001package org.eclipse.aether.internal.impl.synccontext.named;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.util.Collection;
023import java.util.stream.Collectors;
024
025import org.eclipse.aether.RepositorySystemSession;
026import org.eclipse.aether.artifact.Artifact;
027import org.eclipse.aether.metadata.Metadata;
028import org.eclipse.aether.util.ConfigUtils;
029import org.eclipse.aether.util.StringDigestUtil;
030
031import static java.util.Objects.requireNonNull;
032
033/**
034 * Wrapping {@link NameMapper}, that wraps another {@link NameMapper} and hashes resulting strings. It makes use of
035 * fact that (proper) Hash will create unique fixed length string for each different input string (so injection still
036 * stands). This mapper produces file system friendly names. Supports different "depths" (0-4 inclusive) where the
037 * name will contain 0 to 4 level deep directories.
038 * <p>
039 * This mapper is usable in any scenario, but intent was to produce more "compact" name mapper for file locking.
040 *
041 * @since 1.9.0
042 */
043public class HashingNameMapper implements NameMapper
044{
045    private static final String CONFIG_PROP_DEPTH = "aether.syncContext.named.hashing.depth";
046
047    private final NameMapper delegate;
048
049    public HashingNameMapper( final NameMapper delegate )
050    {
051        this.delegate = requireNonNull( delegate );
052    }
053
054    @Override
055    public boolean isFileSystemFriendly()
056    {
057        return true; // hashes delegated strings, so whatever it wrapped, it does not come through
058    }
059
060    @Override
061    public Collection<String> nameLocks( RepositorySystemSession session,
062                                         Collection<? extends Artifact> artifacts,
063                                         Collection<? extends Metadata> metadatas )
064    {
065        final int depth = ConfigUtils.getInteger( session, 2, CONFIG_PROP_DEPTH );
066        if ( depth < 0 || depth > 4 )
067        {
068            throw new IllegalArgumentException( "allowed depth value is between 0 and 4 (inclusive)" );
069        }
070        return delegate.nameLocks( session, artifacts, metadatas ).stream()
071                .map( n -> hashName( n, depth ) )
072                .collect( Collectors.toList() );
073    }
074
075    private String hashName( final String name, final int depth )
076    {
077        String hashedName = StringDigestUtil.sha1( name );
078        if ( depth == 0 )
079        {
080            return hashedName;
081        }
082        StringBuilder prefix = new StringBuilder( "" );
083        int i = 0;
084        while ( i < hashedName.length() && i / 2 < depth )
085        {
086            prefix.append( hashedName, i, i + 2 ).append( "/" );
087            i += 2;
088        }
089        return prefix.append( hashedName ).toString();
090    }
091}