/*
* Copyright (C) 2008-2016 TrinityCore <http://www.trinitycore.org/>
* Copyright (C) 2005-2009 MaNGOS <http://getmangos.com/>
*
* 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, see <http://www.gnu.org/licenses/>.
*/

#include "WorldSocket.h"
#include "BigNumber.h"
#include "Opcodes.h"
#include "ScriptMgr.h"
#include "SHA1.h"
#include "PacketLog.h"

#include <memory>

class EncryptablePacket : public WorldPacket
{
public:
    EncryptablePacket(WorldPacket const& packet, bool encrypt) : WorldPacket(packet), _encrypt(encrypt) { }

    bool NeedsEncryption() const { return _encrypt; }

private:
    bool _encrypt;
};

using boost::asio::ip::tcp;

WorldSocket::WorldSocket(tcp::socket&& socket)
    : Socket(std::move(socket)), _authSeed(rand32()), _OverSpeedPings(0), _worldSession(nullptr), _authed(false)
{
    _headerBuffer.Resize(sizeof(ClientPktHeader));
}

void WorldSocket::Start()
{
    std::string ip_address = GetRemoteIpAddress().to_string();
    PreparedStatement* stmt = LoginDatabase.GetPreparedStatement(LOGIN_SEL_IP_INFO);
    stmt->setString(0, ip_address);
    stmt->setUInt32(1, inet_addr(ip_address.c_str()));

    _queryCallback = std::bind(&WorldSocket::CheckIpCallback, this, std::placeholders::_1);
    _queryFuture = LoginDatabase.AsyncQuery(stmt);
}

void WorldSocket::CheckIpCallback(PreparedQueryResult result)
{
    if (result)
    {
        bool banned = false;
        do
        {
            Field* fields = result->Fetch();
            if (fields[0].GetUInt64() != 0)
                banned = true;

            if (!fields[1].GetString().empty())
                _ipCountry = fields[1].GetString();

        } while (result->NextRow());

        if (banned)
        {
            SendAuthResponseError(AUTH_REJECT);
            TC_LOG_ERROR("network", "WorldSocket::CheckIpCallback: Sent Auth Response (IP %s banned).", GetRemoteIpAddress().to_string().c_str());
            DelayedCloseSocket();
            return;
        }
    }

    AsyncRead();
    HandleSendAuthSession();
}

bool WorldSocket::Update()
{
    EncryptablePacket* queued;
    MessageBuffer buffer;
    while (_bufferQueue.Dequeue(queued))
    {
        ServerPktHeader header(queued->size() + 2, queued->GetOpcode());
        if (queued->NeedsEncryption())
            _authCrypt.EncryptSend(header.header, header.getHeaderLength());

        if (buffer.GetRemainingSpace() < queued->size() + header.getHeaderLength())
        {
            QueuePacket(std::move(buffer));
            buffer.Resize(4096);
        }

        if (buffer.GetRemainingSpace() >= queued->size() + header.getHeaderLength())
        {
            buffer.Write(header.header, header.getHeaderLength());
            if (!queued->empty())
                buffer.Write(queued->contents(), queued->size());
        }
        else    // single packet larger than 4096 bytes
        {
            MessageBuffer packetBuffer(queued->size() + header.getHeaderLength());
            packetBuffer.Write(header.header, header.getHeaderLength());
            if (!queued->empty())
                packetBuffer.Write(queued->contents(), queued->size());

            QueuePacket(std::move(packetBuffer));
        }

        delete queued;
    }

    if (buffer.GetActiveSize() > 0)
        QueuePacket(std::move(buffer));

    if (!BaseSocket::Update())
        return false;

    if (_queryFuture.valid() && _queryFuture.wait_for(std::chrono::seconds(0)) == std::future_status::ready)
    {
        auto callback = _queryCallback;
        _queryCallback = nullptr;
        callback(_queryFuture.get());
    }

    return true;
}

void WorldSocket::HandleSendAuthSession()
{
    WorldPacket packet(SMSG_AUTH_CHALLENGE, 37);
    packet << uint32(1);                                    // 1...31
    packet << uint32(_authSeed);

    BigNumber seed1;
    seed1.SetRand(16 * 8);
    packet.append(seed1.AsByteArray(16).get(), 16);               // new encryption seeds

    BigNumber seed2;
    seed2.SetRand(16 * 8);
    packet.append(seed2.AsByteArray(16).get(), 16);               // new encryption seeds

    SendPacketAndLogOpcode(packet);
}

void WorldSocket::OnClose()
{
    {
        std::lock_guard<std::mutex> sessionGuard(_worldSessionLock);
        _worldSession = nullptr;
    }
}

void WorldSocket::ReadHandler()
{
    if (!IsOpen())
        return;

    MessageBuffer& packet = GetReadBuffer();
    while (packet.GetActiveSize() > 0)
    {
        if (_headerBuffer.GetRemainingSpace() > 0)
        {
            // need to receive the header
            std::size_t readHeaderSize = std::min(packet.GetActiveSize(), _headerBuffer.GetRemainingSpace());
            _headerBuffer.Write(packet.GetReadPointer(), readHeaderSize);
            packet.ReadCompleted(readHeaderSize);

            if (_headerBuffer.GetRemainingSpace() > 0)
            {
                // Couldn't receive the whole header this time.
                ASSERT(packet.GetActiveSize() == 0);
                break;
            }

            // We just received nice new header
            if (!ReadHeaderHandler())
            {
                CloseSocket();
                return;
            }
        }

        // We have full read header, now check the data payload
        if (_packetBuffer.GetRemainingSpace() > 0)
        {
            // need more data in the payload
            std::size_t readDataSize = std::min(packet.GetActiveSize(), _packetBuffer.GetRemainingSpace());
            _packetBuffer.Write(packet.GetReadPointer(), readDataSize);
            packet.ReadCompleted(readDataSize);

            if (_packetBuffer.GetRemainingSpace() > 0)
            {
                // Couldn't receive the whole data this time.
                ASSERT(packet.GetActiveSize() == 0);
                break;
            }
        }

        // just received fresh new payload
        ReadDataHandlerResult result = ReadDataHandler();
        _headerBuffer.Reset();
        if (result != ReadDataHandlerResult::Ok)
        {
            if (result != ReadDataHandlerResult::WaitingForQuery)
                CloseSocket();

            return;
        }
    }

    AsyncRead();
}

bool WorldSocket::ReadHeaderHandler()
{
    ASSERT(_headerBuffer.GetActiveSize() == sizeof(ClientPktHeader));

    _authCrypt.DecryptRecv(_headerBuffer.GetReadPointer(), sizeof(ClientPktHeader));

    ClientPktHeader* header = reinterpret_cast<ClientPktHeader*>(_headerBuffer.GetReadPointer());
    EndianConvertReverse(header->size);
    EndianConvert(header->cmd);

    if (!header->IsValidSize() || !header->IsValidOpcode())
    {
        TC_LOG_ERROR("network", "WorldSocket::ReadHeaderHandler(): client %s sent malformed packet (size: %hu, cmd: %u)",
            GetRemoteIpAddress().to_string().c_str(), header->size, header->cmd);
        return false;
    }

    header->size -= sizeof(header->cmd);
    _packetBuffer.Resize(header->size);
    return true;
}

struct AuthSession
{
    uint32 BattlegroupID = 0;
    uint32 LoginServerType = 0;
    uint32 RealmID = 0;
    uint32 Build = 0;
    uint32 LocalChallenge = 0;
    uint32 LoginServerID = 0;
    uint32 RegionID = 0;
    uint64 DosResponse = 0;
    uint8 Digest[SHA_DIGEST_LENGTH] = {};
    std::string Account;
    ByteBuffer AddonInfo;
};

struct AccountInfo
{
    uint32 Id;
    BigNumber SessionKey;
    std::string LastIP;
    bool IsLockedToIP;
    std::string LockCountry;
    uint8 Expansion;
    int64 MuteTime;
    LocaleConstant Locale;
    uint32 Recruiter;
    std::string OS;
    bool IsRectuiter;
    AccountTypes Security;
    bool IsBanned;

    explicit AccountInfo(Field* fields)
    {
        //           0             1          2         3               4            5           6         7            8     9         10
        // SELECT a.id, a.sessionkey, a.last_ip, a.locked, a.lock_country, a.expansion, a.mutetime, a.locale, a.recruiter, a.os, aa.gmLevel,
        //                                                           11    12
        // ab.unbandate > UNIX_TIMESTAMP() OR ab.unbandate = ab.bandate, r.id
        // FROM account a
        // LEFT JOIN account_access aa ON a.id = aa.id AND aa.RealmID IN (-1, ?)
        // LEFT JOIN account_banned ab ON a.id = ab.id
        // LEFT JOIN account r ON a.id = r.recruiter
        // WHERE a.username = ? ORDER BY aa.RealmID DESC LIMIT 1
        Id = fields[0].GetUInt32();
        SessionKey.SetHexStr(fields[1].GetCString());
        LastIP = fields[2].GetString();
        IsLockedToIP = fields[3].GetBool();
        LockCountry = fields[4].GetString();
        Expansion = fields[5].GetUInt8();
        MuteTime = fields[6].GetInt64();
        Locale = LocaleConstant(fields[7].GetUInt8());
        Recruiter = fields[8].GetUInt32();
        OS = fields[9].GetString();
        Security = AccountTypes(fields[10].GetUInt8());
        IsBanned = fields[11].GetUInt64() != 0;
        IsRectuiter = fields[12].GetUInt32() != 0;

        uint32 world_expansion = sWorld->getIntConfig(CONFIG_EXPANSION);
        if (Expansion > world_expansion)
            Expansion = world_expansion;

        if (Locale >= TOTAL_LOCALES)
            Locale = LOCALE_enUS;
    }
};

WorldSocket::ReadDataHandlerResult WorldSocket::ReadDataHandler()
{
    ClientPktHeader* header = reinterpret_cast<ClientPktHeader*>(_headerBuffer.GetReadPointer());

    uint16 opcode = uint16(header->cmd);

    WorldPacket packet(opcode, std::move(_packetBuffer));

    if (sPacketLog->CanLogPacket())
        sPacketLog->LogPacket(packet, CLIENT_TO_SERVER, GetRemoteIpAddress(), GetRemotePort());

    std::unique_lock<std::mutex> sessionGuard(_worldSessionLock, std::defer_lock);

    switch (opcode)
    {
        case CMSG_PING:
            LogOpcodeText(opcode, sessionGuard);
            return HandlePing(packet) ? ReadDataHandlerResult::Ok : ReadDataHandlerResult::Error;
        case CMSG_AUTH_SESSION:
            LogOpcodeText(opcode, sessionGuard);
            if (_authed)
            {
                // locking just to safely log offending user is probably overkill but we are disconnecting him anyway
                if (sessionGuard.try_lock())
                    TC_LOG_ERROR("network", "WorldSocket::ProcessIncoming: received duplicate CMSG_AUTH_SESSION from %s", _worldSession->GetPlayerInfo().c_str());
                return ReadDataHandlerResult::Error;
            }

            HandleAuthSession(packet);
            return ReadDataHandlerResult::WaitingForQuery;
        case CMSG_KEEP_ALIVE:
            LogOpcodeText(opcode, sessionGuard);
            break;
        default:
        {
            sessionGuard.lock();

            LogOpcodeText(opcode, sessionGuard);

            if (!_worldSession)
            {
                TC_LOG_ERROR("network.opcode", "ProcessIncoming: Client not authed opcode = %u", uint32(opcode));
                return ReadDataHandlerResult::Error;
            }

            // Our Idle timer will reset on any non PING opcodes.
            // Catches people idling on the login screen and any lingering ingame connections.
            _worldSession->ResetTimeOutTime();

            // Copy the packet to the heap before enqueuing
            _worldSession->QueuePacket(new WorldPacket(std::move(packet)));
            break;
        }
    }

    return ReadDataHandlerResult::Ok;
}

void WorldSocket::LogOpcodeText(uint16 opcode, std::unique_lock<std::mutex> const& guard) const
{
    if (!guard)
    {
        TC_LOG_TRACE("network.opcode", "C->S: %s %s", GetRemoteIpAddress().to_string().c_str(), GetOpcodeNameForLogging(opcode).c_str());
    }
    else
    {
        TC_LOG_TRACE("network.opcode", "C->S: %s %s", (_worldSession ? _worldSession->GetPlayerInfo() : GetRemoteIpAddress().to_string()).c_str(),
            GetOpcodeNameForLogging(opcode).c_str());
    }
}

void WorldSocket::SendPacketAndLogOpcode(WorldPacket const& packet)
{
    TC_LOG_TRACE("network.opcode", "S->C: %s %s", GetRemoteIpAddress().to_string().c_str(), GetOpcodeNameForLogging(packet.GetOpcode()).c_str());
    SendPacket(packet);
}

void WorldSocket::SendPacket(WorldPacket const& packet)
{
    if (!IsOpen())
        return;

    if (sPacketLog->CanLogPacket())
        sPacketLog->LogPacket(packet, SERVER_TO_CLIENT, GetRemoteIpAddress(), GetRemotePort());

    _bufferQueue.Enqueue(new EncryptablePacket(packet, _authCrypt.IsInitialized()));
}

void WorldSocket::HandleAuthSession(WorldPacket& recvPacket)
{
    std::shared_ptr<AuthSession> authSession = std::make_shared<AuthSession>();

    // Read the content of the packet
    recvPacket >> authSession->Build;
    recvPacket >> authSession->LoginServerID;
    recvPacket >> authSession->Account;
    recvPacket >> authSession->LoginServerType;
    recvPacket >> authSession->LocalChallenge;
    recvPacket >> authSession->RegionID;
    recvPacket >> authSession->BattlegroupID;
    recvPacket >> authSession->RealmID;               // realmId from auth_database.realmlist table
    recvPacket >> authSession->DosResponse;
    recvPacket.read(authSession->Digest, 20);
    authSession->AddonInfo.append(recvPacket.contents() + recvPacket.rpos(), recvPacket.size() - recvPacket.rpos());

    // Get the account information from the auth database
    PreparedStatement* stmt = LoginDatabase.GetPreparedStatement(LOGIN_SEL_ACCOUNT_INFO_BY_NAME);
    stmt->setInt32(0, int32(realm.Id.Realm));
    stmt->setString(1, authSession->Account);

    _queryCallback = std::bind(&WorldSocket::HandleAuthSessionCallback, this, authSession, std::placeholders::_1);
    _queryFuture = LoginDatabase.AsyncQuery(stmt);
}

void WorldSocket::HandleAuthSessionCallback(std::shared_ptr<AuthSession> authSession, PreparedQueryResult result)
{
    // Stop if the account is not found
    if (!result)
    {
        // We can not log here, as we do not know the account. Thus, no accountId.
        SendAuthResponseError(AUTH_UNKNOWN_ACCOUNT);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: Sent Auth Response (unknown account).");
        DelayedCloseSocket();
        return;
    }

    AccountInfo account(result->Fetch());

    // For hook purposes, we get Remoteaddress at this point.
    std::string address = GetRemoteIpAddress().to_string();

    // As we don't know if attempted login process by ip works, we update last_attempt_ip right away
    PreparedStatement* stmt = LoginDatabase.GetPreparedStatement(LOGIN_UPD_LAST_ATTEMPT_IP);
    stmt->setString(0, address);
    stmt->setString(1, authSession->Account);
    LoginDatabase.Execute(stmt);
    // This also allows to check for possible "hack" attempts on account

    // even if auth credentials are bad, try using the session key we have - client cannot read auth response error without it
    _authCrypt.Init(&account.SessionKey);

    // First reject the connection if packet contains invalid data or realm state doesn't allow logging in
    if (sWorld->IsClosed())
    {
        SendAuthResponseError(AUTH_REJECT);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: World closed, denying client (%s).", GetRemoteIpAddress().to_string().c_str());
        DelayedCloseSocket();
        return;
    }

    if (authSession->RealmID != realm.Id.Realm)
    {
        SendAuthResponseError(REALM_LIST_REALM_NOT_FOUND);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: Client %s requested connecting with realm id %u but this realm has id %u set in config.",
            GetRemoteIpAddress().to_string().c_str(), authSession->RealmID, realm.Id.Realm);
        DelayedCloseSocket();
        return;
    }

    // Must be done before WorldSession is created
    bool wardenActive = sWorld->getBoolConfig(CONFIG_WARDEN_ENABLED);
    if (wardenActive && account.OS != "Win" && account.OS != "OSX")
    {
        SendAuthResponseError(AUTH_REJECT);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: Client %s attempted to log in using invalid client OS (%s).", address.c_str(), account.OS.c_str());
        DelayedCloseSocket();
        return;
    }

    // Check that Key and account name are the same on client and server
    uint32 t = 0;

    SHA1Hash sha;
    sha.UpdateData(authSession->Account);
    sha.UpdateData((uint8*)&t, 4);
    sha.UpdateData((uint8*)&authSession->LocalChallenge, 4);
    sha.UpdateData((uint8*)&_authSeed, 4);
    sha.UpdateBigNumbers(&account.SessionKey, NULL);
    sha.Finalize();

    if (memcmp(sha.GetDigest(), authSession->Digest, SHA_DIGEST_LENGTH) != 0)
    {
        SendAuthResponseError(AUTH_FAILED);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: Authentication failed for account: %u ('%s') address: %s", account.Id, authSession->Account.c_str(), address.c_str());
        DelayedCloseSocket();
        return;
    }

    ///- Re-check ip locking (same check as in auth).
    if (account.IsLockedToIP)
    {
        if (account.LastIP != address)
        {
            SendAuthResponseError(AUTH_FAILED);
            TC_LOG_DEBUG("network", "WorldSocket::HandleAuthSession: Sent Auth Response (Account IP differs. Original IP: %s, new IP: %s).", account.LastIP.c_str(), address.c_str());
            // We could log on hook only instead of an additional db log, however action logger is config based. Better keep DB logging as well
            sScriptMgr->OnFailedAccountLogin(account.Id);
            DelayedCloseSocket();
            return;
        }
    }
    else if (!account.LockCountry.empty() && account.LockCountry != "00" && !_ipCountry.empty())
    {
        if (account.LockCountry != _ipCountry)
        {
            SendAuthResponseError(AUTH_FAILED);
            TC_LOG_DEBUG("network", "WorldSocket::HandleAuthSession: Sent Auth Response (Account country differs. Original country: %s, new country: %s).", account.LockCountry.c_str(), _ipCountry.c_str());
            // We could log on hook only instead of an additional db log, however action logger is config based. Better keep DB logging as well
            sScriptMgr->OnFailedAccountLogin(account.Id);
            DelayedCloseSocket();
            return;
        }
    }

    int64 mutetime = account.MuteTime;
    //! Negative mutetime indicates amount of seconds to be muted effective on next login - which is now.
    if (mutetime < 0)
    {
        mutetime = time(NULL) + llabs(mutetime);

        PreparedStatement* stmt = LoginDatabase.GetPreparedStatement(LOGIN_UPD_MUTE_TIME_LOGIN);
        stmt->setInt64(0, mutetime);
        stmt->setUInt32(1, account.Id);
        LoginDatabase.Execute(stmt);
    }

    if (account.IsBanned)
    {
        SendAuthResponseError(AUTH_BANNED);
        TC_LOG_ERROR("network", "WorldSocket::HandleAuthSession: Sent Auth Response (Account banned).");
        sScriptMgr->OnFailedAccountLogin(account.Id);
        DelayedCloseSocket();
        return;
    }

    // Check locked state for server
    AccountTypes allowedAccountType = sWorld->GetPlayerSecurityLimit();
    TC_LOG_DEBUG("network", "Allowed Level: %u Player Level %u", allowedAccountType, account.Security);
    if (allowedAccountType > SEC_PLAYER && account.Security < allowedAccountType)
    {
        SendAuthResponseError(AUTH_UNAVAILABLE);
        TC_LOG_DEBUG("network", "WorldSocket::HandleAuthSession: User tries to login but his security level is not enough");
        sScriptMgr->OnFailedAccountLogin(account.Id);
        DelayedCloseSocket();
        return;
    }

    TC_LOG_DEBUG("network", "WorldSocket::HandleAuthSession: Client '%s' authenticated successfully from %s.", authSession->Account.c_str(), address.c_str());

    // Update the last_ip in the database as it was successful for login
    stmt = LoginDatabase.GetPreparedStatement(LOGIN_UPD_LAST_IP);

    stmt->setString(0, address);
    stmt->setString(1, authSession->Account);

    LoginDatabase.Execute(stmt);

    // At this point, we can safely hook a successful login
    sScriptMgr->OnAccountLogin(account.Id);

    _authed = true;
    _worldSession = new WorldSession(account.Id, std::move(authSession->Account), shared_from_this(), account.Security,
        account.Expansion, mutetime, account.Locale, account.Recruiter, account.IsRectuiter);
    _worldSession->ReadAddonsInfo(authSession->AddonInfo);

    // Initialize Warden system only if it is enabled by config
    if (wardenActive)
        _worldSession->InitWarden(&account.SessionKey, account.OS);

    _queryCallback = std::bind(&WorldSocket::LoadSessionPermissionsCallback, this, std::placeholders::_1);
    _queryFuture = _worldSession->LoadPermissionsAsync();
    AsyncRead();
}

void WorldSocket::LoadSessionPermissionsCallback(PreparedQueryResult result)
{
    // RBAC must be loaded before adding session to check for skip queue permission
    _worldSession->GetRBACData()->LoadFromDBCallback(result);

    sWorld->AddSession(_worldSession);
}

void WorldSocket::SendAuthResponseError(uint8 code)
{
    WorldPacket packet(SMSG_AUTH_RESPONSE, 1);
    packet << uint8(code);

    SendPacketAndLogOpcode(packet);
}

bool WorldSocket::HandlePing(WorldPacket& recvPacket)
{
    using namespace std::chrono;

    uint32 ping;
    uint32 latency;

    // Get the ping packet content
    recvPacket >> ping;
    recvPacket >> latency;

    if (_LastPingTime == steady_clock::time_point())
    {
        _LastPingTime = steady_clock::now();
    }
    else
    {
        steady_clock::time_point now = steady_clock::now();

        steady_clock::duration diff = now - _LastPingTime;

        _LastPingTime = now;

        if (diff < seconds(27))
        {
            ++_OverSpeedPings;

            uint32 maxAllowed = sWorld->getIntConfig(CONFIG_MAX_OVERSPEED_PINGS);

            if (maxAllowed && _OverSpeedPings > maxAllowed)
            {
                std::unique_lock<std::mutex> sessionGuard(_worldSessionLock);

                if (_worldSession && !_worldSession->HasPermission(rbac::RBAC_PERM_SKIP_CHECK_OVERSPEED_PING))
                {
                    TC_LOG_ERROR("network", "WorldSocket::HandlePing: %s kicked for over-speed pings (address: %s)",
                        _worldSession->GetPlayerInfo().c_str(), GetRemoteIpAddress().to_string().c_str());

                    return false;
                }
            }
        }
        else
            _OverSpeedPings = 0;
    }

    {
        std::lock_guard<std::mutex> sessionGuard(_worldSessionLock);

        if (_worldSession)
        {
            _worldSession->SetLatency(latency);
            _worldSession->ResetClientTimeDelay();
        }
        else
        {
            TC_LOG_ERROR("network", "WorldSocket::HandlePing: peer sent CMSG_PING, but is not authenticated or got recently kicked, address = %s", GetRemoteIpAddress().to_string().c_str());
            return false;
        }
    }

    WorldPacket packet(SMSG_PONG, 4);
    packet << ping;
    SendPacketAndLogOpcode(packet);
    return true;
}