Improve entity kill preview

src/main/java/com/github/quiltservertools/ledger/mixin/preview/EntityTrackerEntryAccessor.java

@@ -0,0 +1,14 @@
+package com.github.quiltservertools.ledger.mixin.preview;
+
+import net.minecraft.entity.Entity;
+import net.minecraft.server.network.EntityTrackerEntry;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Accessor;
+
+@Mixin(EntityTrackerEntry.class)
+public interface EntityTrackerEntryAccessor {
+
+    @Accessor
+    Entity getEntity();
+
+}

src/main/kotlin/com/github/quiltservertools/ledger/actions/EntityKillActionType.kt

@@ -6,10 +6,9 @@ import com.github.quiltservertools.ledger.utility.getWorld
 import net.minecraft.entity.Entity
 import net.minecraft.entity.LivingEntity
 import net.minecraft.nbt.StringNbtReader
-import net.minecraft.network.packet.s2c.play.EntitiesDestroyS2CPacket
-import net.minecraft.network.packet.s2c.play.EntitySpawnS2CPacket
 import net.minecraft.registry.Registries
 import net.minecraft.server.MinecraftServer
+import net.minecraft.server.network.EntityTrackerEntry
 import net.minecraft.server.network.ServerPlayerEntity
 import net.minecraft.util.math.Vec3d
 
@@ -29,8 +28,9 @@ class EntityKillActionType : AbstractActionType() {
         entity.health = entity.defaultMaxHealth.toFloat()
         entity.velocity = Vec3d.ZERO
         entity.fireTicks = 0
-        player.networkHandler.sendPacket(EntitySpawnS2CPacket(entity))
-        preview.spawnedEntityIds.add(entity.id)
+        val entityTrackerEntry = EntityTrackerEntry(world, entity, 1, false) { }
+        entityTrackerEntry.startTracking(player)
+        preview.spawnedEntityTrackers.add(entityTrackerEntry)
     }
 
     override fun previewRestore(preview: Preview, player: ServerPlayerEntity) {
@@ -41,8 +41,9 @@ class EntityKillActionType : AbstractActionType() {
             val uuid = tag.getUuid("UUID")
             val entity = world?.getEntity(uuid)
             entity?.let {
-                player.networkHandler.sendPacket(EntitiesDestroyS2CPacket(it.id))
-                preview.removedEntityUuids.add(it.uuid)
+                val entityTrackerEntry = EntityTrackerEntry(world, entity, 1, false) { }
+                entityTrackerEntry.stopTracking(player)
+                preview.removedEntityTrackers.add(entityTrackerEntry)
             }
         }
     }

src/main/kotlin/com/github/quiltservertools/ledger/actionutils/Preview.kt

@@ -3,14 +3,12 @@ package com.github.quiltservertools.ledger.actionutils
 import com.github.quiltservertools.ledger.actions.ActionType
 import com.github.quiltservertools.ledger.commands.subcommands.RestoreCommand
 import com.github.quiltservertools.ledger.commands.subcommands.RollbackCommand
+import com.github.quiltservertools.ledger.mixin.preview.EntityTrackerEntryAccessor
 import com.github.quiltservertools.ledger.utility.Context
 import com.github.quiltservertools.ledger.utility.TextColorPallet
-import java.util.*
 import net.minecraft.item.ItemStack
 import net.minecraft.network.packet.s2c.play.BlockUpdateS2CPacket
-import net.minecraft.network.packet.s2c.play.BundleS2CPacket
-import net.minecraft.network.packet.s2c.play.EntitiesDestroyS2CPacket
-import net.minecraft.network.packet.s2c.play.EntitySpawnS2CPacket
+import net.minecraft.server.network.EntityTrackerEntry
 import net.minecraft.server.network.ServerPlayerEntity
 import net.minecraft.text.Text
 import net.minecraft.util.math.BlockPos
@@ -22,10 +20,13 @@ class Preview(
     private val type: Type
 ) {
     val positions = mutableSetOf<BlockPos>()
+
     // Preview entities that got spawned. Need to removed
-    val spawnedEntityIds = mutableSetOf<Int>()
+    val spawnedEntityTrackers = mutableSetOf<EntityTrackerEntry>()
+
     // Preview entities that got removed. Need to be spawned
-    val removedEntityUuids = mutableSetOf<UUID>()
+    val removedEntityTrackers = mutableSetOf<EntityTrackerEntry>()
+
     // Preview items that should be modified in screen handlers (true = added, false = removed)
     val modifiedItems = mutableMapOf<BlockPos, MutableList<Pair<ItemStack, Boolean>>>()
 
@@ -56,22 +57,21 @@ class Preview(
 
     private fun cleanup(player: ServerPlayerEntity) {
         // Cleanup preview entities, to keep client and server in sync
-        val destroyPackets = spawnedEntityIds.map {
-            EntitiesDestroyS2CPacket(it)
-        }
-        player.networkHandler.sendPacket(BundleS2CPacket(destroyPackets))
-
-        spawnedEntityIds.forEach {
-            player.networkHandler.sendPacket(EntitiesDestroyS2CPacket(it))
+        spawnedEntityTrackers.forEach {
+            if (!isEntityPresent(it)) {
+                it.stopTracking(player)
+            }
         }
-        val spawnPackets = removedEntityUuids.mapNotNull {
-            val world = player.serverWorld
-            val entity = world?.getEntity(it)
-            entity?.let {
-                EntitySpawnS2CPacket(entity)
+        removedEntityTrackers.forEach {
+            if (isEntityPresent(it)) {
+                it.startTracking(player)
             }
         }
-        player.networkHandler.sendPacket(BundleS2CPacket(spawnPackets))
+    }
+
+    private fun isEntityPresent(entityTrackerEntry: EntityTrackerEntry): Boolean {
+        val entity = (entityTrackerEntry as EntityTrackerEntryAccessor).entity
+        return entity.world.getEntityById(entity.id) != null
     }
 
     fun apply(context: Context) {

src/main/resources/ledger.mixins.json

@@ -91,6 +91,7 @@
         "entities.VillagerEntityMixin",
         "entities.WolfEntityMixin",
         "preview.ChestBlockMixin",
+        "preview.EntityTrackerEntryAccessor",
         "preview.LockableContainerBlockEntityMixin",
         "preview.LootableContainerBlockEntityMixin",
         "preview.ServerPlayerEntityMixin"