src/main/java/us/myles/ViaVersion/metadata/MetadataRewriter.java

package us.myles.ViaVersion.metadata;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.UUID;

import org.bukkit.entity.EntityType;
import org.bukkit.util.EulerAngle;
import org.bukkit.util.Vector;

import io.netty.buffer.ByteBuf;

import us.myles.ViaVersion.util.PacketUtil;

public class MetadataRewriter {

    public static void writeMetadata1_9(EntityType type, List<Entry> list, ByteBuf output) {
        short id = -1;
        int data = -1;
        Iterator<Entry> iterator = list.iterator();
        while (iterator.hasNext()) {
            Entry entry = iterator.next(); //
            MetaIndex metaIndex = entry.index;
            try {
                if (metaIndex.getNewType() != NewType.Discontinued) {
                    if (metaIndex.getNewType() != NewType.BlockID || id != -1 && data == -1 || id == -1 && data != -1) { // block ID is only written if we have both parts
                        output.writeByte(metaIndex.getNewIndex());
                        output.writeByte(metaIndex.getNewType().getTypeID());
                    }
                    Object value = entry.value;
                    switch (metaIndex.getNewType()) {
                        case Byte:
                            // convert from int, byte
                            if (metaIndex.getOldType() == Type.Byte) {
                                output.writeByte(((Byte) value).byteValue());
                            }
                            if (metaIndex.getOldType() == Type.Int) {
                                output.writeByte(((Integer) value).byteValue());
                            }
                            break;
                        case OptUUID:
                            String owner = (String) value;
                            UUID toWrite = null;
                            if (owner.length() != 0) {
                                try {
                                    toWrite = UUID.fromString(owner);
                                } catch (Exception ignored) {
                                }
                            }
                            output.writeBoolean(toWrite != null);
                            if (toWrite != null)
                                PacketUtil.writeUUID((UUID) toWrite, output);
                            break;
                        case BlockID:
                            // if we have both sources :))
                            if (metaIndex.getOldType() == Type.Byte) {
                                data = ((Byte) value).byteValue();
                            }
                            if (metaIndex.getOldType() == Type.Short) {
                                id = ((Short) value).shortValue();
                            }
                            if (id != -1 && data != -1) {
                                int combined = id << 4 | data;
                                data = -1;
                                id = -1;
                                PacketUtil.writeVarInt(combined, output);
                            }
                            break;
                        case VarInt:
                            // convert from int, short, byte
                            if (metaIndex.getOldType() == Type.Byte) {
                                PacketUtil.writeVarInt(((Byte) value).intValue(), output);
                            }
                            if (metaIndex.getOldType() == Type.Short) {
                                PacketUtil.writeVarInt(((Short) value).intValue(), output);
                            }
                            if (metaIndex.getOldType() == Type.Int) {
                                PacketUtil.writeVarInt(((Integer) value).intValue(), output);
                            }
                            break;
                        case Float:
                            output.writeFloat(((Float) value).floatValue());
                            break;
                        case String:
                            PacketUtil.writeString((String) value, output);
                            break;
                        case Boolean:
                            if(metaIndex == MetaIndex.AGEABLE_AGE)
                                output.writeBoolean(((Byte) value).byteValue() < 0);
                            else
                                output.writeBoolean(((Byte) value).byteValue() != 0);
                            break;
                        case Slot:
                            PacketUtil.writeItem(value, output);
                            break;
                        case Position:
                            Vector vector = (Vector) value;
                            output.writeInt((int) vector.getX());
                            output.writeInt((int) vector.getY());
                            output.writeInt((int) vector.getZ());
                            break;
                        case Vector3F:
                            EulerAngle angle = (EulerAngle) value;
                            output.writeFloat((float) angle.getX());
                            output.writeFloat((float) angle.getY());
                            output.writeFloat((float) angle.getZ());
                            break;
                        default:
                            System.out.println("[Out] Unhandled MetaDataType: " + metaIndex.getNewType());
                            break;
                    }
                }
            } catch (Exception e) {
                if (type != null) {
                    System.out.println("An error occurred with entity meta data for " + type);
                    if (metaIndex != null) {
                        System.out.println("Old ID: " + metaIndex.getIndex() + " New ID: " + metaIndex.getNewIndex());
                        System.out.println("Old Type: " + metaIndex.getOldType() + " New Type: " + metaIndex.getNewType());
                    }
                }
                e.printStackTrace();
            }
        }
        output.writeByte(255);
    }

    public static List<Entry> readMetadata1_8(EntityType entityType, ByteBuf buf) {
        List<Entry> entries = new ArrayList<>();
        byte item;
        while ((item = buf.readByte()) != 127) {
            Type type = Type.byId((item & 0xE0) >> 5);
            int id = item & 0x1F;
            MetaIndex index = MetaIndex.getIndex(entityType, id);
            switch (type) {
                case Byte:
                    entries.add(new Entry(index, buf.readByte()));
                    break;
                case Short:
                    entries.add(new Entry(index, buf.readShort()));
                    break;
                case Int:
                    entries.add(new Entry(index, buf.readInt()));
                    break;
                case Float:
                    entries.add(new Entry(index, buf.readFloat()));
                    break;
                case String:
                    entries.add(new Entry(index, PacketUtil.readString(buf)));
                    break;
                case Slot:
                    entries.add(new Entry(index, PacketUtil.readItem(buf)));
                    break;
                case Position: {
                    int x = buf.readInt();
                    int y = buf.readInt();
                    int z = buf.readInt();
                    entries.add(new Entry(index, new Vector(x, y, z)));
                    break;
                }
                case Rotation: {
                    float x = buf.readFloat();
                    float y = buf.readFloat();
                    float z = buf.readFloat();
                    entries.add(new Entry(index, new EulerAngle(x, y, z)));
                    break;
                }
                default:
                    System.out.println("[Out] Unhandled MetaDataType: " + type);
                    break;
            }
        }
        return entries;
    }

    public static class Entry {

        private MetaIndex index;
        private Object value;

        private Entry(MetaIndex index, Object value) {
            this.index = index;
            this.value = value;
        }
    }
}