/*
    * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package de.smartics.properties.resource.maven.repository;
  
  import java.io.File;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.lang.StringUtils;
  import org.sonatype.aether.RepositorySystemSession;
  import org.sonatype.aether.artifact.Artifact;
  import org.sonatype.aether.graph.DependencyFilter;
  import org.sonatype.aether.repository.Authentication;
  import org.sonatype.aether.resolution.DependencyResolutionException;
  import org.sonatype.aether.util.artifact.DefaultArtifact;
  
  import de.smartics.properties.resource.domain.ArtifactId;
  import de.smartics.properties.resource.domain.ClassPathEnvironment;
  import de.smartics.properties.resource.maven.repository.filter.GroupPrefixFilter;
  import de.smartics.properties.resource.repository.RepositoryException;
  import de.smartics.properties.resource.repository.ResourceRepository;
  import de.smartics.util.lang.Arg;
  
  /**
   * Implementation of the {@link ResourceRepository} interface based on Maven.
   */
  public final class SessionedMavenResourceRepository implements
      ResourceRepository
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    // --- members --------------------------------------------------------------
  
    /**
     * The repository adapter to connect to the Maven infrastructure.
     */
    private final MavenRepository repository;
  
    /**
     * The session associated with this instance to access the Maven
     * infrastructure.
     */
    private final RepositorySystemSession session;
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Convenience constructor to consult the environment to create a connection
     * to a Maven repository.
     * <p>
     * The connection properties are defined by
     * {@link de.smartics.properties.resource.maven.repository.ResourceRepositoryProperties}.
     * </p>
     *
     * @throws RepositoryException if the repository cannot be created from
     *           environment information.
     * @see #init(MavenRepository)
     */
    public SessionedMavenResourceRepository() throws RepositoryException
    {
      this(createRepository(null));
    }
  
    /**
     * Default constructor.
     *
     * @param repository the repository adapter to connect to the Maven
     *          infrastructure.
     * @throws NullPointerException if {@code repository} is <code>null</code>.
     */
    public SessionedMavenResourceRepository(final MavenRepository repository)
      throws NullPointerException
    {
      Arg.checkNotNull("repository", repository);
  
      this.repository = repository;
      this.session = repository.createSession();
    }
  
    // ****************************** Inner Classes *****************************
  
    private static MavenRepository createRepository(final Authentication auth)
     throws RepositoryException
   {
     final ResourceRepositoryProperties resourceRepository =
         ResourceRepositoryPropertiesSingleton.instance();
     final List<DependencyFilter> filters = createDependencyFilters();
     final String localRepositoryPath = resourceRepository.localPath();
 
     final MavenRepository repository;
     if (StringUtils.isNotBlank(localRepositoryPath))
     {
       final String remoteRepositoryUrl = resourceRepository.remoteUrl();
       repository =
           new MavenRepository(remoteRepositoryUrl, auth, localRepositoryPath,
               filters, false);
     }
     else
     {
       repository = constructFromSettings(filters);
     }
 
     return repository;
   }
 
   private static List<DependencyFilter> createDependencyFilters()
   {
     final List<DependencyFilter> filters = new ArrayList<DependencyFilter>();
 
     final ResourceRepositoryProperties resourceRepository =
         ResourceRepositoryPropertiesSingleton.instance();
     final String prefix = resourceRepository.filterGroupIdPrefix();
     if (StringUtils.isNotBlank(prefix))
     {
       final DependencyFilter filter = new GroupPrefixFilter(prefix);
       filters.add(filter);
     }
 
     return filters;
   }
 
   private static MavenRepository constructFromSettings(
       final List<DependencyFilter> filters)
   {
     final String defaultSettings = getDefaultSettings();
     final ResourceRepositoryProperties resourceRepository =
         ResourceRepositoryPropertiesSingleton.instance();
     final String userSettings = resourceRepository.settingsFile();
     final String settings =
         StringUtils.isNotBlank(userSettings) ? userSettings : defaultSettings;
 
     return createSettings(settings, filters);
   }
 
   private static MavenRepository createSettings(final String settings,
       final List<DependencyFilter> filters) throws RepositoryException
   {
     final SettingsMavenRepoBuilder builder = new SettingsMavenRepoBuilder();
     final MavenRepository repository = builder.build(settings, filters);
     return repository;
   }
 
   private static String getDefaultSettings()
   {
     final String defaultSettings =
         new File(System.getProperty("user.home"), ".m2/settings.xml")
             .getAbsolutePath();
     return defaultSettings;
   }
 
   // ********************************* Methods ********************************
 
   // --- init -----------------------------------------------------------------
 
   // --- get&set --------------------------------------------------------------
 
   // --- business -------------------------------------------------------------
 
   @Override
   public ClassPathEnvironment resolve(final ArtifactId artifactId)
     throws RepositoryException
   {
     try
     {
       final Artifact artifact = createArtifact(artifactId);
       final ClassPathEnvironment resources =
           repository.resolve(session, artifact);
       return resources;
     }
     catch (final DependencyResolutionException e)
     {
       throw new RepositoryException(new ArtifactIdMessageBean(e, artifactId));
     }
   }
 
   private static Artifact createArtifact(final ArtifactId artifactId)
   {
     final DefaultArtifact artifact =
         new DefaultArtifact(artifactId.getGroupId(), artifactId.getName(),
             artifactId.getClassifier(), artifactId.getArchiveType(),
             artifactId.getVersion());
     return artifact;
   }
 
   @Override
   public String getRemoteRepositoryUrl()
   {
     return repository.getRemoteRepositoryUrl();
   }
 
   // --- object basics --------------------------------------------------------
 
 }