[Spells] Update to SPA 378 SE_SpellEffectResistChance (#4845)

* SPA 378 update

Update to SPA 378

SE_SpellEffectResistChance provides chance to resist specific spell effects.

This updates allows support for multiple resistance checks against different effects in same spell.

Example. If a spell has a silence and a blind effect and the target has an AA that gives 10% chance to resist silence and 5% chance to resist blind. It will roll against effect respectively each giving a chance to resist the spell.

* Update spells.cpp

Unresistable spells (resisttype = 0) do not ever resist a spell even with SPA378

Example: Pheonix Charm in Plane of Fire, or Storm Comet in Bastion of Thunder. Parsed both and never got a resist despite having the AA that has effect specific resists which both those spells match.

zone/bonuses.cpp

@@ -5331,6 +5331,14 @@ void Mob::NegateSpellEffectBonuses(uint16 spell_id)
 							spellbonuses.SEResist[e]     = effect_value;
 							spellbonuses.SEResist[e + 1] = effect_value;
 						}
+						if (negate_itembonus) {
+							itembonuses.SEResist[e] = effect_value;
+							itembonuses.SEResist[e + 1] = effect_value;
+						}
+						if (negate_aabonus) {
+							aabonuses.SEResist[e] = effect_value;
+							aabonuses.SEResist[e + 1] = effect_value;
+						}
 					}
 					break;
 				}

zone/mob.h

@@ -962,7 +962,7 @@ public:
 	uint16 GetSympatheticFocusEffect(focusType type, uint16 spell_id);
 	bool TryFadeEffect(int slot);
 	void DispelMagic(Mob* casterm, uint16 spell_id, int effect_value);
-	uint16 GetSpellEffectResistChance(uint16 spell_id);
+	bool TrySpellEffectResist(uint16 spell_id);
 	int32 GetVulnerability(Mob *caster, uint32 spell_id, uint32 ticsremaining, bool from_buff_tic = false);
 	int64 GetFcDamageAmtIncoming(Mob *caster, int32 spell_id, bool from_buff_tic = false);
 	int64 GetFocusIncoming(focusType type, int effect, Mob *caster, uint32 spell_id); //**** This can be removed when bot healing focus code is updated ****

zone/spell_effects.cpp

@@ -7465,44 +7465,57 @@ void Mob::DispelMagic(Mob* caster, uint16 spell_id, int effect_value)
 	}
 }
 
-uint16 Mob::GetSpellEffectResistChance(uint16 spell_id)
+bool Mob::TrySpellEffectResist(uint16 spell_id)
 {
+	/*
+		SEResist variable
+		0 = spell effect id to be check if can resist
+		1 = percent chance of resistance
+	*/
 
-	if(!IsValidSpell(spell_id))
-		return 0;
 
-	if (!aabonuses.SEResist[1] && !spellbonuses.SEResist[1] && !itembonuses.SEResist[1])
-		return 0;
+	if (!IsValidSpell(spell_id)) {
+		return false;
+	}
 
-	uint16 resist_chance = 0;
+	if (!aabonuses.SEResist[1] && !spellbonuses.SEResist[1] && !itembonuses.SEResist[1]) {
+		return false;
+	}
+
+	int resist_chance = 0;
 
 	for(int i = 0; i < EFFECT_COUNT; ++i)
 	{
-		bool found = false;
+		if (spells[spell_id].effect_id[i] == SE_Blank) {
+			continue;
+		}
 
 		for(int d = 0; d < MAX_RESISTABLE_EFFECTS*2; d+=2)
 		{
+			resist_chance = 0;
 			if (spells[spell_id].effect_id[i] == aabonuses.SEResist[d]){
 				resist_chance += aabonuses.SEResist[d+1];
-				found = true;
 			}
 
 			if (spells[spell_id].effect_id[i] == itembonuses.SEResist[d]){
 				resist_chance += itembonuses.SEResist[d+1];
-				found = true;
 			}
 
-
 			if (spells[spell_id].effect_id[i] == spellbonuses.SEResist[d]){
 				resist_chance += spellbonuses.SEResist[d+1];
-				found = true;
 			}
 
-			if (found)
-				continue;
+			if (resist_chance) {
+				if (zone->random.Roll(resist_chance)) {
+					LogSpells("Resisted spell from Spell Effect Resistance, had [{}] chance to resist spell effect id [{}]", resist_chance, spells[spell_id].effect_id[i]);
+					return true;
+				}
+
+				break;
+			}
 		}
 	}
-	return resist_chance;
+	return false;
 }
 
 bool Mob::TryDispel(uint8 caster_level, uint8 buff_level, int level_modifier){

zone/spells.cpp

@@ -5359,8 +5359,7 @@ float Mob::ResistSpell(uint8 resist_type, uint16 spell_id, Mob *caster, bool use
 
 	if (!CharmTick) {
 		//Check for Spell Effect specific resistance chances (ie AA Mental Fortitude)
-		int se_resist_bonuses = GetSpellEffectResistChance(spell_id);
-		if (se_resist_bonuses && zone->random.Roll(se_resist_bonuses)) {
+		if (resist_type != RESIST_NONE && TrySpellEffectResist(spell_id)) {
 			return 0;
 		}