PacketPipeline

package com.happykiller.weightlimit.server.packet;

import java.util.Collections;
import java.util.Comparator;
import java.util.EnumMap;
import java.util.LinkedList;
import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageCodec;
import net.minecraft.client.Minecraft;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.player.EntityPlayerMP;
import net.minecraft.network.INetHandler;
import net.minecraft.network.NetHandlerPlayServer;
import net.minecraft.network.PacketBuffer;
import net.minecraftforge.fml.common.FMLCommonHandler;
import net.minecraftforge.fml.common.network.FMLEmbeddedChannel;
import net.minecraftforge.fml.common.network.FMLOutboundHandler;
import net.minecraftforge.fml.common.network.NetworkRegistry;
import net.minecraftforge.fml.common.network.internal.FMLProxyPacket;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;

@ChannelHandler.Sharable
public class PacketPipeline extends MessageToMessageCodec<FMLProxyPacket, AbstractPacket> {

    private EnumMap<Side, FMLEmbeddedChannel> channels;
    private LinkedList<Class<? extends AbstractPacket>> packets = new LinkedList<Class<? extends AbstractPacket>>();

    private boolean isPostInitialized = false;

    public boolean registerPacket(Class<? extends AbstractPacket> clazz) {
        if(this.packets.size() > 256) {
            return false;
        }

        if(this.packets.contains(clazz)) {
            return false;
        }

        if(this.isPostInitialized) {
            return false;
        }

        this.packets.add(clazz);

        return true;
    }

    protected void encode(ChannelHandlerContext ctx, AbstractPacket msg, List<Object> out) throws Exception {
        ByteBuf buffer = Unpooled.buffer();
        Class<? extends AbstractPacket> clazz = msg.getClass();

        if(!this.packets.contains(msg.getClass())) {
            throw new NullPointerException("No packet registered for: " + msg.getClass().getCanonicalName());
        }

        byte discriminator = (byte)this.packets.indexOf(clazz);

        buffer.writeByte(discriminator);
        msg.encodeInto(ctx, buffer);
        FMLProxyPacket proxyPacket = new FMLProxyPacket((PacketBuffer)buffer.copy(), ctx.channel().attr(NetworkRegistry.FML_CHANNEL).get());

        out.add(proxyPacket);
    }

    protected void decode(ChannelHandlerContext ctx, FMLProxyPacket msg, List<Object> out) throws Exception {
        ByteBuf payload = msg.payload();
        byte discriminator = payload.readByte();
        Class<? extends AbstractPacket> clazz = this.packets.get(discriminator);

        if(clazz == null) {
            throw new NullPointerException("No packet registered for discriminator: " + discriminator);
        }

        AbstractPacket pkt = clazz.newInstance();
        pkt.decodeInto(ctx, payload.slice());

        EntityPlayer player;

        switch(FMLCommonHandler.instance().getEffectiveSide()) {
            case CLIENT:
                player = this.getClientPlayer();
                pkt.handleClientSide(player);
                break;
            case SERVER:
                INetHandler netHandler = ctx.channel().attr(NetworkRegistry.NET_HANDLER).get();
                player = ((NetHandlerPlayServer)netHandler).playerEntity;
                pkt.handleServerSide(player);
                break;
        }
    }

    public void initialize() {
        this.channels = NetworkRegistry.INSTANCE.newChannel("WLChannel", this);
    }

    public void registerPackets() {
        //ADD OPENGUIPACKET! CHECK EXTENDEDPROP TUTORIAL UNDER UPDATING FROM 1.6.4 to 1.7.2 > Updating the Network
    }

    public void postInitialize() {
        if(this.isPostInitialized) {
            return;
        }

        this.isPostInitialized = true;

        Collections.sort(this.packets, new Comparator<Class<? extends AbstractPacket>>() {

            public int compare(Class<? extends AbstractPacket> clazz1, Class<? extends AbstractPacket> clazz2) {
                int com = String.CASE_INSENSITIVE_ORDER.compare(clazz1.getCanonicalName(), clazz2.getCanonicalName());

                if(com == 0) {
                    com = clazz1.getCanonicalName().compareTo(clazz2.getCanonicalName());
                }

                return com;
            }
        });
    }

    @SideOnly(Side.CLIENT)
    private EntityPlayer getClientPlayer() {
        return Minecraft.getMinecraft().thePlayer;
    }

    public void sendToAll(AbstractPacket message) {
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGET).set(FMLOutboundHandler.OutboundTarget.ALL);
        this.channels.get(Side.SERVER).writeAndFlush(message);
    }

    public void sendTo(AbstractPacket message, EntityPlayerMP player) {
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGET).set(FMLOutboundHandler.OutboundTarget.PLAYER);
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGETARGS).set(player);
        this.channels.get(Side.SERVER).writeAndFlush(message);
    }

    public void sendToAllAround(AbstractPacket message, NetworkRegistry.TargetPoint point) {
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGET).set(FMLOutboundHandler.OutboundTarget.ALLAROUNDPOINT);
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGETARGS).set(point);
        this.channels.get(Side.SERVER).writeAndFlush(message);
    }

    public void sendToDimension(AbstractPacket message, int dimensionId) {
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGET).set(FMLOutboundHandler.OutboundTarget.DIMENSION);
        this.channels.get(Side.SERVER).attr(FMLOutboundHandler.FML_MESSAGETARGETARGS).set(dimensionId);
        this.channels.get(Side.SERVER).writeAndFlush(message);
    }

    public void sendToServer(AbstractPacket message) {
        this.channels.get(Side.CLIENT).attr(FMLOutboundHandler.FML_MESSAGETARGET).set(FMLOutboundHandler.OutboundTarget.TOSERVER);
        this.channels.get(Side.CLIENT).writeAndFlush(message);
    }
}