Fix for impact armor damage formula (#4425)

* Update SkillUtils.java

Add handleArmorDurabilityChange() to handle armor damage reduction correctly

* Update AxesManager.java

Changed method to handle impact damage calculation

* Update SkillUtils.java

src/main/java/com/gmail/nossr50/skills/axes/AxesManager.java

@@ -120,7 +120,7 @@ public class AxesManager extends SkillManager {
         for (ItemStack armor : target.getEquipment().getArmorContents()) {
             if (armor != null && ItemUtils.isArmor(armor)) {
                 if (RandomChanceUtil.isActivationSuccessful(SkillActivationType.RANDOM_STATIC_CHANCE, SubSkillType.AXES_ARMOR_IMPACT, getPlayer())) {
-                    SkillUtils.handleDurabilityChange(armor, durabilityDamage, 1);
+                    SkillUtils.handleArmorDurabilityChange(armor, durabilityDamage, 1);
                 }
             }
         }

src/main/java/com/gmail/nossr50/util/skills/SkillUtils.java

@@ -236,14 +236,14 @@ public final class SkillUtils {
     }
 
     /**
-     * Modify the durability of an ItemStack.
+     * Modify the durability of an ItemStack, using Tools specific formula for unbreaking enchant damage reduction
      *
      * @param itemStack The ItemStack which durability should be modified
      * @param durabilityModifier the amount to modify the durability by
      * @param maxDamageModifier the amount to adjust the max damage by
      */
     public static void handleDurabilityChange(ItemStack itemStack, double durabilityModifier, double maxDamageModifier) {
-        if(itemStack.getItemMeta() != null && itemStack.getItemMeta().isUnbreakable()) {
+        if(itemStack.hasItemMeta() && itemStack.getItemMeta().isUnbreakable()) {
             return;
         }
 
@@ -263,6 +263,26 @@ public final class SkillUtils {
 
         return false;
     }
+    
+    
+    /**
+     * Modify the durability of an ItemStack, using Armor specific formula for unbreaking enchant damage reduction
+     *
+     * @param itemStack The ItemStack which durability should be modified
+     * @param durabilityModifier the amount to modify the durability by
+     * @param maxDamageModifier the amount to adjust the max damage by
+     */
+    public static void handleArmorDurabilityChange(ItemStack itemStack, double durabilityModifier, double maxDamageModifier) {
+        if(itemStack.hasItemMeta() && itemStack.getItemMeta().isUnbreakable()) {
+            return;
+        }
+
+        Material type = itemStack.getType();
+        short maxDurability = mcMMO.getRepairableManager().isRepairable(type) ? mcMMO.getRepairableManager().getRepairable(type).getMaximumDurability() : type.getMaxDurability();
+        durabilityModifier = (int) Math.min(durabilityModifier * (0.6 + 0.4/ (itemStack.getEnchantmentLevel(Enchantment.DURABILITY) + 1)), maxDurability * maxDamageModifier);
+
+        itemStack.setDurability((short) Math.min(itemStack.getDurability() + durabilityModifier, maxDurability));
+    }
 
     @Nullable
     public static Material getRepairAndSalvageItem(@NotNull ItemStack inHand) {