001    /*
002     * Copyright 2004-2005 Stephen J. McConnell.
003     * Copyright 2004 Niclas Hedhman.
004     *
005     * Licensed  under the  Apache License,  Version 2.0  (the "License");
006     * you may not use  this file  except in  compliance with the License.
007     * 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
014     * implied.
015     *
016     * See the License for the specific language governing permissions and
017     * limitations under the License.
018     */
019    
020    package net.dpml.transit.layout;
021    
022    import net.dpml.transit.Artifact;
023    import net.dpml.transit.Layout;
024    import net.dpml.transit.TransitRuntimeException;
025    
026    /** 
027     * The ClassicLayout decodes artifacts into the Classic/Maven layout
028     * of artifacts on a file system or http server.
029     * This format says that for an artifact <code>artifact:[type]:[group]/[name]#[version]</code>
030     * the location of such artifact would be;
031     * <code>[group]/[type]s/[name]-[version].[type]</code>.
032     * Example; <code>artifact:jar:metro/cache/dpml-cache-main#1.0.0</code>
033     * would return the path <code>metro/cache/jars/dpml-cache-main-1.0.0.jar</code>.
034     *
035     * @author <a href="http://www.dpml.net">Digital Product Management Laboratory</a>
036     * @version 2.0.0
037     */
038    public class ClassicLayout extends Layout
039    {
040        private static final String CLASSIC_IDENTIFIER = "classic";
041        
042        /**
043         * Return the layout identifier.  The id value is used
044         * to identify layout instances assigned to cache handlers and 
045         * resource host handlers.
046         *
047         * @return the layout id
048         */
049        public String getID()
050        {
051            return CLASSIC_IDENTIFIER;
052        }
053        
054        /**
055         * Return the base path for an artifact.  The base path is derived from
056         * the artifact group and type.  For an artifact group of "metro/cache" and a
057         * type equal to "jar", the base value will be translated using the pattern
058         * "[group]/[type]s" to form "metro/cache/jars".  The base path value represents
059         * the directory path relative to a repository root of the directory containing
060         * this artifact.
061         *
062         * @param artifact the resource artifact
063         * @return the base path
064         */
065        public final String resolveBase( Artifact artifact )
066        {
067            if( null == artifact.getGroup() )
068            {
069                return artifact.getType() + "s";
070            }
071            else
072            {
073                return artifact.getGroup() + "/" + artifact.getType() + "s";
074            }
075        }
076    
077        /**
078         * Returns the full path of the artifact relative to a logical root directory.
079         * The full path is equivalent to the base path and artifact filename using the
080         * pattern "[base]/[filename]".  Path values may be used to resolve an artifact
081         * from a remote repository or local cache relative to the repository or cache
082         * root. An artifact such as <code>artifact:jar:metro/cache/dpml-cache-main#1.0.0</code>
083         * would return the path <code>metro/cache/jars/dpml-cache-main-1.0.0.jar</code>.
084         *
085         * @param artifact the resource artifact
086         * @see #resolveBase
087         * @see #resolveFilename
088         * @return the logical artifact path
089         */
090        public final String resolvePath( Artifact artifact )
091        {
092            return resolveBase( artifact ) + "/" + resolveFilename( artifact );
093        }
094    
095        /**
096         * Return the expanded filename of the artifact. The filename is expressed
097         * as [name]-[version].[type] or in case of a null version simply [name].[type].
098         *
099         * @param artifact the resource artifact
100         * @return the artifact expanded filename
101         */
102        public String resolveFilename( Artifact artifact )
103        {
104            String scheme = artifact.getScheme();
105            String filename = resolveBaseFilename( artifact );
106            if( "artifact".equals( scheme ) )
107            {
108                return filename;
109            }
110            else if( "link".equals( scheme ) )
111            {
112                return filename + ".link";
113            }
114            else
115            {
116                final String error = 
117                  "Protocol not recognized: " + scheme;
118                throw new TransitRuntimeException( error );
119            }
120        }
121    
122        private String resolveBaseFilename( Artifact artifact )
123        {
124            String ver = artifact.getVersion();
125            if( null == ver )
126            {
127                return artifact.getName() + "." + artifact.getType();
128            }
129            else
130            {
131                return artifact.getName() + "-" + ver + "." + artifact.getType();
132            }
133        }
134    }