Core/Quests: make the player questgiver handling a bit more flexible to allow popup quest accepting at more places in the future

src/server/game/Handlers/QuestHandler.cpp

@@ -127,17 +127,35 @@ void WorldSession::HandleQuestgiverAcceptQuestOpcode(WorldPackets::Quest::QuestG
 
     if (Player* playerQuestObject = object->ToPlayer())
     {
-        if ((!_player->GetPlayerSharingQuest().IsEmpty() && _player->GetPlayerSharingQuest() != packet.QuestGiverGUID)
-            || (_player != playerQuestObject && !playerQuestObject->CanShareQuest(packet.QuestID)))
+        // Various checks for player quest givers
+        if ((!_player->GetPlayerSharingQuest().IsEmpty() && _player->GetPlayerSharingQuest() != packet.QuestGiverGUID)     // Player tries to accept a shared quest from a different questiver
+            || (_player != playerQuestObject && !playerQuestObject->CanShareQuest(packet.QuestID)))                        // Player tries to accept a quest that cannot be shared
         {
             CLOSE_GOSSIP_CLEAR_SHARING_INFO();
             return;
         }
+
+        // Player tries to accept a quest from a player questgiver that he is not in a party/raid with
         if (!_player->IsInSameRaidWith(playerQuestObject))
         {
             CLOSE_GOSSIP_CLEAR_SHARING_INFO();
             return;
         }
+
+        // Player tries to accept a quest from himself that cannot be taken. Such quests must be provided by a quest with flag QUEST_FLAGS_AUTOCOMPLETE prior to that
+        if (_player->GetPopupQuestId())
+        {
+            if (_player->GetPopupQuestId() != packet.QuestID || _player->GetGUID() != packet.QuestGiverGUID)
+            {
+                CLOSE_GOSSIP_CLEAR_SHARING_INFO();
+                return;
+            }
+        }
+        else if (_player->GetGUID() == packet.QuestGiverGUID) // Covering all remaining poossible cheat scenarios when trying to exploit quest sharing
+        {
+            CLOSE_GOSSIP_CLEAR_SHARING_INFO();
+            return;
+        }
     }
     else
     {
@@ -207,6 +225,10 @@ void WorldSession::HandleQuestgiverAcceptQuestOpcode(WorldPackets::Quest::QuestG
             if (quest->GetSrcSpell() > 0)
                 _player->CastSpell(_player, quest->GetSrcSpell(), true);
 
+            // A quest has been accepted, reset popup follow quest ID because the quest has either been taken or another took its place
+            // so the player has to take the follow quest at its corresponding creature questgiver instead.
+            _player->SetPopupQuestId(0);
+
             return;
         }
     }
@@ -239,7 +261,10 @@ void WorldSession::HandleQuestgiverQueryQuestOpcode(WorldPackets::Quest::QuestGi
         if (quest->IsAutoComplete())
             _player->PlayerTalkClass->SendQuestGiverRequestItems(quest, object->GetGUID(), _player->CanCompleteQuest(quest->GetQuestId()), true);
         else
+        {
+            _player->SetPopupQuestId(0);
             _player->PlayerTalkClass->SendQuestGiverQuestDetails(quest, object->GetGUID(), true, false);
+        }
     }
 }
 
@@ -307,6 +332,12 @@ void WorldSession::HandleQuestgiverChooseRewardOpcode(WorldPackets::Quest::Quest
                         if (nextQuest->IsAutoAccept() && _player->CanAddQuest(nextQuest, true))
                             _player->AddQuestAndCheckCompletion(nextQuest, object);
 
+                        // Previous quest has been rewarded via popup. The player may now accept the follow quest from himself.
+                        if (object->IsPlayer() && quest->HasFlag(QUEST_FLAGS_AUTOCOMPLETE) && !nextQuest->IsAutoAccept())
+                            _player->SetPopupQuestId(nextQuest->GetQuestId());
+                        else
+                            _player->SetPopupQuestId(0);
+
                         _player->PlayerTalkClass->SendQuestGiverQuestDetails(nextQuest, packet.QuestGiverGUID, true, false);
                     }
                 }
@@ -327,6 +358,7 @@ void WorldSession::HandleQuestgiverChooseRewardOpcode(WorldPackets::Quest::Quest
                         if (nextQuest->IsAutoAccept() && _player->CanAddQuest(nextQuest, true))
                             _player->AddQuestAndCheckCompletion(nextQuest, object);
 
+                        _player->SetPopupQuestId(0);
                         _player->PlayerTalkClass->SendQuestGiverQuestDetails(nextQuest, packet.QuestGiverGUID, true, false);
                     }
                 }
@@ -614,6 +646,7 @@ void WorldSession::HandlePushQuestToParty(WorldPacket& recvPacket)
             receiver->PlayerTalkClass->SendQuestGiverRequestItems(quest, sender->GetGUID(), receiver->CanCompleteRepeatableQuest(quest), true);
         else
         {
+            receiver->SetPopupQuestId(0);
             receiver->SetQuestSharingInfo(sender->GetGUID(), questId);
             receiver->PlayerTalkClass->SendQuestGiverQuestDetails(quest, receiver->GetGUID(), true, false);
         }