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// Burton Computer Corporation
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package org.javimmutable.collections.serialization;

import org.javimmutable.collections.Maybe;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

public class MaybeProxy
    implements Externalizable
{
    private static final long serialVersionUID = -210221;
    private static final int MAYBE_VERSION = 1001;
    private static final short NONE_CODE = (short)0xaaaa;
    private static final short SOME_CODE = (short)0xbbbb;

    private Maybe value;

    public MaybeProxy()
    {
        this(Maybe.empty());
    }

    public MaybeProxy(Maybe value)
    {
        this.value = value;
    }

    @Override
    public void writeExternal(ObjectOutput out)
        throws IOException
    {
        out.writeInt(MAYBE_VERSION);
        if (value.isEmpty()) {
            out.writeShort(NONE_CODE);
        } else {
            out.writeShort(SOME_CODE);
            out.writeObject(value.unsafeGet());
        }
    }

    @Override
    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException
    {
        final int version = in.readInt();
        if (version != MAYBE_VERSION) {
            throw new IOException("unexpected version number: expected " + MAYBE_VERSION + " found " + version);
        }
        final short valueCode = in.readShort();
        switch (valueCode) {
            case NONE_CODE:
                value = Maybe.empty();
                break;
            case SOME_CODE:
                value = Maybe.of(in.readObject());
                break;
            default:
                throw new IOException("unexpected Maybe type code: expected " + NONE_CODE + " or " + SOME_CODE + " found " + valueCode);
        }
    }

    private Object readResolve()
    {
        return value;
    }
}