/*
    *   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.directory.api.util;
  
  
  import java.io.File;
  import java.io.FileFilter;
  import java.io.IOException;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  import java.util.jar.JarFile;
  import java.util.jar.Manifest;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Utilities for OSGi environments and embedding OSGi containers.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public final class OsgiUtils
  {
      /** A logger */
      private static final Logger LOG = LoggerFactory.getLogger( OsgiUtils.class );
  
  
      /**
       * All the packages that are exported from all bundles found on the system
       * classpath. The provided filter if not null is used to prune classpath
       * elements. Any uses terms found are stripped from the bundles.
       *
       * @param filter The filter to use on the files
       * @param pkgs The set of packages to use
       * @return All the exported packages of all bundles on the classpath.
       */
      public static Set<String> getAllBundleExports( FileFilter filter, Set<String> pkgs )
      {
          if ( pkgs == null )
          {
              pkgs = new HashSet<String>();
          }
  
          Set<File> candidates = getClasspathCandidates( filter );
  
          for ( File candidate : candidates )
          {
              String exports = getBundleExports( candidate );
  
              if ( exports == null )
              {
                  LOG.debug( "No export found for candidate: {}", candidate );
                  continue;
              }
  
              LOG.debug( "Processing exports for candidate: {}\n\n{}\n", candidate, exports );
              splitIntoPackages( exports, pkgs );
          }
  
          return pkgs;
      }
  
  
      /**
       * Splits a Package-Export OSGi Manifest Attribute value into packages
       * while stripping away the key/value properties.
       *
       * @param exports The Package-Export OSGi Manifest Attribute value.
       * @param pkgs The set that will contain the found packages.
       * @return The set of exported packages without properties.
       */
      public static Set<String> splitIntoPackages( String exports, Set<String> pkgs )
      {
          if ( pkgs == null )
          {
              pkgs = new HashSet<String>();
          }
  
          int index = 0;
          boolean inPkg = true;
         boolean inProps = false;
         StringBuilder pkg = new StringBuilder();
 
         while ( index < exports.length() )
         {
             if ( inPkg && exports.charAt( index ) != ';' )
             {
                 pkg.append( exports.charAt( index ) );
                 index++;
             }
             else if ( inPkg && exports.charAt( index ) == ';' )
             {
                 inPkg = false;
                 inProps = true;
 
                 pkgs.add( pkg.toString() );
                 LOG.debug( "Added package: {}", pkg.toString() );
                 pkg.setLength( 0 );
 
                 index += 8;
             }
             else if ( inProps && exports.charAt( index ) == '"'
                 && index + 1 < exports.length()
                 && exports.charAt( index + 1 ) == ',' )
             {
                 inPkg = true;
                 inProps = false;
                 index += 2;
             }
             else if ( inProps )
             {
                 index++;
             }
             else
             {
                 LOG.error( "Unexpected parser condition throwing IllegalStateException." );
                 throw new IllegalStateException( "Should never get here!" );
             }
         }
 
         return pkgs;
     }
 
 
     /**
      * Get the files that fits a given filter
      *
      * @param filter The filter in use
      * @return The set of Files that match the filter
      */
     public static Set<File> getClasspathCandidates( FileFilter filter )
     {
         Set<File> candidates = new HashSet<File>();
         String separator = System.getProperty( "path.separator" );
         String[] cpElements = System.getProperty( "java.class.path" ).split( separator );
 
         for ( String element : cpElements )
         {
             File candidate = new File( element );
 
             if ( candidate.isFile() )
             {
                 if ( filter != null && filter.accept( candidate ) )
                 {
                     candidates.add( candidate );
                     LOG.info( "Accepted candidate with filter: {}", candidate.toString() );
                 }
                 else if ( filter == null && candidate.getName().endsWith( ".jar" ) )
                 {
                     candidates.add( candidate );
                     LOG.info( "Accepted candidate without filter: {}", candidate.toString() );
                 }
                 else
                 {
                     LOG.info( "Rejecting candidate: {}", candidate.toString() );
                 }
             }
         }
 
         return candidates;
     }
 
 
     /**
      * Gets the attribute value for the Export-Bundle OSGi Manifest Attribute.
      * 
      * @param bundle The absolute path to a file bundle.
      * @return The value as it appears in the Manifest, as a comma delimited
      * list of packages with possible "uses" phrases appended to each package
      * or null if the attribute does not exist.
      */
     public static String getBundleExports( File bundle )
     {
         try ( JarFile jar = new JarFile( bundle ) )
         {
             Manifest manifest = jar.getManifest();
 
             if ( manifest == null )
             {
                 return null;
             }
 
             for ( Map.Entry<Object, Object> attr : manifest.getMainAttributes().entrySet() )
             {
                 if ( attr.getKey().toString().equals( "Export-Package" ) )
                 {
                     return attr.getValue().toString();
                 }
             }
 
             return null;
         }
         catch ( IOException e )
         {
             LOG.error( "Failed to open jar file or manifest.", e );
             throw new RuntimeException( "Failed to open jar file or manifest.", e );
         }
     }
 
 
     private OsgiUtils()
     {
     }
 }