#define CBC_ORDER_EXCLUSIVE 3
#define CBC_ORDER_FIRST 1
#define CBC_ORDER_LAST 2
#define CBC_ORDER_ANY 4

entity CallbackChain_New(string name);
float CallbackChain_Add(entity cb, float() func, float order)
float CallbackChain_Remove(entity cb, float() func);
// a callback function is like this:
// float mycallback(entity me)
// {
//   do something
//   return r;
// }
float CallbackChain_Call(entity cb);

#define MUTATOR_REMOVING 0
#define MUTATOR_ADDING 1
float Mutator_Add(float(float) func);
void Mutator_Remove(float(float) func); // calls error() on fail

#define MUTATOR_ADD(name) Mutator_Add(MUTATOR_##name)
#define MUTATOR_REMOVE(name) Mutator_Remove(MUTATOR_##name)
#define MUTATOR_DEFINITION(name) float MUTATOR_##name(float mode)
#define MUTATOR_DECLARATION(name) float MUTATOR_##name(float mode)
#define MUTATOR_HOOKFUNCTION(name) float HOOKFUNCTION_##name()
#define MUTATOR_HOOK(cb,func,order) do { if(mode == MUTATOR_ADDING) { if(!HOOK_##cb) HOOK_##cb = CallbackChain_New(#cb); if(!CallbackChain_Add(HOOK_##cb,HOOKFUNCTION_##func,order)) { print("HOOK FAILED: ", #func, "\n"); return 1; } } else if(mode == MUTATOR_REMOVING) { if(HOOK_##cb) CallbackChain_Remove(HOOK_##cb,HOOKFUNCTION_##func); } } while(0)
#define MUTATOR_ONADD if(mode == MUTATOR_ADDING)
#define MUTATOR_ONREMOVE if(mode == MUTATOR_REMOVING)

#define MUTATOR_HOOKABLE(cb) entity HOOK_##cb
#define MUTATOR_CALLHOOK(cb) CallbackChain_Call(HOOK_##cb)





// register all possible hooks here
MUTATOR_HOOKABLE(MakePlayerObserver);
MUTATOR_HOOKABLE(MakePlayerSpectator);
MUTATOR_HOOKABLE(PlayerSpawn);
MUTATOR_HOOKABLE(ClientDisconnect);
MUTATOR_HOOKABLE(PlayerDies); entity other; entity frag_attacker;
MUTATOR_HOOKABLE(GiveFragsForKill); entity frag_attacker, frag_target; float frag_score;
MUTATOR_HOOKABLE(MatchEnd);
MUTATOR_HOOKABLE(GetTeamCount); float ret_float;
MUTATOR_HOOKABLE(SpectateCopy); entity other;
MUTATOR_HOOKABLE(ForbidThrowCurrentWeapon);
MUTATOR_HOOKABLE(SetStartItems);
MUTATOR_HOOKABLE(BuildMutatorsString); string ret_string;
MUTATOR_HOOKABLE(BuildMutatorsPrettyString); string ret_string;
MUTATOR_HOOKABLE(FilterItem); // return error to request removal, or change self.items or self.weapons
MUTATOR_HOOKABLE(OnEntityPreSpawn); // return error to prevent entity spawn, or modify the entity
MUTATOR_HOOKABLE(PlayerPreThink);