package space.blokk.net

import io.netty.buffer.ByteBuf
import io.netty.channel.ChannelHandlerContext
import io.netty.handler.codec.MessageToMessageCodec
import space.blokk.net.MinecraftProtocolDataTypes.readVarInt
import space.blokk.net.MinecraftProtocolDataTypes.writeVarInt
import java.io.IOException

class PacketMessageCodec(private val session: BlokkSession) : MessageToMessageCodec<ByteBuf, PacketMessage<*>>() {
    override fun channelActive(ctx: ChannelHandlerContext) {
        session.onConnect()
    }

    override fun channelInactive(ctx: ChannelHandlerContext) {
        session.onDisconnect()
    }

    override fun encode(ctx: ChannelHandlerContext, msg: PacketMessage<*>, out: MutableList<Any>) {
        if (msg !is OutgoingPacketMessage<*>) throw UnsupportedOperationException("Only outgoing packets can get encoded")

        val dst = ctx.alloc().buffer()
        dst.writeVarInt(msg.packetCodec.id)
        msg.encodePacket(dst)
        out.add(dst)
    }

    override fun decode(ctx: ChannelHandlerContext, msg: ByteBuf, out: MutableList<Any>) {
        val packetID = msg.readVarInt()

        val codec = session.currentProtocol!!.incomingPacketCodecsByID[packetID]
            ?: throw IOException("Client sent an unknown packet (ID: $packetID)")

        out.add(IncomingPacketMessage(session, codec.decode(msg)))
    }

    override fun exceptionCaught(ctx: ChannelHandlerContext, cause: Throwable) {
        session.failBecauseOfClient("${cause::class.java.name}: ${cause.message}")
    }
}