//
//  cxlxprotocol.cpp
//  xlxd
//
//  Created by Jean-Luc Deltombe (LX3JL) on 28/01/2016.
//  Copyright © 2015 Jean-Luc Deltombe (LX3JL). All rights reserved.
//
// ----------------------------------------------------------------------------
//    This file is part of xlxd.
//
//    xlxd 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 3 of the License, or
//    (at your option) any later version.
//
//    xlxd 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 Foobar.  If not, see <http://www.gnu.org/licenses/>.
// ----------------------------------------------------------------------------

#include "main.h"
#include <string.h>
#include "cxlxclient.h"
#include "cxlxprotocol.h"
#include "creflector.h"
#include "cgatekeeper.h"


////////////////////////////////////////////////////////////////////////////////////////
// operation

bool CXlxProtocol::Init(void)
{
    bool ok;
    
    // base class
    ok = CProtocol::Init();
    
    // update the reflector callsign
    m_ReflectorCallsign.PatchCallsign(0, (const uint8 *)"XLX", 3);
    
    // create our socket
    ok &= m_Socket.Open(XLX_PORT);
    if ( !ok )
    {
        std::cout << "Error opening socket on port UDP" << XLX_PORT << " on ip " << g_Reflector.GetListenIp() << std::endl;
    }
    
    // update time
    m_LastKeepaliveTime.Now();
    
    // done
    return ok;
}

////////////////////////////////////////////////////////////////////////////////////////
// task

void CXlxProtocol::Task(void)
{
    CBuffer             Buffer;
    CIp                 Ip;
    CCallsign           Callsign;
    char                Modules[NB_MODULES_MAX+1];
    CDvHeaderPacket     *Header;
    CDvFramePacket      *Frame;
    CDvLastFramePacket  *LastFrame;
    
    // any incoming packet ?
    if ( m_Socket.Receive(&Buffer, &Ip, 20) != -1 )
    {
        // crack the packet
        if ( (Frame = IsValidDvFramePacket(Buffer)) != NULL )
        {
            //std::cout << "XLX (DExtra) DV frame"  << std::endl;
            
            // handle it
            OnDvFramePacketIn(Frame);
        }
        else if ( (Header = IsValidDvHeaderPacket(Buffer)) != NULL )
        {
            //std::cout << "XLX (DExtra) DV header:"  << std::endl << *Header << std::endl;
            
            // callsign muted?
            if ( g_GateKeeper.MayTransmit(Header->GetMyCallsign(), Ip) )
            {
                // handle it
                OnDvHeaderPacketIn(Header, Ip);
            }
            else
            {
                delete Header;
            }
        }
        else if ( (LastFrame = IsValidDvLastFramePacket(Buffer)) != NULL )
        {
            //std::cout << "XLX (DExtra) DV last frame" << std::endl;
            
            // handle it
            OnDvLastFramePacketIn(LastFrame);
        }
        else if ( IsValidConnectPacket(Buffer, &Callsign, Modules) || IsValidAckPacket(Buffer, &Callsign, Modules)  )
        {
            std::cout << "XLX connect/ack packet for modules " << Modules << " from " << Callsign << " at " << Ip << std::endl;
            
            // already connected ?
            CClients *clients = g_Reflector.GetClients();
            if ( clients->FindClient(Callsign, Ip, PROTOCOL_XLX) == NULL )
            {
                // callsign authorized?
                if ( g_GateKeeper.MayLink(Callsign, Ip, PROTOCOL_XLX, Modules) )
                {
                    // acknowledge the request
                    EncodeConnectAckPacket(&Buffer, Modules);
                    m_Socket.Send(Buffer, Ip);
                    
                    // create the client
                    CXlxClient *client = new CXlxClient(Callsign, Ip, Modules);
                    
                    // and append
                    clients->AddClient(client);
                }
                else
                {
                    // deny the request
                    EncodeConnectNackPacket(&Buffer);
                    m_Socket.Send(Buffer, Ip);
                }
            }
            
            // done
            g_Reflector.ReleaseClients();
            
            
        }
        else if ( IsValidDisconnectPacket(Buffer, &Callsign) )
        {
            std::cout << "XLX disconnect packet from " << Callsign << " at " << Ip << std::endl;
            
            // find client & remove it
            CClients *clients = g_Reflector.GetClients();
            CClient *client = clients->FindClient(Callsign, Ip, PROTOCOL_XLX);
            if ( client != NULL )
            {
                clients->RemoveClient(client);
            }
            g_Reflector.ReleaseClients();
        }
        else if ( IsValidNackPacket(Buffer, &Callsign) )
        {
            std::cout << "XLX nack packet from " << Callsign << " at " << Ip << std::endl;
        }
        else if ( IsValidKeepAlivePacket(Buffer, &Callsign) )
        {
            //std::cout << "XLX keepalive packet from " << Callsign << " at " << Ip << std::endl;
            
            // find client & keep it alive
            CClient *GetClient(const CCallsign &, const CIp &, char, int);
            
            CClient *client = g_Reflector.GetClients()->FindClient(Callsign, Ip, PROTOCOL_XLX);
            if ( client != NULL )
            {
                client->Alive();
            }
            g_Reflector.ReleaseClients();
        }
        else
        {
            std::cout << "XLX packet (" << Buffer.size() << ")" << std::endl;
        }
    }
    
    // handle end of streaming timeout
    CheckStreamsTimeout();
    
    // handle queue from reflector
    HandleQueue();
    
    // keep alive
    if ( m_LastKeepaliveTime.DurationSinceNow() > XLX_KEEPALIVE_PERIOD )
    {
        // handle keep alives
        HandleKeepalives();
        
        // handle remote peers connections
        HandlePeerLinks();
        
        // update time
        m_LastKeepaliveTime.Now();
    }
}

////////////////////////////////////////////////////////////////////////////////////////
// queue helper

void CXlxProtocol::HandleQueue(void)
{
    m_Queue.Lock();
    while ( !m_Queue.empty() )
    {
        // get the packet
        CPacket *packet = m_Queue.front();
        m_Queue.pop();
        
        // check if origin of packet is local
        // if not, do not stream it out as it will cause
        // network loop between linked XLX peers
        if ( packet->IsLocalOrigin() )
        {
            // encode it
            CBuffer buffer;
            if ( EncodeDvPacket(*packet, &buffer) )
            {
                // and push it to all our clients linked to the module and who are not streaming in
                CClients *clients = g_Reflector.GetClients();
                int index = -1;
                CClient *client = NULL;
                while ( (client = clients->FindNextClient(PROTOCOL_XLX, &index)) != NULL )
                {
                    // is this client busy ?
                    // here check that origin module of the stream is listed in client xlx
                    // TODO: and check that client of origin is not another XLX to avoid loops
                    if ( !client->IsAMaster() && client->HasThisReflectorModule(packet->GetModuleId()) )
                    {
                        // no, send the packet
                        m_Socket.Send(buffer, client->GetIp());
                        
                    }
                }
                g_Reflector.ReleaseClients();
            }
        }
        
        // done
        delete packet;
    }
    m_Queue.Unlock();
}

////////////////////////////////////////////////////////////////////////////////////////
// keepalive helpers

void CXlxProtocol::HandleKeepalives(void)
{
    // DExtra protocol sends and monitors keepalives packets
    // event if the client is currently streaming
    // so, send keepalives to all
    CBuffer keepalive;
    EncodeKeepAlivePacket(&keepalive);
    
    // iterate on clients
    CClients *clients = g_Reflector.GetClients();
    int index = -1;
    CClient *client = NULL;
    while ( (client = clients->FindNextClient(PROTOCOL_XLX, &index)) != NULL )
    {
        // send keepalive
        m_Socket.Send(keepalive, client->GetIp());
        
        // client busy ?
        if ( client->IsAMaster() )
        {
            // yes, just tickle it
            client->Alive();
        }
        // otherwise check if still with us
        else if ( !client->IsAlive() )
        {
            // no, disconnect
            CBuffer disconnect;
            EncodeDisconnectPacket(&disconnect);
            m_Socket.Send(disconnect, client->GetIp());
            
            // remove it
            std::cout << "XLX peer " << client->GetCallsign() << " keepalive timeout" << std::endl;
            clients->RemoveClient(client);
        }
        
    }
    g_Reflector.ReleaseClients();
}

////////////////////////////////////////////////////////////////////////////////////////
// Peers helpers

void CXlxProtocol::HandlePeerLinks(void)
{
    CBuffer buffer;
    
    // get the list of peers
    CPeerCallsignList *list = g_GateKeeper.GetPeerList();
    // todo: analyse possibility of double-lock hang-up
    CClients *clients = g_Reflector.GetClients();

    // check if all our connected client are still listed by gatekeeper
    // if not, disconnect
    int index = -1;
    CClient *client = NULL;
    while ( (client = clients->FindNextClient(PROTOCOL_XLX, &index)) != NULL )
    {
        if ( list->FindListItem(client->GetCallsign()) == NULL )
        {
            // send disconnect packet
            EncodeDisconnectPacket(&buffer);
            m_Socket.Send(buffer, client->GetIp());
            std::cout << "Sending disconnect packet to XLX peer " << client->GetCallsign() << std::endl;
            // remove client
            clients->RemoveClient(client);
        }
    }
    
    // check if all ours peers listed by gatekeeper are connected
    // if not, connect or reconnect
    for ( int i = 0; i < list->size(); i++ )
    {
        CCallsignListItem *item = &((list->data())[i]);
        if ( clients->FindClient(item->GetCallsign(), PROTOCOL_XLX) == NULL )
        {
            // send connect packet to re-initiate peer link
            EncodeConnectPacket(&buffer, item->GetModules());
            m_Socket.Send(buffer, item->GetIp(), XLX_PORT);
            std::cout << "Sending connect packet to XLX peer " << item->GetCallsign() << " @ " << item->GetIp() << " for modules " << item->GetModules() << std::endl;
        }
    }
    
    // done
    g_Reflector.ReleaseClients();
    g_GateKeeper.ReleasePeerList();
}


////////////////////////////////////////////////////////////////////////////////////////
// streams helpers

bool CXlxProtocol::OnDvHeaderPacketIn(CDvHeaderPacket *Header, const CIp &Ip)
{
    bool newstream = false;
    CCallsign peer;
    
    // todo: verify Packet.GetModuleId() is in authorized list of XLX of origin
    // todo: do the same for DVFrame and DVLAstFrame packets

    // tag packet as remote peer origin
    Header->SetRemotePeerOrigin();
    
    // find the stream
    CPacketStream *stream = GetStream(Header->GetStreamId());
    if ( stream == NULL )
    {
        // no stream open yet, open a new one
        // find this client
        CClient *client = g_Reflector.GetClients()->FindClient(Ip, PROTOCOL_XLX);
        if ( client != NULL )
        {
            // and try to open the stream
            if ( (stream = g_Reflector.OpenStream(Header, client)) != NULL )
            {
                // keep the handle
                m_Streams.push_back(stream);
                newstream = true;
            }
            // get origin
            peer = client->GetCallsign();
        }
        // release
        g_Reflector.ReleaseClients();
    }
    else
    {
        // stream already open
        // skip packet, but tickle the stream
        stream->Tickle();
    }
    
    // update last heard
    g_Reflector.GetUsers()->Hearing(Header->GetMyCallsign(), Header->GetRpt1Callsign(), peer);
    g_Reflector.ReleaseUsers();
    
    // done
    return newstream;
}

void CXlxProtocol::OnDvFramePacketIn(CDvFramePacket *DvFrame)
{
    // tag packet as remote peer origin
    DvFrame->SetRemotePeerOrigin();
    
    // anc call base class
    CDextraProtocol::OnDvFramePacketIn(DvFrame);
}

void CXlxProtocol::OnDvLastFramePacketIn(CDvLastFramePacket *DvFrame)
{
    // tag packet as remote peer origin
    DvFrame->SetRemotePeerOrigin();
    
    // anc call base class
    CDextraProtocol::OnDvLastFramePacketIn(DvFrame);
}


////////////////////////////////////////////////////////////////////////////////////////
// packet decoding helpers

bool CXlxProtocol::IsValidKeepAlivePacket(const CBuffer &Buffer, CCallsign *callsign)
{
    bool valid = false;
    if (Buffer.size() == 9)
    {
        callsign->SetCallsign(Buffer.data(), 8);
        valid = callsign->IsValid();
    }
    return valid;
}


bool CXlxProtocol::IsValidConnectPacket(const CBuffer &Buffer, CCallsign *callsign, char *modules)
{
    bool valid = false;
    if ((Buffer.size() == 39) && (Buffer.data()[0] == 'L') && (Buffer.data()[38] == 0))
    {
        callsign->SetCallsign((const uint8 *)&(Buffer.data()[1]), 8);
        ::strcpy(modules, (const char *)&(Buffer.data()[12]));
        valid = callsign->IsValid();
        for ( int i = 0; i < ::strlen(modules); i++ )
        {
            valid &= IsLetter(modules[i]);
        }
    }
    return valid;
}

bool CXlxProtocol::IsValidDisconnectPacket(const CBuffer &Buffer, CCallsign *callsign)
{
    bool valid = false;
    if ((Buffer.size() == 10) && (Buffer.data()[0] == 'U') && (Buffer.data()[9] == 0))
    {
        callsign->SetCallsign((const uint8 *)&(Buffer.data()[1]), 8);
        valid = callsign->IsValid();
    }
    return valid;
}

bool CXlxProtocol::IsValidAckPacket(const CBuffer &Buffer, CCallsign *callsign, char *modules)
{
    bool valid = false;
    if ((Buffer.size() == 39) && (Buffer.data()[0] == 'A') && (Buffer.data()[38] == 0))
    {
        callsign->SetCallsign((const uint8 *)&(Buffer.data()[1]), 8);
        ::strcpy(modules, (const char *)&(Buffer.data()[12]));
        valid = callsign->IsValid();
        for ( int i = 0; i < ::strlen(modules); i++ )
        {
            valid &= IsLetter(modules[i]);
        }
    }
    return valid;
}

bool CXlxProtocol::IsValidNackPacket(const CBuffer &Buffer, CCallsign *callsign)
{
    bool valid = false;
    if ((Buffer.size() == 10) && (Buffer.data()[0] == 'N') && (Buffer.data()[9] == 0))
    {
        callsign->SetCallsign((const uint8 *)&(Buffer.data()[1]), 8);
        valid = callsign->IsValid();
    }
    return valid;
}

////////////////////////////////////////////////////////////////////////////////////////
// packet encoding helpers

void CXlxProtocol::EncodeKeepAlivePacket(CBuffer *Buffer)
{
    Buffer->Set(GetReflectorCallsign());
}

void CXlxProtocol::EncodeConnectPacket(CBuffer *Buffer, const char *Modules)
{
    uint8 tag[] = { 'L' };
    
    // tag
    Buffer->Set(tag, sizeof(tag));
    // our callsign
    Buffer->resize(Buffer->size()+8);
    g_Reflector.GetCallsign().GetCallsign(Buffer->data()+1);
    // our version
    Buffer->Append((uint8)VERSION_MAJOR);
    Buffer->Append((uint8)VERSION_MINOR);
    Buffer->Append((uint8)VERSION_REVISION);
    // the modules we share
    Buffer->Append(Modules);
    Buffer->resize(39);
}

void CXlxProtocol::EncodeDisconnectPacket(CBuffer *Buffer)
{
    uint8 tag[] = { 'U' };
    
    // tag
    Buffer->Set(tag, sizeof(tag));
    // our callsign
    Buffer->resize(Buffer->size()+8);
    g_Reflector.GetCallsign().GetCallsign(Buffer->data()+1);
    Buffer->Append((uint8)0);
}

void CXlxProtocol::EncodeConnectAckPacket(CBuffer *Buffer, const char *Modules)
{
    uint8 tag[] = { 'A' };
    
    // tag
    Buffer->Set(tag, sizeof(tag));
    // our callsign
    Buffer->resize(Buffer->size()+8);
    g_Reflector.GetCallsign().GetCallsign(Buffer->data()+1);
    // our version
    Buffer->Append((uint8)VERSION_MAJOR);
    Buffer->Append((uint8)VERSION_MINOR);
    Buffer->Append((uint8)VERSION_REVISION);
    // the modules we share
    Buffer->Append(Modules);
    Buffer->resize(39);
}

void CXlxProtocol::EncodeConnectNackPacket(CBuffer *Buffer)
{
    uint8 tag[] = { 'N' };
    
    // tag
    Buffer->Set(tag, sizeof(tag));
    // our callsign
    Buffer->resize(Buffer->size()+8);
    g_Reflector.GetCallsign().GetCallsign(Buffer->data()+1);
    Buffer->Append((uint8)0);
}