Add Buff infrastructure to go through different logic paths from different patches (#5073)

common/patches/IBuff.h

@@ -0,0 +1,60 @@
+/*	EQEmu: EQEmulator
+
+	Copyright (C) 2001-2026 EQEmu Development Team
+
+	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 3 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/>.
+*/
+
+#pragma once
+
+#include "common/emu_opcodes.h"
+
+#include <vector>
+#include <functional>
+
+class Client;
+class Mob;
+class EQApplicationPacket;
+class Buffs_Struct;
+
+namespace ClientPatch {
+
+class IBuff
+{
+public:
+    using BuffSequenceFunc = std::function<std::unique_ptr<EQApplicationPacket>(const Client*)>;
+
+    IBuff(uint32_t maxLongBuffs, uint32_t maxShortBuffs)
+      : m_maxLongBuffs(maxLongBuffs)
+      , m_maxShortBuffs(maxShortBuffs)
+    {}
+
+    IBuff() = delete;
+    virtual ~IBuff() = default;
+
+	virtual std::unique_ptr<EQApplicationPacket> BuffDefinition(Mob* mob, const Buffs_Struct& buff, uint32_t slot,
+        bool fade) const = 0;
+    virtual std::unique_ptr<EQApplicationPacket> RefreshBuffs(EmuOpcode opcode, Mob* mob, bool remove,
+        bool buff_timers_suspended, const std::vector<uint32_t>& slots) const = 0;
+    virtual void SetRefreshType(std::unique_ptr<EQApplicationPacket>& packet, uint8_t refresh_type) const = 0;
+	virtual bool NeedsWearMessage() const = 0;
+
+    uint32_t ServerToPatchBuffSlot(uint32_t slot) const;
+
+protected:
+    uint32_t m_maxLongBuffs;
+    uint32_t m_maxShortBuffs;
+};
+
+} // namespace Buff