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

package net.shadowfacts.phycon.block.miner

import alexiil.mc.lib.attributes.item.GroupedItemInvView
import alexiil.mc.lib.attributes.item.ItemStackUtil
import alexiil.mc.lib.attributes.item.filter.ItemFilter
import net.minecraft.block.Block
import net.minecraft.block.BlockState
import net.minecraft.item.ItemStack
import net.minecraft.server.world.ServerWorld
import net.minecraft.util.math.BlockPos
import net.minecraft.util.math.Direction
import net.minecraft.world.World
import net.shadowfacts.phycon.api.packet.Packet
import net.shadowfacts.phycon.init.PhyBlockEntities
import net.shadowfacts.phycon.block.DeviceBlockEntity
import net.shadowfacts.phycon.block.terminal.TerminalBlockEntity
import net.shadowfacts.phycon.component.NetworkStackDispatcher
import net.shadowfacts.phycon.component.NetworkStackProvider
import net.shadowfacts.phycon.component.handleItemStack
import net.shadowfacts.phycon.packet.*
import kotlin.math.min

/**
 * @author shadowfacts
 */
class MinerBlockEntity: DeviceBlockEntity(PhyBlockEntities.MINER),
	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)
		}
	}

	private fun handleRequestInventory(packet: RequestInventoryPacket) {
		sendPacket(ReadInventoryPacket(invProxy, ipAddress, packet.source))
	}

	private fun handleLocateStack(packet: LocateStackPacket) {
		val amount = invProxy.getAmount(packet.stack)
		if (amount > 0) {
			sendPacket(StackLocationPacket(packet.stack, amount, this, ipAddress, packet.source))
		}
	}

	private fun handleExtractStack(packet: ExtractStackPacket) {
		// always recalculate immediately before breaking
		val drops = invProxy.getDrops(recalculate = true)
		if (invProxy.getAmount(packet.stack) > 0) {
			world!!.breakBlock(pos.offset(facing), false)

			// send the requested amount back to the requester
			var remaining = packet.amount
			for (droppedStack in drops) {
				if (remaining <= 0) {
					break
				}
				if (!ItemStackUtil.areEqualIgnoreAmounts(droppedStack, packet.stack)) {
					continue
				}
				val copy = droppedStack.copy()

				val toDecr = min(droppedStack.count, remaining)
				droppedStack.decrement(toDecr)
				remaining -= toDecr

				// todo: should this try to combine stacks and send as few packets as possible?
				copy.count = toDecr
				sendPacket(ItemStackPacket(copy, ipAddress, packet.source))
			}

			// dump any remaining drops into the network
			for (droppedStack in drops) {
				if (droppedStack.isEmpty) continue
				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

		private val world: World
			get() = miner.world!!
		private val pos: BlockPos
			get() = miner.pos!!
		private val facing: Direction
			get() = miner.facing

		fun getDrops(recalculate: Boolean = false): List<ItemStack> {
			val targetPos = pos.offset(facing)
			val realState = world.getBlockState(targetPos)
			// 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
				cachedDrops = Block.getDroppedStacks(realState, world as ServerWorld, targetPos, be)
			}
			return cachedDrops!!
		}

		override fun getStoredStacks(): Set<ItemStack> {
			return getDrops().toSet()
		}

		override fun getTotalCapacity(): Int {
			return Int.MAX_VALUE
		}

		override fun getStatistics(filter: ItemFilter): GroupedItemInvView.ItemInvStatistic {
			var totalCount = 0
			for (s in getDrops()) {
				if (filter.matches(s)) {
					totalCount += s.count
				}
			}
			return GroupedItemInvView.ItemInvStatistic(filter, totalCount, 0, Int.MAX_VALUE)
		}
	}

	class PendingInsertion(stack: ItemStack, timestamp: Long): NetworkStackDispatcher.PendingInsertion<PendingInsertion>(stack, timestamp) {
	}

}