Core/Players: Auras that change the rate of energy regeneration should have an effect on client prediction.

(cherry picked from commit 1a3006b20d8c41139b206f610bcb6c22508ec329)

src/server/game/Entities/Player/Player.cpp

@@ -1702,12 +1702,12 @@ void Player::Regenerate(Powers power)
     if (RatesForPower[power] != MAX_RATES)
         addvalue *= sWorld->getRate(RatesForPower[power]);
 
-    // Mana regen calculated in Player::UpdateManaRegen()
-    if (power != POWER_MANA)
+    // Mana regen calculated in Player::UpdateManaRegen(), energy regen calculated in Player::UpdateEnergyRegen()
+    if (power != POWER_MANA && power != POWER_ENERGY)
     {
         addvalue *= GetTotalAuraMultiplierByMiscValue(SPELL_AURA_MOD_POWER_REGEN_PERCENT, power);
 
-        addvalue += GetTotalAuraModifierByMiscValue(SPELL_AURA_MOD_POWER_REGEN, power) * ((power != POWER_ENERGY) ? m_regenTimerCount : m_regenTimer) / (5 * IN_MILLISECONDS);
+        addvalue += GetTotalAuraModifierByMiscValue(SPELL_AURA_MOD_POWER_REGEN, power) * static_cast<float>(m_regenTimer) / static_cast<float>(5 * IN_MILLISECONDS);
     }
 
     int32 minPower = powerType->MinPower;

src/server/game/Entities/Player/Player.h

@@ -2255,6 +2255,7 @@ class TC_GAME_API Player final : public Unit, public GridObject<Player>
         void ApplyManaRegenBonus(int32 amount, bool apply);
         void ApplyHealthRegenBonus(int32 amount, bool apply);
         void UpdateManaRegen();
+        void UpdateEnergyRegen();
         void UpdateAllRunesRegen();
 
         void SetPetSpellPower(uint32 spellPower) { SetUpdateFieldValue(m_values.ModifyValue(&Player::m_activePlayerData).ModifyValue(&UF::ActivePlayerData::PetSpellPower), spellPower); }

src/server/game/Entities/Unit/StatSystem.cpp

@@ -825,6 +825,20 @@ void Player::UpdateManaRegen()
     SetUpdateFieldValue(m_values.ModifyValue(&Unit::m_unitData).ModifyValue(&UF::UnitData::PowerRegenInterruptedFlatModifier, manaIndex), base_regen);
 }
 
+void Player::UpdateEnergyRegen()
+{
+    uint32 energyIndex = GetPowerIndex(POWER_ENERGY);
+    if (energyIndex == MAX_POWERS)
+        return;
+
+    float regenPerSecond = 10.f;   // +10 energy per second
+    regenPerSecond *= GetTotalAuraMultiplierByMiscValue(SPELL_AURA_MOD_POWER_REGEN_PERCENT, POWER_ENERGY);
+    regenPerSecond += GetTotalAuraModifierByMiscValue(SPELL_AURA_MOD_POWER_REGEN, POWER_ENERGY) / static_cast<float>(5 * IN_MILLISECONDS);
+
+    SetUpdateFieldValue(m_values.ModifyValue(&Unit::m_unitData).ModifyValue(&UF::UnitData::PowerRegenFlatModifier, energyIndex), regenPerSecond - 10.f);
+    SetUpdateFieldValue(m_values.ModifyValue(&Unit::m_unitData).ModifyValue(&UF::UnitData::PowerRegenInterruptedFlatModifier, energyIndex), regenPerSecond - 10.f);
+}
+
 void Player::UpdateAllRunesRegen()
 {
     if (GetClass() != CLASS_DEATH_KNIGHT)

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -4085,6 +4085,8 @@ void AuraEffect::HandleModPowerRegen(AuraApplication const* aurApp, uint8 mode,
     // Update manaregen value
     if (GetMiscValue() == POWER_MANA)
         target->ToPlayer()->UpdateManaRegen();
+    else if (GetMiscValue() == POWER_ENERGY)
+        target->ToPlayer()->UpdateEnergyRegen();
     else if (GetMiscValue() == POWER_RUNES)
         target->ToPlayer()->UpdateAllRunesRegen();
     // other powers are not immediate effects - implemented in Player::Regenerate, Creature::Regenerate