[9062] Implement two helper-functions for casting spell in creatureAI.

Function will return a cast result, with fail reasons if spell can not be casted (can be used to take alternative action). Please note this is not a full list of cast fail errors/reasons, but will cover a few basic errors that may occur.
The virtual function CanCastSpell() may be adjusted for custom needs from script library if not the default is sufficient.

Signed-off-by: NoFantasy <nofantasy@nf.no>

src/game/CreatureAI.cpp

@@ -28,3 +28,90 @@ void CreatureAI::AttackedBy( Unit* attacker )
     if(!m_creature->getVictim())
         AttackStart(attacker);
 }
+
+CanCastResult CreatureAI::CanCastSpell(Unit* pTarget, const SpellEntry *pSpell, bool isTriggered)
+{
+    // If not triggered, we check
+    if (!isTriggered)
+    {
+        // State does not allow
+        if (m_creature->hasUnitState(UNIT_STAT_CONFUSED | UNIT_STAT_STUNNED | UNIT_STAT_FLEEING | UNIT_STAT_DIED))
+            return CAST_FAIL_STATE;
+
+        if (pSpell->PreventionType == SPELL_PREVENTION_TYPE_SILENCE && m_creature->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_SILENCED))
+            return CAST_FAIL_STATE;
+
+        if (pSpell->PreventionType == SPELL_PREVENTION_TYPE_PACIFY && m_creature->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_PACIFIED))
+            return CAST_FAIL_STATE;
+
+        // Check for power (also done by Spell::CheckCast())
+        if (m_creature->GetPower((Powers)pSpell->powerType) < pSpell->manaCost)
+            return CAST_FAIL_POWER;
+    }
+
+    if (const SpellRangeEntry *pSpellRange = sSpellRangeStore.LookupEntry(pSpell->rangeIndex))
+    {
+        if (pTarget != m_creature)
+        {
+            // pTarget is out of range of this spell (also done by Spell::CheckCast())
+            float fDistance = m_creature->GetCombatDistance(pTarget);
+
+            if (fDistance > (m_creature->IsHostileTo(pTarget) ? pSpellRange->maxRange : pSpellRange->maxRangeFriendly))
+                return CAST_FAIL_TOO_FAR;
+
+            float fMinRange = m_creature->IsHostileTo(pTarget) ? pSpellRange->minRange : pSpellRange->minRangeFriendly;
+
+            if (fMinRange && fDistance < fMinRange)
+                return CAST_FAIL_TOO_CLOSE;
+        }
+
+        return CAST_OK;
+    }
+    else
+        return CAST_FAIL_OTHER;
+}
+
+CanCastResult CreatureAI::DoCastSpellIfCan(Unit* pTarget, uint32 uiSpell, uint32 uiCastFlags, uint64 uiOriginalCasterGUID)
+{
+    Unit* pCaster = m_creature;
+
+    if (uiCastFlags & CAST_FORCE_TARGET_SELF)
+        pCaster = pTarget;
+
+    // Allowed to cast only if not casting (unless we interrupt ourself) or if spell is triggered
+    if (!pCaster->IsNonMeleeSpellCasted(false) || (uiCastFlags & (CAST_TRIGGERED | CAST_INTURRUPT_PREVIOUS)))
+    {
+        if (const SpellEntry* pSpell = sSpellStore.LookupEntry(uiSpell))
+        {
+            // If cast flag CAST_AURA_NOT_PRESENT is active, check if target already has aura on them
+            if (uiCastFlags & CAST_AURA_NOT_PRESENT)
+            {
+                if (pTarget->HasAura(uiSpell))
+                    return CAST_FAIL_TARGET_AURA;
+            }
+
+            // Check if cannot cast spell
+            if (!(uiCastFlags & (CAST_FORCE_TARGET_SELF | CAST_FORCE_CAST)))
+            {
+                CanCastResult castResult = CanCastSpell(pTarget, pSpell, uiCastFlags & CAST_TRIGGERED);
+
+                if (castResult != CAST_OK)
+                    return castResult;
+            }
+
+            // Interrupt any previous spell
+            if (uiCastFlags & CAST_INTURRUPT_PREVIOUS && pCaster->IsNonMeleeSpellCasted(false))
+                pCaster->InterruptNonMeleeSpells(false);
+
+            pCaster->CastSpell(pTarget, pSpell, uiCastFlags & CAST_TRIGGERED, NULL, NULL, uiOriginalCasterGUID);
+            return CAST_OK;
+        }
+        else
+        {
+            sLog.outErrorDb("DoCastSpellIfCan by creature entry %u attempt to cast spell %u but spell does not exist.", m_creature->GetEntry(), uiSpell);
+            return CAST_FAIL_OTHER;
+        }
+    }
+    else
+        return CAST_FAIL_IS_CASTING;
+}

src/game/CreatureAI.h

@@ -34,6 +34,18 @@ struct SpellEntry;
 #define TIME_INTERVAL_LOOK   5000
 #define VISIBILITY_RANGE    10000
 
+enum CanCastResult
+{
+    CAST_OK                     = 0,
+    CAST_FAIL_IS_CASTING        = 1,
+    CAST_FAIL_OTHER             = 2,
+    CAST_FAIL_TOO_FAR           = 3,
+    CAST_FAIL_TOO_CLOSE         = 4,
+    CAST_FAIL_POWER             = 5,
+    CAST_FAIL_STATE             = 6,
+    CAST_FAIL_TARGET_AURA       = 7
+};
+
 enum CastFlags
 {
     CAST_INTURRUPT_PREVIOUS     = 0x01,                     //Interrupt any spell casting
@@ -68,6 +80,10 @@ class MANGOS_DLL_SPEC CreatureAI
         // Called at any heal cast/item used (call non implemented)
         virtual void HealBy(Unit * /*healer*/, uint32 /*amount_healed*/) {}
 
+        // Helper functions for cast spell
+        CanCastResult DoCastSpellIfCan(Unit* pTarget, uint32 uiSpell, uint32 uiCastFlags = 0, uint64 uiOriginalCasterGUID = 0);
+        virtual CanCastResult CanCastSpell(Unit* pTarget, const SpellEntry *pSpell, bool isTriggered);
+
         // Called at any Damage to any victim (before damage apply)
         virtual void DamageDeal(Unit * /*done_to*/, uint32 & /*damage*/) {}
 

src/shared/revision_nr.h

@@ -1,4 +1,4 @@
 #ifndef __REVISION_NR_H__
 #define __REVISION_NR_H__
- #define REVISION_NR "9061"
+ #define REVISION_NR "9062"
 #endif // __REVISION_NR_H__