make bookshelf power configurable and refresh enchantment hint of menu after editing bookshelf power

paper-api/src/main/java/io/papermc/paper/InternalAPIBridge.java

@@ -6,7 +6,9 @@
 import org.bukkit.block.Biome;
 import org.bukkit.damage.DamageEffect;
 import org.bukkit.damage.DamageSource;
+import org.bukkit.enchantments.EnchantmentOffer;
 import org.bukkit.entity.LivingEntity;
+import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.ApiStatus;
 import org.jspecify.annotations.NullMarked;
 import org.jspecify.annotations.Nullable;
@@ -73,5 +75,22 @@ class Holder {
      * @return combat entry
      */
     CombatEntry createCombatEntry(DamageSource damageSource, float damage, @Nullable FallLocationType fallLocationType, float fallDistance);
+
+    /**
+     * Rolls a new set of enchantment offers based on a target item stack, a seed and a bookshelf count.
+     *
+     * @param targetStack    the itemstack for which the enchantment offers are rolled.
+     * @param seed           the seed used for random selection of enchantments.
+     *                       Mirrors {@link org.bukkit.inventory.view.EnchantmentView#getEnchantmentSeed()}.
+     * @param bookshelfCount the number of virtual bookshelves to consider when rolling the enchantments.
+     * @param offerAmount    the amount of enchantment offers to roll.
+     * @return an array of enchantment offers with size {@code offerAmount}.
+     */
+    @Nullable EnchantmentOffer[] rollEnchantmentOffers(
+        final ItemStack targetStack,
+        final int seed,
+        final int bookshelfCount,
+        final int offerAmount
+    );
 }
 

paper-api/src/main/java/org/bukkit/enchantments/EnchantmentOffer.java

@@ -1,7 +1,11 @@
 package org.bukkit.enchantments;
 
 import com.google.common.base.Preconditions;
+import io.papermc.paper.InternalAPIBridge;
+import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import java.util.Objects;
 
 /**
  * A class for the available enchantment offers in the enchantment table.
@@ -80,4 +84,35 @@ public void setCost(int cost) {
 
         this.cost = cost;
     }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (o == null || getClass() != o.getClass()) return false;
+        final EnchantmentOffer that = (EnchantmentOffer) o;
+        return getEnchantmentLevel() == that.getEnchantmentLevel() && getCost() == that.getCost() && Objects.equals(getEnchantment(), that.getEnchantment());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getEnchantment(), getEnchantmentLevel(), getCost());
+    }
+
+    /**
+     * Rolls a new set of enchantment offers based on a target item stack, a seed and a bookshelf count.
+     *
+     * @param targetStack    the itemstack for which the enchantment offers are rolled.
+     * @param seed           the seed used for random selection of enchantments.
+     *                       Mirrors {@link org.bukkit.inventory.view.EnchantmentView#getEnchantmentSeed()}.
+     * @param bookshelfCount the number of virtual bookshelves to consider when rolling the enchantments.
+     * @param offerAmount    the amount of enchantment offers to roll.
+     * @return an array of enchantment offers with size {@code offerAmount}.
+     */
+    public static @Nullable EnchantmentOffer @NotNull [] rollEnchantmentOffers(
+        final @NotNull ItemStack targetStack,
+        final int seed,
+        final int bookshelfCount,
+        final int offerAmount
+    ) {
+        return InternalAPIBridge.get().rollEnchantmentOffers(targetStack, seed, bookshelfCount, offerAmount);
+    }
 }

paper-server/patches/sources/net/minecraft/world/inventory/EnchantmentMenu.java.patch

@@ -64,10 +64,32 @@
                  this.access.execute((level, blockPos) -> {
                      IdMap<Holder<Enchantment>> holderIdMap = level.registryAccess().lookupOrThrow(Registries.ENCHANTMENT).asHolderIdMap();
                      int i1 = 0;
-@@ -119,6 +_,42 @@
+@@ -97,27 +_,42 @@
                          }
                      }
 
+-                    this.random.setSeed(this.enchantmentSeed.get());
+-
+-                    for (int i2 = 0; i2 < 3; i2++) {
+-                        this.costs[i2] = EnchantmentHelper.getEnchantmentCost(this.random, i2, i1, item);
+-                        this.enchantClue[i2] = -1;
+-                        this.levelClue[i2] = -1;
+-                        if (this.costs[i2] < i2 + 1) {
+-                            this.costs[i2] = 0;
+-                        }
+-                    }
+-
+-                    for (int i2x = 0; i2x < 3; i2x++) {
+-                        if (this.costs[i2x] > 0) {
+-                            List<EnchantmentInstance> enchantmentList = this.getEnchantmentList(level.registryAccess(), item, i2x, this.costs[i2x]);
+-                            if (enchantmentList != null && !enchantmentList.isEmpty()) {
+-                                EnchantmentInstance enchantmentInstance = enchantmentList.get(this.random.nextInt(enchantmentList.size()));
+-                                this.enchantClue[i2x] = holderIdMap.getId(enchantmentInstance.enchantment());
+-                                this.levelClue[i2x] = enchantmentInstance.level();
+-                            }
+-                        }
+-                    }
++                    fillEnchantmentOffers(this.random, this.enchantmentSeed.get(), i1, item, level.registryAccess(), this.costs, this.enchantClue, this.levelClue); // Paper - extracted into net.minecraft.world.inventory.EnchantmentMenu.fillEnchantmentOffers
 +                    // CraftBukkit start
 +                    org.bukkit.craftbukkit.inventory.CraftItemStack craftItemStack = org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(item);
 +                    org.bukkit.enchantments.EnchantmentOffer[] offers = new org.bukkit.enchantments.EnchantmentOffer[3];
@@ -103,10 +125,53 @@
 +                        }
 +                    }
 +                    // CraftBukkit end
-+
+ 
                      this.broadcastChanges();
                  });
-             } else {
+@@ -131,6 +_,43 @@
+         }
+     }
+
++    // Paper - extract offer generation
++    // Extracted over modifications in place given nearly every line has diff to account for non-instance fields for
++    // cost, enchantment and level clues.
++    public static void fillEnchantmentOffers(
++        final RandomSource random,
++        final int seed,
++        final int i1,
++        final ItemStack item,
++        final RegistryAccess registryAccess,
++        final int[] costs,
++        final int[] enchantClue,
++        final int[] levelClue
++    ) {
++        random.setSeed(seed);
++
++        for (int i2 = 0; i2 < costs.length; i2++) {
++            costs[i2] = EnchantmentHelper.getEnchantmentCost(random, i2, i1, item);
++            enchantClue[i2] = -1;
++            levelClue[i2] = -1;
++            if (costs[i2] < i2 + 1) {
++                costs[i2] = 0;
++            }
++        }
++
++        for (int i2x = 0; i2x < costs.length; i2x++) {
++            if (costs[i2x] > 0) {
++                List<EnchantmentInstance> enchantmentList = getEnchantmentList(registryAccess, item, i2x, costs[i2x], random, seed);
++                if (enchantmentList != null && !enchantmentList.isEmpty()) {
++                    EnchantmentInstance enchantmentInstance = enchantmentList.get(random.nextInt(enchantmentList.size()));
++                    enchantClue[i2x] = registryAccess.lookupOrThrow(Registries.ENCHANTMENT).asHolderIdMap().getId(enchantmentInstance.enchantment());
++                    levelClue[i2x] = enchantmentInstance.level();
++                }
++            }
++        }
++    }
++    // Paper - extract offer generation
++
+     @Override
+     public boolean clickMenuButton(Player player, int id) {
+         if (id >= 0 && id < this.costs.length) {
 @@ -145,19 +_,52 @@
                  return false;
              } else {
@@ -171,6 +236,29 @@
                          item1.consume(i, player);
                          if (item1.isEmpty()) {
                              this.enchantSlots.setItem(1, ItemStack.EMPTY);
+@@ -183,14 +_,19 @@
+     }
+
+     private List<EnchantmentInstance> getEnchantmentList(RegistryAccess registryAccess, ItemStack stack, int slot, int cost) {
+-        this.random.setSeed(this.enchantmentSeed.get() + slot);
++    // Paper start - make static and public
++        return getEnchantmentList(registryAccess, stack, slot, cost, this.random, this.enchantmentSeed.get());
++    }
++    public static List<EnchantmentInstance> getEnchantmentList(RegistryAccess registryAccess, ItemStack stack, int slot, int cost, RandomSource random, int seed) {
++    // Paper end - make static and public
++        random.setSeed(seed + slot); // Paper - make static and public
+         Optional<HolderSet.Named<Enchantment>> optional = registryAccess.lookupOrThrow(Registries.ENCHANTMENT).get(EnchantmentTags.IN_ENCHANTING_TABLE);
+         if (optional.isEmpty()) {
+             return List.of();
+         } else {
+-            List<EnchantmentInstance> list = EnchantmentHelper.selectEnchantment(this.random, stack, cost, optional.get().stream());
++            List<EnchantmentInstance> list = EnchantmentHelper.selectEnchantment(random, stack, cost, optional.get().stream()); // Paper - make static and public
+             if (stack.is(Items.BOOK) && list.size() > 1) {
+-                list.remove(this.random.nextInt(list.size()));
++                list.remove(random.nextInt(list.size())); // Paper start - make static and public
+             }
+
+             return list;
 @@ -202,6 +_,12 @@
          return item.isEmpty() ? 0 : item.getCount();
      }

paper-server/src/main/java/io/papermc/paper/PaperServerInternalAPIBridge.java

@@ -5,17 +5,30 @@
 import io.papermc.paper.world.damagesource.PaperCombatEntryWrapper;
 import io.papermc.paper.world.damagesource.PaperCombatTrackerWrapper;
 import net.minecraft.Optionull;
+import net.minecraft.core.Holder;
+import net.minecraft.core.IdMap;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.util.RandomSource;
 import net.minecraft.world.damagesource.FallLocation;
+import net.minecraft.world.inventory.EnchantmentMenu;
+import net.minecraft.world.item.enchantment.Enchantment;
 import org.bukkit.block.Biome;
+import org.bukkit.craftbukkit.CraftRegistry;
 import org.bukkit.craftbukkit.block.CraftBiome;
 import org.bukkit.craftbukkit.damage.CraftDamageEffect;
 import org.bukkit.craftbukkit.damage.CraftDamageSource;
+import org.bukkit.craftbukkit.enchantments.CraftEnchantment;
 import org.bukkit.craftbukkit.entity.CraftLivingEntity;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.craftbukkit.util.RandomSourceWrapper;
 import org.bukkit.damage.DamageEffect;
 import org.bukkit.damage.DamageSource;
+import org.bukkit.enchantments.EnchantmentOffer;
 import org.bukkit.entity.LivingEntity;
+import org.bukkit.inventory.ItemStack;
 import org.jspecify.annotations.NullMarked;
 import org.jspecify.annotations.Nullable;
+import java.util.Random;
 
 @NullMarked
 public class PaperServerInternalAPIBridge implements InternalAPIBridge {
@@ -71,4 +84,43 @@ private CombatEntry createCombatEntry(
             damageSource, damage, fallLocation, fallDistance
         ));
     }
+
+    @Override
+    public @Nullable EnchantmentOffer[] rollEnchantmentOffers(
+        final ItemStack targetStack,
+        final int seed,
+        final int bookshelfCount,
+        final int offerAmount
+    ) {
+        final int[] costs = new int[offerAmount];
+        final int[] enchantClue = new int[offerAmount];
+        final int[] levelClue = new int[offerAmount];
+
+        final RandomSource randomSource = new RandomSourceWrapper(new Random());
+        EnchantmentMenu.fillEnchantmentOffers(
+            randomSource,
+            seed,
+            bookshelfCount,
+            CraftItemStack.unwrap(targetStack),
+            CraftRegistry.getMinecraftRegistry(),
+            costs,
+            enchantClue,
+            levelClue
+        );
+
+        final IdMap<Holder<Enchantment>> holderIdMap = CraftRegistry.getMinecraftRegistry()
+            .lookupOrThrow(Registries.ENCHANTMENT)
+            .asHolderIdMap();
+        final @Nullable EnchantmentOffer[] offers = new EnchantmentOffer[offerAmount];
+        for (int i = 0; i < costs.length; i++) {
+            if (enchantClue[i] < 0) continue;
+            offers[i] = new EnchantmentOffer(
+                CraftEnchantment.minecraftHolderToBukkit(holderIdMap.byId(enchantClue[i])),
+                levelClue[i],
+                costs[i]
+            );
+        }
+
+        return offers;
+    }
 }