/*
 *  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 java.io.IOException;
import java.math.BigInteger;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.zip.CRC32;
import java.util.zip.ZipEntry;

/**
 * Utility class for handling DOS and Java time conversions.
 *
 * @Immutable
 */
public abstract class ZipUtil {

    /**
     * DOS time constant for representing timestamps before 1980. Smallest date/time ZIP can handle.
     * <p>
     * MS-DOS records file dates and times as packed 16-bit values. An MS-DOS date has the following format.
     * </p>
     * <p>
     * Bits Contents
     * </p>
     * <ul>
     * <li>0-4: Day of the month (1-31).</li>
     * <li>5-8: Month (1 = January, 2 = February, and so on).</li>
     * <li>9-15: Year offset from 1980 (add 1980 to get the actual year).</li>
     * </ul>
     *
     * An MS-DOS time has the following format.
     * <p>
     * Bits Contents
     * </p>
     * <ul>
     * <li>0-4: Second divided by 2.</li>
     * <li>5-10: Minute (0-59).</li>
     * <li>11-15: Hour (0-23 on a 24-hour clock).</li>
     * </ul>
     *
     * This constant expresses the minimum DOS date of January 1st 1980 at 00:00:00 or, bit-by-bit:
     * <ul>
     * <li>Year: 0000000</li>
     * <li>Month: 0001</li>
     * <li>Day: 00001</li>
     * <li>Hour: 00000</li>
     * <li>Minute: 000000</li>
     * <li>Seconds: 00000</li>
     * </ul>
     *
     * <p>
     * This was copied from {@link ZipEntry}.
     * </p>
     *
     * @since 1.23
     */
    private static final long DOSTIME_BEFORE_1980 = 1 << 21 | 1 << 16; // 0x210000

    /** Java time representation of the smallest date/time ZIP can handle */
    private static final long DOSTIME_BEFORE_1980_AS_JAVA_TIME = dosToJavaTime(DOSTIME_BEFORE_1980);

    /**
     * Approximately 128 years, in milliseconds (ignoring leap years, etc.).
     *
     * <p>
     * This establish an approximate high-bound value for DOS times in milliseconds since epoch, used to enable an efficient but sufficient bounds check to
     * avoid generating extended last modified time entries.
     * </p>
     * <p>
     * Calculating the exact number is locale dependent, would require loading TimeZone data eagerly, and would make little practical sense. Since DOS times
     * theoretically go to 2107 - with compatibility not guaranteed after 2099 - setting this to a time that is before but near 2099 should be sufficient.
     * </p>
     *
     * <p>
     * This was copied from {@link ZipEntry}.
     * </p>
     *
     * @since 1.23
     */
    private static final long UPPER_DOSTIME_BOUND = 128L * 365 * 24 * 60 * 60 * 1000;

    /**
     * Assumes a negative integer really is a positive integer that has wrapped around and re-creates the original value.
     *
     * @param i the value to treat as unsigned int.
     * @return the unsigned int as a long.
     */
    public static long adjustToLong(final int i) {
        if (i < 0) {
            return 2 * (long) Integer.MAX_VALUE + 2 + i;
        }
        return i;
    }

    /**
     * Converts a BigInteger into a long, and blows up (NumberFormatException) if the BigInteger is too big.
     *
     * @param big BigInteger to convert.
     * @return long representation of the BigInteger.
     */
    static long bigToLong(final BigInteger big) {
        if (big.bitLength() <= 63) { // bitLength() doesn't count the sign bit.
            return big.longValue();
        }
        throw new NumberFormatException("The BigInteger cannot fit inside a 64 bit java long: [" + big + "]");
    }

    /**
     * Tests if this library is able to read or write the given entry.
     */
    static boolean canHandleEntryData(final ZipArchiveEntry entry) {
        return supportsEncryptionOf(entry) && supportsMethodOf(entry);
    }

    /**
     * Checks whether the entry requires features not (yet) supported by the library and throws an exception if it does.
     */
    static void checkRequestedFeatures(final ZipArchiveEntry ze) throws UnsupportedZipFeatureException {
        if (!supportsEncryptionOf(ze)) {
            throw new UnsupportedZipFeatureException(UnsupportedZipFeatureException.Feature.ENCRYPTION, ze);
        }
        if (!supportsMethodOf(ze)) {
            final ZipMethod m = ZipMethod.getMethodByCode(ze.getMethod());
            if (m == null) {
                throw new UnsupportedZipFeatureException(UnsupportedZipFeatureException.Feature.METHOD, ze);
            }
            throw new UnsupportedZipFeatureException(m, ze);
        }
    }

    /**
     * Creates a copy of the given array - or return null if the argument is null.
     */
    static byte[] copy(final byte[] from) {
        if (from != null) {
            return Arrays.copyOf(from, from.length);
        }
        return null;
    }

    static void copy(final byte[] from, final byte[] to, final int offset) {
        if (from != null) {
            System.arraycopy(from, 0, to, offset, from.length);
        }
    }

    private static Date dosToJavaDate(final long dosTime) {
        final Calendar cal = Calendar.getInstance();
        // CheckStyle:MagicNumberCheck OFF - no point
        cal.set(Calendar.YEAR, (int) (dosTime >> 25 & 0x7f) + 1980);
        cal.set(Calendar.MONTH, (int) (dosTime >> 21 & 0x0f) - 1);
        cal.set(Calendar.DATE, (int) (dosTime >> 16) & 0x1f);
        cal.set(Calendar.HOUR_OF_DAY, (int) (dosTime >> 11) & 0x1f);
        cal.set(Calendar.MINUTE, (int) (dosTime >> 5) & 0x3f);
        cal.set(Calendar.SECOND, (int) (dosTime << 1) & 0x3e);
        cal.set(Calendar.MILLISECOND, 0);
        // CheckStyle:MagicNumberCheck ON
        return cal.getTime();
    }

    /**
     * Converts DOS time to Java time (number of milliseconds since epoch).
     *
     * @param dosTime time to convert
     * @return converted time
     */
    public static long dosToJavaTime(final long dosTime) {
        return dosToJavaDate(dosTime).getTime();
    }

    /**
     * Converts a DOS date/time field to a Date object.
     *
     * @param zipDosTime contains the stored DOS time.
     * @return a Date instance corresponding to the given time.
     */
    public static Date fromDosTime(final ZipLong zipDosTime) {
        final long dosTime = zipDosTime.getValue();
        return dosToJavaDate(dosTime);
    }

    /**
     * If the stored CRC matches the one of the given name, return the Unicode name of the given field.
     *
     * <p>
     * If the field is null or the CRCs don't match, return null instead.
     * </p>
     */
    private static String getUnicodeStringIfOriginalMatches(final AbstractUnicodeExtraField f, final byte[] orig) {
        if (f != null) {
            final CRC32 crc32 = new CRC32();
            crc32.update(orig);
            final long origCRC32 = crc32.getValue();

            if (origCRC32 == f.getNameCRC32()) {
                try {
                    return ZipEncodingHelper.ZIP_ENCODING_UTF_8.decode(f.getUnicodeName());
                } catch (final IOException ex) {
                    // UTF-8 unsupported? should be impossible the
                    // Unicode*ExtraField must contain some bad bytes
                }
            }
        }
        // TODO log this anywhere?
        return null;
    }

    /**
     * Tests whether a given time (in milliseconds since Epoch) can be safely represented as DOS time
     *
     * @param time time in milliseconds since epoch
     * @return true if the time can be safely represented as DOS time, false otherwise
     * @since 1.23
     */
    public static boolean isDosTime(final long time) {
        return time <= UPPER_DOSTIME_BOUND &&
                (time == DOSTIME_BEFORE_1980_AS_JAVA_TIME || javaToDosTime(time) != DOSTIME_BEFORE_1980);
    }

    private static LocalDateTime javaEpochToLocalDateTime(final long time) {
        final Instant instant = Instant.ofEpochMilli(time);
        return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
    }

    // version with integer overflow fixed - see https://bugs.openjdk.org/browse/JDK-8130914
    private static long javaToDosTime(final long t) {
        final LocalDateTime ldt = javaEpochToLocalDateTime(t);
        if (ldt.getYear() < 1980) {
            return DOSTIME_BEFORE_1980;
        }
        return (ldt.getYear() - 1980 << 25 | ldt.getMonthValue() << 21 | ldt.getDayOfMonth() << 16 | ldt.getHour() << 11 | ldt.getMinute() << 5
                | ldt.getSecond() >> 1) & 0xffffffffL;
    }

    /**
     * <p>
     * Converts a long into a BigInteger. Negative numbers between -1 and -2^31 are treated as unsigned 32 bit (e.g., positive) integers. Negative numbers below
     * -2^31 cause an IllegalArgumentException to be thrown.
     * </p>
     *
     * @param l long to convert to BigInteger.
     * @return BigInteger representation of the provided long.
     */
    static BigInteger longToBig(long l) {
        if (l < Integer.MIN_VALUE) {
            throw new IllegalArgumentException("Negative longs < -2^31 not permitted: [" + l + "]");
        }
        if (l < 0 && l >= Integer.MIN_VALUE) {
            // If someone passes in a -2, they probably mean 4294967294
            // (For example, Unix UID/GID's are 32 bit unsigned.)
            l = ZipUtil.adjustToLong((int) l);
        }
        return BigInteger.valueOf(l);
    }

    /**
     * Reverses a byte[] array. Reverses in-place (thus provided array is mutated), but also returns same for convenience.
     *
     * @param array to reverse (mutated in-place, but also returned for convenience).
     *
     * @return the reversed array (mutated in-place, but also returned for convenience).
     * @since 1.5
     */
    public static byte[] reverse(final byte[] array) {
        final int z = array.length - 1; // position of last element
        for (int i = 0; i < array.length / 2; i++) {
            final byte x = array[i];
            array[i] = array[z - i];
            array[z - i] = x;
        }
        return array;
    }

    /**
     * If the entry has Unicode*ExtraFields and the CRCs of the names/comments match those of the extra fields, transfer the known Unicode values from the extra
     * field.
     */
    static void setNameAndCommentFromExtraFields(final ZipArchiveEntry ze, final byte[] originalNameBytes, final byte[] commentBytes) {
        final ZipExtraField nameCandidate = ze.getExtraField(UnicodePathExtraField.UPATH_ID);
        final UnicodePathExtraField name = nameCandidate instanceof UnicodePathExtraField ? (UnicodePathExtraField) nameCandidate : null;
        final String newName = getUnicodeStringIfOriginalMatches(name, originalNameBytes);
        if (newName != null) {
            ze.setName(newName);
            ze.setNameSource(ZipArchiveEntry.NameSource.UNICODE_EXTRA_FIELD);
        }

        if (commentBytes != null && commentBytes.length > 0) {
            final ZipExtraField cmtCandidate = ze.getExtraField(UnicodeCommentExtraField.UCOM_ID);
            final UnicodeCommentExtraField cmt = cmtCandidate instanceof UnicodeCommentExtraField ? (UnicodeCommentExtraField) cmtCandidate : null;
            final String newComment = getUnicodeStringIfOriginalMatches(cmt, commentBytes);
            if (newComment != null) {
                ze.setComment(newComment);
                ze.setCommentSource(ZipArchiveEntry.CommentSource.UNICODE_EXTRA_FIELD);
            }
        }
    }

    /**
     * Converts a signed byte into an unsigned integer representation (e.g., -1 becomes 255).
     *
     * @param b byte to convert to int
     * @return int representation of the provided byte
     * @since 1.5
     */
    public static int signedByteToUnsignedInt(final byte b) {
        if (b >= 0) {
            return b;
        }
        return 256 + b;
    }

    /**
     * Tests if this library supports the encryption used by the given entry.
     *
     * @return true if the entry isn't encrypted at all
     */
    private static boolean supportsEncryptionOf(final ZipArchiveEntry entry) {
        return !entry.getGeneralPurposeBit().usesEncryption();
    }

    /**
     * Tests if this library supports the compression method used by the given entry.
     *
     * @return true if the compression method is supported
     */
    private static boolean supportsMethodOf(final ZipArchiveEntry entry) {
        return entry.getMethod() == ZipEntry.STORED || entry.getMethod() == ZipMethod.UNSHRINKING.getCode()
                || entry.getMethod() == ZipMethod.IMPLODING.getCode() || entry.getMethod() == ZipEntry.DEFLATED
                || entry.getMethod() == ZipMethod.ENHANCED_DEFLATED.getCode() || entry.getMethod() == ZipMethod.BZIP2.getCode();
    }

    /**
     * Converts a Date object to a DOS date/time field.
     *
     * @param time the {@code Date} to convert
     * @return the date as a {@code ZipLong}
     */
    public static ZipLong toDosTime(final Date time) {
        return new ZipLong(toDosTime(time.getTime()));
    }

    /**
     * Converts a Date object to a DOS date/time field.
     *
     * <p>
     * Stolen from InfoZip's {@code fileio.c}
     * </p>
     *
     * @param t number of milliseconds since the epoch
     * @return the date as a byte array
     */
    public static byte[] toDosTime(final long t) {
        final byte[] result = new byte[4];
        toDosTime(t, result, 0);
        return result;
    }

    /**
     * Converts a Date object to a DOS date/time field.
     *
     * <p>
     * Stolen from InfoZip's {@code fileio.c}
     * </p>
     *
     * @param t      number of milliseconds since the epoch
     * @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 toDosTime(final long t, final byte[] buf, final int offset) {
        ZipLong.putLong(javaToDosTime(t), buf, offset);
    }

    /**
     * Converts an unsigned integer to a signed byte (e.g., 255 becomes -1).
     *
     * @param i integer to convert to byte
     * @return byte representation of the provided int
     * @throws IllegalArgumentException if the provided integer is not inside the range [0,255].
     * @since 1.5
     */
    public static byte unsignedIntToSignedByte(final int i) {
        if (i > 255 || i < 0) {
            throw new IllegalArgumentException("Can only convert non-negative integers between [0,255] to byte: [" + i + "]");
        }
        if (i < 128) {
            return (byte) i;
        }
        return (byte) (i - 256);
    }
}