/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.maven.plugin.eclipse.writers;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Set;
  import java.util.jar.Attributes;
  import java.util.jar.Manifest;
  
  import org.apache.maven.artifact.repository.ArtifactRepository;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.eclipse.EclipseSourceDir;
  import org.apache.maven.plugin.eclipse.Messages;
  import org.apache.maven.plugin.eclipse.writers.wtp.AbstractWtpResourceWriter;
  import org.apache.maven.plugin.ide.IdeDependency;
  import org.apache.maven.project.MavenProject;
  import org.codehaus.plexus.util.IOUtil;
  
  /**
   * Common behaviours for creating or adapting the manifest files for eclipse environments.
   * 
   * @author <a href="mailto:nir@cfc.at">Richard van Nieuwenhoven </a>
   */
  public abstract class AbstractEclipseManifestWriter
      extends AbstractEclipseWriter
  {
  
      protected static final String MANIFEST_MF_FILENAME = "MANIFEST.MF";
  
      protected static final String META_INF_DIRECTORY = "META-INF";
  
      public AbstractEclipseManifestWriter()
      {
          super();
      }
  
      /**
       * Aphabeticaly sort the classpath. Do this by splitting it up, sort the entries and gleue them together again.
       * 
       * @param newValue classpath to sort
       * @return the sorted classpath
       */
      protected String orderClasspath( String newValue )
      {
          if ( newValue == null )
          {
              return null;
          }
          String[] entries = newValue.split( " " );
          Arrays.sort( entries );
          StringBuffer buffer = new StringBuffer( newValue.length() );
          for ( int index = 0; index < entries.length; index++ )
          {
              buffer.append( entries[index] );
              buffer.append( ' ' );
          }
          return buffer.toString();
      }
  
      /**
       * Read and parse the existing manifest file.
       * 
       * @param manifestFile file
       * @return the read manifest
       * @throws IOException if the file could not be read
       */
      protected Manifest readExistingManifest( File manifestFile )
          throws IOException
      {
          if ( !manifestFile.exists() )
          {
              return null;
          }
  
          Manifest existingManifest = new Manifest();
          FileInputStream inputStream = new FileInputStream( manifestFile );
          try
         {
             existingManifest.read( inputStream );
         }
         finally
         {
             IOUtil.close( inputStream );
         }
         return existingManifest;
     }
 
     /**
      * Add one dependency to the blank separated classpath stringbuffer. When the project is available in the reactor
      * (current build) then the project is used else the jar representing the artifact. System dependencies will only be
      * included if they are in this project.
      * 
      * @param classpath existing classpath to append
      * @param dependency dependency to append as jar or as project
      */
     protected void addDependencyToClassPath( StringBuffer classpath, IdeDependency dependency )
     {
         if ( !dependency.isTestDependency() && !dependency.isProvided()
             && !dependency.isSystemScopedOutsideProject( this.config.getProject() ) )
         {
 
             // blank is the separator in manifest classpath's
             if ( classpath.length() != 0 )
             {
                 classpath.append( ' ' );
             }
             // if the dependency is a workspace project add the project and not
             // the jar
             if ( !dependency.isReferencedProject() )
             {
                 classpath.append( dependency.getFile().getName() );
             }
             else
             {
                 classpath.append( dependency.getEclipseProjectName() + ".jar" );
             }
         }
     }
 
     /**
      * Check if the two manifests are equal. Manifest.equal can not be used because of the special case the Classpath
      * entr, witch must be comaired sorted so that a different oder in the classpath does not result in "not equal".
      * This not not realy correct but in this case it is more important to reduce the number of version-controll files.
      * 
      * @param manifest the new manifest
      * @param existingManifest to compaire the new one with
      * @return are the manifests equal
      */
     protected boolean areManifestsEqual( Manifest manifest, Manifest existingManifest )
     {
         if ( existingManifest == null )
         {
             log.info( "@@@ FALSE - Manifest are not equal because existingManifest is null" );
             return false;
         }
 
         Set keys = new HashSet();
         Attributes existingMap = existingManifest.getMainAttributes();
         Attributes newMap = manifest.getMainAttributes();
         keys.addAll( existingMap.keySet() );
         keys.addAll( newMap.keySet() );
         Iterator iterator = keys.iterator();
         while ( iterator.hasNext() )
         {
             Attributes.Name key = (Attributes.Name) iterator.next();
             String newValue = (String) newMap.get( key );
             String existingValue = (String) existingMap.get( key );
             // special case classpath... they are equal when there entries
             // are equal
             if ( Attributes.Name.CLASS_PATH.equals( key ) )
             {
                 newValue = orderClasspath( newValue );
                 existingValue = orderClasspath( existingValue );
             }
             if ( ( newValue == null || !newValue.equals( existingValue ) )
                 && ( existingValue == null || !existingValue.equals( newValue ) ) )
             {
                 log.info( "@@@ FALSE - Manifest are not equal because key = " + key + " has existing value = "
                     + existingValue + " and new value = " + newValue + " are different" );
                 return false;
             }
         }
         log.info( "@@@ TRUE - Manifests are equal" );
         return true;
     }
 
     /**
      * Convert all dependencies in a blank seperated list of jars and projects representing the classpath.
      * 
      * @return the blank separeted classpath string
      */
     protected String constructManifestClasspath()
     {
         StringBuffer stringBuffer = new StringBuffer();
         IdeDependency[] deps = this.config.getDepsOrdered();
 
         for ( int index = 0; index < deps.length; index++ )
         {
             addDependencyToClassPath( stringBuffer, deps[index] );
         }
 
         return stringBuffer.toString();
     }
 
     /**
      * Create a manifest contaigning the required classpath.
      * 
      * @return the newly created manifest
      */
     protected Manifest createNewManifest()
     {
         Manifest manifest = new Manifest();
         manifest.getMainAttributes().put( Attributes.Name.MANIFEST_VERSION, "1.0" );
         manifest.getMainAttributes().put( Attributes.Name.CLASS_PATH, constructManifestClasspath() );
         return manifest;
     }
 
     /**
      * Verify is the manifest sould be overwritten this sould take in account that the manifest should only be written
      * if the contents of the classpath was changed not the order. The classpath sorting oder should be ignored.
      * 
      * @param manifest the newly created classpath
      * @param manifestFile the file where the manifest
      * @return if the new manifest file must be written
      * @throws MojoExecutionException
      */
     protected boolean shouldNewManifestFileBeWritten( Manifest manifest, File manifestFile )
         throws MojoExecutionException
     {
         try
         {
             Manifest existingManifest = readExistingManifest( manifestFile );
             if ( areManifestsEqual( manifest, existingManifest ) )
             {
                 this.log.info( Messages.getString( "EclipsePlugin.unchangedmanifest", manifestFile.getAbsolutePath() ) );
                 return false;
             }
         }
         catch ( Exception e )
         {
             throw new MojoExecutionException( Messages.getString( "EclipseCleanMojo.nofilefound",
                                                                   manifestFile.getAbsolutePath() ), e );
         }
         return true;
     }
 
     /**
      * Search the project for the existing META-INF directory where the manifest should be located.
      * 
      * @return the absolute path to the META-INF directory
      * @throws MojoExecutionException
      */
     protected abstract String getMetaInfBaseDirectory( MavenProject project )
         throws MojoExecutionException;
 
     /**
      * If the existing manifest file located in <code>getMetaInfBaseDirectory()</code> already has a correct
      * MANIFEST_VERSION and CLASS_PATH value then do nothing.
      * <p>
      * Otherwise generate a <b>NEW</b> (i.e the old one is overwritten) which only contains values for MANIFEST_VERSION
      * and CLASS_PATH, all other previous entries are not kept.
      * 
      * @see AbstractWtpResourceWriter#write(EclipseSourceDir[], ArtifactRepository, File)
      * @param sourceDirs all eclipse source directorys
      * @param localRepository the local reposetory
      * @param buildOutputDirectory build output directory (target)
      * @throws MojoExecutionException when writing the config files was not possible
      */
     public void write()
         throws MojoExecutionException
     {
         String metaInfBaseDirectory = getMetaInfBaseDirectory( this.config.getProject() );
 
         if ( metaInfBaseDirectory == null )
         {
             // TODO: if this really is an error, shouldn't we stop the build??
             throw new MojoExecutionException(
                                               Messages.getString(
                                                                   "EclipseCleanMojo.nofilefound",
                                                                   new Object[] { EclipseManifestWriter.META_INF_DIRECTORY } ) );
         }
         File manifestFile =
             new File( metaInfBaseDirectory + File.separatorChar + EclipseManifestWriter.META_INF_DIRECTORY
                 + File.separatorChar + EclipseManifestWriter.MANIFEST_MF_FILENAME );
         Manifest manifest = createNewManifest();
 
         if ( shouldNewManifestFileBeWritten( manifest, manifestFile ) )
         {
             log.info( "Writing manifest..." );
 
             manifestFile.getParentFile().mkdirs();
 
             try
             {
                 FileOutputStream stream = new FileOutputStream( manifestFile );
 
                 manifest.write( stream );
 
                 stream.close();
 
             }
             catch ( Exception e )
             {
                 this.log.error( Messages.getString( "EclipsePlugin.cantwritetofile",
                                                     new Object[] { manifestFile.getAbsolutePath() } ) );
             }
         }
     }
 
 }