We no longer replace the vanilla apple item.

src/main/java/com/minelittlepony/unicopia/entity/ItemImpl.java

@@ -1,5 +1,6 @@
 package com.minelittlepony.unicopia.entity;
 
+import java.util.List;
 import java.util.Random;
 
 import org.jetbrains.annotations.NotNull;
@@ -113,8 +114,8 @@ public class ItemImpl implements Equine<ItemEntity>, Owned<ItemEntity> {
                 }
             }
 
-            if (stack.getItem() instanceof TickableItem) {
-                return ((TickableItem)stack.getItem()).onGroundTick(i) == ActionResult.SUCCESS;
+            if (stack.getItem() instanceof GroundTickCallback) {
+                return ((GroundTickCallback)stack.getItem()).onGroundTick(i).isAccepted();
             }
         }
 
@@ -165,7 +166,32 @@ public class ItemImpl implements Equine<ItemEntity>, Owned<ItemEntity> {
         return owner;
     }
 
-    public interface TickableItem {
+    public static <T extends Item> T registerTickCallback(T item, GroundTickCallback callback) {
+        ((ItemImpl.TickableItem)item).addGroundTickCallback(callback);
+        return item;
+    }
+
+    public interface TickableItem extends GroundTickCallback {
+
+        List<GroundTickCallback> getCallbacks();
+
+        default void addGroundTickCallback(GroundTickCallback callback) {
+            getCallbacks().add(callback);
+        }
+
+        @Override
+        default ActionResult onGroundTick(IItemEntity entity) {
+            for (var callback : getCallbacks()) {
+                ActionResult result = callback.onGroundTick(entity);
+                if (result.isAccepted()) {
+                    return result;
+                }
+            }
+            return ActionResult.PASS;
+        }
+    }
+
+    public interface GroundTickCallback {
         ActionResult onGroundTick(IItemEntity entity);
     }
 

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

@@ -11,7 +11,6 @@ import com.minelittlepony.unicopia.AwaitTickQueue;
 import com.minelittlepony.unicopia.USounds;
 import com.minelittlepony.unicopia.entity.IItemEntity;
 import com.minelittlepony.unicopia.entity.ItemImpl;
-import com.minelittlepony.unicopia.entity.ItemImpl.TickableItem;
 import com.minelittlepony.unicopia.entity.effect.UEffects;
 import com.minelittlepony.unicopia.entity.player.MagicReserves;
 import com.minelittlepony.unicopia.entity.player.PlayerCharmTracker;
@@ -47,7 +46,7 @@ import net.minecraft.world.LocalDifficulty;
 import net.minecraft.world.World;
 import net.minecraft.world.explosion.Explosion.DestructionType;
 
-public class AlicornAmuletItem extends AmuletItem implements PlayerCharmTracker.Charm, ItemImpl.ClingyItem, TickableItem {
+public class AlicornAmuletItem extends AmuletItem implements PlayerCharmTracker.Charm, ItemImpl.ClingyItem, ItemImpl.GroundTickCallback {
 
     public AlicornAmuletItem(FabricItemSettings settings) {
         super(settings, 0, new AmuletItem.ModifiersBuilder()

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

@@ -1,33 +1,28 @@
 package com.minelittlepony.unicopia.item;
 
-import java.util.List;
-import org.jetbrains.annotations.Nullable;
-
 import com.minelittlepony.unicopia.USounds;
 import com.minelittlepony.unicopia.entity.IItemEntity;
 import com.minelittlepony.unicopia.entity.ItemImpl;
-import com.minelittlepony.unicopia.item.toxin.Toxicity;
 
-import net.minecraft.client.item.TooltipContext;
 import net.minecraft.entity.Entity.RemovalReason;
 import net.minecraft.entity.EntityType;
 import net.minecraft.entity.ItemEntity;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.particle.ParticleTypes;
-import net.minecraft.text.Text;
 import net.minecraft.util.ActionResult;
 import net.minecraft.util.math.MathHelper;
-import net.minecraft.world.World;
 
-public class AppleItem extends Item implements ItemImpl.TickableItem {
+public class AppleItem {
+    private static final ItemImpl.GroundTickCallback TICK_CALLBACK = AppleItem::onGroundTick;
 
-    public AppleItem(Settings settings) {
-        super(settings);
+    private AppleItem() { }
+
+    public static <T extends Item> T registerTickCallback(T item) {
+        return ItemImpl.registerTickCallback(item, TICK_CALLBACK);
     }
 
-    @Override
-    public ActionResult onGroundTick(IItemEntity item) {
+    private static ActionResult onGroundTick(IItemEntity item) {
         ItemEntity entity = item.get().getMaster();
 
         if (!entity.isRemoved() && item.getPickupDelay() == 0 && item.getAge() > 2030 && entity.world.random.nextInt(150) < 10) {
@@ -62,13 +57,4 @@ public class AppleItem extends Item implements ItemImpl.TickableItem {
 
         return ActionResult.PASS;
     }
-
-    @Override
-    public void appendTooltip(ItemStack stack, @Nullable World worldIn, List<Text> tooltip, TooltipContext context) {
-        tooltip.add(getToxicity(stack).getTooltip());
-    }
-
-    public Toxicity getToxicity(ItemStack stack) {
-        return Toxicity.SAFE;
-    }
 }

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

@@ -29,7 +29,7 @@ public class DrinkableItem extends Item {
             stack.decrement(1);
         }
 
-        ((ToxicHolder)this).getToxic().ifPresent(t -> t.finishUsing(stack, world, user));
+        ((ToxicHolder)this).getToxic(stack).ifPresent(t -> t.finishUsing(stack, world, user));
 
         return stack.isEmpty() ? new ItemStack(getRecipeRemainder()) : stack;
     }

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

@@ -33,7 +33,7 @@ import net.minecraft.world.Heightmap;
 import net.minecraft.world.World;
 import net.minecraft.world.WorldEvents;
 
-public class JarItem extends Item implements ProjectileDelegate, ItemImpl.TickableItem {
+public class JarItem extends Item implements ProjectileDelegate, ItemImpl.GroundTickCallback {
 
     private final boolean rain;
     private final boolean thunder;

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

@@ -1,19 +1,12 @@
 package com.minelittlepony.unicopia.item;
 
-import com.minelittlepony.unicopia.entity.IItemEntity;
-
 import net.fabricmc.fabric.api.registry.FuelRegistry;
-import net.minecraft.util.ActionResult;
+import net.minecraft.item.Item;
 
-public class RottenAppleItem extends AppleItem {
+public class RottenAppleItem extends Item {
 
     public RottenAppleItem(Settings settings) {
         super(settings);
         FuelRegistry.INSTANCE.add(this, 150);
     }
-
-    @Override
-    public ActionResult onGroundTick(IItemEntity item) {
-        return ActionResult.PASS;
-    }
 }

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

@@ -6,6 +6,7 @@ import com.minelittlepony.unicopia.item.toxin.ToxicHolder;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemGroup;
 import net.minecraft.item.ItemStack;
+import net.minecraft.item.Items;
 import net.fabricmc.fabric.api.client.itemgroup.FabricItemGroupBuilder;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.collection.DefaultedList;
@@ -13,7 +14,7 @@ import net.minecraft.util.registry.Registry;
 
 public interface UItemGroups {
     ItemGroup ALL_ITEMS = FabricItemGroupBuilder.create(new Identifier("unicopia", "items")).appendItems(list -> {
-        list.addAll(VanillaOverrides.REGISTRY.stream().map(Item::getDefaultStack).collect(Collectors.toList()));
+        list.add(Items.APPLE.getDefaultStack());
 
         DefaultedList<ItemStack> defs = DefaultedList.of();
         UItems.ITEMS.stream()
@@ -25,8 +26,8 @@ public interface UItemGroups {
     }).icon(UItems.EMPTY_JAR::getDefaultStack).build();
     ItemGroup HORSE_FEED = FabricItemGroupBuilder.create(new Identifier("unicopia", "horsefeed")).appendItems(list -> {
         list.addAll(Registry.ITEM.stream()
-                .filter(item -> item instanceof ToxicHolder && ((ToxicHolder)item).getToxic().isPresent())
                 .map(Item::getDefaultStack)
+                .filter(item -> item.getItem() instanceof ToxicHolder && ((ToxicHolder)item.getItem()).getToxic(item).isPresent())
                 .collect(Collectors.toList()));
     }).icon(UItems.ZAP_APPLE::getDefaultStack).build();
 

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

@@ -28,14 +28,14 @@ public interface UItems {
 
     List<Item> ITEMS = new ArrayList<>();
 
-    AppleItem GREEN_APPLE = register("green_apple", new AppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
-    AppleItem SWEET_APPLE = register("sweet_apple", new AppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
-    AppleItem SOUR_APPLE = register("sour_apple", new AppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
+    Item GREEN_APPLE = register("green_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
+    Item SWEET_APPLE = register("sweet_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
+    Item SOUR_APPLE = register("sour_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
 
-    ZapAppleItem ZAP_APPLE = register("zap_apple", new ZapAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.ZAP_APPLE)));
+    ZapAppleItem ZAP_APPLE = register("zap_apple", AppleItem.registerTickCallback(new ZapAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.ZAP_APPLE))));
 
-    AppleItem ROTTEN_APPLE = register("rotten_apple", new RottenAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
-    AppleItem COOKED_ZAP_APPLE = register("cooked_zap_apple", new AppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
+    Item ROTTEN_APPLE = register("rotten_apple", new RottenAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
+    Item COOKED_ZAP_APPLE = register("cooked_zap_apple", new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
 
     Item MUSIC_DISC_CRUSADE = register("music_disc_crusade", USounds.RECORD_CRUSADE);
     Item MUSIC_DISC_PET = register("music_disc_pet", USounds.RECORD_PET);
@@ -114,6 +114,8 @@ public interface UItems {
     }
 
     static void bootstrap() {
+        AppleItem.registerTickCallback(Items.APPLE);
+
         UEnchantments.bootstrap();
         URecipes.bootstrap();
         UItemGroups.bootstrap();

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

@@ -1,22 +0,0 @@
-package com.minelittlepony.unicopia.item;
-
-import com.minelittlepony.unicopia.util.Registries;
-
-import net.minecraft.item.FoodComponents;
-import net.minecraft.item.Item;
-import net.minecraft.item.ItemGroup;
-import net.minecraft.util.Identifier;
-import net.minecraft.util.registry.Registry;
-
-public final class VanillaOverrides {
-
-    public static final Registry<Item> REGISTRY = Registries.createSimple(new Identifier("unicopia", "overrides"));
-
-    private static <T extends Item> T register(String name, T newItem) {
-        return Registry.register(REGISTRY, new Identifier(name), newItem);
-    }
-
-    static {
-        register("apple", new AppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
-    }
-}

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

@@ -1,11 +1,16 @@
 package com.minelittlepony.unicopia.item;
 
+import static com.minelittlepony.unicopia.item.toxin.Toxin.INNERT;
+
 import java.util.Optional;
 
 import com.minelittlepony.unicopia.UTags;
 import com.minelittlepony.unicopia.Unicopia;
 import com.minelittlepony.unicopia.advancement.UCriteria;
 import com.minelittlepony.unicopia.entity.player.Pony;
+import com.minelittlepony.unicopia.item.toxin.Ailment;
+import com.minelittlepony.unicopia.item.toxin.Toxic;
+import com.minelittlepony.unicopia.item.toxin.ToxicHolder;
 import com.minelittlepony.unicopia.item.toxin.Toxicity;
 import com.minelittlepony.unicopia.particle.ParticleUtils;
 import com.minelittlepony.unicopia.particle.UParticles;
@@ -21,6 +26,7 @@ import net.minecraft.entity.mob.CreeperEntity;
 import net.minecraft.entity.passive.PigEntity;
 import net.minecraft.entity.passive.VillagerEntity;
 import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.Item;
 import net.minecraft.item.ItemGroup;
 import net.minecraft.item.ItemStack;
 import net.minecraft.predicate.entity.EntityPredicates;
@@ -37,7 +43,9 @@ import net.minecraft.util.registry.Registry;
 import net.minecraft.world.World;
 import net.minecraft.world.event.GameEvent;
 
-public class ZapAppleItem extends AppleItem implements ChameleonItem {
+public class ZapAppleItem extends Item implements ChameleonItem, ToxicHolder {
+    private static final Optional<Toxic> TOXIC = Optional.of(new Toxic.Builder(Ailment.of(Toxicity.SEVERE, INNERT)).build("zap"));
+    private static final Optional<Toxic> HIDDEN_TOXIC = Optional.of(new Toxic.Builder(Ailment.of(Toxicity.SAFE, INNERT)).build("zap_hidden"));
 
     public ZapAppleItem(Settings settings) {
         super(settings);
@@ -128,8 +136,8 @@ public class ZapAppleItem extends AppleItem implements ChameleonItem {
     }
 
     @Override
-    public Toxicity getToxicity(ItemStack stack) {
-        return hasAppearance(stack) ? Toxicity.SEVERE : Toxicity.SAFE;
+    public Optional<Toxic> getToxic(ItemStack stack) {
+        return hasAppearance(stack) ? TOXIC : HIDDEN_TOXIC;
     }
 
     @Override

src/main/java/com/minelittlepony/unicopia/item/toxin/ToxicHolder.java

@@ -2,8 +2,10 @@ package com.minelittlepony.unicopia.item.toxin;
 
 import java.util.Optional;
 
+import net.minecraft.item.ItemStack;
+
 public interface ToxicHolder {
-    default Optional<Toxic> getToxic() {
+    default Optional<Toxic> getToxic(ItemStack stack) {
         return Optional.empty();
     }
 }

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

@@ -18,14 +18,14 @@ abstract class MixinBlockItem extends Item implements ToxicHolder {
 
     @Override
     public UseAction getUseAction(ItemStack stack) {
-        return getToxic()
+        return getToxic(stack)
                 .map(t -> t.getUseAction(stack))
                 .orElseGet(() -> super.getUseAction(stack));
     }
 
     @Override
     public TypedActionResult<ItemStack> use(World world, PlayerEntity player, Hand hand) {
-        return getToxic()
+        return getToxic(player.getStackInHand(hand))
                 .map(t -> t.use(world, player, hand))
                 .orElseGet(() -> super.use(world, player, hand));
     }

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

@@ -1,11 +1,8 @@
 package com.minelittlepony.unicopia.mixin;
 
-import java.io.OutputStream;
-import java.io.PrintStream;
-import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Optional;
-import java.util.concurrent.CompletableFuture;
-import java.util.stream.Stream;
 
 import org.jetbrains.annotations.Nullable;
 
@@ -15,12 +12,13 @@ import org.spongepowered.asm.mixin.Mutable;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
-import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
 import com.minelittlepony.unicopia.item.toxin.Toxic;
 import com.minelittlepony.unicopia.item.toxin.ToxicHolder;
 import com.minelittlepony.unicopia.item.toxin.Toxics;
+import com.minelittlepony.unicopia.entity.ItemImpl;
+import com.minelittlepony.unicopia.entity.ItemImpl.GroundTickCallback;
 
 import net.minecraft.entity.LivingEntity;
 import net.minecraft.item.FoodComponent;
@@ -29,7 +27,7 @@ import net.minecraft.item.ItemStack;
 import net.minecraft.world.World;
 
 @Mixin(Item.class)
-abstract class MixinItem implements ToxicHolder {
+abstract class MixinItem implements ToxicHolder, ItemImpl.TickableItem {
 
     private boolean foodLoaded;
     @Nullable
@@ -38,8 +36,18 @@ abstract class MixinItem implements ToxicHolder {
     @Shadow @Mutable
     private @Final FoodComponent foodComponent;
 
+    private List<ItemImpl.GroundTickCallback> tickCallbacks;
+
     @Override
-    public Optional<Toxic> getToxic() {
+    public List<GroundTickCallback> getCallbacks() {
+        if (tickCallbacks == null) {
+            tickCallbacks = new ArrayList<>();
+        }
+        return tickCallbacks;
+    }
+
+    @Override
+    public Optional<Toxic> getToxic(ItemStack stack) {
         if (!foodLoaded) {
             foodLoaded = true;
             originalFoodComponent = ((Item)(Object)this).getFoodComponent();
@@ -63,6 +71,6 @@ abstract class MixinItem implements ToxicHolder {
 
     @Inject(method = "finishUsing", at = @At("HEAD"), cancellable = true)
     private void finishUsing(ItemStack stack, World world, LivingEntity entity, CallbackInfoReturnable<ItemStack> info) {
-        getToxic().ifPresent(t -> t.finishUsing(stack, world, entity));
+        getToxic(stack).ifPresent(t -> t.finishUsing(stack, world, entity));
     }
 }

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

@@ -1,30 +0,0 @@
-package com.minelittlepony.unicopia.mixin;
-
-import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.injection.At;
-import org.spongepowered.asm.mixin.injection.ModifyVariable;
-
-import com.minelittlepony.unicopia.item.VanillaOverrides;
-
-import net.minecraft.item.Item;
-import net.minecraft.item.Items;
-import net.minecraft.util.Identifier;
-import net.minecraft.util.registry.Registry;
-
-@Mixin(Items.class)
-abstract class MixinItems {
-    @ModifyVariable(method = "register(Lnet/minecraft/util/Identifier;Lnet/minecraft/item/Item;)Lnet/minecraft/item/Item;",
-            at = @At("HEAD"),
-            index = 1,
-            argsOnly = true)
-    private static Item modifyItem(Item item, Identifier id, Item itemAlso) {
-        // Registry#containsId is client-only :thonkjang:
-        // TODO: Move onGroundTick() event to MixinItem and make it a registerable event so we don't have to do this
-        Item replacement = VanillaOverrides.REGISTRY.get(id);
-        if (replacement != null) {
-            Registry.register(Registry.ITEM, new Identifier("unicopia_overriden", id.getPath()), item);
-            return replacement;
-        }
-        return item;
-    }
-}

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinItem.java

@@ -21,6 +21,6 @@ import net.minecraft.world.World;
 abstract class MixinItem implements ToxicHolder {
     @Inject(method = "appendTooltip", at = @At("RETURN"))
     private void onAppendTooltip(ItemStack stack, @Nullable World world, List<Text> tooltip, TooltipContext context, CallbackInfo into) {
-        getToxic().ifPresent(t -> t.getAilmentFor(MinecraftClient.getInstance().player).appendTooltip(tooltip, context));
+        getToxic(stack).ifPresent(t -> t.getAilmentFor(MinecraftClient.getInstance().player).appendTooltip(tooltip, context));
     }
 }

src/main/resources/unicopia.mixin.json

@@ -16,7 +16,6 @@
     "MixinFallingBlockEntity",
     "MixinItem",
     "MixinItemEntity",
-    "MixinItems",
     "MixinLivingEntity",
     "MixinMilkBucketItem",
     "MixinMobEntity",