Revert "Block: Get rid of state bitmasks"

This reverts commit b7b05e729e.

Apparently this was premature, because we still need these things to deal with default state remapping.

src/pocketmine/block/Block.php

@@ -43,6 +43,8 @@ use pocketmine\Player;
 use pocketmine\plugin\Plugin;
 use pocketmine\tile\TileFactory;
 use function array_merge;
+use function assert;
+use function dechex;
 use function get_class;
 use const PHP_INT_MAX;
 
@@ -80,6 +82,9 @@ class Block extends Position implements BlockIds, Metadatable{
 	 * @param string          $name English name of the block type (TODO: implement translations)
 	 */
 	public function __construct(BlockIdentifier $idInfo, string $name){
+		if(($idInfo->getVariant() & $this->getStateBitmask()) !== 0){
+			throw new \InvalidArgumentException("Variant 0x" . dechex($idInfo->getVariant()) . " collides with state bitmask 0x" . dechex($this->getStateBitmask()));
+		}
 		$this->idInfo = $idInfo;
 		$this->fallbackName = $name;
 	}
@@ -118,7 +123,9 @@ class Block extends Position implements BlockIds, Metadatable{
 	 * @return int
 	 */
 	public function getDamage() : int{
-		return $this->idInfo->getVariant() | $this->writeStateToMeta();
+		$stateMeta = $this->writeStateToMeta();
+		assert(($stateMeta & ~$this->getStateBitmask()) === 0);
+		return $this->idInfo->getVariant() | $stateMeta;
 	}
 
 	protected function writeStateToMeta() : int{
@@ -161,6 +168,15 @@ class Block extends Position implements BlockIds, Metadatable{
 		}
 	}
 
+	/**
+	 * Returns a bitmask used to extract state bits from block metadata.
+	 *
+	 * @return int
+	 */
+	public function getStateBitmask() : int{
+		return 0;
+	}
+
 	/**
 	 * Returns whether the given block has an equivalent type to this one. This compares base legacy ID and variant.
 	 *