PreviewVendor

// Scriptname to put into creature_template: PreviewVendor
// dont forget to add vendor flags to the NPC (128)

#include "ScriptPCH.h"

static UNORDERED_MAP<uint32, std::vector<uint32> > itemList; // holds items from DB after startup

class PreviewLoader : public WorldScript // script that loads items from DB so you can customize the vendors without recompile and restart
{
public:
    PreviewLoader() : WorldScript("PreviewLoader") { }

    void OnStartup()
    {
        itemList.clear(); // reload
        QueryResult result = WorldDatabase.Query("SELECT entry, item FROM npc_vendor_preview");
        if (!result)
            return;
        do
        {
            uint32 entry = (*result)[0].GetUInt32();
            uint32 item = (*result)[1].GetUInt32();
            if (sObjectMgr->GetItemTemplate(item))
                itemList[entry].push_back(item);
        } while (result->NextRow());
    }

    // you can reload config to reload the items.
    // Too lazy to make a command since all the RBAC stuff changes all the time now and not sure how you have it
    void OnConfigLoad(bool reload)
    {
        if (reload)
            OnStartup();
    }
};


class PreviewVendor : public CreatureScript
{
public:
    PreviewVendor() : CreatureScript("PreviewVendor") { }

    bool OnGossipHello(Player* player, Creature* creature)
    {
        CustomSendListInventory(player, creature->GetGUID());
        return true; // stop normal actions
    }

    void CustomSendListInventory(Player* player, uint64 vendorGuid)
    {
        TC_LOG_DEBUG(LOG_FILTER_NETWORKIO, "WORLD: Sent custom SMSG_LIST_INVENTORY");

        WorldSession* session = player->GetSession();

        Creature* vendor = player->GetNPCIfCanInteractWith(vendorGuid, UNIT_NPC_FLAG_VENDOR);
        if (!vendor)
        {
            TC_LOG_DEBUG(LOG_FILTER_NETWORKIO, "WORLD: SendListInventory - Unit (GUID: %u) not found or you can not interact with him.", uint32(GUID_LOPART(vendorGuid)));
            player->SendSellError(SELL_ERR_CANT_FIND_VENDOR, NULL, 0);
            return;
        }

        // remove fake death
        if (player->HasUnitState(UNIT_STATE_DIED))
            player->RemoveAurasByType(SPELL_AURA_FEIGN_DEATH);

        // Stop the npc if moving
        if (vendor->HasUnitState(UNIT_STATE_MOVING))
            vendor->StopMoving();

        // VendorItemData const* items = vendor->GetVendorItems();
        if (itemList.find(vendor->GetEntry()) == itemList.end())
        {
            WorldPacket data(SMSG_LIST_INVENTORY, 8 + 1 + 1);
            data << uint64(vendorGuid);
            data << uint8(0);                                   // count == 0, next will be error code
            data << uint8(0);                                   // "Vendor has no inventory"
            session->SendPacket(&data);
            return;
        }

        std::vector<uint32> items = itemList[vendor->GetEntry()];
        uint8 itemCount = items.size();
        uint8 count = 0;

        WorldPacket data(SMSG_LIST_INVENTORY, 8 + 1 + itemCount * 8 * 4);
        data << uint64(vendorGuid);

        size_t countPos = data.wpos();
        data << uint8(count);

        // float discountMod = player->GetReputationPriceDiscount(vendor);

        for (uint8 slot = 0; slot < itemCount; ++slot)
        {
            if (ItemTemplate const* itemTemplate = sObjectMgr->GetItemTemplate(items[slot]))
            {
                if (!(itemTemplate->AllowableClass & player->getClassMask()) && itemTemplate->Bonding == BIND_WHEN_PICKED_UP && !player->IsGameMaster())
                    continue;
                // Only display items in vendor lists for the team the
                // player is on. If GM on, display all items.
                if (!player->IsGameMaster() && ((itemTemplate->Flags2 & ITEM_FLAGS_EXTRA_HORDE_ONLY && player->GetTeam() == ALLIANCE) || (itemTemplate->Flags2 == ITEM_FLAGS_EXTRA_ALLIANCE_ONLY && player->GetTeam() == HORDE)))
                    continue;

                // Items sold out are not displayed in list
                // uint32 leftInStock = !item->maxcount ? 0xFFFFFFFF : vendor->GetVendorItemCurrentCount(item);
                // if (!player->IsGameMaster() && !leftInStock)
                //     continue;
                uint32 leftInStock = 0xFFFFFFFF; // show all items

                ConditionList conditions = sConditionMgr->GetConditionsForNpcVendorEvent(vendor->GetEntry(), items[slot]);
                if (!sConditionMgr->IsObjectMeetToConditions(player, vendor, conditions))
                {
                    TC_LOG_DEBUG(LOG_FILTER_CONDITIONSYS, "SendListInventory: conditions not met for creature entry %u item %u", vendor->GetEntry(), items[slot]);
                    continue;
                }

                // reputation discount
                // int32 price = item->IsGoldRequired(itemTemplate) ? uint32(floor(itemTemplate->BuyPrice * discountMod)) : 0;
                int32 price = 0;

                data << uint32(slot + 1);       // client expects counting to start at 1
                data << uint32(items[slot]);
                data << uint32(itemTemplate->DisplayInfoID);
                data << int32(leftInStock); // left in stock
                data << uint32(price); // price
                data << uint32(itemTemplate->MaxDurability);
                data << uint32(itemTemplate->BuyCount);
                data << uint32(0); // extended cost

                if (++count >= MAX_VENDOR_ITEMS)
                    break;
            }
        }

        if (count == 0)
        {
            data << uint8(0);
            session->SendPacket(&data);
            return;
        }

        data.put<uint8>(countPos, count);
        session->SendPacket(&data);
    }
};

void AddSC_PreviewVendor()
{
    new PreviewLoader;
    new PreviewVendor;
}