/*  Project nGenEx
    Destroyer Studios LLC
    Copyright © 1997-2004. All Rights Reserved.

    SUBSYSTEM:    NetEx.lib
    FILE:         NetPeer.cpp
    AUTHOR:       John DiCamillo


    OVERVIEW
    ========
    One side of a UDP net link connection
*/


#include "MemDebug.h"
#include <windows.h>
#include "NetPeer.h"
#include "NetGram.h"
#include "NetMsg.h"
#include "NetLayer.h"

#include <stdio.h>

// +-------------------------------------------------------------------+

const int MULTIPART_CHUNKSIZE = 232;
const int MULTIPART_HEADER    =  16;
const int UDP_HEADER_SIZE     =  34;

static NetMsgMultipart  multi_part_buffer;
static DWORD            multi_msg_sequence = 1;

// +-------------------------------------------------------------------+

NetPeer::NetPeer(const NetAddr& a, DWORD id)
   : addr(a), netid(id), sequence(0), pps(0), bps(0), max_qsize(0),
     status(OK), hist_indx(0), send_size(0), recv_size(0),
     chunk_size(MULTIPART_CHUNKSIZE)
{
   ZeroMemory(hist_time, sizeof(hist_time));
   ZeroMemory(hist_size, sizeof(hist_size));

   last_recv_time = NetLayer::GetUTC();
}

NetPeer::~NetPeer()
{
   send_list.destroy();
   recv_list.destroy();

   multi_send_list.destroy();
   multi_recv_list.destroy();
}

// +-------------------------------------------------------------------+

bool
NetPeer::SendMessage(NetMsg* msg)
{
   if (msg) {
      if (max_qsize > 0 && msg->Length() + send_size > max_qsize) {
         status = SEND_OVERFLOW;
         delete msg;
         return false;
      }

      // simple message
      if (msg->Length() <= (int) chunk_size) {
         if (msg->IsPriority())
            send_list.insert(msg);
         else
            send_list.append(msg);

         send_size += msg->Length();
      }

      // multipart message
      else {
         List<NetMsg>* list = &send_list;

         if (msg->IsScatter())
            list = &multi_send_list;

         DWORD nparts = msg->Length() / chunk_size;
         DWORD extra  = msg->Length() % chunk_size;

         if (extra > 0) nparts++;

         multi_part_buffer.type   = NetMsg::MULTIPART;
         multi_part_buffer.msgid  = multi_msg_sequence++;
         multi_part_buffer.nparts = nparts;

         DWORD header_size = (DWORD) (&multi_part_buffer.payload) -
                             (DWORD) (&multi_part_buffer);

         const BYTE* p = msg->Data();

         for (DWORD i = 0; i < nparts; i++) {
            multi_part_buffer.partno = i;
            NetMsg* part = 0;
            DWORD   part_size = chunk_size;

            if (i == nparts-1 && extra > 0) // last partial payload
               part_size = extra;

            CopyMemory(multi_part_buffer.payload, p, part_size);
            p += part_size;
            part = new(__FILE__,__LINE__) NetMsg(msg->NetID(),
                                                 &multi_part_buffer,
                                                 header_size + part_size,
                                                 msg->Flags());

            if (part) {
               list->append(part);
               send_size += part->Length();
            }
         }
      }

      return true;
   }

   return false;
}

// +-------------------------------------------------------------------+

NetMsg*
NetPeer::GetMessage()
{
   if (recv_list.size() > 0) {
      NetMsg* msg = recv_list.removeIndex(0);
      recv_size -= msg->Length();
      return msg;
   }

   return 0;
}

// +-------------------------------------------------------------------+

NetGram*
NetPeer::ComposeGram()
{
   NetGram* g = 0;

   if ((send_list.size() || multi_send_list.size()) && OKtoSend()) {
      AutoThreadSync auto_sync(sync);

      int   xmit_size = send_size;
      int   nmsg      = send_list.size();
      int   limit     = NET_GRAM_MAX_SIZE;
      bool  reliable  = false;
      bool  is_multi  = false;

      NetMsg*        multi_msg = 0;
      List<NetMsg>*  list      = &send_list;

      if (xmit_size > limit) {
         xmit_size = 0;
         nmsg      = 0;

         if (send_list.size() > 0) {
            NetMsg* msg = 0;

            // if there is regular traffic, and multipart traffic
            if (multi_send_list.size()) {
               // just send one multipart message in this packet
               multi_msg = multi_send_list.removeIndex(0);
               limit -= msg->Length();
               reliable = true;
               is_multi = true;
            }

            for (int i = 0; i < send_list.size(); i++) {
               NetMsg* msg = send_list[i];

               if (xmit_size + msg->Length() < limit) {
                  xmit_size += msg->Length();
                  nmsg++;
               }
               else {
                  break;
               }
            }
         }
         else {
            // if there is only multipart traffic,
            // send as many multipart messages as will fit:
            list = &multi_send_list;
            reliable = true;
            is_multi = true;

            for (int i = 0; i < multi_send_list.size(); i++) {
               NetMsg* msg = multi_send_list[i];

               if (xmit_size + msg->Length() < limit) {
                  xmit_size += msg->Length();
                  nmsg++;
               }
               else {
                  break;
               }
            }
         }
      }

      if (xmit_size > 0 && nmsg > 0) {
         BYTE* buffer   = new(__FILE__,__LINE__) BYTE[xmit_size];
         BYTE* p        = buffer;

         if (multi_msg) {
            if (buffer) {
               CopyMemory(p, multi_msg->Data(), multi_msg->Length());
               p[1] = multi_msg->Length();
               p += multi_msg->Length();
            }
            delete multi_msg;
         }

         while (nmsg-- && p < buffer + xmit_size) {
            NetMsg* msg = list->removeIndex(0);

            if (msg) {
               if (msg->IsReliable()) reliable = true;
               if (buffer) {
                  CopyMemory(p, msg->Data(), msg->Length());
                  p[1] = msg->Length();
                  p += msg->Length();
               }
               delete msg;
            }
         }

         if (buffer) {
            Text user_data((const char*) buffer, xmit_size);
            int  retries = 0;

            if (reliable)
               retries = 5;

            if (is_multi)
               retries = 10;

            send_size -= xmit_size;

            hist_size[hist_indx] = xmit_size + UDP_HEADER_SIZE;
            hist_time[hist_indx] = NetLayer::GetTime();
            hist_indx++;

            if (hist_indx >= HIST_SIZE)
               hist_indx = 0;

            g = new(__FILE__,__LINE__) NetGram(addr, user_data, retries);
            delete[] buffer;
         }
      }

      // the next msg is too big to fit in a single packet
      else {
         NetMsg* m = send_list.removeIndex(0);
         send_size -= m->Length();
         delete m;
      }
   }

   return g;
}

// +-------------------------------------------------------------------+

bool
NetPeer::ReceiveGram(NetGram* g, List<NetMsg>* q)
{
   if (g) {
      if (max_qsize > 0 && recv_size + g->Size() > max_qsize) {
         status = RECV_OVERFLOW;
         delete g;
         return false;
      }

      sequence  =  g->Sequence();
      recv_size += g->Size() - NET_GRAM_HEADER_SIZE;

      // PARSE THE BLOCKS:
      BYTE* p = g->UserData();

      while (p < g->Data() + g->Size()) {
         BYTE block_type = p[0];
         BYTE block_size = p[1];

         if (!block_type || !block_size)
            break;

         NetMsg* msg = new(__FILE__,__LINE__) NetMsg(netid, p, block_size);

         if (msg) {
            if (msg->Type() < NetMsg::RESERVED) {
               msg->SetSequence(sequence);

               recv_list.insertSort(msg);

               if (q)
                  q->insertSort(msg);

               p += block_size;
            }

            else if (msg->Type() == NetMsg::MULTIPART) {
               multi_recv_list.insertSort(msg);
               p += block_size;

               CheckMultiRecv(q);
            }
         }
      }

      last_recv_time = NetLayer::GetUTC();

      delete g;
      return true;
   }

   return false;
}

// +-------------------------------------------------------------------+

bool
NetPeer::OKtoSend() const
{
   if (pps || bps) {
      DWORD hist_total  = 0;
      DWORD hist_count  = 0;
      DWORD now         = NetLayer::GetTime();
      DWORD hist_oldest = now;
      DWORD hist_newest = 0;

      for (int i = 0; i < HIST_SIZE; i++) {
         if (hist_size[i] > 0) {
            hist_total += hist_size[i];
            hist_count++;
         }

         if (hist_time[i] > 0) {
            if (hist_time[i] < hist_oldest)
               hist_oldest = hist_time[i];

            if (hist_time[i] > hist_newest)
               hist_newest = hist_time[i];
         }
      }

      if (now - hist_newest < (DWORD) pps)
         return false;

      DWORD delta   = now - hist_oldest;
      DWORD avg_bps = hist_total / delta;

      if (bps > 0 && avg_bps > (DWORD) bps)
         return false;
   }

   return true;
}

// +-------------------------------------------------------------------+

struct PacketAssembly {
   DWORD msgid;
   DWORD netid;
   int   nreq;
   int   nparts;
   int   nbytes;
};

void
NetPeer::CheckMultiRecv(List<NetMsg>* q)
{
   const int MAX_SIMULTANEOUS_MULTI_SEQUENCES = 8;

   PacketAssembly  assy[MAX_SIMULTANEOUS_MULTI_SEQUENCES];
   ZeroMemory(assy, sizeof(assy));

   DWORD header_size = (DWORD) (&multi_part_buffer.payload) -
                       (DWORD) (&multi_part_buffer);

   // Catalog how much of each multipart sequence has been received:
   for (int i = 0; i < multi_recv_list.size(); i++) {
      NetMsg*           msg = multi_recv_list[i];
      NetMsgMultipart*  m   = (NetMsgMultipart*) msg->Data();

      for (int n = 0; n < MAX_SIMULTANEOUS_MULTI_SEQUENCES; n++) {
         PacketAssembly* a = assy + n;

         if (a->msgid == 0 || (a->msgid == m->msgid && a->netid == msg->NetID())) {
            a->msgid  = m->msgid;
            a->netid  = msg->NetID();
            a->nreq   = m->nparts;
            a->nparts += 1;
            a->nbytes += m->len - header_size;
            break;
         }
      }
   }

   for (int n = 0; n < MAX_SIMULTANEOUS_MULTI_SEQUENCES; n++) {
      PacketAssembly* a = assy + n;

      // is this sequence complete?
      if (a->msgid && a->nparts == a->nreq) {
         BYTE* buffer = new BYTE[a->nbytes];
         BYTE* p      = buffer;
         WORD  nid    = 0;

         ListIter<NetMsg> iter = multi_recv_list;
         while (++iter) {
            netid = iter->NetID();
            NetMsgMultipart* m = (NetMsgMultipart*) iter->Data();

            // found part of the sequence
            if (m->msgid == a->msgid && netid == a->netid) {
               // copy it into the buffer
               CopyMemory(p, m->payload, m->len - header_size);
               p += m->len - header_size;

               delete iter.removeItem();
            }
         }

         NetMsg* msg = new(__FILE__,__LINE__) NetMsg(netid, buffer, a->nbytes, NetMsg::RELIABLE);
         if (msg) {
            recv_list.insertSort(msg);

            if (q)
               q->insertSort(msg);
         }
      }
   }
}