/*
 * Copyright 2010 Martin Grotzke
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an &quot;AS IS&quot; BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package com.twitter.chill.java;

import com.twitter.chill.IKryoRegistrar;
import com.twitter.chill.SingleRegistrar;

import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.List;
import java.util.HashMap;
import java.util.Map;

import com.esotericsoftware.kryo.Kryo;
import com.esotericsoftware.kryo.Serializer;
import com.esotericsoftware.kryo.io.Input;
import com.esotericsoftware.kryo.io.Output;

/**
 * A kryo {@link Serializer} for lists created via {@link Arrays#asList(Object...)}.
 * <p>
 * Note: This serializer does not support cyclic references, so if one of the objects
 * gets set the list as attribute this might cause an error during deserialization.
 * </p>
 *
 * @author <a href="mailto:martin.grotzke@javakaffee.de">Martin Grotzke</a>
 */
public class ArraysAsListSerializer extends Serializer<List<?>> {

    private static final Map<Class<?>, Class<?>> primitives = new HashMap<>(8, 1.0F);

    static {
        primitives.put(byte.class, Byte.class);
        primitives.put(short.class, Short.class);
        primitives.put(int.class, Integer.class);
        primitives.put(long.class, Long.class);
        primitives.put(char.class, Character.class);
        primitives.put(float.class, Float.class);
        primitives.put(double.class, Double.class);
        primitives.put(boolean.class, Boolean.class);
    }

    static public IKryoRegistrar registrar() {
      return new SingleRegistrar(Arrays.asList("").getClass(), new ArraysAsListSerializer());
    }

    private Field _arrayField;

    public ArraysAsListSerializer() {
        try {
            _arrayField = Class.forName( "java.util.Arrays$ArrayList" ).getDeclaredField( "a" );
            _arrayField.setAccessible( true );
        } catch ( final Exception e ) {
            throw new RuntimeException( e );
        }
    }

    @Override
    public List<?> read(final Kryo kryo, final Input input, final Class<List<?>> type) {
        final int length = input.readInt(true);
        Class<?> componentType = kryo.readClass(input).getType();
        try {
            final Object items = Array.newInstance(getBoxedClass(componentType), length);
            for (int i = 0; i < length; i++) {
                Array.set(items, i, kryo.readClassAndObject(input));
            }
            return Arrays.asList((Object[]) items);
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void write(final Kryo kryo, final Output output, final List<?> obj) {
        try {
            final Object[] array = (Object[]) _arrayField.get(obj);
            output.writeInt(array.length, true);
            final Class<?> componentType = array.getClass().getComponentType();
            kryo.writeClass(output, componentType);
            for (final Object item : array) {
                kryo.writeClassAndObject(output, item);
            }
        } catch (final RuntimeException e) {
            // Don't eat and wrap RuntimeExceptions because the ObjectBuffer.write...
            // handles SerializationException specifically (resizing the buffer)...
            throw e;
        } catch (final Exception e) {
            throw new RuntimeException(e);
        }
    }
    
    private static Class<?> getBoxedClass(final Class<?> c) {
        if (c.isPrimitive()) {
            Class<?> x;
            return (x = primitives.get(c)) != null ? x : c;
        }
        return c;
    }
}

@@ -1552,16 +1552,34 @@
 HashMap%3C
+Class%3C?%3E, Class%3C?%3E
 %3E(8, 1.0

Update ArraysAsListSerializer.java