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package org.mydotey.codec.probotuf;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.mydotey.codec.CodecException;

import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.Message;
import com.google.protobuf.Parser;

@SuppressWarnings("unchecked")
public class ProtoMessageCodec extends ProtobufCodec {

    public static final ProtoMessageCodec DEFAULT = new ProtoMessageCodec();

    public ProtoMessageCodec() {

    }

    @Override
    protected byte[] doEncode(Object obj) {
        Message message = (Message) obj;
        return message.toByteArray();
    }

    @Override
    protected  T doDecode(byte[] is, Class clazz) {
        Parser parser = getParser(clazz);
        try {
            return (T) parser.parseFrom(is);
        } catch (InvalidProtocolBufferException e) {
            throw new CodecException(e);
        }
    }

    @Override
    protected void doEncode(OutputStream os, Object obj) {
        try {
            Message message = (Message) obj;
            message.writeTo(os);
        } catch (IOException e) {
            throw new CodecException(e);
        }
    }

    @Override
    protected  T doDecode(InputStream is, Class clazz) {
        Parser parser = getParser(clazz);
        try {
            return (T) parser.parseFrom(is);
        } catch (InvalidProtocolBufferException e) {
            throw new CodecException(e);
        }
    }

    protected  Parser getParser(Class clazz) {
        try {
            Method method = clazz.getMethod("parser");
            return (Parser) method.invoke(null);
        } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
            throw new CodecException(
                    "clazz must be a Google PB Message & has an auto generated public static method parser()", e);
        }
    }

}