Custom Potion Mixes

== AT ==
public-f net.minecraft.server.MinecraftServer potionBrewing

paper-server/src/main/java/io/papermc/paper/potion/PaperPotionBrewer.java

@@ -0,0 +1,56 @@
+package io.papermc.paper.potion;
+
+import com.google.common.base.Preconditions;
+import java.util.Collection;
+import net.minecraft.server.MinecraftServer;
+import org.bukkit.NamespacedKey;
+import org.bukkit.potion.PotionBrewer;
+import org.bukkit.potion.PotionEffect;
+import org.bukkit.potion.PotionType;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+@DefaultQualifier(NonNull.class)
+public class PaperPotionBrewer implements PotionBrewer {
+
+    private final MinecraftServer minecraftServer;
+
+    public PaperPotionBrewer(final MinecraftServer minecraftServer) {
+        this.minecraftServer = minecraftServer;
+    }
+
+    @Override
+    @Deprecated(forRemoval = true)
+    public Collection<PotionEffect> getEffects(PotionType type, boolean upgraded, boolean extended) {
+        final org.bukkit.NamespacedKey key = type.getKey();
+
+        Preconditions.checkArgument(!key.getKey().startsWith("strong_"), "Strong potion type cannot be used directly, got %s", key);
+        Preconditions.checkArgument(!key.getKey().startsWith("long_"), "Extended potion type cannot be used directly, got %s", key);
+
+        org.bukkit.NamespacedKey effectiveKey = key;
+        if (upgraded) {
+            effectiveKey = new org.bukkit.NamespacedKey(key.namespace(), "strong_" + key.key());
+        } else if (extended) {
+            effectiveKey = new org.bukkit.NamespacedKey(key.namespace(), "long_" + key.key());
+        }
+
+        final org.bukkit.potion.PotionType effectivePotionType = org.bukkit.Registry.POTION.get(effectiveKey);
+        Preconditions.checkNotNull(type, "Unknown potion type from data " + effectiveKey.asMinimalString()); // Legacy error message in 1.20.4
+        return effectivePotionType.getPotionEffects();
+    }
+
+    @Override
+    public void addPotionMix(final PotionMix potionMix) {
+        this.minecraftServer.potionBrewing().addPotionMix(potionMix);
+    }
+
+    @Override
+    public void removePotionMix(final NamespacedKey key) {
+        this.minecraftServer.potionBrewing.removePotionMix(key);
+    }
+
+    @Override
+    public void resetPotionMixes() {
+        this.minecraftServer.potionBrewing = this.minecraftServer.potionBrewing().reload(this.minecraftServer.getWorldData().enabledFeatures());
+    }
+}

paper-server/src/main/java/io/papermc/paper/potion/PaperPotionMix.java

@@ -0,0 +1,21 @@
+package io.papermc.paper.potion;
+
+import java.util.function.Predicate;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.inventory.CraftRecipe;
+import org.bukkit.inventory.RecipeChoice;
+
+public record PaperPotionMix(ItemStack result, Predicate<ItemStack> input, Predicate<ItemStack> ingredient) {
+
+    public PaperPotionMix(PotionMix potionMix) {
+        this(CraftItemStack.asNMSCopy(potionMix.getResult()), convert(potionMix.getInput()), convert(potionMix.getIngredient()));
+    }
+
+    static Predicate<ItemStack> convert(final RecipeChoice choice) {
+        if (choice instanceof PredicateRecipeChoice predicateRecipeChoice) {
+            return stack -> predicateRecipeChoice.test(CraftItemStack.asBukkitCopy(stack));
+        }
+        return CraftRecipe.toIngredient(choice, true);
+    }
+}

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -311,6 +311,7 @@ public final class CraftServer implements Server {
     private final io.papermc.paper.datapack.PaperDatapackManager datapackManager; // Paper
     public static Exception excessiveVelEx; // Paper - Velocity warnings
     private final io.papermc.paper.logging.SysoutCatcher sysoutCatcher = new io.papermc.paper.logging.SysoutCatcher(); // Paper
+    private final io.papermc.paper.potion.PaperPotionBrewer potionBrewer; // Paper - Custom Potion Mixes
 
     static {
         ConfigurationSerialization.registerClass(CraftOfflinePlayer.class);
@@ -394,6 +395,7 @@ public final class CraftServer implements Server {
         if (this.configuration.getBoolean("settings.use-map-color-cache")) {
             MapPalette.setMapColorCache(new CraftMapColorCache(this.logger));
         }
+        this.potionBrewer = new io.papermc.paper.potion.PaperPotionBrewer(console); // Paper - custom potion mixes
         datapackManager = new io.papermc.paper.datapack.PaperDatapackManager(console.getPackRepository()); // Paper
     }
 
@@ -3076,5 +3078,9 @@ public final class CraftServer implements Server {
         return datapackManager;
     }
 
+    @Override
+    public io.papermc.paper.potion.PaperPotionBrewer getPotionBrewer() {
+        return this.potionBrewer;
+    }
     // Paper end
 }

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java

@@ -23,6 +23,11 @@ public interface CraftRecipe extends Recipe {
     }
 
     default Ingredient toNMS(RecipeChoice bukkit, boolean requireNotEmpty) {
+        // Paper start
+        return toIngredient(bukkit, requireNotEmpty);
+    }
+    static Ingredient toIngredient(RecipeChoice bukkit, boolean requireNotEmpty) {
+        // Paper end
         Ingredient stack;
 
         if (bukkit == null) {