001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.ftp.parser;
019
020import java.util.HashMap;
021import java.util.List;
022import java.util.ListIterator;
023import java.util.regex.MatchResult;
024import java.util.regex.Matcher;
025import java.util.regex.Pattern;
026import java.util.regex.PatternSyntaxException;
027
028import org.apache.commons.net.ftp.FTPClientConfig;
029
030/**
031 * Special implementation VMSFTPEntryParser with versioning turned on. This parser removes all duplicates and only leaves the version with the highest version
032 * number for each file name.
033 * <p>
034 * This is a sample of VMS LIST output
035 * </p>
036 *
037 * <pre>
038 *  "1-JUN.LIS;1              9/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
039 *  "1-JUN.LIS;2              9/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
040 *  "DATA.DIR;1               1/9           2-JUN-1998 07:32:04  [GROUP,OWNER]    (RWED,RWED,RWED,RE)",
041 * </pre>
042 *
043 * @see org.apache.commons.net.ftp.FTPFileEntryParser FTPFileEntryParser (for usage instructions)
044 */
045public class VMSVersioningFTPEntryParser extends VMSFTPEntryParser {
046
047    private static final String PRE_PARSE_REGEX = "(.*?);([0-9]+)\\s*.*";
048    private final Pattern preparsePattern;
049
050    /**
051     * Constructor for a VMSFTPEntryParser object.
052     *
053     * @throws IllegalArgumentException Thrown if the regular expression is unparseable. Should not be seen under normal conditions. If the exception is seen,
054     *                                  this is a sign that <code>REGEX</code> is not a valid regular expression.
055     */
056    public VMSVersioningFTPEntryParser() {
057        this(null);
058    }
059
060    /**
061     * This constructor allows the creation of a VMSVersioningFTPEntryParser object with something other than the default configuration.
062     *
063     * @param config The {@link FTPClientConfig configuration} object used to configure this parser.
064     * @throws IllegalArgumentException Thrown if the regular expression is unparseable. Should not be seen under normal conditions. If the exception is seen,
065     *                                  this is a sign that <code>REGEX</code> is not a valid regular expression.
066     * @since 1.4
067     */
068    public VMSVersioningFTPEntryParser(final FTPClientConfig config) {
069        configure(config);
070        try {
071            // _preparse_matcher_ = new Perl5Matcher();
072            preparsePattern = Pattern.compile(PRE_PARSE_REGEX);
073        } catch (final PatternSyntaxException pse) {
074            throw new IllegalArgumentException("Unparseable regex supplied:  " + PRE_PARSE_REGEX);
075        }
076
077    }
078
079    @Override
080    protected boolean isVersioning() {
081        return true;
082    }
083
084    /**
085     * Implement hook provided for those implementers (such as VMSVersioningFTPEntryParser, and possibly others) which return multiple files with the same name
086     * to remove the duplicates ..
087     *
088     * @param original Original list
089     *
090     * @return Original list purged of duplicates
091     */
092    @Override
093    public List<String> preParse(final List<String> original) {
094        final HashMap<String, Integer> existingEntries = new HashMap<>();
095        final ListIterator<String> iter = original.listIterator();
096        while (iter.hasNext()) {
097            final String entry = iter.next().trim();
098            MatchResult result;
099            final Matcher _preparse_matcher_ = preparsePattern.matcher(entry);
100            if (_preparse_matcher_.matches()) {
101                result = _preparse_matcher_.toMatchResult();
102                final String name = result.group(1);
103                final String version = result.group(2);
104                final Integer nv = Integer.valueOf(version);
105                final Integer existing = existingEntries.get(name);
106                if (null != existing && nv.intValue() < existing.intValue()) {
107                    iter.remove(); // removes older version from original list.
108                    continue;
109                }
110                existingEntries.put(name, nv);
111            }
112
113        }
114        // we've now removed all entries less than with less than the largest
115        // version number for each name that were listed after the largest.
116        // we now must remove those with smaller than the largest version number
117        // for each name that were found before the largest
118        while (iter.hasPrevious()) {
119            final String entry = iter.previous().trim();
120            MatchResult result = null;
121            final Matcher _preparse_matcher_ = preparsePattern.matcher(entry);
122            if (_preparse_matcher_.matches()) {
123                result = _preparse_matcher_.toMatchResult();
124                final String name = result.group(1);
125                final String version = result.group(2);
126                final int nv = Integer.parseInt(version);
127                final Integer existing = existingEntries.get(name);
128                if (null != existing && nv < existing.intValue()) {
129                    iter.remove(); // removes older version from original list.
130                }
131            }
132
133        }
134        return original;
135    }
136
137}