/* 
 * 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 tests.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.URL;

/**
 * This class simplifies the serialization test.
 * 
 */
public class SerializationTester {

	/*
	 * --------------------------------------------------------------------
	 * Class variables
	 * --------------------------------------------------------------------
	 */

	// the last deserialized object
	private static Object lastOutput = null;

	/*
	 * -------------------------------------------------------------------
	 * Constructors
	 * -------------------------------------------------------------------
	 */

	private SerializationTester() {

	}

	/*
	 * -------------------------------------------------------------------
	 * Methods
	 * -------------------------------------------------------------------
	 */

	/**
	 * Serialize an object and then deserialize it.
	 * 
	 * @param inputObject
	 *            the input object
	 * @return the deserialized object
	 */
	public static Object getDeserilizedObject(Object inputObject)
			throws IOException, ClassNotFoundException {
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		ObjectOutputStream oos = new ObjectOutputStream(bos);
		oos.writeObject(inputObject);
		oos.close();

		ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
		ObjectInputStream ois = new ObjectInputStream(bis);
		Object outputObject = ois.readObject();
		lastOutput = outputObject;
		ois.close();
		return outputObject;
	}

	/**
	 * Tests the serialization and deserialization of const objects.
	 * 
	 * @param inputObject
	 *            A const object
	 * @return true if the deserialized object is the same as the input object,
	 *         otherwise false
	 * @throws Exception
	 *             If any occurs.
	 */
	public static boolean assertSame(Object inputObject) throws Exception {
		return inputObject == getDeserilizedObject(inputObject);
	}

	/**
	 * Tests the serialization and deserialization of instance objects.
	 * 
	 * @param inputObject
	 *            An object
	 * @return true if the deserialized object is equal to the input object,
	 *         otherwise false
	 * @throws Exception
	 *             If any occurs.
	 */
	public static boolean assertEquals(Object inputObject) throws Exception {
		return inputObject.equals(getDeserilizedObject(inputObject));
	}

	/**
	 * Tests the serialization compatibility with reference const objects.
	 * 
	 * @param obj
	 *            the object to be checked
	 * @param fileName
	 *            the serialization output file generated by reference
	 * @return true if compatible, otherwise false
	 * @throws Exception
	 *             If any occurs.
	 */
	public static boolean assertCompabilitySame(Object obj, String fileName)
			throws Exception {
		return obj == readObject(obj, fileName);
	}

	/**
	 * Tests the serialization compatibility with reference for instance
	 * objects.
	 * 
	 * @param obj
	 *            the object to be checked
	 * @param fileName
	 *            the serialization output file generated by reference
	 * @return true if compatible, otherwise false
	 * @throws Exception
	 *             If any occurs.
	 */
	public static boolean assertCompabilityEquals(Object obj, String fileName)
			throws Exception {
		return obj.equals(readObject(obj, fileName));
	}

	/**
	 * Deserialize an object from a file.
	 * 
	 * @param obj
	 *            the object to be serialized if no serialization file is found
	 * @param fileName
	 *            the serialization file
	 * @return the deserialized object
	 * @throws Exception
	 *             If any occurs.
	 */
	public static Object readObject(Object obj, String fileName)
			throws Exception {
		InputStream input = null;
		ObjectInputStream oinput = null;
		URL url = SerializationTester.class.getClassLoader().getResource(
				fileName);
		if (null == url) {
			// serialization file does not exist, create one in the current dir
			writeObject(obj, new File(fileName).getName());
			throw new Error(
					"Serialization file does not exist, created in the current dir.");
		}
		input = url.openStream();
		try {
			oinput = new ObjectInputStream(input);
			Object newObj = oinput.readObject();
			return newObj;
		} finally {
			try {
				if (null != oinput) {
					oinput.close();
				}
			} catch (Exception e) {
				// ignore
			}
			try {
				if (null != input) {
					input.close();
				}
			} catch (Exception e) {
				// ignore
			}
		}
	}

	/*
	 * Creates a serialization output.
	 * 
	 * @param obj the object to be serialized @param fileName the output file
	 * @throws Exception If any occurs.
	 */
	public static void writeObject(Object obj, String fileName)
			throws Exception {
		// String path = SerializationTester.class.getResource(".").getPath();
		// if (path.endsWith(".")) {
		// path = path.substring(0, path.length() - 1);
		// }
		// if (!path.endsWith("/")) {
		// path += "/";
		// }
		// path += fileName;
		// System.out.println(path);
		OutputStream output = null;
		ObjectOutputStream ooutput = null;
		try {
			output = new FileOutputStream(fileName);
			ooutput = new ObjectOutputStream(output);
			ooutput.writeObject(obj);
		} finally {
			try {
				if (null != ooutput) {
					ooutput.close();
				}
			} catch (Exception e) {
				// ignore
			}
			try {
				if (null != output) {
					output.close();
				}
			} catch (Exception e) {
				// ignore
			}
		}
	}

	/**
	 * Gets the last deserialized object.
	 * 
	 * @return the last deserialized object
	 */
	public static Object getLastOutput() {
		return lastOutput;
	}

	/*
	 * For test purpose.
	 */
	public static void main(String[] args) {
	}
}