/*
    *  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
    *  
   *    https://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.schema.converter;
  
  
  import java.io.InputStream;
  import java.io.Writer;
  import java.util.List;
  
  import org.apache.directory.api.i18n.I18n;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * A class used to translate a OpenLdap schema file to a Ldif file compatible
   * with the ApacheDS meta schema format
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public final class SchemaToLdif
  {
      /** The ASF Header */
      private static final String HEADER = "#\n" + "#  Licensed to the Apache Software Foundation (ASF) under one\n"
          + "#  or more contributor license agreements.  See the NOTICE file\n"
          + "#  distributed with this work for additional information\n"
          + "#  regarding copyright ownership.  The ASF licenses this file\n"
          + "#  to you under the Apache License, Version 2.0 (the\n"
          + "#  \"License\"); you may not use this file except in compliance\n"
          + "#  with the License.  You may obtain a copy of the License at\n" + "#  \n"
          + "#    https://www.apache.org/licenses/LICENSE-2.0\n" + "#  \n"
          + "#  Unless required by applicable law or agreed to in writing,\n"
          + "#  software distributed under the License is distributed on an\n"
          + "#  \"AS IS\" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY\n"
          + "#  KIND, either express or implied.  See the License for the\n"
          + "#  specific language governing permissions and limitations\n" + "#  under the License. \n" + "#\n"
          + "version: 1\n" + "\n";
  
      /** The logger */
      private static final Logger LOG = LoggerFactory.getLogger( SchemaToLdif.class );
  
  
      /**
       * Private constructor.
       */
      private SchemaToLdif()
      {
      }
  
  
      /**
       * This method takes a list of schema and transform them to Ldif files 
       * 
       * @param schemas The list of schema to be transformed
       * @throws ParserException If we get an error while converting the schemas
       */
      public static void transform( List<Schema> schemas ) throws ParserException
      {
          // Bypass if no schemas have yet been defined 
          if ( ( schemas == null ) || schemas.isEmpty() )
          {
              if ( LOG.isWarnEnabled() )
              {
                  LOG.warn( I18n.msg( I18n.MSG_15000_NO_SCHEMA_DEFINED ) );
              }
              
              return;
          }
  
          // Make sure schema configurations have a name field and set defaults
          // for any other missing properties of the bean: pkg and owner.
          int i = 1;
  
          for ( Schema schema : schemas )
          {
              if ( schema.getName() == null )
              {
                  String msg = I18n.err( I18n.ERR_15000_SCHEMA_ELEMENT_NAME_REQUIRED, i );
                  LOG.error( msg );
                  throw new ParserException( msg );
              }
  
         }
 
         // Generate for each schema 
         for ( Schema schema : schemas )
         {
             try
             {
                 if ( LOG.isInfoEnabled() )
                 {
                     LOG.info( I18n.msg( I18n.MSG_15001_GENERATING_SCHEMA, schema.getName() ) );
                 }
                 
                 generate( schema );
             }
             catch ( Exception e )
             {
                 throw new ParserException( I18n.err( I18n.ERR_15004_CANNOT_GENERATE_SOURCES, schema.getName(),
                     e.getMessage() ) );
             }
         }
     }
 
 
     /**
      * Generate the ldif from a schema. The schema contains the inputStream
      * and Writer.
      * 
      * @param schema The schema to transfom
      * @throws Exception If the conversion fails
      */
     private static void generate( Schema schema ) throws Exception
     {
         try ( InputStream in = schema.getInput() )
         {
             try ( Writer out = schema.getOutput() )
             {
                 // First parse the schema
                 SchemaParser parser = new SchemaParser();
                 List<SchemaElement> elements = parser.parse( in );
         
                 // Start with the header (apache licence)
                 out.write( HEADER );
         
                 // Iterate through each schema elemnts
                 for ( SchemaElement element : elements )
                 {
                     out.write( element.toLdif( schema.getName() ) );
         
                     out.write( '\n' );
                 }
         
                 // Done. Flush the result and close the reader and writer
                 out.flush();
             }
         }
     }
 }