Core/Spells: Expose number of targets selected for each spell effect to scripts to allow implementing spells that do something depending on number of targets hit

Port From (https://github.com/TrinityCore/TrinityCore/commit/1a7779a6e6464d9bc5b367e02820213edd60f704)

Source/Game/Scripting/SpellScript.cs

@@ -257,7 +257,7 @@ namespace Game.Scripting
 
             SpellOnCalcCritChanceFnType _onCalcCritChanceHandlerScript;
         }
-        
+
         public class TargetHook : EffectHook
         {
             public TargetHook(uint effectIndex, Targets targetType, bool area, bool dest = false) : base(effectIndex)
@@ -430,6 +430,15 @@ namespace Game.Scripting
         {
             return m_currentScriptState == (byte)SpellScriptHookType.CheckCast;
         }
+
+        bool IsAfterTargetSelectionPhase()
+        {
+            return IsInHitPhase()
+                || m_currentScriptState == (byte)SpellScriptHookType.OnCast
+                || m_currentScriptState == (byte)SpellScriptHookType.AfterCast
+                || m_currentScriptState == (byte)SpellScriptHookType.CalcCritChance;
+        }
+        
         public bool IsInTargetHook()
         {
             switch ((SpellScriptHookType)m_currentScriptState)
@@ -551,10 +560,40 @@ namespace Game.Scripting
         public Unit GetExplTargetUnit() { return m_spell.m_targets.GetUnitTarget(); }
 
         // returns: GameObject which was selected as an explicit spell target or null if there's no target
-        GameObject GetExplTargetGObj() { return m_spell.m_targets.GetGOTarget(); }
+        public GameObject GetExplTargetGObj() { return m_spell.m_targets.GetGOTarget(); }
 
         // returns: Item which was selected as an explicit spell target or null if there's no target
-        Item GetExplTargetItem() { return m_spell.m_targets.GetItemTarget(); }
+        public Item GetExplTargetItem() { return m_spell.m_targets.GetItemTarget(); }
+
+        public long GetUnitTargetCountForEffect(uint effect)
+        {
+            if (!IsAfterTargetSelectionPhase())
+            {
+                Log.outError(LogFilter.Scripts, $"Script: `{m_scriptName}` Spell: `{m_scriptSpellId}`: function SpellScript.GetUnitTargetCountForEffect was called, but function has no effect in current hook! (spell has not selected targets yet)");
+                return 0;
+            }
+            return m_spell.GetUnitTargetCountForEffect(effect);
+        }
+
+        public long GetGameObjectTargetCountForEffect(uint effect)
+        {
+            if (!IsAfterTargetSelectionPhase())
+            {
+                Log.outError(LogFilter.Scripts, $"Script: `{m_scriptName}` Spell: `{m_scriptSpellId}`: function SpellScript.GetGameObjectTargetCountForEffect was called, but function has no effect in current hook! (spell has not selected targets yet)");
+                return 0;
+            }
+            return m_spell.GetGameObjectTargetCountForEffect(effect);
+        }
+
+        public long GetItemTargetCountForEffect(uint effect)
+        {
+            if (!IsAfterTargetSelectionPhase())
+            {
+                Log.outError(LogFilter.Scripts, $"Script: `{m_scriptName}` Spell: `{m_scriptSpellId}`: function SpellScript.GetItemTargetCountForEffect was called, but function has no effect in current hook! (spell has not selected targets yet)");
+                return 0;
+            }
+            return m_spell.GetItemTargetCountForEffect(effect);
+        }
 
         // methods useable only during spell hit on target, or during spell launch on target:
         // returns: target of current effect if it was Unit otherwise null

Source/Game/Spells/Spell.cs

@@ -1758,6 +1758,21 @@ namespace Game.Spells
             m_destTargets[effIndex] = dest;
         }
 
+        public long GetUnitTargetCountForEffect(uint effect)
+        {
+            return m_UniqueTargetInfo.Count(targetInfo => (targetInfo.effectMask & (1 << (int)effect)) != 0);
+        }
+
+        public long GetGameObjectTargetCountForEffect(uint effect)
+        {
+            return m_UniqueGOTargetInfo.Count(targetInfo => (targetInfo.effectMask & (1 << (int)effect)) != 0);
+        }
+
+        public long GetItemTargetCountForEffect(uint effect)
+        {
+            return m_UniqueItemInfo.Count(targetInfo => (targetInfo.effectMask & (1 << (int)effect)) != 0);
+        }
+
         void DoAllEffectOnTarget(TargetInfo target)
         {
             if (target == null || target.processed)
@@ -6853,9 +6868,9 @@ namespace Game.Spells
 
                             if (m_caster.IsTypeId(TypeId.Player))
                             {
-                                int targetAmount = m_UniqueTargetInfo.Count;
+                                long targetAmount = GetUnitTargetCountForEffect(effect.EffectIndex);
                                 if (targetAmount > 20)
-                                    m_damage = m_damage * 20 / targetAmount;
+                                    m_damage = (int)(m_damage * 20 / targetAmount);
                             }
                         }
                     }

Source/Game/Spells/SpellEffects.cs

@@ -153,11 +153,11 @@ namespace Game.Spells
                 // Meteor like spells (divided damage to targets)
                 if (m_spellInfo.HasAttribute(SpellCustomAttributes.ShareDamage))
                 {
-                    int count = m_UniqueTargetInfo.Count(targetInfo => Convert.ToBoolean(targetInfo.effectMask & (1 << (int)effIndex)));
+                    long count = GetUnitTargetCountForEffect(effIndex);
 
                     // divide to all targets
                     if (count != 0)
-                        damage /= count;
+                        damage /= (int)count;
                 }
 
                 switch (m_spellInfo.SpellFamilyName)