From 4b032c2d960af52e463e60ac5ab539ff4f0a607e Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 14 Jan 2018 17:36:02 -0500
Subject: [PATCH] PlayerNaturallySpawnCreaturesEvent

This event can be used for when you want to exclude a certain player
from triggering monster spawns on a server.

Also a highly more effecient way to blanket block spawns in a world

diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
index 242ff923a0..99a4c0d227 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -502,6 +502,15 @@ public class ChunkProviderServer extends IChunkProvider {
 
             this.world.timings.countNaturalMobs.stopTiming(); // Paper - timings
             this.world.getMethodProfiler().exit();
+            //Paper start - call player naturally spawn event
+            int chunkRange = world.spigotConfig.mobSpawnRange;
+            chunkRange = (chunkRange > world.spigotConfig.viewDistance) ? (byte) world.spigotConfig.viewDistance : chunkRange;
+            chunkRange = Math.min(chunkRange, 8);
+            for (EntityPlayer entityPlayer : this.world.players) {
+                entityPlayer.playerNaturallySpawnedEvent = new com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent(entityPlayer.getBukkitEntity(), (byte) chunkRange);
+                entityPlayer.playerNaturallySpawnedEvent.callEvent();
+            };
+            // Paper end
             this.playerChunkMap.f().forEach((playerchunk) -> {
                 Optional<Chunk> optional = ((Either) playerchunk.b().getNow(PlayerChunk.UNLOADED_CHUNK)).left();
 
diff --git a/src/main/java/net/minecraft/server/EntityPlayer.java b/src/main/java/net/minecraft/server/EntityPlayer.java
index 1296eb04f0..625b684287 100644
--- a/src/main/java/net/minecraft/server/EntityPlayer.java
+++ b/src/main/java/net/minecraft/server/EntityPlayer.java
@@ -1,5 +1,6 @@
 package net.minecraft.server;
 
+import com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent;
 import com.google.common.collect.Lists;
 import com.mojang.authlib.GameProfile;
 import com.mojang.datafixers.util.Either;
@@ -89,6 +90,7 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
     public boolean sentListPacket = false;
     public Integer clientViewDistance;
     // CraftBukkit end
+    public PlayerNaturallySpawnCreaturesEvent playerNaturallySpawnedEvent; // Paper
 
     public final com.destroystokyo.paper.util.misc.PooledLinkedHashSets.PooledObjectLinkedOpenHashSet<EntityPlayer> cachedSingleHashSet; // Paper
 
diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
index 936fc4f6b9..fcf229ad5d 100644
--- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
@@ -881,12 +881,23 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
         chunkRange = (chunkRange > world.spigotConfig.viewDistance) ? (byte) world.spigotConfig.viewDistance : chunkRange;
         chunkRange = (chunkRange > 8) ? 8 : chunkRange;
 
-        double blockRange = (reducedRange) ? Math.pow(chunkRange << 4, 2) : 16384.0D;
+        final int finalChunkRange = chunkRange; // Paper for lambda below
+        //double blockRange = (reducedRange) ? Math.pow(chunkRange << 4, 2) : 16384.0D; // Paper - use from event
         // Spigot end
         long i = chunkcoordintpair.pair();
 
         return !this.chunkDistanceManager.d(i) ? true : this.playerMap.a(i).noneMatch((entityplayer) -> {
-            return !entityplayer.isSpectator() && a(chunkcoordintpair, (Entity) entityplayer) < blockRange; // Spigot
+            // Paper start -
+            com.destroystokyo.paper.event.entity.PlayerNaturallySpawnCreaturesEvent event;
+            double blockRange = 16384.0D;
+            if (reducedRange) {
+                event = entityplayer.playerNaturallySpawnedEvent;
+                if (event == null || event.isCancelled()) return false;
+                blockRange = (double) ((event.getSpawnRadius() << 4) * (event.getSpawnRadius() << 4));
+            }
+
+            return (!entityplayer.isSpectator() && a(chunkcoordintpair, (Entity) entityplayer) < blockRange); // Spigot
+            // Paper end
         });
     }
 
-- 
2.25.0