/*
    * Copyright 2006-2012 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.maven.plugin.buildmetadata.scm.maven;
  
  import java.util.Iterator;
  import java.util.List;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.maven.scm.ChangeFile;
  import org.apache.maven.scm.ChangeSet;
  import org.apache.maven.scm.ScmFile;
  import org.apache.maven.scm.ScmFileSet;
  import org.apache.maven.scm.ScmVersion;
  import org.apache.maven.scm.command.changelog.ChangeLogScmResult;
  import org.apache.maven.scm.command.changelog.ChangeLogSet;
  import org.apache.maven.scm.command.status.StatusScmResult;
  import org.apache.maven.scm.manager.NoSuchScmProviderException;
  import org.apache.maven.scm.manager.ScmManager;
  import org.apache.maven.scm.provider.ScmProvider;
  import org.apache.maven.scm.repository.ScmRepository;
  
  import de.smartics.maven.plugin.buildmetadata.scm.LocallyModifiedInfo;
  import de.smartics.maven.plugin.buildmetadata.scm.Revision;
  import de.smartics.maven.plugin.buildmetadata.scm.RevisionNumberFetcher;
  import de.smartics.maven.plugin.buildmetadata.scm.ScmException;
  
  /**
   * Implementation on the Maven SCM implementation to fetch the latest revision
   * number.
   *
   * @author <a href="mailto:robert.reiner@smartics.de">Robert Reiner</a>
   * @version $Revision:591 $
   */
  public final class MavenScmRevisionNumberFetcher implements RevisionNumberFetcher
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    /**
     * Reference to the logger for this class.
     */
    private static final Log LOG = LogFactory
        .getLog(MavenScmRevisionNumberFetcher.class);
  
    // --- members --------------------------------------------------------------
  
    /**
     * The SCM manager to access to SCM system.
     */
    private final ScmManager scmManager;
  
    /**
     * The information to connect to the SCM system.
     */
    private final ScmConnectionInfo scmConnectionInfo;
  
    /**
     * Information to retrieve the revision information from the SCM after the
     * connection is established.
     */
    private final ScmAccessInfo scmAccessInfo;
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    /**
     * Default constructor.
     *
     * @param scmManager the SCM manager to access to SCM system.
     * @param scmConnectionInfo the information to connect to the SCM system.
     * @param scmAccessInfo the value for scmAccessInfo.
     */
    public MavenScmRevisionNumberFetcher(final ScmManager scmManager,
        final ScmConnectionInfo scmConnectionInfo,
        final ScmAccessInfo scmAccessInfo)
    {
      this.scmManager = scmManager;
      this.scmConnectionInfo = scmConnectionInfo;
      this.scmAccessInfo = scmAccessInfo;
    }
  
    // ****************************** Inner Classes *****************************
 
   // ********************************* Methods ********************************
 
   // --- init -----------------------------------------------------------------
 
   // --- get&set --------------------------------------------------------------
 
   // --- business -------------------------------------------------------------
 
   /**
    * {@inheritDoc}
    *
    * @see de.smartics.maven.plugin.buildmetadata.scm.RevisionNumberFetcher#fetchLatestRevisionNumber()
    */
   public Revision fetchLatestRevisionNumber() throws ScmException
   {
     if (LOG.isDebugEnabled())
     {
       LOG.debug("  Fetching latest revision number.\n    "
                 + this.scmConnectionInfo + "\n    " + this.scmAccessInfo);
     }
 
     final ScmRepository repository =
         scmConnectionInfo.createRepository(scmManager);
     final ScmProvider provider = createScmProvider(repository);
     final ChangeLogScmResult result =
         scmAccessInfo.fetchChangeLog(repository, provider);
 
     if (result != null)
     {
       final ChangeLogSet changeLogSet = result.getChangeLog();
       final Revision revision = findEndVersion(changeLogSet);
       if (LOG.isDebugEnabled())
       {
         LOG.debug("  Found revision '" + revision + "'.");
       }
       return revision;
     }
     else if (LOG.isDebugEnabled())
     {
       LOG.debug("  No revision information found.");
     }
     return null;
   }
 
   /**
    * {@inheritDoc}
    *
    * @see de.smartics.maven.plugin.buildmetadata.scm.RevisionNumberFetcher#containsModifications(org.apache.maven.scm.ScmFileSet)
    */
   public LocallyModifiedInfo containsModifications(final ScmFileSet fileSet)
     throws ScmException
   {
     if (LOG.isDebugEnabled())
     {
       LOG.debug("  Fetching modification information.\n    "
                 + this.scmConnectionInfo + "\n    " + this.scmAccessInfo);
     }
 
     try
     {
       final ScmRepository repository =
           scmConnectionInfo.createRepository(scmManager);
       final ScmProvider provider = createScmProvider(repository);
       final StatusScmResult result = provider.status(repository, fileSet);
 
       if (result.isSuccess())
       {
         return createLocallyModifiedInfo(result);
       }
       else
       {
         final String message =
             result.getProviderMessage() + ": " + result.getCommandOutput();
         if (LOG.isDebugEnabled())
         {
           LOG.debug(message);
         }
 
         throw new ScmException(message);
       }
     }
     catch (final org.apache.maven.scm.ScmException e)
     {
       throw new ScmException(e);
     }
   }
 
   @SuppressWarnings("unchecked")
   private LocallyModifiedInfo createLocallyModifiedInfo(
       final StatusScmResult result)
   {
     final List<ScmFile> changedFiles = filter(result.getChangedFiles());
     final boolean locallyModified = !changedFiles.isEmpty();
     if (LOG.isDebugEnabled())
     {
       LOG.debug("  Modifications have" + (locallyModified ? "" : " not")
                 + " been found.");
     }
     return new LocallyModifiedInfo(locallyModified, locallyModified
         ? toString(changedFiles) : null);
   }
 
   private List<ScmFile> filter(final List<ScmFile> files)
   {
     if (this.scmAccessInfo.isIgnoreDotFilesInBaseDir())
     {
       filterDotFiles(files);
     }
     return files;
   }
 
   private void filterDotFiles(final List<ScmFile> files)
   {
     for (final Iterator<ScmFile> i = files.iterator(); i.hasNext();)
     {
       final ScmFile file = i.next();
       final String path = file.getPath();
       if (path.length() > 0 && path.charAt(0) == '.')
       {
         i.remove();
       }
     }
   }
 
   /**
    * Renders the files to a blank separated list of file names.
    *
    * @param items the file items.
    * @return the string representation of the files.
    */
   private String toString(final List<?> items)
   {
     final StringBuilder buffer = new StringBuilder(512);
     for (Object item : items)
     {
       buffer.append(item).append(' ');
     }
     return StringUtils.chomp(buffer.toString());
   }
 
   /**
    * Finds the largest revision number.
    *
    * @impl Currently we assume the the largest revision is provided by the last
    *       entry of the set.
    * @param changeLogSet the set of change log entries to compare the revision
    *          numbers to find the largest.
    * @return the largest revision number from the set or <code>null</code> if no
    *         end version can be found.
    */
   @SuppressWarnings("unchecked")
   private Revision findEndVersion(final ChangeLogSet changeLogSet)
   {
     if (changeLogSet != null)
     {
       final ScmVersion endVersion = changeLogSet.getEndVersion();
       if (endVersion != null)
       {
         if(LOG.isDebugEnabled())
         {
           LOG.debug("End version found.");
         }
         return new MavenRevision(endVersion, changeLogSet.getEndDate());
       }
 
       final List<ChangeSet> changeSets = changeLogSet.getChangeSets();
       if (!changeSets.isEmpty())
       {
         final int lastIndex = changeSets.size() - 1;
         for (int index = lastIndex; index >= 0; index--)
         {
           final ChangeSet set = changeSets.get(lastIndex);
           final List<ChangeFile> changeFiles = set.getFiles();
           if (!changeFiles.isEmpty())
           {
             final ChangeFile file = changeFiles.get(0);
             final String revision = file.getRevision();
             if (revision != null)
             {
               return new StringRevision(revision, set.getDate());
             }
           }
           else
           {
             if(LOG.isDebugEnabled())
             {
               LOG.debug("No change files found.");
             }
           }
         }
       }
       else
       {
         if(LOG.isDebugEnabled())
         {
           LOG.debug("No change set found.");
         }
       }
     }
     else
     {
       if(LOG.isDebugEnabled())
       {
         LOG.debug("No change log set found.");
       }
     }
 
     return null;
   }
 
   /**
    * Creates the provider instance to access the given repository.
    *
    * @param repository the repository to access with the provider to be created.
    * @return the provider to access the given repository.
    * @throws ScmException if the provider cannot be created.
    */
   private ScmProvider createScmProvider(final ScmRepository repository)
     throws ScmException
   {
     try
     {
       final ScmProvider provider =
           scmManager.getProviderByRepository(repository);
       return provider;
     }
     catch (final NoSuchScmProviderException e)
     {
       throw new ScmException("Cannot create SCM provider.", e);
     }
   }
 
   // --- object basics --------------------------------------------------------
 
 }