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 2ab221e5315dde4e556ee49a6962ae0091ccf616..d03b4f97102dfb88927a94ee5a5d397ac493eaa1 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -1035,6 +1035,7 @@ public class ServerLevel extends net.minecraft.world.level.Level implements Worl
     // CraftBukkit start
     private boolean addEntity0(Entity entity, CreatureSpawnEvent.SpawnReason spawnReason) {
         org.spigotmc.AsyncCatcher.catchOp("entity add"); // Spigot
+        if (entity.spawnReason == null) entity.spawnReason = spawnReason; // Paper
         // Paper start
         if (entity.valid) {
             MinecraftServer.LOGGER.error("Attempted Double World add on " + entity, new Throwable());
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 728eaadd3dc619e414ec30feb38c7d4a84b2e539..4d813b6556030354f51c1ee5f18eac2166b44576 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -331,7 +331,7 @@ 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 d106118dbf4fb270f8526e40a767dd4c563a333f..6faac8773136412ca129dfa884178f311e197f6e 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -63,6 +63,8 @@ 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;
@@ -157,6 +159,7 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
         }
     };
     public List<Entity> entitySlice = null;
+    public org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason;
     // Paper end
 
     public com.destroystokyo.paper.loottable.PaperLootableInventoryData lootableData; // Paper
@@ -1673,6 +1676,9 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
                 tag.setUUID("Paper.OriginWorld", origin.getWorld().getUID());
                 tag.put("Paper.Origin", this.createList(origin.getX(), origin.getY(), origin.getZ()));
             }
+            if (spawnReason != null) {
+                tag.putString("Paper.SpawnReason", spawnReason.name());
+            }
             // Save entity's from mob spawner status
             if (spawnedViaMobSpawner) {
                 tag.putBoolean("Paper.FromMobSpawner", true);
@@ -1811,6 +1817,26 @@ public abstract class Entity implements Nameable, CommandSource, net.minecraft.s
             }
 
             spawnedViaMobSpawner = tag.getBoolean("Paper.FromMobSpawner"); // Restore entity's from mob spawner status
+            if (tag.contains("Paper.SpawnReason")) {
+                String spawnReasonName = tag.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 (!tag.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 1ce675d0d24ceb5724f5ac2d8f671e38f2735f74..3a7aec9bd2f3fd1b4a1981fb6a8c64b69e4875f8 100644
--- a/src/main/java/net/minecraft/world/level/BaseSpawner.java
+++ b/src/main/java/net/minecraft/world/level/BaseSpawner.java
@@ -183,6 +183,7 @@ 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, blockposition).isCancelled()) {
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
index e1bbaf620f3ed2a6cb9ce8007a78c4cee47b653e..7ad4fb57af32cc1b8278688381e1b058ed8437db 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftEntity.java
@@ -1106,5 +1106,10 @@ 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
 }