/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * 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 "WorldSession.h"
#include "Battleground.h"
#include "Corpse.h"
#include "DB2Stores.h"
#include "FlightPathMovementGenerator.h"
#include "GameTime.h"
#include "Garrison.h"
#include "InstancePackets.h"
#include "InstanceSaveMgr.h"
#include "Log.h"
#include "MapManager.h"
#include "MiscPackets.h"
#include "MovementPackets.h"
#include "ObjectMgr.h"
#include "Player.h"
#include "SpellInfo.h"
#include "MotionMaster.h"
#include "MovementGenerator.h"
#include "MoveSpline.h"
#include "Transport.h"
#include "Vehicle.h"
#include "SpellMgr.h"
#include <boost/accumulators/statistics/variance.hpp>
#include <boost/accumulators/accumulators.hpp>
#include <boost/accumulators/statistics.hpp>

void WorldSession::HandleMoveWorldportAckOpcode(WorldPackets::Movement::WorldPortResponse& /*packet*/)
{
    HandleMoveWorldportAck();
}

void WorldSession::HandleMoveWorldportAck()
{
    Player* player = GetPlayer();
    // ignore unexpected far teleports
    if (!player->IsBeingTeleportedFar())
        return;

    bool seamlessTeleport = player->IsBeingTeleportedSeamlessly();
    player->SetSemaphoreTeleportFar(false);

    // get the teleport destination
    WorldLocation const& loc = player->GetTeleportDest();

    // possible errors in the coordinate validity check
    if (!MapManager::IsValidMapCoord(loc))
    {
        LogoutPlayer(false);
        return;
    }

    // get the destination map entry, not the current one, this will fix homebind and reset greeting
    MapEntry const* mEntry = sMapStore.LookupEntry(loc.GetMapId());
    InstanceTemplate const* mInstance = sObjectMgr->GetInstanceTemplate(loc.GetMapId());

    // reset instance validity, except if going to an instance inside an instance
    if (player->m_InstanceValid == false && !mInstance)
        player->m_InstanceValid = true;

    Map* oldMap = player->GetMap();
    Map* newMap = sMapMgr->CreateMap(loc.GetMapId(), player);

    if (player->IsInWorld())
    {
        TC_LOG_ERROR("network", "%s %s is still in world when teleported from map %s (%u) to new map %s (%u)", player->GetGUID().ToString().c_str(), player->GetName().c_str(), oldMap->GetMapName(), oldMap->GetId(), newMap ? newMap->GetMapName() : "Unknown", loc.GetMapId());
        oldMap->RemovePlayerFromMap(player, false);
    }

    // relocate the player to the teleport destination
    // the CannotEnter checks are done in TeleporTo but conditions may change
    // while the player is in transit, for example the map may get full
    if (!newMap || newMap->CannotEnter(player))
    {
        TC_LOG_ERROR("network", "Map %d (%s) could not be created for player %s (%s), porting player to homebind", loc.GetMapId(), newMap ? newMap->GetMapName() : "Unknown", player->GetGUID().ToString().c_str(), player->GetName().c_str());
        player->TeleportTo(player->m_homebind);
        return;
    }

    float z = loc.GetPositionZ() + player->GetHoverOffset();
    player->Relocate(loc.GetPositionX(), loc.GetPositionY(), z, loc.GetOrientation());
    player->SetFallInformation(0, player->GetPositionZ());

    player->ResetMap();
    player->SetMap(newMap);

    WorldPackets::Movement::ResumeToken resumeToken;
    resumeToken.SequenceIndex = player->m_movementCounter;
    resumeToken.Reason = seamlessTeleport ? 2 : 1;
    SendPacket(resumeToken.Write());

    if (!seamlessTeleport)
        player->SendInitialPacketsBeforeAddToMap();

    if (!player->GetMap()->AddPlayerToMap(player, !seamlessTeleport))
    {
        TC_LOG_ERROR("network", "WORLD: failed to teleport player %s %s to map %d (%s) because of unknown reason!",
            player->GetName().c_str(), player->GetGUID().ToString().c_str(), loc.GetMapId(), newMap ? newMap->GetMapName() : "Unknown");
        player->ResetMap();
        player->SetMap(oldMap);
        player->TeleportTo(player->m_homebind);
        return;
    }

    // battleground state prepare (in case join to BG), at relogin/tele player not invited
    // only add to bg group and object, if the player was invited (else he entered through command)
    if (player->InBattleground())
    {
        // cleanup setting if outdated
        if (!mEntry->IsBattlegroundOrArena())
        {
            // We're not in BG
            player->SetBattlegroundId(0, BATTLEGROUND_TYPE_NONE);
            // reset destination bg team
            player->SetBGTeam(0);
        }
        // join to bg case
        else if (Battleground* bg = player->GetBattleground())
        {
            if (player->IsInvitedForBattlegroundInstance(player->GetBattlegroundId()))
                bg->AddPlayer(player);
        }
    }

    if (!seamlessTeleport)
        player->SendInitialPacketsAfterAddToMap();
    else
    {
        player->UpdateVisibilityForPlayer();
        if (Garrison* garrison = player->GetGarrison())
            garrison->SendRemoteInfo();
    }

    // flight fast teleport case
    if (player->IsInFlight())
    {
        if (!player->InBattleground())
        {
            if (!seamlessTeleport)
            {
                // short preparations to continue flight
                MovementGenerator* movementGenerator = player->GetMotionMaster()->GetCurrentMovementGenerator();
                movementGenerator->Initialize(player);
            }
            return;
        }

        // battleground state prepare, stop flight
        player->FinishTaxiFlight();
    }

    if (!player->IsAlive() && player->GetTeleportOptions() & TELE_REVIVE_AT_TELEPORT)
        player->ResurrectPlayer(0.5f);

    // resurrect character at enter into instance where his corpse exist after add to map
    if (mEntry->IsDungeon() && !player->IsAlive())
    {
        if (player->GetCorpseLocation().GetMapId() == mEntry->ID)
        {
            player->ResurrectPlayer(0.5f);
            player->SpawnCorpseBones();
        }
    }

    if (mInstance)
    {
        // check if this instance has a reset time and send it to player if so
        Difficulty diff = newMap->GetDifficultyID();
        if (MapDifficultyEntry const* mapDiff = sDB2Manager.GetMapDifficultyData(mEntry->ID, diff))
        {
            if (mapDiff->GetRaidDuration())
            {
                if (time_t timeReset = sInstanceSaveMgr->GetResetTimeFor(mEntry->ID, diff))
                {
                    uint32 timeleft = uint32(timeReset - GameTime::GetGameTime());
                    player->SendInstanceResetWarning(mEntry->ID, diff, timeleft, true);
                }
            }
        }

        // check if instance is valid
        if (!player->CheckInstanceValidity(false))
            player->m_InstanceValid = false;
    }

    // update zone immediately, otherwise leave channel will cause crash in mtmap
    uint32 newzone, newarea;
    player->GetZoneAndAreaId(newzone, newarea);
    player->UpdateZone(newzone, newarea);

    // honorless target
    if (player->pvpInfo.IsHostile)
        player->CastSpell(player, 2479, true);

    // in friendly area
    else if (player->IsPvP() && !player->HasPlayerFlag(PLAYER_FLAGS_IN_PVP))
        player->UpdatePvP(false, false);

    // resummon pet
    player->ResummonPetTemporaryUnSummonedIfAny();

    //lets process all delayed operations on successful teleport
    player->ProcessDelayedOperations();
}

void WorldSession::HandleSuspendTokenResponse(WorldPackets::Movement::SuspendTokenResponse& /*suspendTokenResponse*/)
{
    if (!_player->IsBeingTeleportedFar())
        return;

    WorldLocation const& loc = GetPlayer()->GetTeleportDest();

    if (sMapStore.AssertEntry(loc.GetMapId())->IsDungeon())
    {
        WorldPackets::Instance::UpdateLastInstance updateLastInstance;
        updateLastInstance.MapID = loc.GetMapId();
        SendPacket(updateLastInstance.Write());
    }

    WorldPackets::Movement::NewWorld packet;
    packet.MapID = loc.GetMapId();
    packet.Loc.Pos = loc;
    packet.Reason = !_player->IsBeingTeleportedSeamlessly() ? NEW_WORLD_NORMAL : NEW_WORLD_SEAMLESS;
    SendPacket(packet.Write());

    if (_player->IsBeingTeleportedSeamlessly())
        HandleMoveWorldportAck();
}

void WorldSession::HandleMoveTeleportAck(WorldPackets::Movement::MoveTeleportAck& packet)
{
    TC_LOG_DEBUG("network", "CMSG_MOVE_TELEPORT_ACK: Guid: %s, Sequence: %u, Time: %u", packet.MoverGUID.ToString().c_str(), packet.AckIndex, packet.MoveTime);

    Player* plMover = _player->GetUnitBeingMoved()->ToPlayer();

    if (!plMover || !plMover->IsBeingTeleportedNear())
        return;

    if (packet.MoverGUID != plMover->GetGUID())
        return;

    plMover->SetSemaphoreTeleportNear(false);

    uint32 old_zone = plMover->GetZoneId();

    WorldLocation const& dest = plMover->GetTeleportDest();

    plMover->UpdatePosition(dest, true);
    plMover->SetFallInformation(0, GetPlayer()->GetPositionZ());

    uint32 newzone, newarea;
    plMover->GetZoneAndAreaId(newzone, newarea);
    plMover->UpdateZone(newzone, newarea);

    // new zone
    if (old_zone != newzone)
    {
        // honorless target
        if (plMover->pvpInfo.IsHostile)
            plMover->CastSpell(plMover, 2479, true);

        // in friendly area
        else if (plMover->IsPvP() && !plMover->HasPlayerFlag(PLAYER_FLAGS_IN_PVP))
            plMover->UpdatePvP(false, false);
    }

    // resummon pet
    GetPlayer()->ResummonPetTemporaryUnSummonedIfAny();

    //lets process all delayed operations on successful teleport
    GetPlayer()->ProcessDelayedOperations();
}

void WorldSession::HandleMovementOpcodes(WorldPackets::Movement::ClientPlayerMovement& packet)
{
    HandleMovementOpcode(packet.GetOpcode(), packet.Status);
}

void WorldSession::HandleMovementOpcode(OpcodeClient opcode, MovementInfo& movementInfo)
{
    Unit* mover = _player->GetUnitBeingMoved();

    ASSERT(mover != nullptr);                      // there must always be a mover

    Player* plrMover = mover->ToPlayer();

    TC_LOG_TRACE("opcodes.movement", "HandleMovementOpcode Name %s: opcode %u %s Flags %u Flags2 %u Pos %s",
        mover->GetName().c_str(), opcode, GetOpcodeNameForLogging(opcode).c_str(),
        movementInfo.flags, movementInfo.flags2, movementInfo.pos.ToString().c_str());

    // ignore, waiting processing in WorldSession::HandleMoveWorldportAckOpcode and WorldSession::HandleMoveTeleportAck
    if (plrMover && plrMover->IsBeingTeleported())
        return;

    GetPlayer()->ValidateMovementInfo(&movementInfo);

    // prevent tampered movement data
    if (movementInfo.guid != mover->GetGUID())
    {
        TC_LOG_ERROR("network", "HandleMovementOpcodes: guid error");
        return;
    }

    if (!movementInfo.pos.IsPositionValid())
    {
        TC_LOG_ERROR("network", "HandleMovementOpcodes: Invalid Position");
        return;
    }

    if (!mover->movespline->Finalized())
        return;

    // stop some emotes at player move
    if (plrMover && (plrMover->GetEmoteState() != 0))
        plrMover->SetEmoteState(EMOTE_ONESHOT_NONE);

    /* handle special cases */
    if (!movementInfo.transport.guid.IsEmpty())
    {
        // We were teleported, skip packets that were broadcast before teleport
        if (movementInfo.pos.GetExactDist2d(mover) > SIZE_OF_GRIDS)
            return;

        // transports size limited
        // (also received at zeppelin leave by some reason with t_* as absolute in continent coordinates, can be safely skipped)
        if (fabs(movementInfo.transport.pos.GetPositionX()) > 75.0f || fabs(movementInfo.transport.pos.GetPositionY()) > 75.0f || fabs(movementInfo.transport.pos.GetPositionZ()) > 75.0f)
        {
            return;
        }

        if (!Trinity::IsValidMapCoord(movementInfo.pos.GetPositionX() + movementInfo.transport.pos.GetPositionX(), movementInfo.pos.GetPositionY() + movementInfo.transport.pos.GetPositionY(),
            movementInfo.pos.GetPositionZ() + movementInfo.transport.pos.GetPositionZ(), movementInfo.pos.GetOrientation() + movementInfo.transport.pos.GetOrientation()))
        {
            return;
        }

        // if we boarded a transport, add us to it
        if (plrMover)
        {
            if (!plrMover->GetTransport())
            {
                if (Transport* transport = plrMover->GetMap()->GetTransport(movementInfo.transport.guid))
                    transport->AddPassenger(plrMover);
            }
            else if (plrMover->GetTransport()->GetGUID() != movementInfo.transport.guid)
            {
                plrMover->GetTransport()->RemovePassenger(plrMover);
                if (Transport* transport = plrMover->GetMap()->GetTransport(movementInfo.transport.guid))
                    transport->AddPassenger(plrMover);
                else
                    movementInfo.ResetTransport();
            }
        }

        if (!mover->GetTransport() && !mover->GetVehicle())
        {
            GameObject* go = mover->GetMap()->GetGameObject(movementInfo.transport.guid);
            if (!go || go->GetGoType() != GAMEOBJECT_TYPE_TRANSPORT)
                movementInfo.transport.Reset();
        }
    }
    else if (plrMover && plrMover->GetTransport())                // if we were on a transport, leave
        plrMover->m_transport->RemovePassenger(plrMover);

    // fall damage generation (ignore in flight case that can be triggered also at lags in moment teleportation to another map).
    if (opcode == CMSG_MOVE_FALL_LAND && plrMover && !plrMover->IsInFlight())
        plrMover->HandleFall(movementInfo);

    // interrupt parachutes upon falling or landing in water
    if (opcode == CMSG_MOVE_FALL_LAND || opcode == CMSG_MOVE_START_SWIM || opcode == CMSG_MOVE_SET_FLY)
        mover->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::LandingOrFlight); // Parachutes

    /* process position-change */
    movementInfo.guid = mover->GetGUID();
    movementInfo.time = AdjustClientMovementTime(movementInfo.time);
    mover->m_movementInfo = movementInfo;

    // Some vehicles allow the passenger to turn by himself
    if (Vehicle* vehicle = mover->GetVehicle())
    {
        if (VehicleSeatEntry const* seat = vehicle->GetSeatForPassenger(mover))
        {
            if (seat->Flags & VEHICLE_SEAT_FLAG_ALLOW_TURNING)
            {
                if (movementInfo.pos.GetOrientation() != mover->GetOrientation())
                {
                    mover->SetOrientation(movementInfo.pos.GetOrientation());
                    mover->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::Turning);
                }
            }
        }
        return;
    }

    mover->UpdatePosition(movementInfo.pos);

    WorldPackets::Movement::MoveUpdate moveUpdate;
    moveUpdate.Status = &mover->m_movementInfo;
    mover->SendMessageToSet(moveUpdate.Write(), _player);

    if (plrMover)                                            // nothing is charmed, or player charmed
    {
        if (plrMover->IsSitState() && (movementInfo.flags & (MOVEMENTFLAG_MASK_MOVING | MOVEMENTFLAG_MASK_TURNING)))
            plrMover->SetStandState(UNIT_STAND_STATE_STAND);

        plrMover->UpdateFallInformationIfNeed(movementInfo, opcode);

        if (movementInfo.pos.GetPositionZ() < plrMover->GetMap()->GetMinHeight(plrMover->GetPhaseShift(), movementInfo.pos.GetPositionX(), movementInfo.pos.GetPositionY()))
        {
            if (!(plrMover->GetBattleground() && plrMover->GetBattleground()->HandlePlayerUnderMap(_player)))
            {
                // NOTE: this is actually called many times while falling
                // even after the player has been teleported away
                /// @todo discard movement packets after the player is rooted
                if (plrMover->IsAlive())
                {
                    plrMover->AddPlayerFlag(PLAYER_FLAGS_IS_OUT_OF_BOUNDS);
                    plrMover->EnvironmentalDamage(DAMAGE_FALL_TO_VOID, GetPlayer()->GetMaxHealth());
                    // player can be alive if GM/etc
                    // change the death state to CORPSE to prevent the death timer from
                    // starting in the next player update
                    if (plrMover->IsAlive())
                        plrMover->KillPlayer();
                }
            }
        }
        else
            plrMover->RemovePlayerFlag(PLAYER_FLAGS_IS_OUT_OF_BOUNDS);

        if (opcode == CMSG_MOVE_JUMP)
        {
            plrMover->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags2::Jump);
            Unit::ProcSkillsAndAuras(plrMover, nullptr, PROC_FLAG_JUMP, PROC_FLAG_NONE, PROC_SPELL_TYPE_MASK_ALL, PROC_SPELL_PHASE_NONE, PROC_HIT_NONE, nullptr, nullptr, nullptr);
        }
    }
}

void WorldSession::HandleForceSpeedChangeAck(WorldPackets::Movement::MovementSpeedAck& packet)
{

    GetPlayer()->ValidateMovementInfo(&packet.Ack.Status);

    // now can skip not our packet
    if (_player->GetGUID() != packet.Ack.Status.guid)
        return;

    /*----------------*/

    // client ACK send one packet for mounted/run case and need skip all except last from its
    // in other cases anti-cheat check can be fail in false case
    UnitMoveType move_type;

    static char const* const move_type_name[MAX_MOVE_TYPE] =
    {
        "Walk",
        "Run",
        "RunBack",
        "Swim",
        "SwimBack",
        "TurnRate",
        "Flight",
        "FlightBack",
        "PitchRate"
    };

    OpcodeClient opcode = packet.GetOpcode();
    switch (opcode)
    {

        case CMSG_MOVE_FORCE_WALK_SPEED_CHANGE_ACK:        move_type = MOVE_WALK;        break;
        case CMSG_MOVE_FORCE_RUN_SPEED_CHANGE_ACK:         move_type = MOVE_RUN;         break;
        case CMSG_MOVE_FORCE_RUN_BACK_SPEED_CHANGE_ACK:    move_type = MOVE_RUN_BACK;    break;
        case CMSG_MOVE_FORCE_SWIM_SPEED_CHANGE_ACK:        move_type = MOVE_SWIM;        break;
        case CMSG_MOVE_FORCE_SWIM_BACK_SPEED_CHANGE_ACK:   move_type = MOVE_SWIM_BACK;   break;
        case CMSG_MOVE_FORCE_TURN_RATE_CHANGE_ACK:         move_type = MOVE_TURN_RATE;   break;
        case CMSG_MOVE_FORCE_FLIGHT_SPEED_CHANGE_ACK:      move_type = MOVE_FLIGHT;      break;
        case CMSG_MOVE_FORCE_FLIGHT_BACK_SPEED_CHANGE_ACK: move_type = MOVE_FLIGHT_BACK; break;
        case CMSG_MOVE_FORCE_PITCH_RATE_CHANGE_ACK:        move_type = MOVE_PITCH_RATE;  break;

        default:
            TC_LOG_ERROR("network", "WorldSession::HandleForceSpeedChangeAck: Unknown move type opcode: %u", opcode);
            return;
    }

    // skip all forced speed changes except last and unexpected
    // in run/mounted case used one ACK and it must be skipped. m_forced_speed_changes[MOVE_RUN] store both.
    if (_player->m_forced_speed_changes[move_type] > 0)
    {
        --_player->m_forced_speed_changes[move_type];
        if (_player->m_forced_speed_changes[move_type] > 0)
            return;
    }

    if (!_player->GetTransport() && std::fabs(_player->GetSpeed(move_type) - packet.Speed) > 0.01f)
    {
        if (_player->GetSpeed(move_type) > packet.Speed)         // must be greater - just correct
        {
            TC_LOG_ERROR("network", "%sSpeedChange player %s is NOT correct (must be %f instead %f), force set to correct value",
                move_type_name[move_type], _player->GetName().c_str(), _player->GetSpeed(move_type), packet.Speed);
            _player->SetSpeedRate(move_type, _player->GetSpeedRate(move_type));
        }
        else                                                // must be lesser - cheating
        {
            TC_LOG_DEBUG("misc", "Player %s from account id %u kicked for incorrect speed (must be %f instead %f)",
                _player->GetName().c_str(), _player->GetSession()->GetAccountId(), _player->GetSpeed(move_type), packet.Speed);
            _player->GetSession()->KickPlayer("WorldSession::HandleForceSpeedChangeAck Incorrect speed");
        }
    }
}

void WorldSession::HandleSetActiveMoverOpcode(WorldPackets::Movement::SetActiveMover& packet)
{
    if (GetPlayer()->IsInWorld())
        if (_player->GetUnitBeingMoved()->GetGUID() != packet.ActiveMover)
            TC_LOG_DEBUG("network", "HandleSetActiveMoverOpcode: incorrect mover guid: mover is %s and should be %s" , packet.ActiveMover.ToString().c_str(), _player->GetUnitBeingMoved()->GetGUID().ToString().c_str());
}

void WorldSession::HandleMoveKnockBackAck(WorldPackets::Movement::MoveKnockBackAck& movementAck)
{
    GetPlayer()->ValidateMovementInfo(&movementAck.Ack.Status);

    if (_player->m_unitMovedByMe->GetGUID() != movementAck.Ack.Status.guid)
        return;

    _player->m_movementInfo = movementAck.Ack.Status;

    WorldPackets::Movement::MoveUpdateKnockBack updateKnockBack;
    updateKnockBack.Status = &_player->m_movementInfo;
    _player->SendMessageToSet(updateKnockBack.Write(), false);
}

void WorldSession::HandleMovementAckMessage(WorldPackets::Movement::MovementAckMessage& movementAck)
{
    GetPlayer()->ValidateMovementInfo(&movementAck.Ack.Status);
}

void WorldSession::HandleSummonResponseOpcode(WorldPackets::Movement::SummonResponse& packet)
{
    if (!_player->IsAlive() || _player->IsInCombat())
        return;

    _player->SummonIfPossible(packet.Accept);
}

void WorldSession::HandleSetCollisionHeightAck(WorldPackets::Movement::MoveSetCollisionHeightAck& setCollisionHeightAck)
{
    GetPlayer()->ValidateMovementInfo(&setCollisionHeightAck.Data.Status);
}

void WorldSession::HandleMoveApplyMovementForceAck(WorldPackets::Movement::MoveApplyMovementForceAck& moveApplyMovementForceAck)
{
    Unit* mover = _player->m_unitMovedByMe;
    ASSERT(mover != nullptr);
    _player->ValidateMovementInfo(&moveApplyMovementForceAck.Ack.Status);

    // prevent tampered movement data
    if (moveApplyMovementForceAck.Ack.Status.guid != mover->GetGUID())
    {
        TC_LOG_ERROR("network", "HandleMoveApplyMovementForceAck: guid error, expected %s, got %s",
            mover->GetGUID().ToString().c_str(), moveApplyMovementForceAck.Ack.Status.guid.ToString().c_str());
        return;
    }

    moveApplyMovementForceAck.Ack.Status.time = AdjustClientMovementTime(moveApplyMovementForceAck.Ack.Status.time);

    WorldPackets::Movement::MoveUpdateApplyMovementForce updateApplyMovementForce;
    updateApplyMovementForce.Status = &moveApplyMovementForceAck.Ack.Status;
    updateApplyMovementForce.Force = &moveApplyMovementForceAck.Force;
    mover->SendMessageToSet(updateApplyMovementForce.Write(), false);
}

void WorldSession::HandleMoveRemoveMovementForceAck(WorldPackets::Movement::MoveRemoveMovementForceAck& moveRemoveMovementForceAck)
{
    Unit* mover = _player->m_unitMovedByMe;
    ASSERT(mover != nullptr);
    _player->ValidateMovementInfo(&moveRemoveMovementForceAck.Ack.Status);

    // prevent tampered movement data
    if (moveRemoveMovementForceAck.Ack.Status.guid != mover->GetGUID())
    {
        TC_LOG_ERROR("network", "HandleMoveRemoveMovementForceAck: guid error, expected %s, got %s",
            mover->GetGUID().ToString().c_str(), moveRemoveMovementForceAck.Ack.Status.guid.ToString().c_str());
        return;
    }

    moveRemoveMovementForceAck.Ack.Status.time = AdjustClientMovementTime(moveRemoveMovementForceAck.Ack.Status.time);

    WorldPackets::Movement::MoveUpdateRemoveMovementForce updateRemoveMovementForce;
    updateRemoveMovementForce.Status = &moveRemoveMovementForceAck.Ack.Status;
    updateRemoveMovementForce.TriggerGUID = moveRemoveMovementForceAck.ID;
    mover->SendMessageToSet(updateRemoveMovementForce.Write(), false);
}

void WorldSession::HandleMoveSetModMovementForceMagnitudeAck(WorldPackets::Movement::MovementSpeedAck& setModMovementForceMagnitudeAck)
{
    Unit* mover = _player->m_unitMovedByMe;
    ASSERT(mover != nullptr);                      // there must always be a mover
    _player->ValidateMovementInfo(&setModMovementForceMagnitudeAck.Ack.Status);

    // prevent tampered movement data
    if (setModMovementForceMagnitudeAck.Ack.Status.guid != mover->GetGUID())
    {
        TC_LOG_ERROR("network", "HandleSetModMovementForceMagnitudeAck: guid error, expected %s, got %s",
            mover->GetGUID().ToString().c_str(), setModMovementForceMagnitudeAck.Ack.Status.guid.ToString().c_str());
        return;
    }

    // skip all except last
    if (_player->m_movementForceModMagnitudeChanges > 0)
    {
        --_player->m_movementForceModMagnitudeChanges;
        if (!_player->m_movementForceModMagnitudeChanges)
        {
            float expectedModMagnitude = 1.0f;
            if (MovementForces const* movementForces = mover->GetMovementForces())
                expectedModMagnitude = movementForces->GetModMagnitude();

            if (std::fabs(expectedModMagnitude - setModMovementForceMagnitudeAck.Speed) > 0.01f)
            {
                TC_LOG_DEBUG("misc", "Player %s from account id %u kicked for incorrect movement force magnitude (must be %f instead %f)",
                    _player->GetName().c_str(), _player->GetSession()->GetAccountId(), expectedModMagnitude, setModMovementForceMagnitudeAck.Speed);
                _player->GetSession()->KickPlayer("WorldSession::HandleMoveSetModMovementForceMagnitudeAck Incorrect magnitude");
                return;
            }
        }
    }

    setModMovementForceMagnitudeAck.Ack.Status.time = AdjustClientMovementTime(setModMovementForceMagnitudeAck.Ack.Status.time);

    WorldPackets::Movement::MoveUpdateSpeed updateModMovementForceMagnitude(SMSG_MOVE_UPDATE_MOD_MOVEMENT_FORCE_MAGNITUDE);
    updateModMovementForceMagnitude.Status = &setModMovementForceMagnitudeAck.Ack.Status;
    updateModMovementForceMagnitude.Speed = setModMovementForceMagnitudeAck.Speed;
    mover->SendMessageToSet(updateModMovementForceMagnitude.Write(), false);
}

void WorldSession::HandleMoveSplineDoneOpcode(WorldPackets::Movement::MoveSplineDone& moveSplineDone)
{
    MovementInfo movementInfo = moveSplineDone.Status;
    _player->ValidateMovementInfo(&movementInfo);

    // in taxi flight packet received in 2 case:
    // 1) end taxi path in far (multi-node) flight
    // 2) switch from one map to other in case multim-map taxi path
    // we need process only (1)

    uint32 curDest = GetPlayer()->m_taxi.GetTaxiDestination();
    if (curDest)
    {
        TaxiNodesEntry const* curDestNode = sTaxiNodesStore.LookupEntry(curDest);

        // far teleport case
        if (curDestNode && curDestNode->ContinentID != GetPlayer()->GetMapId() && GetPlayer()->GetMotionMaster()->GetCurrentMovementGeneratorType() == FLIGHT_MOTION_TYPE)
        {
            if (FlightPathMovementGenerator* flight = dynamic_cast<FlightPathMovementGenerator*>(GetPlayer()->GetMotionMaster()->GetCurrentMovementGenerator()))
            {
                // short preparations to continue flight
                flight->SetCurrentNodeAfterTeleport();
                TaxiPathNodeEntry const* node = flight->GetPath()[flight->GetCurrentNode()];
                flight->SkipCurrentNode();

                GetPlayer()->TeleportTo(curDestNode->ContinentID, node->Loc.X, node->Loc.Y, node->Loc.Z, GetPlayer()->GetOrientation());
            }
        }

        return;
    }

    // at this point only 1 node is expected (final destination)
    if (GetPlayer()->m_taxi.GetPath().size() != 1)
        return;

    GetPlayer()->CleanupAfterTaxiFlight();
    GetPlayer()->SetFallInformation(0, GetPlayer()->GetPositionZ());
    if (GetPlayer()->pvpInfo.IsHostile)
        GetPlayer()->CastSpell(GetPlayer(), 2479, true);
}

void WorldSession::HandleMoveTimeSkippedOpcode(WorldPackets::Movement::MoveTimeSkipped& moveTimeSkipped)
{
    Unit* mover = GetPlayer()->m_unitMovedByMe;
    if (!mover)
    {
        TC_LOG_WARN("entities.player", "WorldSession::HandleMoveTimeSkippedOpcode wrong mover state from the unit moved by %s", GetPlayer()->GetGUID().ToString().c_str());
        return;
    }

    // prevent tampered movement data
    if (moveTimeSkipped.MoverGUID != mover->GetGUID())
    {
        TC_LOG_WARN("entities.player", "WorldSession::HandleMoveTimeSkippedOpcode wrong guid from the unit moved by %s", GetPlayer()->GetGUID().ToString().c_str());
        return;
    }

    mover->m_movementInfo.time += moveTimeSkipped.TimeSkipped;

    WorldPackets::Movement::MoveSkipTime moveSkipTime;
    moveSkipTime.MoverGUID = moveTimeSkipped.MoverGUID;
    moveSkipTime.TimeSkipped = moveTimeSkipped.TimeSkipped;
    mover->SendMessageToSet(moveSkipTime.Write(), _player);
}

void WorldSession::HandleTimeSyncResponse(WorldPackets::Misc::TimeSyncResponse& timeSyncResponse)
{
    if (_pendingTimeSyncRequests.count(timeSyncResponse.SequenceIndex) == 0)
        return;

    uint32 serverTimeAtSent = _pendingTimeSyncRequests.at(timeSyncResponse.SequenceIndex);
    _pendingTimeSyncRequests.erase(timeSyncResponse.SequenceIndex);

    // time it took for the request to travel to the client, for the client to process it and reply and for response to travel back to the server.
    // we are going to make 2 assumptions:
    // 1) we assume that the request processing time equals 0.
    // 2) we assume that the packet took as much time to travel from server to client than it took to travel from client to server.
    uint32 roundTripDuration = getMSTimeDiff(serverTimeAtSent, timeSyncResponse.GetReceivedTime());
    uint32 lagDelay = roundTripDuration / 2;

    /*
    clockDelta = serverTime - clientTime
    where
    serverTime: time that was displayed on the clock of the SERVER at the moment when the client processed the SMSG_TIME_SYNC_REQUEST packet.
    clientTime:  time that was displayed on the clock of the CLIENT at the moment when the client processed the SMSG_TIME_SYNC_REQUEST packet.

    Once clockDelta has been computed, we can compute the time of an event on server clock when we know the time of that same event on the client clock,
    using the following relation:
    serverTime = clockDelta + clientTime
    */
    int64 clockDelta = (int64)(serverTimeAtSent + lagDelay) - (int64)timeSyncResponse.ClientTime;
    _timeSyncClockDeltaQueue.push_back(std::pair<int64, uint32>(clockDelta, roundTripDuration));
    ComputeNewClockDelta();
}

void WorldSession::ComputeNewClockDelta()
{
    // implementation of the technique described here: https://web.archive.org/web/20180430214420/http://www.mine-control.com/zack/timesync/timesync.html
    // to reduce the skew induced by dropped TCP packets that get resent.

    using namespace boost::accumulators;

    accumulator_set<uint32, features<tag::mean, tag::median, tag::variance(lazy)> > latencyAccumulator;

    for (auto pair : _timeSyncClockDeltaQueue)
        latencyAccumulator(pair.second);

    uint32 latencyMedian = static_cast<uint32>(std::round(median(latencyAccumulator)));
    uint32 latencyStandardDeviation = static_cast<uint32>(std::round(sqrt(variance(latencyAccumulator))));

    accumulator_set<int64, features<tag::mean> > clockDeltasAfterFiltering;
    uint32 sampleSizeAfterFiltering = 0;
    for (auto pair : _timeSyncClockDeltaQueue)
    {
        if (pair.second < latencyStandardDeviation + latencyMedian) {
            clockDeltasAfterFiltering(pair.first);
            sampleSizeAfterFiltering++;
        }
    }

    if (sampleSizeAfterFiltering != 0)
    {
        int64 meanClockDelta = static_cast<int64>(std::round(mean(clockDeltasAfterFiltering)));
        if (std::abs(meanClockDelta - _timeSyncClockDelta) > 25)
            _timeSyncClockDelta = meanClockDelta;
    }
    else if (_timeSyncClockDelta == 0)
    {
        std::pair<int64, uint32> back = _timeSyncClockDeltaQueue.back();
        _timeSyncClockDelta = back.first;
    }
}