KStarbound/src/main/kotlin/ru/dbotthepony/kstarbound/network/Connection.kt

package ru.dbotthepony.kstarbound.network

import com.google.common.util.concurrent.ThreadFactoryBuilder
import io.netty.channel.Channel
import io.netty.channel.ChannelHandlerContext
import io.netty.channel.ChannelInboundHandlerAdapter
import io.netty.channel.ChannelOption
import io.netty.channel.nio.NioEventLoopGroup
import it.unimi.dsi.fastutil.ints.IntAVLTreeSet
import org.apache.logging.log4j.LogManager
import ru.dbotthepony.kommons.io.StreamCodec
import ru.dbotthepony.kommons.io.VarIntValueCodec
import ru.dbotthepony.kommons.util.AABBi
import ru.dbotthepony.kommons.vector.Vector2d
import ru.dbotthepony.kommons.vector.Vector2i
import ru.dbotthepony.kstarbound.GlobalDefaults
import ru.dbotthepony.kstarbound.network.syncher.BasicNetworkedElement
import ru.dbotthepony.kstarbound.network.syncher.NetworkedGroup
import ru.dbotthepony.kstarbound.network.syncher.MasterElement
import ru.dbotthepony.kstarbound.network.syncher.networkedSignedInt
import ru.dbotthepony.kstarbound.player.Avatar
import ru.dbotthepony.kstarbound.server.ServerChannels
import ru.dbotthepony.kstarbound.world.entities.player.PlayerEntity
import java.io.Closeable
import kotlin.math.roundToInt
import kotlin.properties.Delegates

abstract class Connection(val side: ConnectionSide, val type: ConnectionType) : ChannelInboundHandlerAdapter(), Closeable {
	abstract override fun channelRead(ctx: ChannelHandlerContext, msg: Any)

	var avatar: Avatar? = null
	var character: PlayerEntity? = null
	val rpc = JsonRPC()

	var entityIDRange: IntRange by Delegates.notNull()
		private set

	var connectionID: Int = -1
		set(value) {
			require(value in 1 .. ServerChannels.MAX_PLAYERS) { "Connection ID is out of range: $value" }
			field = value
			val begin = value * -65536
			entityIDRange = begin .. begin + 65535
		}

	var nickname: String = ""

	val hasChannel get() = ::channel.isInitialized
	lateinit var channel: Channel
		private set

	var isLegacy: Boolean = true
		protected set

	private val handshakeValidator = PacketRegistry.HANDSHAKE.Validator(side)
	private val handshakeSerializer = PacketRegistry.HANDSHAKE.Serializer(side)

	private val nativeValidator = PacketRegistry.NATIVE.Validator(side)
	private val nativeSerializer = PacketRegistry.NATIVE.Serializer(side)

	private val legacyValidator = PacketRegistry.LEGACY.Validator(side)
	private val legacySerializer = PacketRegistry.LEGACY.Serializer(side)

	var isConnected = false
		private set

	open fun setupLegacy() {
		isConnected = true
		LOGGER.info("Handshake successful on ${channel.remoteAddress()}, channel is using legacy protocol")

		if (type == ConnectionType.MEMORY) {
			channel.pipeline().remove(handshakeValidator)
			channel.pipeline().addFirst(legacyValidator)
		} else {
			channel.pipeline().remove(handshakeSerializer)
			channel.pipeline().addFirst(legacySerializer)
		}

		isLegacy = true
	}

	open fun setupNative() {
		isConnected = true
		LOGGER.info("Handshake successful on ${channel.remoteAddress()}, channel is using native protocol")

		if (type == ConnectionType.MEMORY) {
			channel.pipeline().remove(handshakeValidator)
			channel.pipeline().addFirst(nativeValidator)
		} else {
			channel.pipeline().remove(handshakeSerializer)
			channel.pipeline().addFirst(nativeSerializer)
		}

		isLegacy = false

		inGame()
	}

	protected open fun onChannelClosed() {
		LOGGER.info("$this is terminated")
	}

	fun bind(channel: Channel) {
		channel.config().setOption(ChannelOption.TCP_NODELAY, true)
		this.channel = channel

		if (type == ConnectionType.MEMORY)
			channel.pipeline().addFirst(handshakeValidator)
		else
			channel.pipeline().addFirst(handshakeSerializer)

		channel.pipeline().addLast(this)

		channel.closeFuture().addListener {
			onChannelClosed()
		}
	}

	// one connection can be reused for second channel (while first is being closed)
	override fun isSharable(): Boolean {
		return true
	}

	override fun ensureNotSharable() {

	}

	abstract fun inGame()

	fun send(packet: IPacket) {
		if (channel.isOpen && isConnected) {
			channel.write(packet)
		}
	}

	fun sendAndFlush(packet: IPacket) {
		if (channel.isOpen && isConnected) {
			channel.write(packet)
			flush()
		}
	}

	open fun flush() {
		channel.flush()
	}

	abstract fun disconnect(reason: String = "")

	override fun close() {
		channel.close()
	}

	val windowXMin = networkedSignedInt()
	val windowYMin = networkedSignedInt()
	val windowWidth = networkedSignedInt()
	val windowHeight = networkedSignedInt()
	val playerID = networkedSignedInt()

	var playerEntity: PlayerEntity? = null
		protected set

	// holy shit
	val clientSpectatingEntities = BasicNetworkedElement(IntAVLTreeSet(), StreamCodec.Collection(VarIntValueCodec) { IntAVLTreeSet() })
	val clientStateGroup = MasterElement(NetworkedGroup(windowXMin, windowYMin, windowWidth, windowHeight, playerID, clientSpectatingEntities))

	// in tiles
	fun trackingTileRegions(): List<AABBi> {
		val result = ArrayList<AABBi>()

		val mins = Vector2i(windowXMin.get() - GlobalDefaults.client.windowMonitoringBorder, windowYMin.get() - GlobalDefaults.client.windowMonitoringBorder)
		val maxs = Vector2i(windowWidth.get() + GlobalDefaults.client.windowMonitoringBorder, windowHeight.get() + GlobalDefaults.client.windowMonitoringBorder)
		val window = AABBi(mins, maxs + mins)

		if (window.mins != Vector2i.ZERO && window.maxs != Vector2i.ZERO) {
			result.add(window)
		}

		val playerEntity = playerEntity

		if (playerEntity != null) {
			// add an extra region the size of the window centered on the player's position to prevent nearby sectors
			// being unloaded due to camera panning or centering on other entities
			val diff = Vector2d(window.width / 2.0, window.height / 2.0)

			val pmins = playerEntity.position - diff
			val pmaxs = playerEntity.position + diff

			result.add(AABBi(
				Vector2i(pmins.x.roundToInt(), pmins.y.roundToInt()),
				Vector2i(pmaxs.x.roundToInt(), pmaxs.y.roundToInt()),
			))
		}

		for (entity in clientSpectatingEntities.get()) {
			// TODO
		}

		return result
	}

	companion object {
		private val LOGGER = LogManager.getLogger()

		val NIO_POOL by lazy {
			NioEventLoopGroup(1, ThreadFactoryBuilder().setDaemon(true).setNameFormat("Starbound Network IO %d").build())
		}
	}
}