Implement anvil damage on fall (#5345)

src/block/Anvil.php

@@ -30,12 +30,15 @@ use pocketmine\block\utils\HorizontalFacingTrait;
 use pocketmine\block\utils\SupportType;
 use pocketmine\data\runtime\RuntimeDataReader;
 use pocketmine\data\runtime\RuntimeDataWriter;
+use pocketmine\entity\object\FallingBlock;
 use pocketmine\item\Item;
 use pocketmine\math\AxisAlignedBB;
 use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\player\Player;
 use pocketmine\world\BlockTransaction;
+use function lcg_value;
+use function round;
 
 class Anvil extends Transparent implements Fallable{
 	use FallableTrait;
@@ -95,4 +98,15 @@ class Anvil extends Transparent implements Fallable{
 		}
 		return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
 	}
+
+	public function onHitGround(FallingBlock $blockEntity) : bool{
+		if(lcg_value() < 0.05 + (round($blockEntity->getFallDistance()) - 1) * 0.05){
+			if($this->damage !== self::VERY_DAMAGED){
+				$this->damage = $this->damage + 1;
+			}else{
+				return false;
+			}
+		}
+		return true;
+	}
 }

src/block/utils/Fallable.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\block\utils;
 
 use pocketmine\block\Block;
+use pocketmine\entity\object\FallingBlock;
 
 interface Fallable{
 
@@ -33,4 +34,10 @@ interface Fallable{
 	 * Return null if you don't want to change the usual behaviour.
 	 */
 	public function tickFalling() : ?Block;
+
+	/**
+	 * Called when FallingBlock hits the ground.
+	 * Returns whether the block should be placed.
+	 */
+	public function onHitGround(FallingBlock $blockEntity) : bool;
 }

src/block/utils/FallableTrait.php

@@ -58,4 +58,8 @@ trait FallableTrait{
 	public function tickFalling() : ?Block{
 		return null;
 	}
+
+	public function onHitGround(FallingBlock $blockEntity) : bool{
+		return true;
+	}
 }

src/entity/object/FallingBlock.php

@@ -145,6 +145,13 @@ class FallingBlock extends Entity{
 		return $hasUpdate;
 	}
 
+	protected function onHitGround() : ?float{
+		if($this->block instanceof Fallable && !$this->block->onHitGround($this)){
+			$this->flagForDespawn();
+		}
+		return null;
+	}
+
 	public function getBlock() : Block{
 		return $this->block;
 	}