From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 24 Mar 2019 00:24:52 -0400
Subject: [PATCH] Entity#getEntitySpawnReason

Allows you to return the SpawnReason for why an Entity Spawned

Pre existing entities will return NATURAL if it was a non
persistenting Living Entity, SPAWNER for spawners,
or DEFAULT since data was not stored.

diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index 434f3a56e373e584801d66c13ba2c045a383beea..1192033c0c2248554ba452c7f3f8f05f29d9ac3a 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -1111,6 +1111,7 @@ public class ServerLevel extends net.minecraft.world.level.Level implements Worl
             return true;
         }
         // Paper end
+        if (entity.spawnReason == null) entity.spawnReason = spawnReason; // Paper
         if (entity.isRemoved()) {
             // Paper start
             if (DEBUG_ENTITIES) {
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index ea336bdf2f15aabe74de82ef6c29b93573254e31..da3100d6577166e222164c174b28020541dd8e3a 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -335,7 +335,7 @@ public abstract class PlayerList {
             // CraftBukkit start
             ServerLevel finalWorldServer = worldserver1;
             Entity entity = EntityType.loadEntityRecursive(nbttagcompound1.getCompound("Entity"), finalWorldServer, (entity1) -> {
-                return !finalWorldServer.addWithUUID(entity1) ? null : entity1;
+                return !finalWorldServer.addEntitySerialized(entity1, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.MOUNT) ? null : entity1; // Paper
                 // CraftBukkit end
             });
 
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 21aebe12db1544d0b8958c7db35a98cb92174630..88b9a6b7157c9e1b6d1acf80b95fb15004e9c4d3 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -67,6 +67,8 @@ import net.minecraft.world.InteractionHand;
 import net.minecraft.world.InteractionResult;
 import net.minecraft.world.Nameable;
 import net.minecraft.world.damagesource.DamageSource;
+import net.minecraft.world.entity.animal.AbstractFish;
+import net.minecraft.world.entity.animal.Animal;
 import net.minecraft.world.entity.item.ItemEntity;
 import net.minecraft.world.entity.player.Player;
 import net.minecraft.world.entity.vehicle.Boat;
@@ -166,6 +168,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
             }
         }
     };
+    public org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason;
     // Paper end
 
     public com.destroystokyo.paper.loottable.PaperLootableInventoryData lootableData; // Paper
@@ -1863,6 +1866,9 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
                 nbt.setUUID("Paper.OriginWorld", originWorld);
                 nbt.put("Paper.Origin", this.newDoubleList(origin.getX(), origin.getY(), origin.getZ()));
             }
+            if (spawnReason != null) {
+                nbt.putString("Paper.SpawnReason", spawnReason.name());
+            }
             // Save entity's from mob spawner status
             if (spawnedViaMobSpawner) {
                 nbt.putBoolean("Paper.FromMobSpawner", true);
@@ -2006,6 +2012,26 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, n
             }
 
             spawnedViaMobSpawner = nbt.getBoolean("Paper.FromMobSpawner"); // Restore entity's from mob spawner status
+            if (nbt.contains("Paper.SpawnReason")) {
+                String spawnReasonName = nbt.getString("Paper.SpawnReason");
+                try {
+                    spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.valueOf(spawnReasonName);
+                } catch (Exception ignored) {
+                    LogManager.getLogger().error("Unknown SpawnReason " + spawnReasonName + " for " + this);
+                }
+            }
+            if (spawnReason == null) {
+                if (spawnedViaMobSpawner) {
+                    spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER;
+                } else if (this instanceof Mob && (this instanceof Animal || this instanceof AbstractFish) && !((Mob) this).removeWhenFarAway(0.0)) {
+                    if (!nbt.getBoolean("PersistenceRequired")) {
+                        spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.NATURAL;
+                    }
+                }
+            }
+            if (spawnReason == null) {
+                spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.DEFAULT;
+            }
             // Paper end
 
         } catch (Throwable throwable) {
diff --git a/src/main/java/net/minecraft/world/level/BaseSpawner.java b/src/main/java/net/minecraft/world/level/BaseSpawner.java
index 7bf688057d684aa1b60f29294c9a7e81ab6742d1..66ae43c40d4bad373b3a5269e8c78d7a3b3ac498 100644
--- a/src/main/java/net/minecraft/world/level/BaseSpawner.java
+++ b/src/main/java/net/minecraft/world/level/BaseSpawner.java
@@ -188,6 +188,7 @@ public abstract class BaseSpawner {
                             // Spigot End
                         }
                         entity.spawnedViaMobSpawner = true; // Paper
+                        entity.spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER; // Paper
                         flag = true; // Paper
                         // Spigot Start
                         if (org.bukkit.craftbukkit.event.CraftEventFactory.callSpawnerSpawnEvent(entity, pos).isCancelled()) {
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index 7f1d9932e0e4e09c3727544d053ad61a365290af..5bf488e5ed1981ef121291867062c2c2efaed6fc 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -1173,5 +1173,10 @@ public abstract class CraftEntity implements org.bukkit.entity.Entity {
     public boolean fromMobSpawner() {
         return getHandle().spawnedViaMobSpawner;
     }
+
+    @Override
+    public org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason getEntitySpawnReason() {
+        return getHandle().spawnReason;
+    }
     // Paper end
 }