/*
    *   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.ldap.schemaextractor.impl;
  
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.net.URL;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.regex.Pattern;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipException;
  import java.util.zip.ZipFile;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * Lists LDIF resources available from the classpath.
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public final class ResourceMap
  {
      /** the system property which can be used to load schema from a user specified
       *  resource like a absolute path to a directory or jar file.
       *  This is useful to start embedded DirectoryService in a servlet container environment
       *
       *  usage: -Dschema.resource.location=/tmp/schema
       *                OR
       *         -Dschema.resource.location=/tmp/api-ldap-schema-1.0.0-M13.jar
       *  */
      private static final String SCHEMA_RESOURCE_LOCATION = "schema.resource.location";
  
      /** The logger. */
      private static final Logger LOG = LoggerFactory.getLogger( ResourceMap.class );
  
  
      /**
       * Private constructor.
       */
      private ResourceMap()
      {
      }
  
  
      /**
       * For all elements of java.class.path OR from the resource name set in the
       * system property 'schema.resource.location' get a Map of resources
       * Pattern pattern = Pattern.compile(".*").
       * The keys represent resource names and the boolean parameter indicates
       * whether or not the resource is in a Jar file.
       *
       * @param pattern the pattern to match
       * @return the resources with markers - true if resource is in Jar
       */
      public static Map<String, Boolean> getResources( Pattern pattern )
      {
          HashMap<String, Boolean> retval = new HashMap<String, Boolean>();
  
          String schemaResourceLoc = System.getProperty( SCHEMA_RESOURCE_LOCATION, "" );
  
          if ( schemaResourceLoc.trim().length() > 0 )
          {
              LOG.debug( "loading from the user provider schema resource {}", schemaResourceLoc );
  
              File file = new File( schemaResourceLoc );
  
              if ( file.exists() )
              {
                  getResources( retval, schemaResourceLoc, pattern );
              }
              else
              {
                  LOG.error( "unable to load schema from the given resource value {}", schemaResourceLoc );
              }
         }
         else
         {
             getResourcesFromClassloader( retval, pattern );
         }
 
         return retval;
     }
 
 
     private static void getResources( HashMap<String, Boolean> map,
         String element, Pattern pattern )
     {
         File file = new File( element );
 
         if ( !file.exists() )
         {
             // this may happen if the class path contains an element that doesn't exist
             LOG.debug( "element {} does not exist", element );
 
             return;
         }
 
         if ( file.isDirectory() )
         {
             getResourcesFromDirectory( map, file, pattern );
         }
         else
         {
             getResourcesFromJarFile( map, file, pattern );
         }
     }
 
 
     private static void getResourcesFromJarFile( HashMap<String, Boolean> map,
         File file, Pattern pattern )
     {
         ZipFile zf;
 
         try
         {
             zf = new ZipFile( file );
         }
         catch ( ZipException e )
         {
             throw new Error( e );
         }
         catch ( IOException e )
         {
             throw new Error( e );
         }
 
         Enumeration<? extends ZipEntry> e = zf.entries();
 
         while ( e.hasMoreElements() )
         {
             ZipEntry ze = e.nextElement();
             String fileName = ze.getName();
             boolean accept = pattern.matcher( fileName ).matches();
 
             if ( accept )
             {
                 map.put( fileName, Boolean.TRUE );
             }
         }
         try
         {
             zf.close();
         }
         catch ( IOException e1 )
         {
             throw new Error( e1 );
         }
     }
 
 
     private static void getResourcesFromDirectory(
         HashMap<String, Boolean> map, File directory, Pattern pattern )
     {
         File[] fileList = directory.listFiles();
 
         for ( File file : fileList )
         {
             if ( file.isDirectory() )
             {
                 getResourcesFromDirectory( map, file, pattern );
             }
             else
             {
                 try
                 {
                     String fileName = file.getCanonicalPath();
                     boolean accept = pattern.matcher( fileName ).matches();
 
                     if ( accept )
                     {
                         map.put( fileName, Boolean.FALSE );
                     }
                 }
                 catch ( IOException e )
                 {
                     LOG.error( "Cannot load file {} : {}", file.getAbsolutePath(), e.getMessage() );
 
                     // Continue...
                 }
             }
         }
     }
 
 
     private static void getResourcesFromClassloader( HashMap<String, Boolean> map, Pattern pattern )
     {
         try
         {
             ClassLoader cl = ResourceMap.class.getClassLoader();
             Enumeration<URL> indexes = cl.getResources( "META-INF/apacheds-schema.index" );
 
             while ( indexes.hasMoreElements() )
             {
                 URL index = null;
 
                 try
                 {
                     index = indexes.nextElement();
                     InputStream in = index.openStream();
                     BufferedReader reader = new BufferedReader( new InputStreamReader( in, "UTF-8" ) );
                     String line = reader.readLine();
 
                     while ( line != null )
                     {
                         boolean accept = pattern.matcher( line ).matches();
 
                         if ( accept )
                         {
                             map.put( line, Boolean.TRUE );
                         }
 
                         line = reader.readLine();
                     }
 
                     reader.close();
                 }
                 catch ( IOException ioe )
                 {
                     LOG.debug( "Cannot load resource {} : {}", index, ioe.getMessage() );
                     // Continue...
                 }
             }
         }
         catch ( IOException e )
         {
             LOG.debug( "Error while loading  resuce from class loaded : {}", e.getMessage() );
             throw new Error( e );
         }
     }
 }