Leashable API (#10961)

3 files changed, 248 insertions, 0 deletions

diff --git a/patches/api/0053-Fix-upstream-javadocs.patch b/patches/api/0053-Fix-upstream-javadocs.patch
index a47008818b..f23a8a7e79 100644
--- a/patches/api/0053-Fix-upstream-javadocs.patch
+++ b/patches/api/0053-Fix-upstream-javadocs.patch
@@ -444,6 +444,19 @@ index b688b3856cb3068a539fcecfbfa113f8ab4160a9..c275b881cbd11307a6dcc7190d7a7d40
       *
       * @return whether the item frame is visible or not
       */
+diff --git a/src/main/java/org/bukkit/entity/LivingEntity.java b/src/main/java/org/bukkit/entity/LivingEntity.java
+index 32e89741ffd895e31af0104a0126c2f72742a1bb..bc17c86da49faf4b6e07d4fb4c53649da0384d69 100644
+--- a/src/main/java/org/bukkit/entity/LivingEntity.java
++++ b/src/main/java/org/bukkit/entity/LivingEntity.java
+@@ -502,7 +502,7 @@ public interface LivingEntity extends Attributable, Damageable, ProjectileSource
+     /**
+      * Sets the leash on this entity to be held by the supplied entity.
+      * <p>
+-     * This method has no effect on EnderDragons, Withers, Players, or Bats.
++     * This method has no effect on players.
+      * Non-living entities excluding leashes will not persist as leash
+      * holders.
+      *
 diff --git a/src/main/java/org/bukkit/entity/Mob.java b/src/main/java/org/bukkit/entity/Mob.java
 index f3f62e13cc1b6172808c52f2d5f520f1f584e6db..ad5dbf310fe7b34c997bb339f09697222f862005 100644
 --- a/src/main/java/org/bukkit/entity/Mob.java
diff --git a/patches/api/0485-Leashable-API.patch b/patches/api/0485-Leashable-API.patch
new file mode 100644
index 0000000000..e5b1a4857d
--- /dev/null
+++ b/patches/api/0485-Leashable-API.patch
@@ -0,0 +1,74 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Lulu13022002 <[email protected]>
+Date: Sat, 22 Jun 2024 21:11:58 +0200
+Subject: [PATCH] Leashable API
+
+
+diff --git a/src/main/java/io/papermc/paper/entity/Leashable.java b/src/main/java/io/papermc/paper/entity/Leashable.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..7402bab20db0ebcac5b2d492ad002ecf9669caad
+--- /dev/null
++++ b/src/main/java/io/papermc/paper/entity/Leashable.java
+@@ -0,0 +1,36 @@
++package io.papermc.paper.entity;
++
++import org.bukkit.entity.Entity;
++import org.checkerframework.checker.nullness.qual.NonNull;
++import org.checkerframework.checker.nullness.qual.Nullable;
++
++/**
++ * Represents an entity that can be leashed.
++ */
++public interface Leashable extends Entity {
++
++    /**
++     * Returns whether the entity is currently leashed.
++     *
++     * @return whether the entity is leashed
++     */
++    boolean isLeashed();
++
++    /**
++     * Gets the entity that is currently leading this entity.
++     *
++     * @return the entity holding the leash
++     * @throws IllegalStateException if not currently leashed
++     */
++    @NonNull Entity getLeashHolder() throws IllegalStateException;
++
++    /**
++     * Sets the leash on this entity to be held by the supplied entity.
++     * <p>
++     * This method has no effect on players.
++     *
++     * @param holder the entity to leash this entity to, or {@code null} to unleash
++     * @return whether the operation was successful
++     */
++    boolean setLeashHolder(@Nullable Entity holder);
++}
+diff --git a/src/main/java/org/bukkit/entity/Boat.java b/src/main/java/org/bukkit/entity/Boat.java
+index 2ac685fb1817f3ce06ebe6391cc863712d68367c..d80524fe32672a8b8940d1028abf22026dace8d2 100644
+--- a/src/main/java/org/bukkit/entity/Boat.java
++++ b/src/main/java/org/bukkit/entity/Boat.java
+@@ -7,7 +7,7 @@ import org.jetbrains.annotations.NotNull;
+ /**
+  * Represents a boat entity.
+  */
+-public interface Boat extends Vehicle {
++public interface Boat extends Vehicle, io.papermc.paper.entity.Leashable { // Paper - Leashable API
+ 
+     /**
+      * Gets the wood type of the boat.
+diff --git a/src/main/java/org/bukkit/entity/Mob.java b/src/main/java/org/bukkit/entity/Mob.java
+index 256e5645bcfa76e7ede58ae365e69b4a4bed6204..9a10262a952e330f42187d6e4edab5a225bfba62 100644
+--- a/src/main/java/org/bukkit/entity/Mob.java
++++ b/src/main/java/org/bukkit/entity/Mob.java
+@@ -8,7 +8,7 @@ import org.jetbrains.annotations.Nullable;
+ /**
+  * Represents a Mob. Mobs are living entities with simple AI.
+  */
+-public interface Mob extends LivingEntity, Lootable {
++public interface Mob extends LivingEntity, Lootable, io.papermc.paper.entity.Leashable { // Paper - Leashable API
+ 
+     // Paper start
+     @Override
diff --git a/patches/server/1049-Leashable-API.patch b/patches/server/1049-Leashable-API.patch
new file mode 100644
index 0000000000..b93323b964
--- /dev/null
+++ b/patches/server/1049-Leashable-API.patch
@@ -0,0 +1,161 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Lulu13022002 <[email protected]>
+Date: Sat, 22 Jun 2024 21:17:54 +0200
+Subject: [PATCH] Leashable API
+
+
+diff --git a/src/main/java/io/papermc/paper/entity/PaperLeashable.java b/src/main/java/io/papermc/paper/entity/PaperLeashable.java
+new file mode 100644
+index 0000000000000000000000000000000000000000..a9ddf9a4a07cd29833f38d7e5f42b2b14ec98f78
+--- /dev/null
++++ b/src/main/java/io/papermc/paper/entity/PaperLeashable.java
+@@ -0,0 +1,50 @@
++package io.papermc.paper.entity;
++
++import com.google.common.base.Preconditions;
++import net.minecraft.world.entity.Leashable;
++import org.bukkit.craftbukkit.entity.CraftEntity;
++import org.bukkit.entity.Entity;
++
++public interface PaperLeashable extends io.papermc.paper.entity.Leashable {
++
++    Leashable getHandle();
++
++    @Override
++    default boolean isLeashed() {
++        return this.getHandle().getLeashHolder() != null;
++    }
++
++    @Override
++    default Entity getLeashHolder() throws IllegalStateException {
++        Preconditions.checkState(this.isLeashed(), "Entity not leashed");
++        return this.getHandle().getLeashHolder().getBukkitEntity();
++    }
++
++    private boolean unleash() {
++        if (!this.isLeashed()) {
++            return false;
++        }
++
++        this.getHandle().dropLeash(true, false);
++        return true;
++    }
++
++    @Override
++    default boolean setLeashHolder(Entity holder) {
++        if (this.getHandle() instanceof net.minecraft.world.entity.Entity entity && entity.generation) {
++            return false;
++        }
++
++        if (holder == null) {
++            return this.unleash();
++        }
++
++        if (holder.isDead()) {
++            return false;
++        }
++
++        this.unleash();
++        this.getHandle().setLeashedTo(((CraftEntity) holder).getHandle(), true);
++        return true;
++    }
++}
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftBoat.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftBoat.java
+index e33b1b6fd50a4eea57500cc00dba20d6edcab75d..01a9660de65688b7c1a4f9dafcb650774ce1853b 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftBoat.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftBoat.java
+@@ -7,7 +7,7 @@ import org.bukkit.craftbukkit.CraftServer;
+ import org.bukkit.entity.Boat;
+ import org.bukkit.entity.Entity;
+ 
+-public class CraftBoat extends CraftVehicle implements Boat {
++public class CraftBoat extends CraftVehicle implements Boat, io.papermc.paper.entity.PaperLeashable { // Paper - Leashable API
+ 
+     public CraftBoat(CraftServer server, net.minecraft.world.entity.vehicle.Boat entity) {
+         super(server, entity);
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
+index d2bb0831394c03b620b2cbd8306cb82b621f34f7..beb6ad312028adb14053e3f019a4fcf6c9149373 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java
+@@ -753,43 +753,17 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
+ 
+     @Override
+     public boolean isLeashed() {
+-        if (!(this.getHandle() instanceof Mob)) {
+-            return false;
+-        }
+-        return ((Mob) this.getHandle()).getLeashHolder() != null;
++        return false; // Paper - implement in CraftMob & PaperLeashable
+     }
+ 
+     @Override
+     public Entity getLeashHolder() throws IllegalStateException {
+-        Preconditions.checkState(this.isLeashed(), "Entity not leashed");
+-        return ((Mob) this.getHandle()).getLeashHolder().getBukkitEntity();
+-    }
+-
+-    private boolean unleash() {
+-        if (!this.isLeashed()) {
+-            return false;
+-        }
+-        ((Mob) this.getHandle()).dropLeash(true, false);
+-        return true;
++        throw new IllegalStateException("Entity not leashed"); // Paper - implement in CraftMob & PaperLeashable
+     }
+ 
+     @Override
+     public boolean setLeashHolder(Entity holder) {
+-        if (this.getHandle().generation || (this.getHandle() instanceof WitherBoss) || !(this.getHandle() instanceof Mob)) {
+-            return false;
+-        }
+-
+-        if (holder == null) {
+-            return this.unleash();
+-        }
+-
+-        if (holder.isDead()) {
+-            return false;
+-        }
+-
+-        this.unleash();
+-        ((Mob) this.getHandle()).setLeashedTo(((CraftEntity) holder).getHandle(), true);
+-        return true;
++        return false; // Paper - implement in CraftMob & PaperLeashable
+     }
+ 
+     @Override
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
+index deb66c04abefb4a88521483db1612e494bd27164..5f9f7e325e3e0276f7a475c4a4725cc0e1b54afd 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftMob.java
+@@ -11,7 +11,7 @@ import org.bukkit.entity.LivingEntity;
+ import org.bukkit.entity.Mob;
+ import org.bukkit.loot.LootTable;
+ 
+-public abstract class CraftMob extends CraftLivingEntity implements Mob {
++public abstract class CraftMob extends CraftLivingEntity implements Mob, io.papermc.paper.entity.PaperLeashable { // Paper - Leashable API
+     public CraftMob(CraftServer server, net.minecraft.world.entity.Mob entity) {
+         super(server, entity);
+          paperPathfinder = new com.destroystokyo.paper.entity.PaperPathfinder(entity); // Paper - Mob Pathfinding API
+@@ -175,4 +175,21 @@ public abstract class CraftMob extends CraftLivingEntity implements Mob {
+         return getHandle().getExperienceReward((ServerLevel) this.getHandle().level(), null);
+     }
+     // Paper end
++
++    // Paper start - Leashable API
++    @Override
++    public boolean isLeashed() {
++        return io.papermc.paper.entity.PaperLeashable.super.isLeashed();
++    }
++
++    @Override
++    public org.bukkit.entity.Entity getLeashHolder() throws IllegalStateException {
++        return io.papermc.paper.entity.PaperLeashable.super.getLeashHolder();
++    }
++
++    @Override
++    public boolean setLeashHolder(final org.bukkit.entity.Entity holder) {
++        return io.papermc.paper.entity.PaperLeashable.super.setLeashHolder(holder);
++    }
++    // Paper end - Leashable API
+ }