Add Movable Amethyst Rule (#894)

* Add Pushable Amethyst Rule

As discussed in #79 of ilmangos peaceful challenge. He said he'd do it, I figured I could beat him to the punch :)
https://youtu.be/0-fAKpr_J8k?t=1076

* Name change - movableAmethyst

Co-authored-by: hugeblank <hugeblank@gmail.com>

src/main/java/carpet/CarpetSettings.java

@@ -315,6 +315,9 @@ public class CarpetSettings
     )
     public static boolean hopperCounters = false;
 
+    @Rule( desc = "Allows Budding Amethyst blocks to be moved by pistons", category = FEATURE )
+    public static boolean movableAmethyst = false;
+
     @Rule( desc = "Guardians turn into Elder Guardian when struck by lightning", category = FEATURE )
     public static boolean renewableSponges = false;
 

src/main/java/carpet/mixins/BuddingAmethystBlock_getPistonBehaviorMixin.java

@@ -0,0 +1,18 @@
+package carpet.mixins;
+
+import carpet.CarpetSettings;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.BuddingAmethystBlock;
+import net.minecraft.block.piston.PistonBehavior;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+@Mixin(BuddingAmethystBlock.class)
+public class BuddingAmethystBlock_getPistonBehaviorMixin {
+    @Inject(at = @At("HEAD"), method = "getPistonBehavior(Lnet/minecraft/block/BlockState;)Lnet/minecraft/block/piston/PistonBehavior;", cancellable = true)
+    void getPistonBehavior(BlockState state, CallbackInfoReturnable<PistonBehavior> cir) {
+        if (CarpetSettings.movableAmethyst) cir.setReturnValue(PistonBehavior.NORMAL);
+    }
+}

src/main/resources/carpet.mixins.json

@@ -89,6 +89,7 @@
     "ServerWorld_onePlayerSleepingMixin",
     "CoralBlockMixin",
     "CoralFeatureMixin",
+    "BuddingAmethystBlock_getPistonBehaviorMixin",
     "FluidBlock_renewableBlackstoneMixin",
     "FluidBlock_renewableDeepslateMixin",
     "LavaFluid_renewableDeepslateMixin",