Add entity removal reason API

Author: NoyException

paper-api/src/main/java/io/papermc/paper/entity/RemovalReason.java

@@ -0,0 +1,41 @@
+package io.papermc.paper.entity;
+
+import org.bukkit.entity.Entity;
+
+/**
+ * Represents the reason an entity was removed.
+ *
+ * @see Entity#getRemovalReason()
+ */
+public enum RemovalReason {
+    // Start generate - RemovalReason
+    // @GeneratedFrom 1.21.8
+    KILLED(true, false),
+    DISCARDED(true, false),
+    UNLOADED_TO_CHUNK(false, true),
+    UNLOADED_WITH_PLAYER(false, false),
+    CHANGED_DIMENSION(false, false);
+    // End generate - RemovalReason
+
+    private final boolean destroy;
+    private final boolean save;
+
+    RemovalReason(final boolean destroy, final boolean save) {
+        this.destroy = destroy;
+        this.save = save;
+    }
+
+    /**
+     * {@return whether the entity should be destroyed after being removed}
+     */
+    public boolean shouldDestroy() {
+        return this.destroy;
+    }
+
+    /**
+     * {@return whether the entity should be saved after being removed}
+     */
+    public boolean shouldSave() {
+        return this.save;
+    }
+}

paper-api/src/main/java/org/bukkit/entity/Entity.java

@@ -5,6 +5,7 @@
 import java.util.UUID;
 import io.papermc.paper.datacomponent.DataComponentView;
 import io.papermc.paper.entity.LookAnchor;
+import io.papermc.paper.entity.RemovalReason;
 import net.kyori.adventure.util.TriState;
 import org.bukkit.Chunk; // Paper
 import org.bukkit.EntityEffect;
@@ -424,6 +425,16 @@ final class Holder {
      */
     public void remove();
 
+    /**
+     * {@return true if it was removed by a plugin}
+     */
+    boolean isPluginRemoved();
+
+    /**
+     * {@return the reason this entity was removed}
+     */
+    @Nullable RemovalReason getRemovalReason();
+
     /**
      * Returns true if this entity has been marked for removal.
      *

paper-generator/src/main/java/io/papermc/generator/Rewriters.java

@@ -24,6 +24,7 @@
 import io.papermc.generator.utils.Formatting;
 import io.papermc.paper.datacomponent.item.consumable.ItemUseAnimation;
 import io.papermc.paper.dialog.Dialog;
+import io.papermc.paper.entity.RemovalReason;
 import io.papermc.typewriter.preset.EnumCloneRewriter;
 import io.papermc.typewriter.preset.model.EnumValue;
 import io.papermc.typewriter.replace.SearchMetadata;
@@ -102,6 +103,12 @@ private static void bootstrapApi(PatternSourceSetRewriter sourceSet) {
         sourceSet
             .register("PotionType", PotionType.class, new EnumRegistryRewriter<>(Registries.POTION))
             .register("EntityType", EntityType.class, new EntityTypeRewriter())
+            .register("RemovalReason", RemovalReason.class, new EnumCloneRewriter<>(net.minecraft.world.entity.Entity.RemovalReason.class) {
+                @Override
+                protected EnumValue.Builder rewriteEnumValue(net.minecraft.world.entity.Entity.RemovalReason reason) {
+                    return super.rewriteEnumValue(reason).arguments(Boolean.toString(reason.shouldDestroy()), Boolean.toString(reason.shouldSave()));
+                }
+            })
             .register("DisplaySlot", DisplaySlot.class, new EnumCloneRewriter<>(net.minecraft.world.scores.DisplaySlot.class) {
                 @Override
                 protected EnumValue.Builder rewriteEnumValue(net.minecraft.world.scores.DisplaySlot slot) {

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java

@@ -7,6 +7,7 @@
 import com.google.common.collect.Lists;
 import com.mojang.logging.LogUtils;
 import io.papermc.paper.datacomponent.DataComponentType;
+import io.papermc.paper.entity.RemovalReason;
 import io.papermc.paper.entity.TeleportFlag;
 import java.util.HashSet;
 import java.util.List;
@@ -469,6 +470,17 @@ public void remove() {
         this.entity.discard(this.getHandle().generation ? null : EntityRemoveEvent.Cause.PLUGIN);
     }
 
+    @Override
+    public boolean isPluginRemoved() {
+        return this.entity.pluginRemoved;
+    }
+
+    @Override
+    public @Nullable RemovalReason getRemovalReason() {
+        if (this.entity.removalReason == null) return null;
+        return RemovalReason.valueOf(this.entity.removalReason.name());
+    }
+
     @Override
     public boolean isDead() {
         return !this.entity.isAlive();