Flammable blocks adjacent to fire now burn away

There are some strange bugs with blockupdating causing invisible client-side-only fires that need to be investigated.

src/pocketmine/block/Block.php

@@ -534,6 +534,13 @@ class Block extends Position implements BlockIds, Metadatable{
 		return $this->getFlammability() > 0;
 	}
 
+	/**
+	 * Called when this block is burned away by being on fire.
+	 */
+	public function onIncinerate() : void{
+
+	}
+
 	/**
 	 * Returns the Block on the side $side, works like Vector3::getSide()
 	 *

src/pocketmine/block/Fire.php

@@ -81,6 +81,8 @@ class Fire extends Flowable{
 	public function onNearbyBlockChange() : void{
 		if(!$this->getSide(Vector3::SIDE_DOWN)->isSolid() and !$this->hasAdjacentFlammableBlocks()){
 			$this->getLevel()->setBlock($this, BlockFactory::get(Block::AIR), true);
+		}else{
+			$this->level->scheduleDelayedBlockUpdate($this, mt_rand(30, 40));
 		}
 	}
 
@@ -96,13 +98,17 @@ class Fire extends Flowable{
 			$this->meta++;
 			$result = $this;
 		}
+		$canSpread = true;
 
 		if(!$down->burnsForever()){
+			//TODO: check rain
 			if($this->meta === 15){
 				if(!$down->isFlammable() and mt_rand(0, 3) === 3){ //1/4 chance to extinguish
+					$canSpread = false;
 					$result = BlockFactory::get(Block::AIR);
 				}
 			}elseif(!$this->hasAdjacentFlammableBlocks()){
+				$canSpread = false;
 				if(!$down->isSolid() or $this->meta > 3){ //fire older than 3, or without a solid block below
 					$result = BlockFactory::get(Block::AIR);
 				}
@@ -111,14 +117,23 @@ class Fire extends Flowable{
 
 		if($result !== null){
 			$this->level->setBlock($this, $result);
-			if($result->getId() !== $this->id){
-				return;
-			}
 		}
 
-		$this->level->scheduleDelayedBlockUpdate($this, 30 + mt_rand(0, 10));
+		if($canSpread){
+			$this->level->scheduleDelayedBlockUpdate($this, mt_rand(30, 40));
 
-		//TODO: fire spread
+			//TODO: raise upper bound for chance in humid biomes
+
+			foreach($this->getHorizontalSides() as $side){
+				$this->burnBlock($side, 300);
+			}
+
+			//vanilla uses a 250 upper bound here, but I don't think they intended to increase the chance of incineration
+			$this->burnBlock($this->getSide(Vector3::SIDE_UP), 350);
+			$this->burnBlock($this->getSide(Vector3::SIDE_DOWN), 350);
+
+			//TODO: fire spread
+		}
 	}
 
 	public function onScheduledUpdate() : void{
@@ -134,4 +149,16 @@ class Fire extends Flowable{
 
 		return false;
 	}
+
+	private function burnBlock(Block $block, int $chanceBound) : void{
+		if(mt_rand(0, $chanceBound) < $block->getFlammability()){
+			$block->onIncinerate();
+
+			if(mt_rand(0, $this->meta + 9) < 5){ //TODO: check rain
+				$this->level->setBlock($block, BlockFactory::get(Block::FIRE, min(15, $this->meta + (mt_rand(0, 4) >> 2))));
+			}else{
+				$this->level->setBlock($block, BlockFactory::get(Block::AIR));
+			}
+		}
+	}
 }

src/pocketmine/block/TNT.php

@@ -76,4 +76,8 @@ class TNT extends Solid{
 	public function getFlammability() : int{
 		return 100;
 	}
+
+	public function onIncinerate() : void{
+		$this->ignite();
+	}
 }