[refactor] New buff framework (player implementation)

Get rid of `iConditionBitFlag` in favor of a system of individual buff
objects that get composited to a bitflag on-the-fly.
Buff objects can have callbacks for application, expiration, and tick,
making them pretty flexible. Scripting languages can eventually use
these for custom behavior, too.

TODO:
- Get rid of bitflag in BaseNPC
- Apply buffs from passive nano powers
- Apply buffs from active nano powers
- Move eggs to new system
- ???

src/Buffs.hpp

@@ -0,0 +1,90 @@
+#pragma once
+
+#include "core/Core.hpp"
+
+#include "EntityRef.hpp"
+
+#include <vector>
+#include <functional>
+
+/* forward declaration(s) */
+class Buff;
+template<class... Types>
+using BuffCallback = std::function<void(EntityRef, Buff*, Types...)>;
+
+#define CSB_FROM_ECSB(x) (1 << (x - 1))
+
+enum class BuffClass {
+    NONE = ETBT_NONE,
+	NANO = ETBT_NANO,
+	GROUP_NANO = ETBT_GROUPNANO,
+	EGG = ETBT_SHINY,
+	ENVIRONMENT = ETBT_LANDEFFECT,
+	ITEM = ETBT_ITEM,
+	CASH_ITEM = ETBT_CASHITEM
+};
+
+enum class BuffValueSelector {
+    MAX_VALUE,
+    MIN_VALUE,
+    MAX_MAGNITUDE,
+    MIN_MAGNITUDE,
+    NET_TOTAL
+};
+
+struct BuffStack {
+    int durationTicks;
+    int value;
+    EntityRef source;
+    BuffClass buffStackClass;
+};
+
+class Buff {
+private:
+    EntityRef self;
+    std::vector<BuffStack> stacks;
+
+public:
+    int id;
+    /* called just after a stack is added or removed */
+    BuffCallback<int, BuffStack*> onUpdate;
+    /* called when the buff is combat-ticked */
+    BuffCallback<time_t> onCombatTick;
+
+    void tick(time_t);
+    void combatTick(time_t);
+    void clear();
+    void clear(BuffClass buffClass);
+    void addStack(BuffStack* stack);
+
+    /*
+    * Sometimes we need to determine if a buff
+    * is covered by a certain class, ex: nano
+    * vs. coco egg in the case of infection protection
+    */
+    bool hasClass(BuffClass buffClass);
+    BuffClass maxClass();
+
+    int getValue(BuffValueSelector selector);
+
+    /* 
+     * In general, a Buff object won't exist
+     * unless it has stacks. However, when
+     * popping stacks during iteration (onExpire),
+     * stacks will be empty for a brief moment
+     * when the last stack is popped.
+     */
+    bool isStale();
+
+    void updateCallbacks(BuffCallback<int, BuffStack*> fOnUpdate, BuffCallback<time_t> fonTick);
+
+    Buff(int iid, EntityRef pSelf, BuffCallback<int, BuffStack*> fOnUpdate, BuffCallback<time_t> fOnCombatTick, BuffStack* firstStack)
+        : self(pSelf), id(iid), onUpdate(fOnUpdate), onCombatTick(fOnCombatTick) {
+        addStack(firstStack);
+    }
+};
+
+namespace Buffs {
+    void timeBuffUpdate(EntityRef self, Buff* buff, int status, BuffStack* stack);
+    void timeBuffTimeout(EntityRef self);
+}