/*
 *  The Mana Client
 *  Copyright (C) 2004-2009  The Mana World Development Team
 *  Copyright (C) 2009-2012  The Mana Developers
 *
 *  This file is part of The Mana Client.
 *
 *  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
 *  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, see <http://www.gnu.org/licenses/>.
 */

#include "net/tmwa/network.h"

#include "log.h"

#include "net/tmwa/messagein.h"
#include "net/tmwa/protocol.h"

#include "utils/gettext.h"
#include "utils/stringutils.h"

#include <cassert>
#include <sstream>

/** Warning: buffers and other variables are shared,
    so there can be only one connection active at a time */

// indicator for a variable-length packet
const uint16_t VAR = 1;

uint16_t packet_lengths[] = {
   10,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
// #0x0040
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
    0, 50,  3,VAR, 55, 17,  3, 37, 46,VAR, 23,VAR,  3,108,  3,  2,
    3, 28, 19, 11,  3,VAR,  9,  5, 54, 53, 58, 60, 41,  2,  6,  6,
// #0x0080
    7,  3,  2,  2,  2,  5, 16, 12, 10,  7, 29, 23,VAR,VAR,VAR,  0,
    7, 22, 28,  2,  6, 30,VAR,VAR,  3,VAR,VAR,  5,  9, 17, 17,  6,
   23,  6,  6,VAR,VAR,VAR,VAR,  8,  7,  6,  7,  4,  7,  0,VAR,  6,
    8,  8,  3,  3,VAR,  6,  6,VAR,  7,  6,  2,  5,  6, 44,  5,  3,
// #0x00C0
    7,  2,  6,  8,  6,  7,VAR,VAR,VAR,VAR,  3,  3,  6,  6,  2, 27,
    3,  4,  4,  2,VAR,VAR,  3,VAR,  6, 14,  3,VAR, 28, 29,VAR,VAR,
   30, 30, 26,  2,  6, 26,  3,  3,  8, 19,  5,  2,  3,  2,  2,  2,
    3,  2,  6,  8, 21,  8,  8,  2,  2, 26,  3,VAR,  6, 27, 30, 10,
// #0x0100
    2,  6,  6, 30, 79, 31, 10, 10,VAR,VAR,  4,  6,  6,  2, 11,VAR,
   10, 39,  4, 10, 31, 35, 10, 18,  2, 13, 15, 20, 68,  2,  3, 16,
    6, 14,VAR,VAR, 21,  8,  8,  8,  8,  8,  2,  2,  3,  4,  2,VAR,
    6, 86,  6,VAR,VAR,  7,VAR,  6,  3, 16,  4,  4,  4,  6, 24, 26,
// #0x0140
   22, 14,  6, 10, 23, 19,  6, 39,  8,  9,  6, 27,VAR,  2,  6,  6,
  110,  6,VAR,VAR,VAR,VAR,VAR,  6,VAR, 54, 66, 54, 90, 42,  6, 42,
  VAR,VAR,VAR,VAR,VAR, 30,VAR,  3, 14,  3, 30, 10, 43, 14,186,182,
   14, 30, 10,  3,VAR,  6,106,VAR,  4,  5,  4,VAR,  6,  7,VAR,VAR,
// #0x0180
    6,  3,106, 10, 10, 34,  0,  6,  8,  4,  4,  4, 29,VAR, 10,  6,
   90, 86, 24,  6, 30, 102,  9,  4,  8,  4, 14, 10,  4,  6,  2,  6,
    3,  3, 35,  5, 11, 26,VAR,  4,  4,  6, 10, 12,  6,VAR,  4,  4,
   11,  7,VAR, 67, 12, 18,114,  6,  3,  6, 26, 26, 26, 26,  2,  3,
// #0x01C0
    2, 14, 10,VAR, 22, 22,  4,  2, 13, 97,  0,  9,  9, 29,  6, 28,
    8, 14, 10, 35,  6,VAR,  4, 11, 54, 53, 60,  2,VAR, 47, 33,  6,
   30,  8, 34, 14,  2,  6, 26,  2, 28, 81,  6, 10, 26,  2,VAR,VAR,
  VAR,VAR, 20, 10, 32,  9, 34, 14,  2,  6, 48, 56,VAR,  4,  5, 10,
// #0x0200
   26,  0,  0,  0, 18,  0,  0,  0,  0,  0,  0, 19, 10,  0,  0,  0,
    2,VAR, 16,  0,  8,VAR,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
  VAR,122,VAR,VAR,VAR,VAR, 10,  0,  0,  0,  0,  0,  0,  0,  0,  0,
};

static const int packet_lengths_size
     = static_cast<int>(sizeof(packet_lengths) / sizeof(uint16_t));
const unsigned int BUFFER_SIZE = 65536;

namespace TmwAthena {

int networkThread(void *data)
{
    auto *network = static_cast<Network*>(data);

    if (!network->realConnect())
        return -1;

    network->receive();

    return 0;
}

Network *Network::mInstance = nullptr;

Network::Network():
    mSocket(nullptr),
    mInBuffer(new char[BUFFER_SIZE]),
    mOutBuffer(new char[BUFFER_SIZE]),
    mInSize(0), mOutSize(0),
    mToSkip(0),
    mState(IDLE),
    mWorkerThread(nullptr)
{
    SDLNet_Init();

    mInstance = this;
}

Network::~Network()
{
    clearHandlers();

    if (mState != IDLE && mState != NET_ERROR)
        disconnect();

    mInstance = nullptr;

    delete[] mInBuffer;
    delete[] mOutBuffer;

    SDLNet_Quit();
}

bool Network::connect(const ServerInfo &server)
{
    if (mState != IDLE && mState != NET_ERROR)
    {
        logger->log("Tried to connect an already connected socket!");
        assert(false);
        return false;
    }

    if (server.hostname.empty())
    {
        setError(_("Empty address given to Network::connect()!"));
        return false;
    }

    logger->log("Network::Connecting to %s:%i", server.hostname.c_str(),
                                                server.port);

    mServer.hostname = server.hostname;
    mServer.port = server.port;

    // Reset to sane values
    mOutSize = 0;
    mInSize = 0;
    mToSkip = 0;

    mState = CONNECTING;
    mWorkerThread = SDL_CreateThread(networkThread, "Network", this);
    if (!mWorkerThread)
    {
        setError("Unable to create network worker thread");
        return false;
    }

    return true;
}

void Network::disconnect()
{
    mState = IDLE;

    if (mWorkerThread)
    {
        SDL_WaitThread(mWorkerThread, nullptr);
        mWorkerThread = nullptr;
    }

    if (mSocket)
    {
        SDLNet_TCP_Close(mSocket);
        mSocket = nullptr;
    }
}

void Network::registerHandler(MessageHandler *handler)
{
    for (const Uint16 *i = handler->handledMessages; *i; ++i)
    {
        mMessageHandlers[*i] = handler;
    }

    handler->setNetwork(this);
}

void Network::unregisterHandler(MessageHandler *handler)
{
    for (const Uint16 *i = handler->handledMessages; *i; ++i)
    {
        mMessageHandlers.erase(*i);
    }

    handler->setNetwork(nullptr);
}

void Network::clearHandlers()
{
    MessageHandlerIterator i;
    for (i = mMessageHandlers.begin(); i != mMessageHandlers.end(); ++i)
    {
        i->second->setNetwork(nullptr);
    }
    mMessageHandlers.clear();
}

void Network::dispatchMessages()
{
    while (messageReady())
    {
        MessageIn msg = getNextMessage();

        auto iter = mMessageHandlers.find(msg.getId());

        if (msg.getLength() == 0)
            logger->error("Zero length packet received. Exiting.");

        if (iter != mMessageHandlers.end())
        {
            iter->second->handleMessage(msg);
        }
        else
        {
            logger->log("Unhandled packet: %x", msg.getId());
        }

        skip(msg.getLength());
    }
}

void Network::flush()
{
    if (!mOutSize || mState != CONNECTED)
        return;

    int ret;

    MutexLocker lock(&mMutex);
    ret = SDLNet_TCP_Send(mSocket, mOutBuffer, mOutSize);
    if (ret < (int)mOutSize)
    {
        setError("Error in SDLNet_TCP_Send(): " +
                 std::string(SDLNet_GetError()));
    }
    mOutSize = 0;
}

void Network::skip(int len)
{
    MutexLocker lock(&mMutex);
    mToSkip += len;
    if (!mInSize)
        return;

    if (mInSize >= mToSkip)
    {
        mInSize -= mToSkip;
        memmove(mInBuffer, mInBuffer + mToSkip, mInSize);
        mToSkip = 0;
    }
    else
    {
        mToSkip -= mInSize;
        mInSize = 0;
    }
}

bool Network::messageReady()
{
    MutexLocker lock(&mMutex);
    if (mInSize < 2)
        return false;
    uint16_t msgId = readWord(0);
    uint16_t len = 0;
    // TODO don't hard-code this single case
    if (msgId == SMSG_SERVER_VERSION_RESPONSE)
        len = 10;
    else if (msgId < packet_lengths_size)
        len = packet_lengths[msgId];

    if (len == VAR)
    {
        if (mInSize < 4)
            return false;
        len = readWord(2);
    }
    return mInSize >= len;
}

MessageIn Network::getNextMessage()
{
    while (!messageReady())
    {
        if (mState == NET_ERROR)
            break;
    }

    MutexLocker lock(&mMutex);
    uint16_t msgId = readWord(0);
    uint16_t len = 0;
    if (msgId == SMSG_SERVER_VERSION_RESPONSE)
        len = 10;
    else if (msgId < 0x220)
        len = packet_lengths[msgId];

    if (len == VAR)
        len = readWord(2);

#ifdef DEBUG
    logger->log("Received packet 0x%x of length %d", msgId, len);
#endif

    return MessageIn(mInBuffer, len);
}

bool Network::realConnect()
{
    IPaddress ipAddress;

    if (SDLNet_ResolveHost(&ipAddress, mServer.hostname.c_str(),
                           mServer.port) == -1)
    {
        std::string errorMessage = _("Unable to resolve host \"") +
                                   mServer.hostname + "\"";
        setError(errorMessage);
        logger->log("SDLNet_ResolveHost: %s", errorMessage.c_str());
        return false;
    }

    mState = CONNECTING;

    mSocket = SDLNet_TCP_Open(&ipAddress);
    if (!mSocket)
    {
        logger->log("Error in SDLNet_TCP_Open(): %s", SDLNet_GetError());
        setError(SDLNet_GetError());
        return false;
    }

    logger->log("Network::Started session with %s:%i",
                ipToString(ipAddress.host), ipAddress.port);

    mState = CONNECTED;

    return true;
}

void Network::receive()
{
    SDLNet_SocketSet set;

    if (!(set = SDLNet_AllocSocketSet(1)))
    {
        setError("Error in SDLNet_AllocSocketSet(): " +
                 std::string(SDLNet_GetError()));
        return;
    }

    if (SDLNet_TCP_AddSocket(set, mSocket) == -1)
    {
        setError("Error in SDLNet_AddSocket(): " +
                 std::string(SDLNet_GetError()));
    }

    while (mState == CONNECTED)
    {
        // TODO Try to get this to block all the time while still being able
        // to escape the loop
        int numReady = SDLNet_CheckSockets(set, ((Uint32)500));
        int ret;
        switch (numReady)
        {
            case -1:
                logger->log("Error: SDLNet_CheckSockets");
                // FALLTHROUGH
            case 0:
                break;

            case 1:
            {
                // Receive data from the socket
                MutexLocker lock(&mMutex);
                ret = SDLNet_TCP_Recv(mSocket, mInBuffer + mInSize, BUFFER_SIZE - mInSize);

                if (!ret)
                {
                    // We got disconnected
                    mState = IDLE;
                    logger->log("Disconnected.");
                }
                else if (ret < 0)
                {
                    setError(_("Connection to server terminated. ") +
                             std::string(SDLNet_GetError()));
                }
                else
                {
                    mInSize += ret;
                    if (mToSkip)
                    {
                        if (mInSize >= mToSkip)
                        {
                            mInSize -= mToSkip;
                            memmove(mInBuffer, mInBuffer + mToSkip, mInSize);
                            mToSkip = 0;
                        }
                        else
                        {
                            mToSkip -= mInSize;
                            mInSize = 0;
                        }
                    }
                }
                break;
            }

            default:
                // more than one socket is ready..
                // this should not happen since we only listen once socket.
                std::stringstream errorStream;
                errorStream << "Error in SDLNet_TCP_Recv(), " << numReady
                            << " sockets are ready: " << SDLNet_GetError();
                setError(errorStream.str());
                break;
        }
    }

    if (SDLNet_TCP_DelSocket(set, mSocket) == -1)
    {
        logger->log("Error in SDLNet_DelSocket(): %s", SDLNet_GetError());
    }

    SDLNet_FreeSocketSet(set);
}

Network *Network::instance()
{
    return mInstance;
}

void Network::setError(const std::string &error)
{
    logger->log("Network error: %s", error.c_str());
    mError = error;
    mState = NET_ERROR;
}

Uint16 Network::readWord(int pos)
{
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    return SDL_Swap16((*(Uint16*)(mInBuffer+(pos))));
#else
    return (*(Uint16*)(mInBuffer+(pos)));
#endif
}

} // namespace TmwAthena