/*
 * Copyright (C) 2005-2010 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "Common.h"
#include "WorldPacket.h"
#include "WorldSession.h"
#include "World.h"
#include "ObjectAccessor.h"
#include "Log.h"
#include "Opcodes.h"
#include "Player.h"
#include "Item.h"
#include "Spell.h"
#include "SocialMgr.h"
#include "Language.h"

void WorldSession::SendTradeStatus(TradeStatus status)
{
    WorldPacket data;

    switch(status)
    {
        case TRADE_STATUS_BEGIN_TRADE:
            data.Initialize(SMSG_TRADE_STATUS, 4+8);
            data << uint32(status);
            data << uint64(0);
            break;
        case TRADE_STATUS_OPEN_WINDOW:
            data.Initialize(SMSG_TRADE_STATUS, 4+4);
            data << uint32(status);
            data << uint32(0);                              // added in 2.4.0
            break;
        case TRADE_STATUS_CLOSE_WINDOW:
            data.Initialize(SMSG_TRADE_STATUS, 4+4+1+4);
            data << uint32(status);
            data << uint32(0);
            data << uint8(0);
            data << uint32(0);
            break;
        case TRADE_STATUS_ONLY_CONJURED:
            data.Initialize(SMSG_TRADE_STATUS, 4+1);
            data << uint32(status);
            data << uint8(0);
            break;
        default:
            data.Initialize(SMSG_TRADE_STATUS, 4);
            data << uint32(status);
            break;
    }

    SendPacket(&data);
}

void WorldSession::HandleIgnoreTradeOpcode(WorldPacket& /*recvPacket*/)
{
    DEBUG_LOG( "WORLD: Ignore Trade %u",_player->GetGUIDLow());
    // recvPacket.print_storage();
}

void WorldSession::HandleBusyTradeOpcode(WorldPacket& /*recvPacket*/)
{
    DEBUG_LOG( "WORLD: Busy Trade %u",_player->GetGUIDLow());
    // recvPacket.print_storage();
}

void WorldSession::SendUpdateTrade(bool trader_state /*= true*/)
{
    TradeData* view_trade = trader_state ? _player->GetTradeData()->GetTraderData() : _player->GetTradeData();

    WorldPacket data(SMSG_TRADE_STATUS_EXTENDED, (100));    // guess size
    data << uint8(trader_state ? 1 : 0);                    // send trader or own trade windows state (last need for proper show spell apply to non-trade slot)
    data << uint32(0);                                      // added in 2.4.0, this value must be equal to value from TRADE_STATUS_OPEN_WINDOW status packet (different value for different players to block multiple trades?)
    data << uint32(TRADE_SLOT_COUNT);                       // trade slots count/number?, = next field in most cases
    data << uint32(TRADE_SLOT_COUNT);                       // trade slots count/number?, = prev field in most cases
    data << uint32(view_trade->GetMoney());                 // trader gold
    data << uint32(view_trade->GetSpell());                 // spell casted on lowest slot item

    for(uint8 i = 0; i < TRADE_SLOT_COUNT; ++i)
    {
        data << uint8(i);                                   // trade slot number, if not specified, then end of packet

        if (Item* item = view_trade->GetItem(TradeSlots(i)))
        {
            data << uint32(item->GetProto()->ItemId);       // entry
            data << uint32(item->GetProto()->DisplayInfoID);// display id
            data << uint32(item->GetCount());               // stack count
                                                            // wrapped: hide stats but show giftcreator name
            data << uint32(item->HasFlag(ITEM_FIELD_FLAGS, ITEM_DYNFLAG_WRAPPED) ? 1 : 0);
            data << item->GetGuidValue(ITEM_FIELD_GIFTCREATOR);

            data << uint32(item->GetEnchantmentId(PERM_ENCHANTMENT_SLOT));
            for(uint32 enchant_slot = SOCK_ENCHANTMENT_SLOT; enchant_slot < SOCK_ENCHANTMENT_SLOT+MAX_GEM_SOCKETS; ++enchant_slot)
                data << uint32(item->GetEnchantmentId(EnchantmentSlot(enchant_slot)));
                                                            // creator
            data << item->GetGuidValue(ITEM_FIELD_CREATOR);
            data << uint32(item->GetSpellCharges());        // charges
            data << uint32(item->GetItemSuffixFactor());    // SuffixFactor
            data << uint32(item->GetItemRandomPropertyId());// random properties id
            data << uint32(item->GetProto()->LockID);       // lock id
                                                            // max durability
            data << uint32(item->GetUInt32Value(ITEM_FIELD_MAXDURABILITY));
                                                            // durability
            data << uint32(item->GetUInt32Value(ITEM_FIELD_DURABILITY));
        }
        else
        {
            for(uint8 j = 0; j < 18; ++j)
                data << uint32(0);
        }
    }
    SendPacket(&data);
}

//==============================================================
// transfer the items to the players

void WorldSession::moveItems(Item* myItems[], Item* hisItems[])
{
    Player* trader = _player->GetTrader();
    if (!trader)
        return;


    for(int i = 0; i < TRADE_SLOT_TRADED_COUNT; ++i)
    {
        ItemPosCountVec traderDst;
        ItemPosCountVec playerDst;
        bool traderCanTrade = (myItems[i]==NULL || trader->CanStoreItem( NULL_BAG, NULL_SLOT, traderDst, myItems[i], false ) == EQUIP_ERR_OK);
        bool playerCanTrade = (hisItems[i]==NULL || _player->CanStoreItem( NULL_BAG, NULL_SLOT, playerDst, hisItems[i], false ) == EQUIP_ERR_OK);
        if (traderCanTrade && playerCanTrade )
        {
            // Ok, if trade item exists and can be stored
            // If we trade in both directions we had to check, if the trade will work before we actually do it
            // A roll back is not possible after we stored it
            if (myItems[i])
            {
                // logging
                DEBUG_LOG("partner storing: %s", myItems[i]->GetObjectGuid().GetString().c_str());
                if (_player->GetSession()->GetSecurity() > SEC_PLAYER && sWorld.getConfig(CONFIG_BOOL_GM_LOG_TRADE))
                {
                    sLog.outCommand(_player->GetSession()->GetAccountId(),"GM %s (Account: %u) trade: %s (Entry: %d Count: %u) to player: %s (Account: %u)",
                        _player->GetName(), _player->GetSession()->GetAccountId(),
                        myItems[i]->GetProto()->Name1, myItems[i]->GetEntry(), myItems[i]->GetCount(),
                        trader->GetName(), trader->GetSession()->GetAccountId());
                }

                // store
                trader->MoveItemToInventory( traderDst, myItems[i], true, true);
            }

            if (hisItems[i])
            {
                // logging
                DEBUG_LOG("player storing: %s", hisItems[i]->GetObjectGuid().GetString().c_str());
                if (trader->GetSession()->GetSecurity() > SEC_PLAYER && sWorld.getConfig(CONFIG_BOOL_GM_LOG_TRADE))
                {
                    sLog.outCommand(trader->GetSession()->GetAccountId(),"GM %s (Account: %u) trade: %s (Entry: %d Count: %u) to player: %s (Account: %u)",
                        trader->GetName(), trader->GetSession()->GetAccountId(),
                        hisItems[i]->GetProto()->Name1, hisItems[i]->GetEntry(), hisItems[i]->GetCount(),
                        _player->GetName(), _player->GetSession()->GetAccountId());
                }

                // store
                _player->MoveItemToInventory( playerDst, hisItems[i], true, true);
            }
        }
        else
        {
            // in case of fatal error log error message
            // return the already removed items to the original owner
            if (myItems[i])
            {
                if (!traderCanTrade)
                    sLog.outError("trader can't store item: %s", myItems[i]->GetObjectGuid().GetString().c_str());
                if (_player->CanStoreItem( NULL_BAG, NULL_SLOT, playerDst, myItems[i], false ) == EQUIP_ERR_OK)
                    _player->MoveItemToInventory(playerDst, myItems[i], true, true);
                else
                    sLog.outError("player can't take item back: %s", myItems[i]->GetObjectGuid().GetString().c_str());
            }
            // return the already removed items to the original owner
            if (hisItems[i])
            {
                if (!playerCanTrade)
                    sLog.outError("player can't store item: %s", hisItems[i]->GetObjectGuid().GetString().c_str());
                if (trader->CanStoreItem( NULL_BAG, NULL_SLOT, traderDst, hisItems[i], false ) == EQUIP_ERR_OK)
                    trader->MoveItemToInventory(traderDst, hisItems[i], true, true);
                else
                    sLog.outError("trader can't take item back: %s", hisItems[i]->GetObjectGuid().GetString().c_str());
            }
        }
    }
}

//==============================================================
static void setAcceptTradeMode(TradeData* myTrade, TradeData* hisTrade, Item **myItems, Item **hisItems)
{
    myTrade->SetInAcceptProcess(true);
    hisTrade->SetInAcceptProcess(true);

    // store items in local list and set 'in-trade' flag
    for(int i = 0; i < TRADE_SLOT_TRADED_COUNT; ++i)
    {
        if (Item* item = myTrade->GetItem(TradeSlots(i)))
        {
            DEBUG_LOG("player trade item %s bag: %u slot: %u", item->GetObjectGuid().GetString().c_str(), item->GetBagSlot(), item->GetSlot());
            //Can return NULL
            myItems[i] = item;
            myItems[i]->SetInTrade();
        }

        if (Item* item = hisTrade->GetItem(TradeSlots(i)))
        {
            DEBUG_LOG("partner trade item %s bag: %u slot: %u", item->GetObjectGuid().GetString().c_str(), item->GetBagSlot(), item->GetSlot());
            hisItems[i] = item;
            hisItems[i]->SetInTrade();
        }
    }
}

static void clearAcceptTradeMode(TradeData* myTrade, TradeData* hisTrade)
{
    myTrade->SetInAcceptProcess(false);
    hisTrade->SetInAcceptProcess(false);
}

static void clearAcceptTradeMode(Item **myItems, Item **hisItems)
{
    // clear 'in-trade' flag
    for (int i = 0; i < TRADE_SLOT_TRADED_COUNT; ++i)
    {
        if (myItems[i])
            myItems[i]->SetInTrade(false);
        if (hisItems[i])
            hisItems[i]->SetInTrade(false);
    }
}

void WorldSession::HandleAcceptTradeOpcode(WorldPacket& recvPacket)
{
    recvPacket.read_skip<uint32>();                         // 7, amount traded slots ?

    TradeData* my_trade = _player->m_trade;
    if (!my_trade)
        return;

    Player* trader = my_trade->GetTrader();

    TradeData* his_trade = trader->m_trade;
    if (!his_trade)
        return;

    Item *myItems[TRADE_SLOT_TRADED_COUNT]  = { NULL, NULL, NULL, NULL, NULL, NULL };
    Item *hisItems[TRADE_SLOT_TRADED_COUNT] = { NULL, NULL, NULL, NULL, NULL, NULL };
    bool myCanCompleteTrade=true,hisCanCompleteTrade=true;

    // set before checks for propertly undo at problems (it already set in to client)
    my_trade->SetAccepted(true);

    // not accept case incorrect money amount
    if (my_trade->GetMoney() > _player->GetMoney())
    {
        SendNotification(LANG_NOT_ENOUGH_GOLD);
        my_trade->SetAccepted(false, true);
        return;
    }

    // not accept case incorrect money amount
    if (his_trade->GetMoney() > trader->GetMoney())
    {
        trader->GetSession( )->SendNotification(LANG_NOT_ENOUGH_GOLD);
        his_trade->SetAccepted(false, true);
        return;
    }

    // not accept if some items now can't be trade (cheating)
    for(int i = 0; i < TRADE_SLOT_TRADED_COUNT; ++i)
    {
        if (Item* item = my_trade->GetItem(TradeSlots(i)))
        {
            if (!item->CanBeTraded())
            {
                SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
                return;
            }
        }

        if (Item* item  = his_trade->GetItem(TradeSlots(i)))
        {
            if (!item->CanBeTraded())
            {
                SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
                return;
            }
        }
    }

    if (his_trade->IsAccepted())
    {
        setAcceptTradeMode(my_trade, his_trade, myItems, hisItems);

        Spell* my_spell = NULL;
        SpellCastTargets my_targets;

        Spell* his_spell = NULL;
        SpellCastTargets his_targets;

        // not accept if spell can't be casted now (cheating)
        if (uint32 my_spell_id = my_trade->GetSpell())
        {
            SpellEntry const* spellEntry = sSpellStore.LookupEntry(my_spell_id);
            Item* castItem = my_trade->GetSpellCastItem();

            if (!spellEntry || !his_trade->GetItem(TRADE_SLOT_NONTRADED) ||
                my_trade->HasSpellCastItem() && !castItem)
            {
                clearAcceptTradeMode(my_trade, his_trade);
                clearAcceptTradeMode(myItems, hisItems);

                my_trade->SetSpell(0);
                return;
            }

            my_spell = new Spell(_player, spellEntry, true);
            my_spell->m_CastItem = castItem;
            my_targets.setTradeItemTarget(_player);
            my_spell->m_targets = my_targets;

            SpellCastResult res = my_spell->CheckCast(true);
            if (res != SPELL_CAST_OK)
            {
                my_spell->SendCastResult(res);

                clearAcceptTradeMode(my_trade, his_trade);
                clearAcceptTradeMode(myItems, hisItems);

                delete my_spell;
                my_trade->SetSpell(0);
                return;
            }
        }

        // not accept if spell can't be casted now (cheating)
        if (uint32 his_spell_id = his_trade->GetSpell())
        {
            SpellEntry const* spellEntry = sSpellStore.LookupEntry(his_spell_id);
            Item* castItem = his_trade->GetSpellCastItem();

            if (!spellEntry || !my_trade->GetItem(TRADE_SLOT_NONTRADED) ||
                his_trade->HasSpellCastItem() && !castItem)
            {
                delete my_spell;
                his_trade->SetSpell(0);

                clearAcceptTradeMode(my_trade, his_trade);
                clearAcceptTradeMode(myItems, hisItems);
                return;
            }

            his_spell = new Spell(trader, spellEntry, true);
            his_spell->m_CastItem = castItem;
            his_targets.setTradeItemTarget(trader);
            his_spell->m_targets = his_targets;

            SpellCastResult res = his_spell->CheckCast(true);
            if (res != SPELL_CAST_OK)
            {
                his_spell->SendCastResult(res);

                clearAcceptTradeMode(my_trade, his_trade);
                clearAcceptTradeMode(myItems, hisItems);

                delete my_spell;
                delete his_spell;

                his_trade->SetSpell(0);
                return;
            }
        }

        // inform partner client
        trader->GetSession()->SendTradeStatus(TRADE_STATUS_TRADE_ACCEPT);

        // test if item will fit in each inventory
        hisCanCompleteTrade =  (trader->CanStoreItems( myItems,TRADE_SLOT_TRADED_COUNT )== EQUIP_ERR_OK);
        myCanCompleteTrade = (_player->CanStoreItems( hisItems,TRADE_SLOT_TRADED_COUNT ) == EQUIP_ERR_OK);

        clearAcceptTradeMode(myItems, hisItems);

        // in case of missing space report error
        if(!myCanCompleteTrade)
        {
            clearAcceptTradeMode(my_trade, his_trade);

            SendNotification(LANG_NOT_FREE_TRADE_SLOTS);
            trader->GetSession( )->SendNotification(LANG_NOT_PARTNER_FREE_TRADE_SLOTS);
            my_trade->SetAccepted(false);
            his_trade->SetAccepted(false);
            return;
        }
        else if (!hisCanCompleteTrade)
        {
            clearAcceptTradeMode(my_trade, his_trade);

            SendNotification(LANG_NOT_PARTNER_FREE_TRADE_SLOTS);
            trader->GetSession()->SendNotification(LANG_NOT_FREE_TRADE_SLOTS);
            my_trade->SetAccepted(false);
            his_trade->SetAccepted(false);
            return;
        }

        // execute trade: 1. remove
        for(int i = 0; i < TRADE_SLOT_TRADED_COUNT; ++i)
        {
            if (Item* item = myItems[i])
            {
                item->SetGuidValue(ITEM_FIELD_GIFTCREATOR, _player->GetObjectGuid());
                _player->MoveItemFromInventory(item->GetBagSlot(), item->GetSlot(), true);
            }
            if (Item* item = hisItems[i])
            {
                item->SetGuidValue(ITEM_FIELD_GIFTCREATOR, trader->GetObjectGuid());
                trader->MoveItemFromInventory(item->GetBagSlot(), item->GetSlot(), true);
            }
        }

        // execute trade: 2. store
        moveItems(myItems, hisItems);

        // logging money
        if (sWorld.getConfig(CONFIG_BOOL_GM_LOG_TRADE))
        {
            if (_player->GetSession()->GetSecurity() > SEC_PLAYER && my_trade->GetMoney() > 0)
            {
                sLog.outCommand(_player->GetSession()->GetAccountId(),"GM %s (Account: %u) give money (Amount: %u) to player: %s (Account: %u)",
                    _player->GetName(),_player->GetSession()->GetAccountId(),
                    my_trade->GetMoney(),
                    trader->GetName(), trader->GetSession()->GetAccountId());
            }
            if (trader->GetSession()->GetSecurity() > SEC_PLAYER && his_trade->GetMoney() > 0)
            {
                sLog.outCommand(trader->GetSession()->GetAccountId(),"GM %s (Account: %u) give money (Amount: %u) to player: %s (Account: %u)",
                    trader->GetName(), trader->GetSession()->GetAccountId(),
                    his_trade->GetMoney(),
                    _player->GetName(),_player->GetSession()->GetAccountId());
            }
        }

        // update money
        _player->ModifyMoney( -int32(my_trade->GetMoney()) );
        _player->ModifyMoney(his_trade->GetMoney());
        trader->ModifyMoney( -int32(his_trade->GetMoney()) );
        trader->ModifyMoney(my_trade->GetMoney());

        if (my_spell)
            my_spell->prepare(&my_targets);

        if (his_spell)
            his_spell->prepare(&his_targets);

        // cleanup
        clearAcceptTradeMode(my_trade, his_trade);
        delete _player->m_trade;
        _player->m_trade = NULL;
        delete trader->m_trade;
        trader->m_trade = NULL;

        // desynchronized with the other saves here (SaveInventoryAndGoldToDB() not have own transaction guards)
        CharacterDatabase.BeginTransaction();
        _player->SaveInventoryAndGoldToDB();
        trader->SaveInventoryAndGoldToDB();
        CharacterDatabase.CommitTransaction();

        trader->GetSession()->SendTradeStatus(TRADE_STATUS_TRADE_COMPLETE);
        SendTradeStatus(TRADE_STATUS_TRADE_COMPLETE);
    }
    else
    {
        trader->GetSession()->SendTradeStatus(TRADE_STATUS_TRADE_ACCEPT);
    }
}

void WorldSession::HandleUnacceptTradeOpcode(WorldPacket& /*recvPacket*/)
{
    TradeData* my_trade = _player->m_trade;
    if (!my_trade)
        return;

    my_trade->SetAccepted(false, true);
}

void WorldSession::HandleBeginTradeOpcode(WorldPacket& /*recvPacket*/)
{
    TradeData* my_trade = _player->m_trade;
    if (!my_trade)
        return;

    my_trade->GetTrader()->GetSession()->SendTradeStatus(TRADE_STATUS_OPEN_WINDOW);
    SendTradeStatus(TRADE_STATUS_OPEN_WINDOW);
}

void WorldSession::SendCancelTrade()
{
    if (m_playerRecentlyLogout)
        return;

    SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
}

void WorldSession::HandleCancelTradeOpcode(WorldPacket& /*recvPacket*/)
{
    // sended also after LOGOUT COMPLETE
    if (_player)                                            // needed because STATUS_LOGGEDIN_OR_RECENTLY_LOGGOUT
        _player->TradeCancel(true);
}

void WorldSession::HandleInitiateTradeOpcode(WorldPacket& recvPacket)
{
    uint64 ID;
    recvPacket >> ID;

    if (GetPlayer()->m_trade)
        return;

    if (!GetPlayer()->isAlive())
    {
        SendTradeStatus(TRADE_STATUS_YOU_DEAD);
        return;
    }

    if (GetPlayer()->hasUnitState(UNIT_STAT_STUNNED))
    {
        SendTradeStatus(TRADE_STATUS_YOU_STUNNED);
        return;
    }

    if (isLogingOut())
    {
        SendTradeStatus(TRADE_STATUS_YOU_LOGOUT);
        return;
    }

    if (GetPlayer()->IsTaxiFlying())
    {
        SendTradeStatus(TRADE_STATUS_TARGET_TO_FAR);
        return;
    }

    Player* pOther = ObjectAccessor::FindPlayer( ID );

    if (!pOther)
    {
        SendTradeStatus(TRADE_STATUS_NO_TARGET);
        return;
    }

    if (pOther == GetPlayer() || pOther->m_trade)
    {
        SendTradeStatus(TRADE_STATUS_BUSY);
        return;
    }

    if (!pOther->isAlive())
    {
        SendTradeStatus(TRADE_STATUS_TARGET_DEAD);
        return;
    }

    if (pOther->IsTaxiFlying())
    {
        SendTradeStatus(TRADE_STATUS_TARGET_TO_FAR);
        return;
    }

    if (pOther->hasUnitState(UNIT_STAT_STUNNED))
    {
        SendTradeStatus(TRADE_STATUS_TARGET_STUNNED);
        return;
    }

    if (pOther->GetSession()->isLogingOut())
    {
        SendTradeStatus(TRADE_STATUS_TARGET_LOGOUT);
        return;
    }

    if (pOther->GetSocial()->HasIgnore(GetPlayer()->GetGUIDLow()))
    {
        SendTradeStatus(TRADE_STATUS_IGNORE_YOU);
        return;
    }

    if (pOther->GetTeam() !=_player->GetTeam() )
    {
        SendTradeStatus(TRADE_STATUS_WRONG_FACTION);
        return;
    }

    if (!pOther->IsWithinDistInMap(_player,10.0f,false))
    {
        SendTradeStatus(TRADE_STATUS_TARGET_TO_FAR);
        return;
    }

    // OK start trade
    _player->m_trade = new TradeData(_player, pOther);
    pOther->m_trade = new TradeData(pOther, _player);

    WorldPacket data(SMSG_TRADE_STATUS, 12);
    data << (uint32) TRADE_STATUS_BEGIN_TRADE;
    data << (uint64)_player->GetGUID();
    pOther->GetSession()->SendPacket(&data);
}

void WorldSession::HandleSetTradeGoldOpcode(WorldPacket& recvPacket)
{
    uint32 gold;

    recvPacket >> gold;

    TradeData* my_trade = _player->GetTradeData();
    if (!my_trade)
        return;

    // gold can be incorrect, but this is checked at trade finished.
    my_trade->SetMoney(gold);
}

void WorldSession::HandleSetTradeItemOpcode(WorldPacket& recvPacket)
{
    // send update
    uint8 tradeSlot;
    uint8 bag;
    uint8 slot;

    recvPacket >> tradeSlot;
    recvPacket >> bag;
    recvPacket >> slot;

    TradeData* my_trade = _player->m_trade;
    if (!my_trade)
        return;

    // invalid slot number
    if (tradeSlot >= TRADE_SLOT_COUNT)
    {
        SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
        return;
    }

    // check cheating, can't fail with correct client operations
    Item* item = _player->GetItemByPos(bag, slot);
    if (!item || (tradeSlot != TRADE_SLOT_NONTRADED && !item->CanBeTraded()))
    {
        SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
        return;
    }

    // prevent place single item into many trade slots using cheating and client bugs
    if (my_trade->HasItem(item->GetObjectGuid()))
    {
        // cheating attempt
        SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
        return;
    }

    my_trade->SetItem(TradeSlots(tradeSlot), item);
}

void WorldSession::HandleClearTradeItemOpcode(WorldPacket& recvPacket)
{
    uint8 tradeSlot;
    recvPacket >> tradeSlot;

    TradeData* my_trade = _player->m_trade;
    if (!my_trade)
        return;

    // invalid slot number
    if (tradeSlot >= TRADE_SLOT_COUNT)
        return;

    my_trade->SetItem(TradeSlots(tradeSlot), NULL);
}