fix: piston block entity special behavior (#27)

Most block entity will try to create one if there are none. for maybe some reason to save storage usage.

Due to Mojang's strange logic, pistons does not--they returns null instead of create a piston block entity.

This fix uses reflection to create a block entity--this may not suitable for all types of blocks and maybe not performative enough but it should works.

Mojang-ma=ojng

Note: The block entities will tick itself--so even if we dont add a BE ot scheduled tick, after redo, the pistons will still keep working instead of stopping. We think this works as intended due to mojang's bull-shit game mechanics.

close: #27

src/main/java/com/github/zly2006/reden/access/PlayerData.kt

@@ -2,8 +2,11 @@ package com.github.zly2006.reden.access
 
 import com.github.zly2006.reden.carpet.RedenCarpetSettings
 import com.github.zly2006.reden.malilib.UNDO_CHEATING_ONLY
+import com.github.zly2006.reden.utils.debugLogger
 import com.github.zly2006.reden.utils.isClient
 import com.github.zly2006.reden.utils.isSinglePlayerAndCheating
+import net.minecraft.block.Blocks
+import net.minecraft.block.entity.BlockEntity
 import net.minecraft.command.EntitySelector
 import net.minecraft.entity.EntityType
 import net.minecraft.entity.TntEntity
@@ -32,6 +35,7 @@ class PlayerData(
 
     data class Entry(
         val blockState: NbtCompound,
+        val blockEntityClazz: Class<BlockEntity>?,
         val blockEntity: NbtCompound?,
     ) {
 
@@ -55,10 +59,16 @@ class PlayerData(
         val data: MutableMap<Long, Entry> = mutableMapOf()
     ) {
         fun fromWorld(world: World, pos: BlockPos): Entry {
+            val be = world.getBlockEntity(pos)
             return Entry(
                 NbtHelper.fromBlockState(world.getBlockState(pos)),
+                be?.javaClass,
                 world.getBlockEntity(pos)?.createNbt()
             ).apply {
+                if (world.getBlockState(pos).isOf(Blocks.MOVING_PISTON) &&
+                    blockEntity == null) {
+                    debugLogger("OHHHHHHHHH")
+                }
                 if (world.getBlockState(pos).getCollisionShape(world, pos).boundingBoxes.size != 0) {
                     val list = world.getEntitiesByType(
                         EntitySelector.PASSTHROUGH_FILTER,

src/main/java/com/github/zly2006/reden/network/Rollback.kt

@@ -13,6 +13,7 @@ import net.fabricmc.fabric.api.networking.v1.FabricPacket
 import net.fabricmc.fabric.api.networking.v1.PacketType
 import net.fabricmc.fabric.api.networking.v1.ServerPlayNetworking
 import net.minecraft.block.Block
+import net.minecraft.block.BlockState
 import net.minecraft.entity.SpawnReason
 import net.minecraft.nbt.NbtHelper
 import net.minecraft.network.PacketByteBuf
@@ -49,7 +50,18 @@ class Rollback(
                 fluidTickScheduler.removeTicksIf { it.pos == pos }
                 // apply block entity
                 entry.blockEntity?.let { be ->
-                    world.getBlockEntity(BlockPos.fromLong(posLong))?.readNbt(be)
+                    var blockEntity = world.getBlockEntity(BlockPos.fromLong(posLong))
+                    if (blockEntity == null) {
+                        try {
+                            // force add block entities, got blocks like piston.
+                            blockEntity = entry.blockEntityClazz!!
+                                .getConstructor(BlockPos::class.java, BlockState::class.java)
+                                .newInstance(pos, state).also(world::addBlockEntity)
+                        } catch (e: Exception) {
+                            Reden.LOGGER.error("Failed to create block entity for $pos, $state", e)
+                        }
+                    }
+                    blockEntity?.readNbt(be)
                 }
             }
             record.entities.forEach {
@@ -74,6 +86,7 @@ class Rollback(
                 if (last.data.isNotEmpty() || last.entities.isNotEmpty()) {
                     return last
                 }
+                // if the last record is empty, remove it
                 UpdateMonitorHelper.removeRecord(last.id)
                 this.removeLast()
             }

src/main/resources/reden.accesswidener

@@ -39,3 +39,4 @@ accessible field net/minecraft/world/tick/ChunkTickScheduler queuedTicks Ljava/u
 accessible field net/minecraft/block/entity/PistonBlockEntity progress F
 accessible field net/minecraft/block/entity/PistonBlockEntity lastProgress F
 accessible method net/minecraft/client/network/ClientPlayerInteractionManager sendSequencedPacket (Lnet/minecraft/client/world/ClientWorld;Lnet/minecraft/client/network/SequencedPacketCreator;)V
+accessible field net/minecraft/world/tick/ChunkTickScheduler tickQueue Ljava/util/Queue;