Improve Miner handling of excess items

src/main/java/net/shadowfacts/phycon/api/NetworkComponentBlock.java

@@ -3,7 +3,7 @@ package net.shadowfacts.phycon.api;
 import net.minecraft.block.BlockState;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Direction;
-import net.minecraft.world.World;
+import net.minecraft.world.WorldAccess;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -15,9 +15,9 @@ import java.util.Collection;
 public interface NetworkComponentBlock {
 
 	@NotNull
-	Collection<Direction> getNetworkConnectedSides(@NotNull BlockState state, @NotNull World world, @NotNull BlockPos pos);
+	Collection<Direction> getNetworkConnectedSides(@NotNull BlockState state, @NotNull WorldAccess world, @NotNull BlockPos pos);
 
 	@Nullable
-	Interface getNetworkInterfaceForSide(@NotNull Direction side, @NotNull BlockState state, @NotNull World world, @NotNull BlockPos pos);
+	Interface getNetworkInterfaceForSide(@NotNull Direction side, @NotNull BlockState state, @NotNull WorldAccess world, @NotNull BlockPos pos);
 
 }

src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlock.kt

@@ -5,6 +5,7 @@ import net.minecraft.entity.player.PlayerEntity
 import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.api.Interface
 import net.shadowfacts.phycon.api.NetworkComponentBlock
 import net.shadowfacts.phycon.block.BlockWithEntity
@@ -14,9 +15,9 @@ import net.shadowfacts.phycon.block.BlockWithEntity
  */
 abstract class DeviceBlock<T: DeviceBlockEntity>(settings: Settings): BlockWithEntity<T>(settings), NetworkComponentBlock {
 
-	abstract override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction>
+	abstract override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction>
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		return getBlockEntity(world, pos)!!
 	}
 

src/main/kotlin/net/shadowfacts/phycon/network/DeviceBlockEntity.kt

@@ -45,7 +45,7 @@ abstract class DeviceBlockEntity(type: BlockEntityType<*>): BlockEntity(type),
 	private val arpTable = mutableMapOf<IPAddress, MACAddress>()
 	private val packetQueue = LinkedList<PendingPacket>()
 
-	protected var counter: Long = 0
+	var counter: Long = 0
 
 	override fun getIPAddress() = ipAddress
 	override fun getMACAddress() = macAddress

src/main/kotlin/net/shadowfacts/phycon/network/block/cable/CableBlock.kt

@@ -67,7 +67,7 @@ class CableBlock: Block(
 		}
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		val set = EnumSet.noneOf(Direction::class.java)
 		for ((side, prop) in CONNECTIONS) {
 			if (state[prop] == CableConnection.ON) {
@@ -100,8 +100,10 @@ class CableBlock: Block(
 	}
 
 	private fun getConnectionStateInDirection(world: WorldAccess, pos: BlockPos, direction: Direction): CableConnection {
-		val state = world.getBlockState(pos.offset(direction))
-		return when (state.block) {
+		val offsetPos = pos.offset(direction)
+		val state = world.getBlockState(offsetPos)
+		val block = state.block
+		return when (block) {
 			this -> {
 				val prop = CONNECTIONS[direction.opposite]
 				when (state[prop]) {
@@ -109,12 +111,18 @@ class CableBlock: Block(
 					else -> CableConnection.ON
 				}
 			}
-			is NetworkComponentBlock -> CableConnection.ON
+			is NetworkComponentBlock -> {
+				if (block.getNetworkConnectedSides(state, world, offsetPos).contains(direction.opposite)) {
+					CableConnection.ON
+				} else {
+					CableConnection.OFF
+				}
+			}
 			else -> CableConnection.OFF
 		}
 	}
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		// cables don't have network interfaces
 		return null
 	}

src/main/kotlin/net/shadowfacts/phycon/network/block/extractor/ExtractorBlock.kt

@@ -16,6 +16,7 @@ import net.minecraft.util.shape.VoxelShape
 import net.minecraft.util.shape.VoxelShapes
 import net.minecraft.world.BlockView
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.api.Interface
 import net.shadowfacts.phycon.network.DeviceBlock
@@ -67,11 +68,11 @@ class ExtractorBlock: DeviceBlock<ExtractorBlockEntity>(Settings.of(Material.MET
 		}
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		return EnumSet.of(state[FACING].opposite)
 	}
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		return if (side == state[FACING].opposite) {
 			getBlockEntity(world, pos)
 		} else {

src/main/kotlin/net/shadowfacts/phycon/network/block/miner/MinerBlock.kt

@@ -13,6 +13,7 @@ import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.BlockView
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.api.Interface
 import net.shadowfacts.phycon.network.DeviceBlock
@@ -29,11 +30,11 @@ class MinerBlock: DeviceBlock<MinerBlockEntity>(Settings.of(Material.METAL)) {
 		val FACING = Properties.FACING
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		return EnumSet.of(state[FACING].opposite)
 	}
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		return if (side == state[FACING]) {
 			null
 		} else {

src/main/kotlin/net/shadowfacts/phycon/network/block/miner/MinerBlockEntity.kt

@@ -14,7 +14,11 @@ import net.shadowfacts.phycon.api.packet.Packet
 import net.shadowfacts.phycon.api.util.IPAddress
 import net.shadowfacts.phycon.init.PhyBlockEntities
 import net.shadowfacts.phycon.network.DeviceBlockEntity
+import net.shadowfacts.phycon.network.block.terminal.TerminalBlockEntity
+import net.shadowfacts.phycon.network.component.NetworkStackDispatcher
 import net.shadowfacts.phycon.network.component.NetworkStackProvider
+import net.shadowfacts.phycon.network.component.handleItemStack
+import net.shadowfacts.phycon.network.component.spawnItemStack
 import net.shadowfacts.phycon.network.packet.*
 import kotlin.math.min
 
@@ -22,18 +26,24 @@ import kotlin.math.min
  * @author shadowfacts
  */
 class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
-	NetworkStackProvider {
+	NetworkStackProvider,
+	NetworkStackDispatcher<MinerBlockEntity.PendingInsertion> {
 
 	private val facing: Direction
 		get() = cachedState[MinerBlock.FACING]
 
 	private val invProxy = MinerInvProxy(this)
 
+	override val pendingInsertions = mutableListOf<PendingInsertion>()
+	override val dispatchStackTimeout = TerminalBlockEntity.INSERTION_TIMEOUT
+
 	override fun handle(packet: Packet) {
 		when (packet) {
 			is RequestInventoryPacket -> handleRequestInventory(packet)
 			is LocateStackPacket -> handleLocateStack(packet)
 			is ExtractStackPacket -> handleExtractStack(packet)
+			is CapacityPacket -> handleCapacity(packet)
+			is ItemStackPacket -> handleItemStack(packet)
 		}
 	}
 
@@ -50,7 +60,7 @@ class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
 
 	private fun handleExtractStack(packet: ExtractStackPacket) {
 		// always recalculate immediately before breaking
-		val drops = invProxy.getDrops(true)
+		val drops = invProxy.getDrops(recalculate = true)
 		if (invProxy.getAmount(packet.stack) > 0) {
 			world!!.breakBlock(pos.offset(facing), false)
 
@@ -77,11 +87,18 @@ class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
 			// dump any remaining drops into the network
 			for (droppedStack in drops) {
 				if (droppedStack.isEmpty) continue
-				sendPacket(ItemStackPacket(droppedStack, ipAddress, IPAddress.BROADCAST))
+				dispatchItemStack(droppedStack)
 			}
 		}
 	}
 
+	override fun doHandleItemStack(packet: ItemStackPacket): ItemStack {
+		// miner can't receive stacks, so remaining is the entire packet stack
+		return packet.stack
+	}
+
+	override fun createPendingInsertion(stack: ItemStack) = PendingInsertion(stack, counter)
+
 	class MinerInvProxy(val miner: MinerBlockEntity): GroupedItemInvView {
 		private var cachedState: BlockState? = null
 		private var cachedDrops: List<ItemStack>? = null
@@ -96,7 +113,7 @@ class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
 		fun getDrops(recalculate: Boolean = false): List<ItemStack> {
 			val targetPos = pos.offset(facing)
 			val realState = world.getBlockState(targetPos)
-			// todo: does BlockState.equals actually work?
+			// todo: does BlockState.equals actually work or is reference equality fine for BlockStates?
 			if (cachedDrops == null || realState != cachedState || recalculate) {
 				cachedState = realState
 				val be = if (realState.block.hasBlockEntity()) world.getBlockEntity(targetPos) else null
@@ -124,4 +141,7 @@ class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
 		}
 	}
 
+	class PendingInsertion(stack: ItemStack, timestamp: Long): NetworkStackDispatcher.PendingInsertion<PendingInsertion>(stack, timestamp) {
+	}
+
 }

src/main/kotlin/net/shadowfacts/phycon/network/block/netinterface/InterfaceBlock.kt

@@ -63,13 +63,13 @@ class InterfaceBlock: DeviceBlock<InterfaceBlockEntity>(Settings.of(Material.MET
 		}
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		val set = EnumSet.of(state[CABLE_CONNECTION])
 		set.remove(state[FACING])
 		return set
 	}
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		return if (side == state[FACING]) {
 			null
 		} else {

src/main/kotlin/net/shadowfacts/phycon/network/block/netswitch/SwitchBlock.kt

@@ -9,6 +9,7 @@ import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.BlockView
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.api.Interface
 import net.shadowfacts.phycon.api.NetworkComponentBlock
@@ -26,11 +27,11 @@ class SwitchBlock: BlockWithEntity<SwitchBlockEntity>(Settings.of(Material.METAL
 		val ID = Identifier(PhysicalConnectivity.MODID, "switch")
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		return EnumSet.allOf(Direction::class.java)
 	}
 
-	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: World, pos: BlockPos): Interface? {
+	override fun getNetworkInterfaceForSide(side: Direction, state: BlockState, world: WorldAccess, pos: BlockPos): Interface? {
 		return getBlockEntity(world, pos)?.interfaces?.find { it.side == side }
 	}
 

src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlock.kt

@@ -13,6 +13,7 @@ import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.BlockView
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.api.NetworkComponentBlock
 import net.shadowfacts.phycon.network.DeviceBlock
@@ -29,7 +30,7 @@ class TerminalBlock: DeviceBlock<TerminalBlockEntity>(Settings.of(Material.METAL
 		val ID = Identifier(PhysicalConnectivity.MODID, "terminal")
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): Collection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): Collection<Direction> {
 		return EnumSet.allOf(Direction::class.java)
 	}
 

src/main/kotlin/net/shadowfacts/phycon/network/block/terminal/TerminalBlockEntity.kt

@@ -3,7 +3,6 @@ package net.shadowfacts.phycon.network.block.terminal
 import alexiil.mc.lib.attributes.item.GroupedItemInvView
 import alexiil.mc.lib.attributes.item.ItemStackCollections
 import alexiil.mc.lib.attributes.item.ItemStackUtil
-import it.unimi.dsi.fastutil.ints.Int2ObjectArrayMap
 import net.fabricmc.fabric.api.block.entity.BlockEntityClientSerializable
 import net.fabricmc.fabric.api.screenhandler.v1.ExtendedScreenHandlerFactory
 import net.minecraft.block.BlockState
@@ -26,23 +25,26 @@ import net.shadowfacts.phycon.api.util.IPAddress
 import net.shadowfacts.phycon.init.PhyBlockEntities
 import net.shadowfacts.phycon.network.DeviceBlockEntity
 import net.shadowfacts.phycon.network.NetworkUtil
-import net.shadowfacts.phycon.network.component.ItemStackPacketHandler
-import net.shadowfacts.phycon.network.component.NetworkStackProvider
-import net.shadowfacts.phycon.network.component.NetworkStackReceiver
-import net.shadowfacts.phycon.network.component.handleItemStack
+import net.shadowfacts.phycon.network.component.*
 import net.shadowfacts.phycon.network.packet.*
 import java.lang.ref.WeakReference
 import java.util.*
 import kotlin.math.min
+import kotlin.properties.Delegates
 
 /**
  * @author shadowfacts
  */
-class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), InventoryChangedListener, BlockEntityClientSerializable, Tickable, ItemStackPacketHandler {
+class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL),
+	InventoryChangedListener,
+	BlockEntityClientSerializable,
+	Tickable,
+	ItemStackPacketHandler,
+	NetworkStackDispatcher<TerminalBlockEntity.PendingInsertion> {
 
 	companion object {
-		val LOCATE_REQUEST_TIMEOUT = 40 // ticks
-        val INSERTION_TIMEOUT = 40
+		val LOCATE_REQUEST_TIMEOUT: Long = 40 // ticks
+		val INSERTION_TIMEOUT: Long = 40
 	}
 
 	private val inventoryCache = mutableMapOf<IPAddress, GroupedItemInvView>()
@@ -50,7 +52,8 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 
 	private val locateRequestQueue = LinkedList<StackLocateRequest>()
 	private val pendingRequests = LinkedList<StackLocateRequest>()
-    private val pendingInsertions = Int2ObjectArrayMap<PendingStackInsertion>()
+	override val pendingInsertions = mutableListOf<PendingInsertion>()
+	override val dispatchStackTimeout = INSERTION_TIMEOUT
 
 	private var observers = 0
 	val cachedNetItems = ItemStackCollections.intMap()
@@ -117,18 +120,6 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 		return remaining
 	}
 
-	private fun handleCapacity(packet: CapacityPacket) {
-		val insertion = pendingInsertions.values.firstOrNull {
-			ItemStackUtil.areEqualIgnoreAmounts(packet.stack, it.stack)
-		}
-		if (insertion != null) {
-			insertion.results.add(packet.capacity to packet.stackReceiver)
-			if (insertion.isFinishable(counter)) {
-				finishInsertion(insertion)
-			}
-		}
-	}
-
 	private fun updateNetItems() {
 		cachedNetItems.clear()
 		for (inventory in inventoryCache.values) {
@@ -150,19 +141,11 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 
 		for (slot in 0 until internalBuffer.size()) {
 			if (internalBuffer.getMode(slot) != TerminalBufferInventory.Mode.TO_NETWORK) continue
-			if (slot in pendingInsertions) continue
+			if (pendingInsertions.any { it.bufferSlot == slot }) continue
 			val stack = internalBuffer.getStack(slot)
-			pendingInsertions[slot] = PendingStackInsertion(slot, stack, counter)
-			sendPacket(CheckCapacityPacket(stack, ipAddress, IPAddress.BROADCAST))
-		}
-	}
-
-	private fun finishPendingInsertions() {
-		if (world!!.isClient) return
-
-		for (insertion in pendingInsertions.values) {
-			if (!insertion.isFinishable(counter)) continue
-			finishInsertion(insertion)
+			dispatchItemStack(stack) { insertion ->
+				insertion.bufferSlot = slot
+			}
 		}
 	}
 
@@ -202,7 +185,7 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 				sendEnqueuedLocateRequests()
 				finishPendingRequests()
 				beginInsertions()
-				finishPendingInsertions()
+				finishTimedOutPendingInsertions()
 			}
 
 			if (observers > 0) {
@@ -257,24 +240,17 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 		}
 	}
 
-	private fun finishInsertion(insertion: PendingStackInsertion) {
-		pendingInsertions.remove(insertion.bufferSlot)
+	override fun createPendingInsertion(stack: ItemStack) = PendingInsertion(stack, counter)
 
-		// todo: also sort results by interface priority
-		val sortedResults = insertion.results.sortedBy { it.first }.toMutableList()
-		val remaining = insertion.stack
-		while (!remaining.isEmpty && sortedResults.isNotEmpty()) {
-			val (capacity, receivingInterface) = sortedResults.removeAt(0)
-			if (capacity <= 0) continue
-			sendPacket(ItemStackPacket(remaining.copy(), ipAddress, receivingInterface.ipAddress))
-			// todo: the interface should confirm how much was actually inserted, in case of race condition
-			remaining.count -= capacity
-		}
-        internalBuffer.setStack(insertion.bufferSlot, remaining)
+	override fun finishInsertion(insertion: PendingInsertion): ItemStack {
+		val remaining = super.finishInsertion(insertion)
+		internalBuffer.setStack(insertion.bufferSlot, remaining)
 
 		// as with extracting, we "know" the new amounts and so can update instantly without actually sending out packets
 		updateNetItems()
 		sync()
+
+		return remaining
 	}
 
 	override fun onInventoryChanged(inv: Inventory) {
@@ -327,6 +303,10 @@ class TerminalBlockEntity: DeviceBlockEntity(PhyBlockEntities.TERMINAL), Invento
 		fun netItemsChanged()
 	}
 
+	class PendingInsertion(stack: ItemStack, timestamp: Long): NetworkStackDispatcher.PendingInsertion<PendingInsertion>(stack, timestamp) {
+		var bufferSlot by Delegates.notNull<Int>()
+	}
+
 }
 
 data class StackLocateRequest(
@@ -342,17 +322,3 @@ data class StackLocateRequest(
 		return totalResultAmount >= amount || currentTimestamp - timestamp >= TerminalBlockEntity.LOCATE_REQUEST_TIMEOUT
 	}
 }
-
-data class PendingStackInsertion(
-	val bufferSlot: Int,
-	val stack: ItemStack,
-	val timestamp: Long,
-	val results: MutableSet<Pair<Int, NetworkStackReceiver>> = mutableSetOf(),
-) {
-	val totalCapacity: Int
-		get() = results.fold(0) { acc, (amount, _) -> acc + amount }
-
-	fun isFinishable(currentTimestamp: Long): Boolean {
-		return totalCapacity >= stack.count || currentTimestamp - timestamp >= TerminalBlockEntity.INSERTION_TIMEOUT
-	}
-}

src/main/kotlin/net/shadowfacts/phycon/network/block/test/DestBlock.kt

@@ -11,6 +11,7 @@ import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.BlockView
 import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.network.DeviceBlock
 import java.util.*
@@ -28,7 +29,7 @@ class DestBlock: DeviceBlock<DestBlockEntity>(Settings.of(Material.METAL)) {
 		return DestBlockEntity()
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): MutableCollection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): MutableCollection<Direction> {
 		return EnumSet.allOf(Direction::class.java)
 	}
 

src/main/kotlin/net/shadowfacts/phycon/network/block/test/SourceBlock.kt

@@ -6,7 +6,7 @@ import net.minecraft.util.Identifier
 import net.minecraft.util.math.BlockPos
 import net.minecraft.util.math.Direction
 import net.minecraft.world.BlockView
-import net.minecraft.world.World
+import net.minecraft.world.WorldAccess
 import net.shadowfacts.phycon.PhysicalConnectivity
 import net.shadowfacts.phycon.network.DeviceBlock
 import java.util.*
@@ -24,7 +24,7 @@ class SourceBlock: DeviceBlock<SourceBlockEntity>(Settings.of(Material.METAL)) {
 		return SourceBlockEntity()
 	}
 
-	override fun getNetworkConnectedSides(state: BlockState, world: World, pos: BlockPos): MutableCollection<Direction> {
+	override fun getNetworkConnectedSides(state: BlockState, world: WorldAccess, pos: BlockPos): MutableCollection<Direction> {
 		return EnumSet.allOf(Direction::class.java)
 	}
 

src/main/kotlin/net/shadowfacts/phycon/network/component/ItemStackPacketHandler.kt

@@ -14,18 +14,22 @@ interface ItemStackPacketHandler: PacketSink, PacketSource {
 	fun doHandleItemStack(packet: ItemStackPacket): ItemStack
 }
 
-fun <BE> BE.handleItemStack(packet: ItemStackPacket) where BE: BlockEntity, BE: ItemStackPacketHandler {
+fun <Self> Self.handleItemStack(packet: ItemStackPacket) where Self: BlockEntity, Self: ItemStackPacketHandler {
 	// todo: is 5 a good number?
 	// the max bounce count should always be odd, so the item is spawned in-world at the
 	if (packet.bounceCount == 5) {
-		// todo: calculate entity spawn point by finding non-obstructed location
-		val entity = ItemEntity(world!!, pos.x.toDouble(), pos.y + 1.0, pos.z.toDouble(), packet.stack)
-		world!!.spawnEntity(entity)
+		spawnItemStack(packet.stack)
 		return
 	}
 	val remainder = doHandleItemStack(packet)
 	// if there are any items remaining, send them back to the source with incremented bounce count
 	if (!remainder.isEmpty) {
-//		sendToSingle(ItemStackPacket(remainder, packet.bounceCount + 1, macAddress, packet.source))
+		sendPacket(ItemStackPacket(remainder, packet.bounceCount + 1, ipAddress, packet.source))
 	}
+}
+
+fun <Self> Self.spawnItemStack(stack: ItemStack) where Self: BlockEntity, Self: ItemStackPacketHandler {
+	// todo: calculate entity spawn point by finding non-obstructed location
+	val entity = ItemEntity(world!!, pos.x.toDouble(), pos.y + 1.0, pos.z.toDouble(), stack)
+	world!!.spawnEntity(entity)
 }

src/main/kotlin/net/shadowfacts/phycon/network/component/NetworkStackDispatcher.kt

@@ -0,0 +1,80 @@
+package net.shadowfacts.phycon.network.component
+
+import alexiil.mc.lib.attributes.item.ItemStackUtil
+import net.minecraft.block.entity.BlockEntity
+import net.minecraft.item.ItemStack
+import net.shadowfacts.phycon.api.util.IPAddress
+import net.shadowfacts.phycon.network.packet.CapacityPacket
+import net.shadowfacts.phycon.network.packet.CheckCapacityPacket
+import net.shadowfacts.phycon.network.packet.ItemStackPacket
+
+/**
+ * @author shadowfacts
+ */
+interface NetworkStackDispatcher<Insertion: NetworkStackDispatcher.PendingInsertion<Insertion>>: ItemStackPacketHandler {
+
+	val counter: Long
+	val dispatchStackTimeout: Long
+	val pendingInsertions: MutableList<Insertion>
+
+	fun createPendingInsertion(stack: ItemStack): Insertion
+
+	fun dispatchItemStack(stack: ItemStack, modifyInsertion: ((Insertion) -> Unit)? = null) {
+		val insertion = createPendingInsertion(stack)
+		modifyInsertion?.invoke(insertion)
+		pendingInsertions.add(insertion)
+		sendPacket(CheckCapacityPacket(insertion.stack, ipAddress, IPAddress.BROADCAST))
+	}
+
+	fun handleCapacity(packet: CapacityPacket) {
+		val insertion = pendingInsertions.firstOrNull {
+			ItemStackUtil.areEqualIgnoreAmounts(packet.stack, it.stack)
+		}
+		if (insertion != null) {
+			insertion.results.add(packet.capacity to packet.stackReceiver)
+			if (insertion.isFinishable(this)) {
+				finishInsertion(insertion)
+			}
+		}
+	}
+
+	fun finishInsertion(insertion: Insertion): ItemStack {
+		pendingInsertions.remove(insertion)
+
+		// todo: also sort results by interface priority
+		val sortedResults = insertion.results.sortedBy { it.first }.toMutableList()
+		val remaining = insertion.stack
+		while (!remaining.isEmpty && sortedResults.isNotEmpty()) {
+			val (capacity, receivingInterface) = sortedResults.removeFirst()
+			if (capacity <= 0) continue
+			sendPacket(ItemStackPacket(remaining.copy(), ipAddress, receivingInterface.ipAddress))
+			// todo: the destination should confirm how much was actually inserted, in case of race condition
+			remaining.count -= capacity
+		}
+
+		return remaining
+	}
+
+	open class PendingInsertion<Self: PendingInsertion<Self>>(
+		val stack: ItemStack,
+		val timestamp: Long
+	) {
+		val results = mutableSetOf<Pair<Int, NetworkStackReceiver>>()
+
+		val totalCapacity: Int
+			get() = results.fold(0) { acc, (amount, _) -> acc + amount }
+
+		fun isFinishable(owner: NetworkStackDispatcher<Self>): Boolean {
+			return totalCapacity >= stack.count || owner.counter - timestamp >= owner.dispatchStackTimeout
+		}
+	}
+}
+
+fun <Self, Insertion: NetworkStackDispatcher.PendingInsertion<Insertion>> Self.finishTimedOutPendingInsertions() where Self: BlockEntity, Self: NetworkStackDispatcher<Insertion> {
+	if (world!!.isClient) return
+
+	pendingInsertions
+		.filter { it.isFinishable(this) }
+		.forEach(::finishInsertion)
+	// todo: if a timed-out insertion can't be finished, we should probably retry after some time (exponential backoff?)
+}