4AddressHelper.NewNetwork ();
  Ipv4InterfaceContainer enbSgwIpIfaces = m_s1uIpv4AddressHelper.Assign (enbSgwDevices);
  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB after assigning Ipv4 addr to S1 dev: " << enb->GetObject<Ipv4> ()->GetNInterfaces ());
  
  Ipv4Address enbAddress = enbSgwIpIfaces.GetAddress (0);
  Ipv4Address sgwAddress = enbSgwIpIfaces.GetAddress (1);

  // create S1-U socket for the ENB
  Ptr<Socket> enbS1uSocket = Socket::CreateSocket (enb, TypeId::LookupByName ("ns3::UdpSocketFactory"));
  int retval = enbS1uSocket->Bind (InetSocketAddress (enbAddress, m_gtpuUdpPort));
  NS_ASSERT (retval == 0);
  

  // give PacketSocket powers to the eNB
  //PacketSocketHelper packetSocket;
  //packetSocket.Install (enb); 
  
  // create LTE socket for the ENB 
  Ptr<Socket> enbLteSocket = Socket::CreateSocket (enb, TypeId::LookupByName ("ns3::PacketSocketFactory"));
  PacketSocketAddress enbLteSocketBindAddress;
  enbLteSocketBindAddress.SetSingleDevice (lteEnbNetDevice->GetIfIndex ());
  enbLteSocketBindAddress.SetProtocol (Ipv4L3Protocol::PROT_NUMBER);
  retval = enbLteSocket->Bind (enbLteSocketBindAddress);
  NS_ASSERT (retval == 0);  
  PacketSocketAddress enbLteSocketConnectAddress;
  enbLteSocketConnectAddress.SetPhysicalAddress (Mac48Address::GetBroadcast ());
  enbLteSocketConnectAddress.SetSingleDevice (lteEnbNetDevice->GetIfIndex ());
  enbLteSocketConnectAddress.SetProtocol (Ipv4L3Protocol::PROT_NUMBER);
  retval = enbLteSocket->Connect (enbLteSocketConnectAddress);
  NS_ASSERT (retval == 0);  
  

  NS_LOG_INFO ("create EpcEnbApplication");
  Ptr<EpcEnbApplication> enbApp = CreateObject<EpcEnbApplication> (enbLteSocket, enbS1uSocket, sgwAddress);
  enb->AddApplication (enbApp);
  NS_ASSERT (enb->GetNApplications () == 1);
  NS_ASSERT_MSG (enb->GetApplication (0)->GetObject<EpcEnbApplication> () != 0, "cannot retrieve EpcEnbApplication");
  NS_LOG_LOGIC ("enb: " << enb << ", enb->GetApplication (0): " << enb->GetApplication (0));
  
}


void
EpcHelper::ActivateEpsBearer (Ptr<NetDevice> ueLteDevice, Ptr<NetDevice> enbLteDevice, Ptr<LteTft> tft, uint16_t rnti, uint8_t lcid)
{
  Ptr<Node> ueNode = ueLteDevice->GetNode (); 
  Ptr<Ipv4> ueIpv4 = ueNode->GetObject<Ipv4> ();
  int32_t interface =  ueIpv4->GetInterfaceForDevice (ueLteDevice);
  NS_ASSERT (interface >= 0);
  NS_ASSERT (ueIpv4->GetNAddresses (interface) == 1);
  Ipv4Address ueAddr = ueIpv4->GetAddress (interface, 0).GetLocal ();
  NS_LOG_LOGIC (" UE IP address: " << ueAddr);

  // NOTE: unlike ueLteDevice, enbLteDevice is NOT an Ipv4 enabled
  // device. In fact we are interested in the S1 device of the eNB.
  // We find it by relying on the assumption that the S1 device is the
  // only Ipv4 enabled device of the eNB besides the localhost interface.
  Ptr<Node> enbNode = enbLteDevice->GetNode (); 
  NS_ASSERT (enbNode != 0);
  Ptr<Ipv4> enbIpv4 = enbNode->GetObject<Ipv4> ();
  NS_LOG_LOGIC ("number of Ipv4 ifaces of the eNB: " << enbIpv4->GetNInterfaces ());
  // two ifaces total: loopback + the S1-U interface
  NS_ASSERT (enbIpv4->GetNInterfaces () == 2); 
  NS_ASSERT (ueIpv4->GetNAddresses (1) == 1);
  // iface index 0 is loopback, index 1 is the S1-U interface
  Ipv4Address enbAddr = enbIpv4->GetAddress (1, 0).GetLocal (); 
  NS_LOG_LOGIC (" ENB IP address: " << enbAddr);

  // setup S1 bearer at EpcSgwPgwApplication
  uint32_t teid = m_sgwPgwApp->ActivateS1Bearer (ueAddr, enbAddr, tft);

  // setup S1 bearer at EpcEnbApplication
  NS_LOG_LOGIC ("enb: " << enbNode << ", enb->GetApplication (0): " << enbNode->GetApplication (0));
  NS_ASSERT (enbNode->GetNApplications () == 1);
  Ptr<Application> app =  enbNode->GetApplication (0);
  NS_ASSERT (app != 0);
  Ptr<EpcEnbApplication> epcEnbApp = app->GetObject<EpcEnbApplication> ();
  NS_ASSERT (epcEnbApp != 0);
  epcEnbApp->ErabSetupRequest (teid, rnti, lcid);
  
  
}


Ptr<Node>
EpcHelper::GetPgwNode ()
{
  return m_sgwPgw;
}


Ipv4InterfaceContainer 
EpcHelper::AssignUeIpv4Address (NetDeviceContainer ueDevices)
{
  return m_ueAddressHelper.Assign (ueDevices);
}



Ipv4Address
EpcHelper::GetUeDefaultGatewayAddress ()
{
  // return the address of the tun device
  return m_sgwPgw->GetObject<Ipv4> ()->GetAddress (1, 0).GetLocal ();
}


} // namespace ns3