Polearms can no longer accept the sweeping enchant. Closes #408

src/main/java/com/minelittlepony/unicopia/item/PolearmItem.java

@@ -7,14 +7,17 @@ import com.google.common.collect.Multimap;
 import com.minelittlepony.unicopia.UTags;
 import com.minelittlepony.unicopia.entity.Living;
 import com.minelittlepony.unicopia.entity.mob.UEntityAttributes;
+import com.minelittlepony.unicopia.item.enchantment.CustomEnchantableItem;
 
 import net.minecraft.block.*;
+import net.minecraft.enchantment.Enchantment;
+import net.minecraft.enchantment.Enchantments;
 import net.minecraft.entity.EquipmentSlot;
 import net.minecraft.entity.LivingEntity;
 import net.minecraft.entity.attribute.*;
 import net.minecraft.item.*;
 
-public class PolearmItem extends SwordItem {
+public class PolearmItem extends SwordItem implements CustomEnchantableItem {
     static final UUID ATTACK_RANGE_MODIFIER_ID = UUID.fromString("A7B3659C-AA74-469C-963A-09A391DCAA0F");
 
     private final Multimap<EntityAttribute, EntityAttributeModifier> attributeModifiers;
@@ -65,4 +68,9 @@ public class PolearmItem extends SwordItem {
 
         return true;
     }
+
+    @Override
+    public boolean isAcceptableEnchant(ItemStack stack, Enchantment enchantment) {
+        return enchantment != Enchantments.SWEEPING;
+    }
 }

src/main/java/com/minelittlepony/unicopia/item/enchantment/CustomEnchantableItem.java

@@ -0,0 +1,8 @@
+package com.minelittlepony.unicopia.item.enchantment;
+
+import net.minecraft.enchantment.Enchantment;
+import net.minecraft.item.ItemStack;
+
+public interface CustomEnchantableItem {
+    boolean isAcceptableEnchant(ItemStack stack, Enchantment enchantment);
+}

src/main/java/com/minelittlepony/unicopia/mixin/MixinEnchantment.java

@@ -0,0 +1,21 @@
+package com.minelittlepony.unicopia.mixin;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+import com.minelittlepony.unicopia.item.enchantment.CustomEnchantableItem;
+
+import net.minecraft.enchantment.Enchantment;
+import net.minecraft.item.ItemStack;
+
+@Mixin(Enchantment.class)
+abstract class MixinEnchantment {
+    @Inject(method = "isAcceptableItem", at = @At("HEAD"), cancellable = true)
+    private void onIsAcceptableItem(ItemStack stack, CallbackInfoReturnable<Boolean> info) {
+        if (stack.getItem() instanceof CustomEnchantableItem item && !item.isAcceptableEnchant(stack, (Enchantment)(Object)this)) {
+            info.setReturnValue(false);
+        }
+    }
+}

src/main/java/com/minelittlepony/unicopia/mixin/MixinEnchantmentHelper.java

@@ -1,5 +1,7 @@
 package com.minelittlepony.unicopia.mixin;
 
+import java.util.List;
+
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
@@ -9,7 +11,9 @@ import com.minelittlepony.unicopia.entity.player.Pony;
 
 import net.minecraft.enchantment.Enchantment;
 import net.minecraft.enchantment.EnchantmentHelper;
+import net.minecraft.enchantment.EnchantmentLevelEntry;
 import net.minecraft.entity.LivingEntity;
+import net.minecraft.item.ItemStack;
 
 @Mixin(EnchantmentHelper.class)
 abstract class MixinEnchantmentHelper {
@@ -23,4 +27,9 @@ abstract class MixinEnchantmentHelper {
             }
         });
     }
+
+    @Inject(method = "getPossibleEntries", at = @At("RETURN"))
+    private static void onGetPossibleEntries(int power, ItemStack stack, boolean treasureAllowed, CallbackInfoReturnable<List<EnchantmentLevelEntry>> info) {
+        info.getReturnValue().removeIf(entry -> !entry.enchantment.isAcceptableItem(stack));
+    }
 }

src/main/resources/unicopia.mixin.json

@@ -17,6 +17,7 @@
     "MixinChunkBlockLightProvider",
     "MutableBlockLightStorage",
     "MixinDamageSource",
+    "MixinEnchantment",
     "MixinEnchantmentHelper",
     "MixinFallLocation",
     "MixinEntity",