Core/AHBot: Adjust AHBot bid and buyout chances

Apply an exponential formula to define the chance to bid/buyout an auction depending on auction price and item price ratio. The formula can be adjusted changing the new AuctionHouseBot.Buyer.ChanceFactor config parameter
Chance = 100 ^ (1 + (1 - (auction_price / item_price) / k)
k is the config parameter AuctionHouseBot.Buyer.ChanceFactor, the higher the number the higher chance to buy overpriced auctions.

(cherry picked from commit 177b6319d1ad49a38fbd06f37671da1e3d1ae4e6)

Conflicts:
	src/server/game/AuctionHouseBot/AuctionHouseBotBuyer.cpp

4 files changed, 38 insertions, 18 deletions

diff --git a/src/server/game/AuctionHouseBot/AuctionHouseBot.cpp b/src/server/game/AuctionHouseBot/AuctionHouseBot.cpp
index fd78e933960..5f791becf41 100644
--- a/src/server/game/AuctionHouseBot/AuctionHouseBot.cpp
+++ b/src/server/game/AuctionHouseBot/AuctionHouseBot.cpp
@@ -97,6 +97,11 @@ void AuctionBotConfig::SetConfig(AuctionBotConfigBoolValues index, char const* f
     SetConfig(index, sConfigMgr->GetBoolDefault(fieldname, defvalue));
 }
 
+void AuctionBotConfig::SetConfig(AuctionBotConfigFloatValues index, char const* fieldname, float defvalue)
+{
+    SetConfig(index, sConfigMgr->GetFloatDefault(fieldname, defvalue));
+}
+
 //Get AuctionHousebot configuration file
 void AuctionBotConfig::GetConfigFromFile()
 {
@@ -111,6 +116,8 @@ void AuctionBotConfig::GetConfigFromFile()
     SetConfig(CONFIG_AHBOT_BUYER_HORDE_ENABLED, "AuctionHouseBot.Buyer.Horde.Enabled", false);
     SetConfig(CONFIG_AHBOT_BUYER_NEUTRAL_ENABLED, "AuctionHouseBot.Buyer.Neutral.Enabled", false);
 
+    SetConfig(CONFIG_AHBOT_BUYER_CHANCE_FACTOR, "AuctionHouseBot.Buyer.ChanceFactor", 2.0f);
+
     SetConfig(CONFIG_AHBOT_ITEMS_VENDOR, "AuctionHouseBot.Items.Vendor", false);
     SetConfig(CONFIG_AHBOT_ITEMS_LOOT, "AuctionHouseBot.Items.Loot", true);
     SetConfig(CONFIG_AHBOT_ITEMS_MISC, "AuctionHouseBot.Items.Misc", false);
diff --git a/src/server/game/AuctionHouseBot/AuctionHouseBot.h b/src/server/game/AuctionHouseBot/AuctionHouseBot.h
index d7570c37d44..225d3b7ee25 100644
--- a/src/server/game/AuctionHouseBot/AuctionHouseBot.h
+++ b/src/server/game/AuctionHouseBot/AuctionHouseBot.h
@@ -174,6 +174,12 @@ enum AuctionBotConfigBoolValues
     CONFIG_UINT32_AHBOT_BOOL_COUNT
 };
 
+enum AuctionBotConfigFloatValues
+{
+    CONFIG_AHBOT_BUYER_CHANCE_FACTOR,
+    CONFIG_AHBOT_FLOAT_COUNT
+};
+
 // All basic config data used by other AHBot classes for self-configure.
 class AuctionBotConfig
 {
@@ -196,8 +202,10 @@ public:
 
     uint32 GetConfig(AuctionBotConfigUInt32Values index) const { return _configUint32Values[index]; }
     bool GetConfig(AuctionBotConfigBoolValues index) const { return _configBoolValues[index]; }
+    float GetConfig(AuctionBotConfigFloatValues index) const { return _configFloatValues[index]; }
     void SetConfig(AuctionBotConfigBoolValues index, bool value) { _configBoolValues[index] = value; }
     void SetConfig(AuctionBotConfigUInt32Values index, uint32 value) { _configUint32Values[index] = value; }
+    void SetConfig(AuctionBotConfigFloatValues index, float value) { _configFloatValues[index] = value; }
 
     uint32 GetConfigItemAmountRatio(AuctionHouseType houseType) const;
     bool GetConfigBuyerEnabled(AuctionHouseType houseType) const;
@@ -217,6 +225,7 @@ private:
 
     uint32 _configUint32Values[CONFIG_UINT32_AHBOT_UINT32_COUNT];
     bool _configBoolValues[CONFIG_UINT32_AHBOT_BOOL_COUNT];
+    float _configFloatValues[CONFIG_AHBOT_FLOAT_COUNT];
 
     void SetAHBotIncludes(const std::string& AHBotIncludes) { _AHBotIncludes = AHBotIncludes; }
     void SetAHBotExcludes(const std::string& AHBotExcludes) { _AHBotExcludes = AHBotExcludes; }
@@ -225,6 +234,7 @@ private:
     void SetConfigMax(AuctionBotConfigUInt32Values index, char const* fieldname, uint32 defvalue, uint32 maxvalue);
     void SetConfigMinMax(AuctionBotConfigUInt32Values index, char const* fieldname, uint32 defvalue, uint32 minvalue, uint32 maxvalue);
     void SetConfig(AuctionBotConfigBoolValues index, char const* fieldname, bool defvalue);
+    void SetConfig(AuctionBotConfigFloatValues index, char const* fieldname, float defvalue);
     void GetConfigFromFile();
 };
 
diff --git a/src/server/game/AuctionHouseBot/AuctionHouseBotBuyer.cpp b/src/server/game/AuctionHouseBot/AuctionHouseBotBuyer.cpp
index 993494c8b80..06ca0b02640 100644
--- a/src/server/game/AuctionHouseBot/AuctionHouseBotBuyer.cpp
+++ b/src/server/game/AuctionHouseBot/AuctionHouseBotBuyer.cpp
@@ -157,18 +157,18 @@ bool AuctionBotBuyer::RollBuyChance(const BuyerItemInfo* ahInfo, const Item* ite
     if (!auction->buyout)
         return false;
 
-    uint32 itemBuyPrice = auction->buyout / item->GetCount();
-    uint32 itemPrice = item->GetTemplate()->GetSellPrice() ? item->GetTemplate()->GetSellPrice() : GetVendorPrice(item->GetTemplate()->GetQuality());
+    float itemBuyPrice = float(auction->buyout / item->GetCount());
+    float itemPrice = float(item->GetTemplate()->GetSellPrice() ? item->GetTemplate()->GetSellPrice() : GetVendorPrice(item->GetTemplate()->GetQuality()));
     // The AH cut needs to be added to the price, but we dont want a 100% chance to buy if the price is exactly AH default
     itemPrice *= 1.4f;
 
     // This value is between 0 and 100 and is used directly as the chance to buy or bid
     // Value equal or above 100 means 100% chance and value below 0 means 0% chance
-    float chance = 100 / sqrt(itemBuyPrice / float(itemPrice));
+    float chance = std::min(100.f, std::pow(100.f, 1.f + (1.f - itemBuyPrice / itemPrice) / sAuctionBotConfig->GetConfig(CONFIG_AHBOT_BUYER_CHANCE_FACTOR)));
 
     // If a player has bidded on item, have fifth of normal chance
     if (auction->bidder)
-        chance = chance / 5;
+        chance = chance / 5.f;
 
     if (ahInfo)
     {
@@ -178,31 +178,29 @@ bool AuctionBotBuyer::RollBuyChance(const BuyerItemInfo* ahInfo, const Item* ite
 
         // If there are more than 5 items on AH of this entry, try weigh in the average buyout price
         if (ahInfo->BuyItemCount > 5)
-        {
-            chance *= 1 / sqrt(itemBuyPrice / avgBuyPrice);
-        }
+            chance *= 1.f / std::sqrt(itemBuyPrice / avgBuyPrice);
     }
 
     // Add config weigh in for quality
     chance *= GetChanceMultiplier(item->GetTemplate()->GetQuality()) / 100.0f;
 
-    float rand = frand(0, 100);
+    float rand = frand(0.f, 100.f);
     bool win = rand <= chance;
-    TC_LOG_DEBUG("ahbot", "AHBot: %s BUY! chance = %.2f, price = %u, buyprice = %u.", win ? "WIN" : "LOSE", chance, itemPrice, itemBuyPrice);
+    TC_LOG_DEBUG("ahbot", "AHBot: %s BUY! chance = %.2f, price = %u, buyprice = %u.", win ? "WIN" : "LOSE", chance, uint32(itemPrice), uint32(itemBuyPrice));
     return win;
 }
 
 // ahInfo can be NULL
 bool AuctionBotBuyer::RollBidChance(const BuyerItemInfo* ahInfo, const Item* item, const AuctionEntry* auction, uint32 bidPrice)
 {
-    uint32 itemBidPrice = bidPrice / item->GetCount();
-    uint32 itemPrice = item->GetTemplate()->GetSellPrice() ? item->GetTemplate()->GetSellPrice() : GetVendorPrice(item->GetTemplate()->GetQuality());
+    float itemBidPrice = float(bidPrice / item->GetCount());
+    float itemPrice = float(item->GetTemplate()->GetSellPrice() ? item->GetTemplate()->GetSellPrice() : GetVendorPrice(item->GetTemplate()->GetQuality()));
     // The AH cut needs to be added to the price, but we dont want a 100% chance to buy if the price is exactly AH default
     itemPrice *= 1.4f;
 
     // This value is between 0 and 100 and is used directly as the chance to buy or bid
     // Value equal or above 100 means 100% chance and value below 0 means 0% chance
-    float chance = 100 / sqrt(itemBidPrice / float(itemPrice));
+    float chance = std::min(100.f, std::pow(100.f, 1.f + (1.f - itemBidPrice / itemPrice) / sAuctionBotConfig->GetConfig(CONFIG_AHBOT_BUYER_CHANCE_FACTOR)));
 
     if (ahInfo)
     {
@@ -212,21 +210,19 @@ bool AuctionBotBuyer::RollBidChance(const BuyerItemInfo* ahInfo, const Item* ite
 
         // If there are more than 5 items on AH of this entry, try weigh in the average bid price
         if (ahInfo->BidItemCount >= 5)
-        {
-            chance *= 1 / sqrt(itemBidPrice / avgBidPrice);
-        }
+            chance *= 1.f / std::sqrt(itemBidPrice / avgBidPrice);
     }
 
     // If a player has bidded on item, have fifth of normal chance
     if (auction->bidder)
-        chance = chance / 5;
+        chance = chance / 5.f;
 
     // Add config weigh in for quality
     chance *= GetChanceMultiplier(item->GetTemplate()->GetQuality()) / 100.0f;
 
-    float rand = frand(0, 100);
+    float rand = frand(0.f, 100.f);
     bool win = rand <= chance;
-    TC_LOG_DEBUG("ahbot", "AHBot: %s BID! chance = %.2f, price = %u, bidprice = %u.", win ? "WIN" : "LOSE", chance, itemPrice, itemBidPrice);
+    TC_LOG_DEBUG("ahbot", "AHBot: %s BID! chance = %.2f, price = %u, bidprice = %u.", win ? "WIN" : "LOSE", chance, uint32(itemPrice), uint32(itemBidPrice));
     return win;
 }
 
diff --git a/src/server/worldserver/worldserver.conf.dist b/src/server/worldserver/worldserver.conf.dist
index 2465bdd3bdb..bb9c6ae9b0a 100644
--- a/src/server/worldserver/worldserver.conf.dist
+++ b/src/server/worldserver/worldserver.conf.dist
@@ -3153,6 +3153,13 @@ AuctionHouseBot.Buyer.Alliance.Enabled = 0
 AuctionHouseBot.Buyer.Horde.Enabled = 0
 AuctionHouseBot.Buyer.Neutral.Enabled = 0
 
+#    AuctionHouseBot.Buyer.ChanceFactor
+#       Description: k value in the formula used for the chance to buy an item "100^(1 + (1 - (AuctionBid / ItemPrice)) / k)"
+#                    It must be a decimal number in the range of (0, +infinity). The higher the number the higher chance to buy overpriced auctions
+#       Default:     2
+
+AuctionHouseBot.Buyer.ChanceFactor = 2
+
 #
 #    AuctionHouseBot.Buyer.Baseprice.QUALITY
 #       Description: Base sellprices in copper for non priced items for each quality.