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

package net.shadowfacts.phycon.network.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.api.util.IPAddress
import net.shadowfacts.phycon.init.PhyBlockEntities
import net.shadowfacts.phycon.network.DeviceBlockEntity
import net.shadowfacts.phycon.network.component.NetworkStackProvider
import net.shadowfacts.phycon.network.packet.*
import kotlin.math.min

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

	private val facing: Direction
		get() = cachedState[MinerBlock.FACING]

	private val invProxy = MinerInvProxy(this)

	override fun handle(packet: Packet) {
		when (packet) {
			is RequestInventoryPacket -> handleRequestInventory(packet)
			is LocateStackPacket -> handleLocateStack(packet)
			is ExtractStackPacket -> handleExtractStack(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(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
				sendPacket(ItemStackPacket(droppedStack, ipAddress, IPAddress.BROADCAST))
			}
		}
	}

	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?
			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)
		}
	}

}