Implement item hooks for potions and enchantments (#8718)

* Implement item hooks for potions and enchantments

* code style fixes

src/main/java/net/minecraftforge/common/extensions/IForgeEnchantment.java

@@ -6,6 +6,8 @@
 package net.minecraftforge.common.extensions;
 
 import net.minecraft.world.entity.MobType;
+import net.minecraft.world.item.CreativeModeTab;
+import net.minecraft.world.item.Item;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.enchantment.Enchantment;
 
@@ -28,4 +30,26 @@ public interface IForgeEnchantment
     {
         return self().getDamageBonus(level, mobType);
     }
+
+    /**
+     * Determines what creative tabs this enchantment's variant of an enchanted book or similar item should appear in.
+     * @param book The item being added to the creative tab
+     * @param tab The creative tab that items are being added to
+     * @return whether the given Item's variant for this enchantment should appear in the respective creative tab
+     */
+    default boolean allowedInCreativeTab(Item book, CreativeModeTab tab)
+    {
+        if (!self().isAllowedOnBooks())
+        {
+            return false;
+        }
+        else if (tab == CreativeModeTab.TAB_SEARCH)
+        {
+            return self().category != null;
+        }
+        else
+        {
+            return tab.hasEnchantmentCategory(self().category);
+        }
+    }
 }

src/main/java/net/minecraftforge/common/extensions/IForgePotion.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.common.extensions;
+
+import net.minecraft.world.item.CreativeModeTab;
+import net.minecraft.world.item.Item;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.alchemy.Potion;
+import net.minecraft.world.item.alchemy.PotionUtils;
+
+public interface IForgePotion
+{
+    private Potion self()
+    {
+        return (Potion) this;
+    }
+
+    /**
+     * Determines what creative tabs this potion's variant of a potion-related item (e.g. bottles, tipped arrows) should appear in.
+     * @param item The item being added to a creative tab
+     * @param tab The creative tab that items are being added to
+     * @param isDefaultTab whether the tab is the default tab for this item (e.g. Brewing for bottles, Combat for tipped arrows)
+     * @return whether the given Item's variant for this enchantment should appear in the respective creative tab
+     */
+    default boolean allowedInCreativeTab(Item item, CreativeModeTab tab, boolean isDefaultTab)
+    {
+        return isDefaultTab;
+    }
+
+    /**
+     * Determines whether the potion bottle item should be enchanted.
+     * Not called for tipped arrows or if the item is already enchanted.
+     * @param stack The potion bottle
+     * @return whether the item should appear enchanted.
+     */
+    default boolean isFoil(ItemStack stack)
+    {
+        return !PotionUtils.getMobEffects(stack).isEmpty();
+    }
+}