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/*
 * Copyright (c) CQSE GmbH
 *
 * 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 "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.conqat.lib.commons.collections;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Arrays;
import java.util.Objects;

import org.conqat.lib.commons.string.StringUtils;
import org.conqat.lib.commons.test.IndexValueClass;

/**
 * A wrapper class around a byte array that supports a clean implementation of {@link #hashCode()}
 * and {@link #equals(Object)}, so byte arrays can be used, e.g., in a {@link java.util.HashMap}.
 * 
 * The class is immutable.
 * 
 * @implNote Custom (de)serialization is provided to make this efficient to use in storage or RMI
 *           scenarios.
 */
@IndexValueClass(containedInBackup = true)
public class ByteArrayWrapper implements Serializable, Comparable {

	/** Version used for serialization. */
	private static final long serialVersionUID = 1;

	/** The wrapped array. */
	protected byte[] array;

	/** Constructor. */
	public ByteArrayWrapper(byte[] array) {
		this.array = array.clone();
	}

	/** Returns a copy of the internal byte representation. */
	public byte[] getBytes() {
		return array.clone();
	}

	/** Returns the length of this array in bytes. */
	public int getLength() {
		return array.length;
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) {
			return true;
		}
		if (!(o instanceof ByteArrayWrapper)) {
			return false;
		}
		ByteArrayWrapper that = (ByteArrayWrapper) o;
		if (!that.canEqual(this)) {
			return false;
		}
		return Objects.deepEquals(array, that.array);
	}

	/**
	 * @return Whether {@code other} can be equal to this object.
	 * @apiNote This is called during {@link #equals(Object)} on the other object, to make sure
	 *          that the equality is symmetric.
	 * @see How to Write an Equality
	 *      Method in Java
	 */
	protected boolean canEqual(Object other) {
		return other instanceof ByteArrayWrapper;
	}

	@Override
	public int hashCode() {
		return Arrays.hashCode(array);
	}

	@Override
	public String toString() {
		return StringUtils.encodeAsHex(array);
	}

	@Override
	public int compareTo(ByteArrayWrapper other) {
		int lengthDelta = array.length - other.array.length;
		if (lengthDelta != 0) {
			return lengthDelta;
		}

		for (int i = 0; i < array.length; ++i) {
			int delta = array[i] - other.array[i];
			if (delta != 0) {
				return delta;
			}
		}

		return 0;
	}

	/** Custom serialization. */
	private void writeObject(ObjectOutputStream out) throws IOException {
		out.writeInt(array.length);
		out.write(array);
	}

	/** Custom deserialization. */
	private void readObject(ObjectInputStream in) throws IOException {
		int size = in.readInt();
		array = new byte[size];
		int pos = 0;
		while (pos < size) {
			pos += in.read(array, pos, size - pos);
		}
	}
}