/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 "AS IS" 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 org.apache.commons.lang3;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import net.lax1dude.eaglercraft.v1_8.EaglerInputStream;

/**
 * <p>
 * Assists with the serialization process and performs additional functionality
 * based on serialization.
 * </p>
 *
 * <ul>
 * <li>Deep clone using serialization
 * <li>Serialize managing finally and IOException
 * <li>Deserialize managing finally and IOException
 * </ul>
 *
 * <p>
 * This class throws exceptions for invalid {@code null} inputs. Each method
 * documents its behavior in more detail.
 * </p>
 *
 * <p>
 * #ThreadSafe#
 * </p>
 * 
 * @since 1.0
 */
public class SerializationUtils {

	/**
	 * <p>
	 * Custom specialization of the standard JDK {@link java.io.ObjectInputStream}
	 * that uses a custom {@code ClassLoader} to resolve a class. If the specified
	 * {@code ClassLoader} is not able to resolve the class, the context classloader
	 * of the current thread will be used. This way, the standard deserialization
	 * work also in web-application containers and application servers, no matter in
	 * which of the {@code ClassLoader} the particular class that encapsulates
	 * serialization/deserialization lives.
	 * </p>
	 *
	 * <p>
	 * For more in-depth information about the problem for which this class here is
	 * a workaround, see the JIRA issue LANG-626.
	 * </p>
	 */
	static class ClassLoaderAwareObjectInputStream extends ObjectInputStream {
		private static final Map<String, Class<?>> primitiveTypes = new HashMap<>();

		static {
			primitiveTypes.put("byte", byte.class);
			primitiveTypes.put("short", short.class);
			primitiveTypes.put("int", int.class);
			primitiveTypes.put("long", long.class);
			primitiveTypes.put("float", float.class);
			primitiveTypes.put("double", double.class);
			primitiveTypes.put("boolean", boolean.class);
			primitiveTypes.put("char", char.class);
			primitiveTypes.put("void", void.class);
		}

		private final ClassLoader classLoader;

		/**
		 * Constructor.
		 * 
		 * @param in          The {@code InputStream}.
		 * @param classLoader classloader to use
		 * @throws IOException if an I/O error occurs while reading stream header.
		 * @see java.io.ObjectInputStream
		 */
		ClassLoaderAwareObjectInputStream(final InputStream in, final ClassLoader classLoader) throws IOException {
			super(in);
			this.classLoader = classLoader;
		}

		/**
		 * Overridden version that uses the parameterized {@code ClassLoader} or the
		 * {@code ClassLoader} of the current {@code Thread} to resolve the class.
		 * 
		 * @param desc An instance of class {@code ObjectStreamClass}.
		 * @return A {@code Class} object corresponding to {@code desc}.
		 * @throws IOException            Any of the usual Input/Output exceptions.
		 * @throws ClassNotFoundException If class of a serialized object cannot be
		 *                                found.
		 */
		@Override
		protected Class<?> resolveClass(final ObjectStreamClass desc) throws IOException, ClassNotFoundException {
			final String name = desc.getName();
			try {
				return Class.forName(name, false, classLoader);
			} catch (final ClassNotFoundException ex) {
				try {
					return Class.forName(name, false, Thread.currentThread().getContextClassLoader());
				} catch (final ClassNotFoundException cnfe) {
					final Class<?> cls = primitiveTypes.get(name);
					if (cls != null) {
						return cls;
					}
					throw cnfe;
				}
			}
		}

	}

	/**
	 * <p>
	 * Deep clone an {@code Object} using serialization.
	 * </p>
	 *
	 * <p>
	 * This is many times slower than writing clone methods by hand on all objects
	 * in your object graph. However, for complex object graphs, or for those that
	 * don't support deep cloning this can be a simple alternative implementation.
	 * Of course all the objects must be {@code Serializable}.
	 * </p>
	 *
	 * @param <T>    the type of the object involved
	 * @param object the {@code Serializable} object to clone
	 * @return the cloned object
	 * @throws SerializationException (runtime) if the serialization fails
	 */
	public static <T extends Serializable> T clone(final T object) {
		if (object == null) {
			return null;
		}
		final byte[] objectData = serialize(object);
		final EaglerInputStream bais = new EaglerInputStream(objectData);

		try (ClassLoaderAwareObjectInputStream in = new ClassLoaderAwareObjectInputStream(bais,
				object.getClass().getClassLoader())) {
			/*
			 * when we serialize and deserialize an object, it is reasonable to assume the
			 * deserialized object is of the same type as the original serialized object
			 */
			@SuppressWarnings("unchecked") // see above
			final T readObject = (T) in.readObject();
			return readObject;

		} catch (final ClassNotFoundException ex) {
			throw new SerializationException("ClassNotFoundException while reading cloned object data", ex);
		} catch (final IOException ex) {
			throw new SerializationException("IOException while reading or closing cloned object data", ex);
		}
	}

	/**
	 * <p>
	 * Deserializes a single {@code Object} from an array of bytes.
	 * </p>
	 *
	 * <p>
	 * If the call site incorrectly types the return value, a
	 * {@link ClassCastException} is thrown from the call site. Without Generics in
	 * this declaration, the call site must type cast and can cause the same
	 * ClassCastException. Note that in both cases, the ClassCastException is in the
	 * call site, not in this method.
	 * </p>
	 *
	 * @param <T>        the object type to be deserialized
	 * @param objectData the serialized object, must not be null
	 * @return the deserialized object
	 * @throws NullPointerException   if {@code objectData} is {@code null}
	 * @throws SerializationException (runtime) if the serialization fails
	 */
	public static <T> T deserialize(final byte[] objectData) {
		Validate.notNull(objectData, "objectData");
		return deserialize(new EaglerInputStream(objectData));
	}

	/**
	 * <p>
	 * Deserializes an {@code Object} from the specified stream.
	 * </p>
	 *
	 * <p>
	 * The stream will be closed once the object is written. This avoids the need
	 * for a finally clause, and maybe also exception handling, in the application
	 * code.
	 * </p>
	 *
	 * <p>
	 * The stream passed in is not buffered internally within this method. This is
	 * the responsibility of your application if desired.
	 * </p>
	 *
	 * <p>
	 * If the call site incorrectly types the return value, a
	 * {@link ClassCastException} is thrown from the call site. Without Generics in
	 * this declaration, the call site must type cast and can cause the same
	 * ClassCastException. Note that in both cases, the ClassCastException is in the
	 * call site, not in this method.
	 * </p>
	 *
	 * @param <T>         the object type to be deserialized
	 * @param inputStream the serialized object input stream, must not be null
	 * @return the deserialized object
	 * @throws NullPointerException   if {@code inputStream} is {@code null}
	 * @throws SerializationException (runtime) if the serialization fails
	 */
	@SuppressWarnings("resource") // inputStream is managed by the caller
	public static <T> T deserialize(final InputStream inputStream) {
		Validate.notNull(inputStream, "inputStream");
		try (ObjectInputStream in = new ObjectInputStream(inputStream)) {
			@SuppressWarnings("unchecked")
			final T obj = (T) in.readObject();
			return obj;
		} catch (final ClassNotFoundException | IOException ex) {
			throw new SerializationException(ex);
		}
	}

	/**
	 * Performs a serialization roundtrip. Serializes and deserializes the given
	 * object, great for testing objects that implement {@link Serializable}.
	 *
	 * @param <T> the type of the object involved
	 * @param obj the object to roundtrip
	 * @return the serialized and deserialized object
	 * @since 3.3
	 */
	@SuppressWarnings("unchecked") // OK, because we serialized a type `T`
	public static <T extends Serializable> T roundtrip(final T obj) {
		return (T) deserialize(serialize(obj));
	}

	/**
	 * <p>
	 * Serializes an {@code Object} to a byte array for storage/serialization.
	 * </p>
	 *
	 * @param obj the object to serialize to bytes
	 * @return a byte[] with the converted Serializable
	 * @throws SerializationException (runtime) if the serialization fails
	 */
	public static byte[] serialize(final Serializable obj) {
		final ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
		serialize(obj, baos);
		return baos.toByteArray();
	}

	/**
	 * <p>
	 * Serializes an {@code Object} to the specified stream.
	 * </p>
	 *
	 * <p>
	 * The stream will be closed once the object is written. This avoids the need
	 * for a finally clause, and maybe also exception handling, in the application
	 * code.
	 * </p>
	 *
	 * <p>
	 * The stream passed in is not buffered internally within this method. This is
	 * the responsibility of your application if desired.
	 * </p>
	 *
	 * @param obj          the object to serialize to bytes, may be null
	 * @param outputStream the stream to write to, must not be null
	 * @throws NullPointerException   if {@code outputStream} is {@code null}
	 * @throws SerializationException (runtime) if the serialization fails
	 */
	@SuppressWarnings("resource") // outputStream is managed by the caller
	public static void serialize(final Serializable obj, final OutputStream outputStream) {
		Validate.notNull(outputStream, "outputStream");
		try (ObjectOutputStream out = new ObjectOutputStream(outputStream)) {
			out.writeObject(obj);
		} catch (final IOException ex) {
			throw new SerializationException(ex);
		}
	}

	/**
	 * <p>
	 * SerializationUtils instances should NOT be constructed in standard
	 * programming. Instead, the class should be used as
	 * {@code SerializationUtils.clone(object)}.
	 * </p>
	 *
	 * <p>
	 * This constructor is public to permit tools that require a JavaBean instance
	 * to operate.
	 * </p>
	 * 
	 * @since 2.0
	 */
	public SerializationUtils() {
	}

}