From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 17 Apr 2016 17:27:09 -0400
Subject: [PATCH] Prevent Fire from loading chunks & wrongly spread

This causes the nether to spam unload/reload chunks, plus overall
bad behavior.

This also stops fire from spreading to illegal locations.



This shouldn't need to be included in post 1.14 versions, as blocks no longer tick without at least 1 radius
chunk loaded.

diff --git a/src/main/java/net/minecraft/world/level/block/FireBlock.java b/src/main/java/net/minecraft/world/level/block/FireBlock.java
index 700078c2fd536cc22351eadf51503efb9acd9df9..85170008de6e77cfb8e4f55ae440a8428d868af4 100644
--- a/src/main/java/net/minecraft/world/level/block/FireBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/FireBlock.java
@@ -134,7 +134,7 @@ public class FireBlock extends BaseFireBlock {
                 BooleanProperty blockstateboolean = (BooleanProperty) FireBlock.PROPERTY_BY_DIRECTION.get(enumdirection);
 
                 if (blockstateboolean != null) {
-                    iblockdata1 = (BlockState) iblockdata1.setValue(blockstateboolean, this.canBurn(world.getBlockState(pos.relative(enumdirection))));
+                    iblockdata1 = (BlockState) iblockdata1.setValue(blockstateboolean, this.canBurn(world.getTypeIfLoaded(pos.relative(enumdirection)))); // Paper - prevent chunk loads
                 }
             }
 
@@ -214,6 +214,7 @@ public class FireBlock extends BaseFireBlock {
                                 }
 
                                 blockposition_mutableblockposition.setWithOffset((Vec3i) pos, l, j1, i1);
+                                if (blockposition_mutableblockposition.isInvalidYLocation() || !world.hasChunkAt(blockposition_mutableblockposition)) continue; // Paper
                                 int l1 = this.getFireOdds((LevelReader) world, (BlockPos) blockposition_mutableblockposition);
 
                                 if (l1 > 0) {
@@ -259,10 +260,16 @@ public class FireBlock extends BaseFireBlock {
     }
 
     private void trySpread(Level world, BlockPos blockposition, int i, Random random, int j, BlockPos sourceposition) { // CraftBukkit add sourceposition
-        int k = this.getBurnOdd(world.getBlockState(blockposition));
+        // Paper start
+        final BlockState iblockdata = world.getTypeIfLoaded(blockposition);
+        if (iblockdata == null) {
+            return;
+        }
+        int k = this.getBurnOdd(iblockdata);
+        // Paper end
 
         if (random.nextInt(i) < k) {
-            BlockState iblockdata = world.getBlockState(blockposition);
+            //IBlockData iblockdata = world.getType(blockposition); // Paper
 
             // CraftBukkit start
             org.bukkit.block.Block theBlock = world.getWorld().getBlockAt(blockposition.getX(), blockposition.getY(), blockposition.getZ());
@@ -308,7 +315,7 @@ public class FireBlock extends BaseFireBlock {
         for (int j = 0; j < i; ++j) {
             Direction enumdirection = aenumdirection[j];
 
-            if (this.canBurn(world.getBlockState(pos.relative(enumdirection)))) {
+            if (this.canBurn(world.getTypeIfLoaded(pos.relative(enumdirection)))) { // Paper - prevent chunk loads
                 return true;
             }
         }
@@ -326,7 +333,12 @@ public class FireBlock extends BaseFireBlock {
 
             for (int k = 0; k < j; ++k) {
                 Direction enumdirection = aenumdirection[k];
-                BlockState iblockdata = iworldreader.getBlockState(pos.relative(enumdirection));
+                // Paper start
+                BlockState iblockdata = iworldreader.getTypeIfLoaded(pos.relative(enumdirection));
+                if (iblockdata == null) {
+                    continue;
+                }
+                // Paper end
 
                 i = Math.max(this.getFlameOdds(iblockdata), i);
             }
@@ -337,7 +349,7 @@ public class FireBlock extends BaseFireBlock {
 
     @Override
     protected boolean canBurn(BlockState state) {
-        return this.getFlameOdds(state) > 0;
+        return state != null && this.getFlameOdds(state) > 0;  // Paper - iblockdata can be nullable if chunk is unloaded now
     }
 
     @Override