/*
 *   ORXONOX - the hottest 3D action shooter ever to exist
 *                    > www.orxonox.net <
 *
 *
 *   License notice:
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation; either version 2
 *   of the License, or (at your option) any later version.
 *
 *   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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 *   Author:
 *      Oliver Scheuss
 *   Co-authors:
 *      ...
 *
 */

#include "Connection.h"

#include <cassert>
#include <deque>
#define WIN32_LEAN_AND_MEAN
#include <enet/enet.h>
#include <boost/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/date_time.hpp>

#include "packet/Packet.h"
#include "util/Output.h"
#include <util/Sleep.h>

namespace orxonox
{
  const boost::posix_time::millisec NETWORK_COMMUNICATION_THREAD_WAIT_TIME(200);
  const unsigned int                NETWORK_DISCONNECT_TIMEOUT = 500;

  /**
   * Constructor
   * @param firstPeerId The initial value of nextPeerID_
   */
  Connection::Connection(uint32_t firstPeerID):
    host_(nullptr), bCommunicationThreadRunning_(false), nextPeerID_(firstPeerID)
  {
    // Global initialization of ENet
    enet_initialize();

    // Register enet_deinitialize to be executed when the program exits normally
    atexit(enet_deinitialize);

    // Create mutexes for incoming and outgoing events
    this->incomingEventsMutex_ = new boost::mutex;
    this->outgoingEventsMutex_ = new boost::mutex;
  }

  /**
   * Destructor
   */
  Connection::~Connection()
  {
    // Delete the mutexes
    delete this->incomingEventsMutex_;
    delete this->outgoingEventsMutex_;
  }

  /**
   * Start the main communication thread.
   */
  void Connection::startCommunicationThread()
  {
    this->bCommunicationThreadRunning_ = true;
    this->communicationThread_ = new boost::thread(&Connection::communicationThread, this);
  }
  
  /**
   * Stop the main communication thread.
   */
  void Connection::stopCommunicationThread()
  {
    this->bCommunicationThreadRunning_ = false;
    // Wait for peaceful termination
    if(!this->communicationThread_->timed_join(NETWORK_COMMUNICATION_THREAD_WAIT_TIME))
    {
      // Force thread to stop if the waiting time runs out.
      this->communicationThread_->interrupt();
    }
    delete this->communicationThread_;
  }

  /**
   * Send an outgoing event of type 'disconnectPeer'.
   * @param peerID The peer to which the event is sent
   */
  void Connection::disconnectPeer(uint32_t peerID)
  {
    outgoingEvent outEvent = { peerID, OutgoingEventType::disconnectPeer, nullptr, 0 };
    
    this->outgoingEventsMutex_->lock();
    this->outgoingEvents_.push_back(outEvent);
    this->outgoingEventsMutex_->unlock();
  }

  /**
   * Send an outgoing event of type 'disconnectPeers'.
   */
  void Connection::disconnectPeers()
  {
    outgoingEvent outEvent = { 0, OutgoingEventType::disconnectPeers, nullptr, 0 };
    
    this->outgoingEventsMutex_->lock();
    this->outgoingEvents_.push_back(outEvent);
    this->outgoingEventsMutex_->unlock();
  }

  /**
   * Send a packet.
   * @param packet Pointer to the packet to send
   * @param peerID The peer to which the event is sent
   * @param channelId The channel ID
   */
  void Connection::addPacket(ENetPacket* packet, uint32_t peerID, uint8_t channelID)
  {
    outgoingEvent outEvent = { peerID, OutgoingEventType::sendPacket, packet, channelID };
    
    this->outgoingEventsMutex_->lock();
    this->outgoingEvents_.push_back(outEvent);
    this->outgoingEventsMutex_->unlock();
  }
  
  /**
   * Send a broadcast packet.
   * @param packet Pointer to the packet to send
   * @param channelId The channel ID
   */
  void Connection::broadcastPacket(ENetPacket* packet, uint8_t channelID)
  {
    outgoingEvent outEvent = { 0, OutgoingEventType::broadcastPacket, packet, channelID };
    
    this->outgoingEventsMutex_->lock();
    this->outgoingEvents_.push_back(outEvent);
    this->outgoingEventsMutex_->unlock();
  }

  
  /**
   * Main communication thread
   */
  void Connection::communicationThread()
  {
    ENetEvent event;
    
    while(this->bCommunicationThreadRunning_)
    {
      // Receive all pending incoming Events (such as packets, connects and disconnects)
      while(enet_host_check_events(this->host_, &event ) > 0)
      {
        this->processIncomingEvent(event);
      }
      
      // Sleep for 1ms
      msleep(1);
      
      // Send all waiting outgoing packets
      this->outgoingEventsMutex_->lock();
      uint32_t outgoingEventsCount = this->outgoingEvents_.size();
      this->outgoingEventsMutex_->unlock();

      while(outgoingEventsCount > 0)
      {
        this->outgoingEventsMutex_->lock();
        outgoingEvent outEvent = this->outgoingEvents_.front();
        this->outgoingEvents_.pop_front();
        this->outgoingEventsMutex_->unlock();
        
        this->processOutgoingEvent(outEvent);
        
        this->outgoingEventsMutex_->lock();
        outgoingEventsCount = this->outgoingEvents_.size();
        this->outgoingEventsMutex_->unlock();
      }
      
      // Wait for incoming events (at most NETWORK_WAIT_TIMEOUT ms)
      if(enet_host_service(this->host_, &event, NETWORK_WAIT_TIMEOUT) > 0)
      {
        this->processIncomingEvent(event);
      }
    }
  }
  
  /**
   * Handle an incoming event.
   * @param event The incoming event
   */
  void Connection::processIncomingEvent(ENetEvent& event)
  {
    incomingEvent inEvent;
    // preprocess event
    switch(event.type)
    {
      case ENET_EVENT_TYPE_CONNECT:
        inEvent = preprocessConnectEvent(event);
        break;
      case ENET_EVENT_TYPE_RECEIVE:
        inEvent = preprocessReceiveEvent(event);
        break;
      case ENET_EVENT_TYPE_DISCONNECT:
        inEvent = preprocessDisconnectEvent(event);
        break;
      case ENET_EVENT_TYPE_NONE:
      default:
        return;
    }
    
    // pushing event to queue
    this->incomingEventsMutex_->lock();
    this->incomingEvents_.push_back(inEvent);
    this->incomingEventsMutex_->unlock();
  }
  
  /**
   * Send an event.
   * @param event The event to send
   */
  void Connection::processOutgoingEvent(outgoingEvent& event)
  {
    ENetPeer* peer;
    switch(event.type)
    {
      case OutgoingEventType::sendPacket:
        // check whether the peer is still/already in the peer list
        if(this->peerMap_.find(event.peerID) != this->peerMap_.end())
        {
          peer = this->peerMap_[event.peerID];
          enet_peer_send(peer, event.channelID, event.packet);
        }
        else
        {
          // peer probably already disconnected so just discard packet
          orxout(message) << "Trying to send packet to peer that is not in peer list. Ignoring packet." << endl;
          enet_packet_destroy(event.packet);
        }
        break;
      case OutgoingEventType::disconnectPeer:
        if(this->peerMap_.find(event.peerID) != this->peerMap_.end())
        {
          peer = this->peerMap_[event.peerID];
          enet_peer_disconnect(peer, 0);
        }
        else
        {
          // peer probably already disconnected so just discard disconnect event
          assert(event.peerID < this->nextPeerID_);
        }
        break;
      case OutgoingEventType::disconnectPeers:
        this->disconnectPeersInternal();
        break;
      case OutgoingEventType::broadcastPacket:
        enet_host_broadcast( this->host_, event.channelID, event.packet );
        break;
      default:
        assert(0);
    }
  }

  void Connection::disconnectPeersInternal()
  {
    for( const auto& mapEntry : this->peerMap_ )
    {
      enet_peer_disconnect(mapEntry.second, 0);
    }
    uint32_t iterations = NETWORK_DISCONNECT_TIMEOUT / NETWORK_WAIT_TIMEOUT;
    uint32_t i = 0;
    while( this->peerMap_.size() && i++ < iterations )
    {
      ENetEvent event;
      if( enet_host_service( this->host_, &event, NETWORK_WAIT_TIMEOUT ) > 0 )
      {
        processIncomingEvent(event);
      }
    }
  }

  void Connection::processQueue()
  {
    incomingEvent inEvent;

    this->incomingEventsMutex_->lock();
    uint32_t incomingEventsCount = this->incomingEvents_.size();
    this->incomingEventsMutex_->unlock();
    while( incomingEventsCount > 0 )
    {
      // pop event from queue
      this->incomingEventsMutex_->lock();
      inEvent = this->incomingEvents_.front();
      this->incomingEvents_.pop_front();
      this->incomingEventsMutex_->unlock();
      
      // process event
      switch( inEvent.type )
      {
        case IncomingEventType::peerConnect:
          addPeer(inEvent.peerID);
          break;
        case IncomingEventType::peerDisconnect:
          removePeer(inEvent.peerID);
          break;
        case IncomingEventType::receivePacket:
          processPacket(inEvent.packet);
          break;
        default:
          break;
      }
      
      // check whether there are still events in the queue
      this->incomingEventsMutex_->lock();
      incomingEventsCount = this->incomingEvents_.size();
      this->incomingEventsMutex_->unlock();
    }
  }
  
  void Connection::waitOutgoingQueue()
  {
    uint32_t outgoingEventsCount;
    this->outgoingEventsMutex_->lock();
    outgoingEventsCount = this->outgoingEvents_.size();
    this->outgoingEventsMutex_->unlock();
    while( outgoingEventsCount )
    {
      msleep(1);
      this->outgoingEventsMutex_->lock();
      outgoingEventsCount = this->outgoingEvents_.size();
      this->outgoingEventsMutex_->unlock();
    }
  }


  incomingEvent Connection::preprocessConnectEvent(ENetEvent& event)
  {
    // make sure this peer doesn't exist
    assert( this->peerMap_.find(this->nextPeerID_) == this->peerMap_.end() );
    assert( this->peerIDMap_.find(event.peer) == this->peerIDMap_.end() );
    
    // give peer a new id and increase peerID for next peer
    uint32_t peerID = this->nextPeerID_;
    ++this->nextPeerID_;
    
    // add peer/peerID into peerMap_ and peerIDMap_
    this->peerMap_[peerID] = event.peer;
    this->peerIDMap_[event.peer] = peerID;
    
    // create new peerEvent and return it
    incomingEvent inEvent = { peerID, IncomingEventType::peerConnect, nullptr };
    return inEvent;
  }
  
  incomingEvent Connection::preprocessDisconnectEvent(ENetEvent& event)
  {
    // assert that the peer exists and get peerID
    assert( this->peerIDMap_.find(event.peer) != this->peerIDMap_.end() );
    uint32_t peerID = this->peerIDMap_[event.peer];
    
    // remove peer/peerID from maps
    this->peerIDMap_.erase(this->peerIDMap_.find(event.peer));
    this->peerMap_.erase(this->peerMap_.find(peerID));
    
    // create new peerEvent and return it
    incomingEvent inEvent = { peerID, IncomingEventType::peerDisconnect, nullptr };
    return inEvent;
  }
  
  incomingEvent Connection::preprocessReceiveEvent(ENetEvent& event)
  {
    // assert that the peer exists and get peerID
    assert( this->peerIDMap_.find(event.peer) != this->peerIDMap_.end() );
    uint32_t peerID = this->peerIDMap_[event.peer];
    
    // create new Packet from ENetPacket
    packet::Packet* p = packet::Packet::createPacket(event.packet, peerID);
    
    // create new peerEvent and return it
    incomingEvent inEvent = { peerID, IncomingEventType::receivePacket, p };
    return inEvent;
  }

  
  void Connection::enableCompression()
  {
    enet_host_compress_with_range_coder( this->host_ );
  }

}