/*

 * Copyright (c) 2009, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.nio.zipfs;

import java.io.IOException;

import java.io.OutputStream;

import java.nio.file.attribute.PosixFilePermission;

import java.time.DateTimeException;

import java.time.Instant;

import java.time.LocalDateTime;

import java.time.ZoneId;

import java.util.Arrays;

import java.util.Date;

import java.util.Set;

import java.util.concurrent.TimeUnit;

import java.util.regex.PatternSyntaxException;

/**

 * @author Xueming Shen

 */

class ZipUtils {

    /**

     * The bit flag used to specify read permission by the owner.

     */

    static final int POSIX_USER_READ = 0400;

    /**

     * The bit flag used to specify write permission by the owner.

     */

    static final int POSIX_USER_WRITE = 0200;

    /**

     * The bit flag used to specify execute permission by the owner.

     */

    static final int POSIX_USER_EXECUTE = 0100;

    /**

     * The bit flag used to specify read permission by the group.

     */

    static final int POSIX_GROUP_READ = 040;

    /**

     * The bit flag used to specify write permission by the group.

     */

    static final int POSIX_GROUP_WRITE = 020;

    /**

     * The bit flag used to specify execute permission by the group.

     */

    static final int POSIX_GROUP_EXECUTE = 010;

    /**

     * The bit flag used to specify read permission by others.

     */

    static final int POSIX_OTHER_READ = 04;

    /**

     * The bit flag used to specify write permission by others.

     */

    static final int POSIX_OTHER_WRITE = 02;

    /**

     * The bit flag used to specify execute permission by others.

     */

    static final int POSIX_OTHER_EXECUTE = 01;

    /**

     * Convert a {@link PosixFilePermission} object into the appropriate bit

     * flag.

     *

     * @param perm The {@link PosixFilePermission} object.

     * @return The bit flag as int.

     */

    static int permToFlag(PosixFilePermission perm) {

        switch(perm) {

        case OWNER_READ:

            return POSIX_USER_READ;

        case OWNER_WRITE:

            return POSIX_USER_WRITE;

        case OWNER_EXECUTE:

            return POSIX_USER_EXECUTE;

        case GROUP_READ:

            return POSIX_GROUP_READ;

        case GROUP_WRITE:

            return POSIX_GROUP_WRITE;

        case GROUP_EXECUTE:

            return POSIX_GROUP_EXECUTE;

        case OTHERS_READ:

            return POSIX_OTHER_READ;

        case OTHERS_WRITE:

            return POSIX_OTHER_WRITE;

        case OTHERS_EXECUTE:

            return POSIX_OTHER_EXECUTE;

        default:

            return 0;

        }

    }

    /**

     * Converts a set of {@link PosixFilePermission}s into an int value where

     * the according bits are set.

     *

     * @param perms A Set of {@link PosixFilePermission} objects.

     *

     * @return A bit mask representing the input Set.

     */

    static int permsToFlags(Set<PosixFilePermission> perms) {

        if (perms == null) {

            return -1;

        }

        int flags = 0;

        for (PosixFilePermission perm : perms) {

            flags |= permToFlag(perm);

        }

        return flags;

    }

    /*

     * Writes a 16-bit short to the output stream in little-endian byte order.

     */

    public static void writeShort(OutputStream os, int v) throws IOException {

        os.write(v & 0xff);

        os.write((v >>> 8) & 0xff);

    }

    /*

     * Writes a 32-bit int to the output stream in little-endian byte order.

     */

    public static void writeInt(OutputStream os, long v) throws IOException {

        os.write((int)(v & 0xff));

        os.write((int)((v >>>  8) & 0xff));

        os.write((int)((v >>> 16) & 0xff));

        os.write((int)((v >>> 24) & 0xff));

    }

    /*

     * Writes a 64-bit int to the output stream in little-endian byte order.

     */

    public static void writeLong(OutputStream os, long v) throws IOException {

        os.write((int)(v & 0xff));

        os.write((int)((v >>>  8) & 0xff));

        os.write((int)((v >>> 16) & 0xff));

        os.write((int)((v >>> 24) & 0xff));

        os.write((int)((v >>> 32) & 0xff));

        os.write((int)((v >>> 40) & 0xff));

        os.write((int)((v >>> 48) & 0xff));

        os.write((int)((v >>> 56) & 0xff));

    }

    /*

     * Writes an array of bytes to the output stream.

     */

    public static void writeBytes(OutputStream os, byte[] b)

        throws IOException

    {

        os.write(b, 0, b.length);

    }

    /*

     * Writes an array of bytes to the output stream.

     */

    public static void writeBytes(OutputStream os, byte[] b, int off, int len)

        throws IOException

    {

        os.write(b, off, len);

    }

    /*

     * Append a slash at the end, if it does not have one yet

     */

    public static byte[] toDirectoryPath(byte[] dir) {

        if (dir.length != 0 && dir[dir.length - 1] != '/') {

            dir = Arrays.copyOf(dir, dir.length + 1);

            dir[dir.length - 1] = '/';

        }

        return dir;

    }

    /*

     * Converts DOS time to Java time (number of milliseconds since epoch).

     */

    public static long dosToJavaTime(long dtime) {

        int year = (int) (((dtime >> 25) & 0x7f) + 1980);

        int month = (int) ((dtime >> 21) & 0x0f);

        int day = (int) ((dtime >> 16) & 0x1f);

        int hour = (int) ((dtime >> 11) & 0x1f);

        int minute = (int) ((dtime >> 5) & 0x3f);

        int second = (int) ((dtime << 1) & 0x3e);

        if (month > 0 && month < 13 && day > 0 && hour < 24 && minute < 60 && second < 60) {

            try {

                LocalDateTime ldt = LocalDateTime.of(year, month, day, hour, minute, second);

                return TimeUnit.MILLISECONDS.convert(ldt.toEpochSecond(

                        ZoneId.systemDefault().getRules().getOffset(ldt)), TimeUnit.SECONDS);

            } catch (DateTimeException dte) {

                // ignore

            }

        }

        return overflowDosToJavaTime(year, month, day, hour, minute, second);

    }

    /*

     * Deal with corner cases where an arguably mal-formed DOS time is used

     */

    @SuppressWarnings("deprecation") // Use of Date constructor

    private static long overflowDosToJavaTime(int year, int month, int day,

                                              int hour, int minute, int second) {

        return new Date(year - 1900, month - 1, day, hour, minute, second).getTime();

    }

    /*

     * Converts Java time to DOS time.

     */

    public static long javaToDosTime(long time) {

        Instant instant = Instant.ofEpochMilli(time);

        LocalDateTime ldt = LocalDateTime.ofInstant(

                instant, ZoneId.systemDefault());

        int year = ldt.getYear() - 1980;

        if (year < 0) {

            return (1 << 21) | (1 << 16);

        }

        return (year << 25 |

            ldt.getMonthValue() << 21 |

            ldt.getDayOfMonth() << 16 |

            ldt.getHour() << 11 |

            ldt.getMinute() << 5 |

            ldt.getSecond() >> 1) & 0xffffffffL;

    }

    // used to adjust values between Windows and java epoch

    private static final long WINDOWS_EPOCH_IN_MICROSECONDS = -11644473600000000L;

    public static final long winToJavaTime(long wtime) {

        return TimeUnit.MILLISECONDS.convert(

               wtime / 10 + WINDOWS_EPOCH_IN_MICROSECONDS, TimeUnit.MICROSECONDS);

    }

    public static final long javaToWinTime(long time) {

        return (TimeUnit.MICROSECONDS.convert(time, TimeUnit.MILLISECONDS)

               - WINDOWS_EPOCH_IN_MICROSECONDS) * 10;

    }

    public static final long unixToJavaTime(long utime) {

        return TimeUnit.MILLISECONDS.convert(utime, TimeUnit.SECONDS);

    }

    public static final long javaToUnixTime(long time) {

        return TimeUnit.SECONDS.convert(time, TimeUnit.MILLISECONDS);

    }

    private static final String regexMetaChars = ".^$+{[]|()";

    private static final String globMetaChars = "\\*?[{";

    private static boolean isRegexMeta(char c) {

        return regexMetaChars.indexOf(c) != -1;

    }

    private static boolean isGlobMeta(char c) {

        return globMetaChars.indexOf(c) != -1;

    }

    private static char EOL = 0;  //TBD

    private static char next(String glob, int i) {

        if (i < glob.length()) {

            return glob.charAt(i);

        }

        return EOL;

    }

    /*

     * Creates a regex pattern from the given glob expression.

     *

     * @throws  PatternSyntaxException

     */

    public static String toRegexPattern(String globPattern) {

        boolean inGroup = false;

        StringBuilder regex = new StringBuilder("^");

        int i = 0;

        while (i < globPattern.length()) {

            char c = globPattern.charAt(i++);

            switch (c) {

                case '\\':

                    // escape special characters

                    if (i == globPattern.length()) {

                        throw new PatternSyntaxException("No character to escape",

                                globPattern, i - 1);

                    }

                    char next = globPattern.charAt(i++);

                    if (isGlobMeta(next) || isRegexMeta(next)) {

                        regex.append('\\');

                    }

                    regex.append(next);

                    break;

                case '/':

                    regex.append(c);

                    break;

                case '[':

                    // don't match name separator in class

                    regex.append("[[^/]&&[");

                    if (next(globPattern, i) == '^') {

                        // escape the regex negation char if it appears

                        regex.append("\\^");

                        i++;

                    } else {

                        // negation

                        if (next(globPattern, i) == '!') {

                            regex.append('^');

                            i++;

                        }

                        // hyphen allowed at start

                        if (next(globPattern, i) == '-') {

                            regex.append('-');

                            i++;

                        }

                    }

                    boolean hasRangeStart = false;

                    char last = 0;

                    while (i < globPattern.length()) {

                        c = globPattern.charAt(i++);

                        if (c == ']') {

                            break;

                        }

                        if (c == '/') {

                            throw new PatternSyntaxException("Explicit 'name separator' in class",

                                    globPattern, i - 1);

                        }

                        // TBD: how to specify ']' in a class?

                        if (c == '\\' || c == '[' ||

                                c == '&' && next(globPattern, i) == '&') {

                            // escape '\', '[' or "&&" for regex class

                            regex.append('\\');

                        }

                        regex.append(c);

                        if (c == '-') {

                            if (!hasRangeStart) {

                                throw new PatternSyntaxException("Invalid range",

                                        globPattern, i - 1);

                            }

                            if ((c = next(globPattern, i++)) == EOL || c == ']') {

                                break;

                            }

                            if (c < last) {

                                throw new PatternSyntaxException("Invalid range",

                                        globPattern, i - 3);

                            }

                            regex.append(c);

                            hasRangeStart = false;

                        } else {

                            hasRangeStart = true;

                            last = c;

                        }

                    }

                    if (c != ']') {

                        throw new PatternSyntaxException("Missing ']", globPattern, i - 1);

                    }

                    regex.append("]]");

                    break;

                case '{':

                    if (inGroup) {

                        throw new PatternSyntaxException("Cannot nest groups",

                                globPattern, i - 1);

                    }

                    regex.append("(?:(?:");

                    inGroup = true;

                    break;

                case '}':

                    if (inGroup) {

                        regex.append("))");

                        inGroup = false;

                    } else {

                        regex.append('}');

                    }

                    break;

                case ',':

                    if (inGroup) {

                        regex.append(")|(?:");

                    } else {

                        regex.append(',');

                    }

                    break;

                case '*':

                    if (next(globPattern, i) == '*') {

                        // crosses directory boundaries

                        regex.append(".*");

                        i++;

                    } else {

                        // within directory boundary

                        regex.append("[^/]*");

                    }

                    break;

                case '?':

                   regex.append("[^/]");

                   break;

                default:

                    if (isRegexMeta(c)) {

                        regex.append('\\');

                    }

                    regex.append(c);

            }

        }

        if (inGroup) {

            throw new PatternSyntaxException("Missing '}", globPattern, i - 1);

        }

        return regex.append('$').toString();

    }

}