package org.apache.rat.config.exclusion.plexus;

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.codehaus.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "Ant" and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact codehaus@codehaus.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.codehaus.org/>.
 *
 */
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

@SuppressWarnings({"checkstyle:RegexpSingleLine", "checkstyle:JavadocVariable"})
/**
 * <p>This is a utility class used by selectors and DirectoryScanner. The functionality more properly belongs just to
 * selectors, but unfortunately DirectoryScanner exposed these as protected methods. Thus we have to support any
 * subclasses of DirectoryScanner that may access these methods.</p>
 *
 *
 * <p>This is a Singleton.</p>
 * <p>Based on code from plexus-utils.</p>
 *
 * @author Arnout J. Kuiper <a href="mailto:ajkuiper@wxs.nl">ajkuiper@wxs.nl</a>
 * @author Magesh Umasankar
 * @author <a href="mailto:bruce@callenish.com">Bruce Atherton</a>
 * @see <a href="https://github.com/codehaus-plexus/plexus-utils/blob/master/src/main/java/org/codehaus/plexus/util/SelectorUtils.java">
 * plexus-utils SelectorUtils</a>
 */
public final class SelectorUtils {

    public static final String PATTERN_HANDLER_PREFIX = "[";

    public static final String PATTERN_HANDLER_SUFFIX = "]";

    public static final String REGEX_HANDLER_PREFIX = "%regex" + PATTERN_HANDLER_PREFIX;

    public static final String ANT_HANDLER_PREFIX = "%ant" + PATTERN_HANDLER_PREFIX;

    private static final SelectorUtils INSTANCE = new SelectorUtils();

    /**
     * Private Constructor
     */
    private SelectorUtils() {
    }

    /**
     * @return Retrieves the manager of the Singleton.
     */
    public static SelectorUtils getInstance() {
        return INSTANCE;
    }

    /**
     * <p>Tests whether or not a given path matches the start of a given pattern up to the first "**".</p>
     *
     * <p>This is not a general purpose test and should only be used if you can live with false positives. For example,
     * <code>pattern=**\a</code> and <code>str=b</code> will yield <code>true</code>.</p>
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The path to match, as a String. Must not be <code>null</code>.
     * @return whether or not a given path matches the start of a given pattern up to the first "**".
     */
    public static boolean matchPatternStart(final String pattern, final String str) {
        return matchPatternStart(pattern, str, true);
    }

    /**
     * <p>Tests whether or not a given path matches the start of a given pattern up to the first "**".</p>
     *
     * <p>This is not a general purpose test and should only be used if you can live with false positives. For example,
     * <code>pattern=**\a</code> and <code>str=b</code> will yield <code>true</code>.</p>
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The path to match, as a String. Must not be <code>null</code>.
     * @param isCaseSensitive Whether or not matching should be performed case sensitively.
     * @return whether or not a given path matches the start of a given pattern up to the first "**".
     */
    public static boolean matchPatternStart(final String pattern, final String str, final boolean isCaseSensitive) {
        if (isRegexPrefixedPattern(pattern)) {
            // FIXME: ICK! But we can't do partial matches for regex, so we have to reserve judgement until we have
            // a file to deal with, or we can definitely say this is an exclusion...
            return true;
        }
        String workingPattern = isAntPrefixedPattern(pattern) ?
            pattern.substring(ANT_HANDLER_PREFIX.length(), pattern.length() - PATTERN_HANDLER_SUFFIX.length())
                : pattern;

        String altStr = str.replace('\\', '/');

        return matchAntPathPatternStart(workingPattern, str, File.separator, isCaseSensitive)
                || matchAntPathPatternStart(workingPattern, altStr, "/", isCaseSensitive);

    }

    public static boolean isAntPrefixedPattern(final String pattern) {
        return pattern.length() > (ANT_HANDLER_PREFIX.length() + PATTERN_HANDLER_SUFFIX.length() + 1)
                && pattern.startsWith(ANT_HANDLER_PREFIX)
                && pattern.endsWith(PATTERN_HANDLER_SUFFIX);
    }

    @SuppressWarnings("SimplifiableIfStatement")
    static boolean matchAntPathPatternStart(final MatchPattern pattern, final String str, final String separator, final boolean isCaseSensitive) {
        if (separatorPatternStartSlashMismatch(pattern, str, separator)) {
            return false;
        }

        return matchAntPathPatternStart(pattern.getTokenizedPathString(), str, separator, isCaseSensitive);
    }

    static boolean matchAntPathPatternStart(final String pattern, final String str, final String separator, final boolean isCaseSensitive) {
        // When str starts with a File.separator, pattern has to start with a
        // File.separator.
        // When pattern starts with a File.separator, str has to start with a
        // File.separator.
        if (separatorPatternStartSlashMismatch(pattern, str, separator)) {
            return false;
        }

        String[] patDirs = tokenizePathToString(pattern, separator);
        return matchAntPathPatternStart(patDirs, str, separator, isCaseSensitive);
    }

    // When str starts with a File.separator, pattern has to start with a
    // File.separator.
    // When pattern starts with a File.separator, str has to start with a
    // File.separator.
    private static boolean separatorPatternStartSlashMismatch(final String pattern, final String str, final String separator) {
        return str.startsWith(separator) != pattern.startsWith(separator);
    }

    private static boolean separatorPatternStartSlashMismatch(final MatchPattern matchPattern, final String str, final String separator) {
        return str.startsWith(separator) != matchPattern.startsWith(separator);
    }

    static boolean matchAntPathPatternStart(final String[] patDirs, final String str, final String separator, final boolean isCaseSensitive) {
        String[] strDirs = tokenizePathToString(str, separator);

        int patIdxStart = 0;
        int patIdxEnd = patDirs.length - 1;
        int strIdxStart = 0;
        int strIdxEnd = strDirs.length - 1;

        // up to first '**'
        while (patIdxStart <= patIdxEnd && strIdxStart <= strIdxEnd) {
            String patDir = patDirs[patIdxStart];
            if (patDir.equals("**")) {
                break;
            }
            if (!match(patDir, strDirs[strIdxStart], isCaseSensitive)) {
                return false;
            }
            patIdxStart++;
            strIdxStart++;
        }

        return strIdxStart > strIdxEnd || patIdxStart <= patIdxEnd;
    }

    /**
     * Tests whether or not a given path matches a given pattern.
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The path to match, as a String. Must not be <code>null</code>.
     * @return <code>true</code> if the pattern matches against the string, or <code>false</code> otherwise.
     */
    public static boolean matchPath(final String pattern, final String str) {
        return matchPath(pattern, str, true);
    }

    /**
     * Tests whether or not a given path matches a given pattern.
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The path to match, as a String. Must not be <code>null</code>.
     * @param isCaseSensitive Whether or not matching should be performed case sensitively.
     * @return <code>true</code> if the pattern matches against the string, or <code>false</code> otherwise.
     */
    public static boolean matchPath(final String pattern, final String str, final boolean isCaseSensitive) {
        return matchPath(pattern, str, File.separator, isCaseSensitive);
    }

    public static String extractPattern(final String pattern, final String separator) {
        if (isRegexPrefixedPattern(pattern)) {
            return pattern.substring(
                    REGEX_HANDLER_PREFIX.length(), pattern.length() - PATTERN_HANDLER_SUFFIX.length());
        } else {
            String localPattern = isAntPrefixedPattern(pattern)
                    ? pattern.substring(ANT_HANDLER_PREFIX.length(), pattern.length() - PATTERN_HANDLER_SUFFIX.length())
                    : pattern;
            return toOSRelatedPath(localPattern, separator);
        }
    }

    public static boolean matchPath(final String pattern, final String str, final String separator, final boolean isCaseSensitive) {
        if (isRegexPrefixedPattern(pattern)) {
            String localPattern = pattern.substring(
                    REGEX_HANDLER_PREFIX.length(), pattern.length() - PATTERN_HANDLER_SUFFIX.length());

            return str.matches(localPattern);
        } else {
            String localPattern = isAntPrefixedPattern(pattern)
                    ? pattern.substring(ANT_HANDLER_PREFIX.length(), pattern.length() - PATTERN_HANDLER_SUFFIX.length())
                    : pattern;
            final String osRelatedPath = toOSRelatedPath(str, separator);
            final String osRelatedPattern = toOSRelatedPath(localPattern, separator);
            return matchAntPathPattern(osRelatedPattern, osRelatedPath, separator, isCaseSensitive);
        }
    }

    private static String toOSRelatedPath(final String pattern, final String separator) {
        if ("/".equals(separator)) {
            return pattern.replace("\\", separator);
        }
        if ("\\".equals(separator)) {
            return pattern.replace("/", separator);
        }
        return pattern;
    }

    public static boolean isRegexPrefixedPattern(final String pattern) {
        return pattern.length() > (REGEX_HANDLER_PREFIX.length() + PATTERN_HANDLER_SUFFIX.length() + 1)
                && pattern.startsWith(REGEX_HANDLER_PREFIX)
                && pattern.endsWith(PATTERN_HANDLER_SUFFIX);
    }

    static boolean matchAntPathPattern(final MatchPattern matchPattern, final String str, final String separator, final boolean isCaseSensitive) {
        if (separatorPatternStartSlashMismatch(matchPattern, str, separator)) {
            return false;
        }
        String[] patDirs = matchPattern.getTokenizedPathString();
        String[] strDirs = tokenizePathToString(str, separator);
        return matchAntPathPattern(patDirs, strDirs, isCaseSensitive);
    }

    static boolean matchAntPathPattern(final String pattern, final String str, final String separator, final boolean isCaseSensitive) {
        if (separatorPatternStartSlashMismatch(pattern, str, separator)) {
            return false;
        }
        String[] patDirs = tokenizePathToString(pattern, separator);
        String[] strDirs = tokenizePathToString(str, separator);
        return matchAntPathPattern(patDirs, strDirs, isCaseSensitive);
    }

    static boolean matchAntPathPattern(final String[] patDirs, final String[] strDirs, final boolean isCaseSensitive) {
        int patIdxStart = 0;
        int patIdxEnd = patDirs.length - 1;
        int strIdxStart = 0;
        int strIdxEnd = strDirs.length - 1;

        // up to first '**'
        while (patIdxStart <= patIdxEnd && strIdxStart <= strIdxEnd) {
            String patDir = patDirs[patIdxStart];
            if (patDir.equals("**")) {
                break;
            }
            if (!match(patDir, strDirs[strIdxStart], isCaseSensitive)) {
                return false;
            }
            patIdxStart++;
            strIdxStart++;
        }
        if (strIdxStart > strIdxEnd) {
            // String is exhausted
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (!patDirs[i].equals("**")) {
                    return false;
                }
            }
            return true;
        } else {
            if (patIdxStart > patIdxEnd) {
                // String not exhausted, but pattern is. Failure.
                return false;
            }
        }

        // up to last '**'
        while (patIdxStart <= patIdxEnd && strIdxStart <= strIdxEnd) {
            String patDir = patDirs[patIdxEnd];
            if (patDir.equals("**")) {
                break;
            }
            if (!match(patDir, strDirs[strIdxEnd], isCaseSensitive)) {
                return false;
            }
            patIdxEnd--;
            strIdxEnd--;
        }
        if (strIdxStart > strIdxEnd) {
            // String is exhausted
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (!patDirs[i].equals("**")) {
                    return false;
                }
            }
            return true;
        }

        while (patIdxStart != patIdxEnd && strIdxStart <= strIdxEnd) {
            int patIdxTmp = -1;
            for (int i = patIdxStart + 1; i <= patIdxEnd; i++) {
                if (patDirs[i].equals("**")) {
                    patIdxTmp = i;
                    break;
                }
            }
            if (patIdxTmp == patIdxStart + 1) {
                // '**/**' situation, so skip one
                patIdxStart++;
                continue;
            }
            // Find the pattern between padIdxStart & padIdxTmp in str between
            // strIdxStart & strIdxEnd
            int patLength = patIdxTmp - patIdxStart - 1;
            int strLength = strIdxEnd - strIdxStart + 1;
            int foundIdx = -1;
            strLoop:
            for (int i = 0; i <= strLength - patLength; i++) {
                for (int j = 0; j < patLength; j++) {
                    String subPat = patDirs[patIdxStart + j + 1];
                    String subStr = strDirs[strIdxStart + i + j];
                    if (!match(subPat, subStr, isCaseSensitive)) {
                        continue strLoop;
                    }
                }

                foundIdx = strIdxStart + i;
                break;
            }

            if (foundIdx == -1) {
                return false;
            }

            patIdxStart = patIdxTmp;
            strIdxStart = foundIdx + patLength;
        }

        for (int i = patIdxStart; i <= patIdxEnd; i++) {
            if (!patDirs[i].equals("**")) {
                return false;
            }
        }

        return true;
    }

    static boolean matchAntPathPattern(final char[][] patDirs, final char[][] strDirs, final boolean isCaseSensitive) {
        int patIdxStart = 0;
        int patIdxEnd = patDirs.length - 1;
        int strIdxStart = 0;
        int strIdxEnd = strDirs.length - 1;

        // up to first '**'
        while (patIdxStart <= patIdxEnd && strIdxStart <= strIdxEnd) {
            char[] patDir = patDirs[patIdxStart];
            if (isDoubleStar(patDir)) {
                break;
            }
            if (!match(patDir, strDirs[strIdxStart], isCaseSensitive)) {
                return false;
            }
            patIdxStart++;
            strIdxStart++;
        }
        if (strIdxStart > strIdxEnd) {
            // String is exhausted
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (!isDoubleStar(patDirs[i])) {
                    return false;
                }
            }
            return true;
        } else {
            if (patIdxStart > patIdxEnd) {
                // String not exhausted, but pattern is. Failure.
                return false;
            }
        }

        // up to last '**'
        while (patIdxStart <= patIdxEnd && strIdxStart <= strIdxEnd) {
            char[] patDir = patDirs[patIdxEnd];
            if (isDoubleStar(patDir)) {
                break;
            }
            if (!match(patDir, strDirs[strIdxEnd], isCaseSensitive)) {
                return false;
            }
            patIdxEnd--;
            strIdxEnd--;
        }
        if (strIdxStart > strIdxEnd) {
            // String is exhausted
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (!isDoubleStar(patDirs[i])) {
                    return false;
                }
            }
            return true;
        }

        while (patIdxStart != patIdxEnd && strIdxStart <= strIdxEnd) {
            int patIdxTmp = -1;
            for (int i = patIdxStart + 1; i <= patIdxEnd; i++) {
                if (isDoubleStar(patDirs[i])) {
                    patIdxTmp = i;
                    break;
                }
            }
            if (patIdxTmp == patIdxStart + 1) {
                // '**/**' situation, so skip one
                patIdxStart++;
                continue;
            }
            // Find the pattern between padIdxStart & padIdxTmp in str between
            // strIdxStart & strIdxEnd
            int patLength = patIdxTmp - patIdxStart - 1;
            int strLength = strIdxEnd - strIdxStart + 1;
            int foundIdx = -1;
            strLoop:
            for (int i = 0; i <= strLength - patLength; i++) {
                for (int j = 0; j < patLength; j++) {
                    char[] subPat = patDirs[patIdxStart + j + 1];
                    char[] subStr = strDirs[strIdxStart + i + j];
                    if (!match(subPat, subStr, isCaseSensitive)) {
                        continue strLoop;
                    }
                }

                foundIdx = strIdxStart + i;
                break;
            }

            if (foundIdx == -1) {
                return false;
            }

            patIdxStart = patIdxTmp;
            strIdxStart = foundIdx + patLength;
        }

        for (int i = patIdxStart; i <= patIdxEnd; i++) {
            if (!isDoubleStar(patDirs[i])) {
                return false;
            }
        }

        return true;
    }

    private static boolean isDoubleStar(final char[] patDir) {
        return patDir != null && patDir.length == 2 && patDir[0] == '*' && patDir[1] == '*';
    }

    /**
     * Tests whether or not a string matches against a pattern. The pattern may contain two special characters:<br>
     * '*' means zero or more characters<br>
     * '?' means one and only one character
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The string which must be matched against the pattern. Must not be <code>null</code>.
     * @return <code>true</code> if the string matches against the pattern, or <code>false</code> otherwise.
     */
    public static boolean match(final String pattern, final String str) {
        return match(pattern, str, true);
    }

    /**
     * Tests whether or not a string matches against a pattern. The pattern may contain two special characters:<br>
     * '*' means zero or more characters<br>
     * '?' means one and only one character
     *
     * @param pattern The pattern to match against. Must not be <code>null</code>.
     * @param str The string which must be matched against the pattern. Must not be <code>null</code>.
     * @param isCaseSensitive Whether or not matching should be performed case sensitively.
     * @return <code>true</code> if the string matches against the pattern, or <code>false</code> otherwise.
     */
    public static boolean match(final String pattern, final String str, final boolean isCaseSensitive) {
        char[] patArr = pattern.toCharArray();
        char[] strArr = str.toCharArray();
        return match(patArr, strArr, isCaseSensitive);
    }

    public static boolean match(final char[] patArr, final char[] strArr, final boolean isCaseSensitive) {
        int patIdxStart = 0;
        int patIdxEnd = patArr.length - 1;
        int strIdxStart = 0;
        int strIdxEnd = strArr.length - 1;
        char ch;

        boolean containsStar = false;
        for (char aPatArr : patArr) {
            if (aPatArr == '*') {
                containsStar = true;
                break;
            }
        }

        if (!containsStar) {
            // No '*'s, so we make a shortcut
            if (patIdxEnd != strIdxEnd) {
                return false; // Pattern and string do not have the same size
            }
            for (int i = 0; i <= patIdxEnd; i++) {
                ch = patArr[i];
                if (ch != '?' && !equals(ch, strArr[i], isCaseSensitive)) {
                    return false; // Character mismatch
                }
            }
            return true; // String matches against pattern
        }

        if (patIdxEnd == 0) {
            return true; // Pattern contains only '*', which matches anything
        }

        // Process characters before first star
        while ((ch = patArr[patIdxStart]) != '*' && strIdxStart <= strIdxEnd) {
            if (ch != '?' && !equals(ch, strArr[strIdxStart], isCaseSensitive)) {
                return false; // Character mismatch
            }
            patIdxStart++;
            strIdxStart++;
        }
        if (strIdxStart > strIdxEnd) {
            // All characters in the string are used. Check if only '*'s are
            // left in the pattern. If so, we succeeded. Otherwise failure.
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (patArr[i] != '*') {
                    return false;
                }
            }
            return true;
        }

        // Process characters after last star
        while ((ch = patArr[patIdxEnd]) != '*' && strIdxStart <= strIdxEnd) {
            if (ch != '?' && !equals(ch, strArr[strIdxEnd], isCaseSensitive)) {
                return false; // Character mismatch
            }
            patIdxEnd--;
            strIdxEnd--;
        }
        if (strIdxStart > strIdxEnd) {
            // All characters in the string are used. Check if only '*'s are
            // left in the pattern. If so, we succeeded. Otherwise failure.
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (patArr[i] != '*') {
                    return false;
                }
            }
            return true;
        }

        // process pattern between stars. padIdxStart and patIdxEnd point
        // always to a '*'.
        while (patIdxStart != patIdxEnd && strIdxStart <= strIdxEnd) {
            int patIdxTmp = -1;
            for (int i = patIdxStart + 1; i <= patIdxEnd; i++) {
                if (patArr[i] == '*') {
                    patIdxTmp = i;
                    break;
                }
            }
            if (patIdxTmp == patIdxStart + 1) {
                // Two stars next to each other, skip the first one.
                patIdxStart++;
                continue;
            }
            // Find the pattern between padIdxStart & padIdxTmp in str between
            // strIdxStart & strIdxEnd
            int patLength = patIdxTmp - patIdxStart - 1;
            int strLength = strIdxEnd - strIdxStart + 1;
            int foundIdx = -1;
            strLoop:
            for (int i = 0; i <= strLength - patLength; i++) {
                for (int j = 0; j < patLength; j++) {
                    ch = patArr[patIdxStart + j + 1];
                    if (ch != '?' && !equals(ch, strArr[strIdxStart + i + j], isCaseSensitive)) {
                        continue strLoop;
                    }
                }

                foundIdx = strIdxStart + i;
                break;
            }

            if (foundIdx == -1) {
                return false;
            }

            patIdxStart = patIdxTmp;
            strIdxStart = foundIdx + patLength;
        }

        // All characters in the string are used. Check if only '*'s are left
        // in the pattern. If so, we succeeded. Otherwise failure.
        for (int i = patIdxStart; i <= patIdxEnd; i++) {
            if (patArr[i] != '*') {
                return false;
            }
        }
        return true;
    }

    /**
     * Tests whether two characters are equal.
     */
    private static boolean equals(final char c1, final char c2, final boolean isCaseSensitive) {
        if (c1 == c2) {
            return true;
        }
        if (!isCaseSensitive) {
            // NOTE: Try both upper case and lower case as done by String.equalsIgnoreCase()
            return Character.toUpperCase(c1) == Character.toUpperCase(c2)
                    || Character.toLowerCase(c1) == Character.toLowerCase(c2);
        }
        return false;
    }

    private static String[] tokenizePathToString(final String path, final String separator) {
        List<String> ret = new ArrayList<>();
        StringTokenizer st = new StringTokenizer(path, separator);
        while (st.hasMoreTokens()) {
            ret.add(st.nextToken());
        }
        return ret.toArray(new String[0]);
    }

    /**
     * Returns dependency information on these two files. If src has been modified later than target, it returns true.
     * If target doesn't exist, it likewise returns true. Otherwise, target is newer than src and is not out of date,
     * thus the method returns false. It also returns false if the src file doesn't even exist, since how could the
     * target then be out of date.
     *
     * @param src the original file
     * @param target the file being compared against
     * @param granularity the amount in seconds of slack we will give in determining out of dateness
     * @return whether the target is out of date
     */
    public static boolean isOutOfDate(final File src, final File target, final int granularity) {
        if (!src.exists()) {
            return false;
        }
        if (!target.exists()) {
            return true;
        }
        return (src.lastModified() - granularity) > target.lastModified();
    }

    /**
     * "Flattens" a string by removing all whitespace (space, tab, linefeed, carriage return, and formfeed). This uses
     * StringTokenizer and the default set of tokens as documented in the single argument constructor.
     *
     * @param input a String to remove all whitespace.
     * @return a String that has had all whitespace removed.
     */
    public static String removeWhitespace(final String input) {
        StringBuilder result = new StringBuilder();
        if (input != null) {
            StringTokenizer st = new StringTokenizer(input);
            while (st.hasMoreTokens()) {
                result.append(st.nextToken());
            }
        }
        return result.toString();
    }
}
