ZipLong

/*
 *  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.compress.archivers.zip;

import static org.apache.commons.compress.archivers.zip.ZipConstants.WORD;

import java.io.Serializable;

import org.apache.commons.compress.utils.ByteUtils;

/**
 * Utility class that represents a four byte integer with conversion rules for the little-endian byte order of ZIP files.
 *
 * @Immutable
 */
public final class ZipLong implements Cloneable, Serializable {

    private static final long serialVersionUID = 1L;

    /** Central File Header Signature */
    public static final ZipLong CFH_SIG = new ZipLong(0X02014B50L);

    /** Local File Header Signature */
    public static final ZipLong LFH_SIG = new ZipLong(0X04034B50L);

    /**
     * Data Descriptor signature.
     *
     * <p>
     * Actually, PKWARE uses this as marker for split/spanned archives and other archivers have started to use it as Data Descriptor signature (as well).
     * </p>
     *
     * @since 1.1
     */
    public static final ZipLong DD_SIG = new ZipLong(0X08074B50L);

    /**
     * Value stored in size and similar fields if ZIP64 extensions are used.
     *
     * @since 1.3
     */
    static final ZipLong ZIP64_MAGIC = new ZipLong(ZipConstants.ZIP64_MAGIC);

    /**
     * Marks ZIP archives that were supposed to be split or spanned but only needed a single segment in then end (so are actually neither split nor spanned).
     *
     * <p>
     * This is the "PK00" prefix found in some archives.
     * </p>
     *
     * @since 1.5
     */
    public static final ZipLong SINGLE_SEGMENT_SPLIT_MARKER = new ZipLong(0X30304B50L);

    /**
     * Archive extra data record signature.
     *
     * @since 1.5
     */
    public static final ZipLong AED_SIG = new ZipLong(0X08064B50L);

    /**
     * Gets value as four bytes in big-endian byte order.
     *
     * @param value the value to convert
     * @return value as four bytes in big-endian byte order
     */
    public static byte[] getBytes(final long value) {
        final byte[] result = new byte[WORD];
        putLong(value, result, 0);
        return result;
    }

    /**
     * Helper method to get the value as a Java long from a four-byte array
     *
     * @param bytes the array of bytes
     * @return the corresponding Java long value
     */
    public static long getValue(final byte[] bytes) {
        return getValue(bytes, 0);
    }

    /**
     * Helper method to get the value as a Java long from four bytes starting at given array offset
     *
     * @param bytes  the array of bytes
     * @param offset the offset to start
     * @return the corresponding Java long value
     */
    public static long getValue(final byte[] bytes, final int offset) {
        return ByteUtils.fromLittleEndian(bytes, offset, 4);
    }

    /**
     * put the value as four bytes in big-endian byte order.
     *
     * @param value  the Java long to convert to bytes
     * @param buf    the output buffer
     * @param offset The offset within the output buffer of the first byte to be written. must be non-negative and no larger than {@code buf.length-4}
     */

    public static void putLong(final long value, final byte[] buf, final int offset) {
        ByteUtils.toLittleEndian(buf, value, offset, 4);
    }

    private final long value;

    /**
     * Constructs a new instance from bytes.
     *
     * @param bytes the bytes to store as a ZipLong
     */
    public ZipLong(final byte[] bytes) {
        this(bytes, 0);
    }

    /**
     * Creates instance from the four bytes starting at offset.
     *
     * @param bytes  the bytes to store as a ZipLong
     * @param offset the offset to start
     */
    public ZipLong(final byte[] bytes, final int offset) {
        value = getValue(bytes, offset);
    }

    /**
     * create instance from a Java int.
     *
     * @param value the int to store as a ZipLong
     * @since 1.15
     */
    public ZipLong(final int value) {
        this.value = value;
    }

    /**
     * Creates instance from a number.
     *
     * @param value the long to store as a ZipLong
     */
    public ZipLong(final long value) {
        this.value = value;
    }

    @Override
    public Object clone() {
        try {
            return super.clone();
        } catch (final CloneNotSupportedException cnfe) {
            // impossible
            throw new UnsupportedOperationException(cnfe); // NOSONAR
        }
    }

    /**
     * Override to make two instances with same value equal.
     *
     * @param o an object to compare
     * @return true if the objects are equal
     */
    @Override
    public boolean equals(final Object o) {
        if (!(o instanceof ZipLong)) {
            return false;
        }
        return value == ((ZipLong) o).getValue();
    }

    /**
     * Gets value as four bytes in big-endian byte order.
     *
     * @return value as four bytes in big-endian order
     */
    public byte[] getBytes() {
        return getBytes(value);
    }

    /**
     * Gets value as a (signed) Java int
     *
     * @return value as int
     * @since 1.15
     */
    public int getIntValue() {
        return (int) value;
    }

    /**
     * Gets value as Java long.
     *
     * @return value as a long
     */
    public long getValue() {
        return value;
    }

    /**
     * Override to make two instances with same value equal.
     *
     * @return the value stored in the ZipLong
     */
    @Override
    public int hashCode() {
        return (int) value;
    }

    public void putLong(final byte[] buf, final int offset) {
        putLong(value, buf, offset);
    }

    @Override
    public String toString() {
        return "ZipLong value: " + value;
    }
}