/*
    *  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.model.schema.parsers;
  
  
  import java.io.StringReader;
  import java.text.ParseException;
  import java.util.List;
  
  import org.apache.directory.api.i18n.I18n;
  import org.apache.directory.api.ldap.model.constants.MetaSchemaConstants;
  import org.apache.directory.api.ldap.model.schema.SchemaObject;
  import org.apache.directory.api.util.Strings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import antlr.RecognitionException;
  import antlr.TokenStreamException;
  import antlr.TokenStreamRecognitionException;
  
  
  /**
   * Base class of all schema parsers.
   * 
   * @param <T> The type of SchemaObject
   *
   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
   */
  public abstract class AbstractSchemaParser<T extends SchemaObject>
  {
      /** The LoggerFactory used by this class */
      protected static final Logger LOG = LoggerFactory.getLogger( AbstractSchemaParser.class );
  
      /** the monitor to use for this parser */
      protected ParserMonitor monitor = new ParserMonitorAdapter();
  
      /** the antlr generated parser being wrapped */
      protected ReusableAntlrSchemaParser parser;
  
      /** the antlr generated lexer being wrapped */
      protected ReusableAntlrSchemaLexer lexer;
  
      /** the schema object sub-type */
      private Class<T> schemaObjectType;
  
      /** error code used when schema descritpion is null */
      private I18n errorCodeOnNull;
  
      /** error code used on parse error when position is known */
      private I18n errorCodeOnParseExceptionWithPosition;
  
      /** error code used on parse error when position is unknown */
      private I18n errorCodeOnParseException;
  
  
      /**
       * Instantiates a new abstract schema parser.
       * 
       * @param schemaObjectType The Schema object type
       * @param errorCodeOnNull error code used when schema element is null
       * @param errorCodeOnParseExceptionWithPosition error code used on parse error when position is known
       * @param errorCodeOnParseException error code used on parse error when position is unknown
       */
      protected AbstractSchemaParser( Class<T> schemaObjectType, I18n errorCodeOnNull,
          I18n errorCodeOnParseExceptionWithPosition,
          I18n errorCodeOnParseException )
      {
          this.schemaObjectType = schemaObjectType;
          this.errorCodeOnNull = errorCodeOnNull;
          this.errorCodeOnParseExceptionWithPosition = errorCodeOnParseExceptionWithPosition;
          this.errorCodeOnParseException = errorCodeOnParseException;
          lexer = new ReusableAntlrSchemaLexer( new StringReader( "" ) );
          parser = new ReusableAntlrSchemaParser( lexer );
      }
  
  
      /**
       * Initializes the plumbing by creating a pipe and coupling the parser/lexer
       * pair with it. param spec the specification to be parsed
       *
       * @param spec the spec
       */
     protected void reset( String spec )
     {
         StringReader in = new StringReader( spec );
         lexer.prepareNextInput( in );
         parser.resetState();
     }
 
 
     /**
      * Sets the parser monitor.
      * 
      * @param parserMonitor the new parser monitor
      */
     public void setParserMonitor( ParserMonitor parserMonitor )
     {
         this.monitor = parserMonitor;
         parser.setParserMonitor( parserMonitor );
     }
 
 
     /**
      * Sets the quirks mode. 
      * 
      * If enabled the parser accepts non-numeric OIDs and some 
      * special characters in descriptions.
      * 
      * @param enabled the new quirks mode
      */
     public void setQuirksMode( boolean enabled )
     {
         parser.setQuirksMode( enabled );
     }
 
 
     /**
      * Checks if quirks mode is enabled.
      * 
      * @return true, if is quirks mode is enabled
      */
     public boolean isQuirksMode()
     {
         return parser.isQuirksMode();
     }
 
 
     /**
      * Parse a SchemaObject description and returns back an instance of SchemaObject.
      * 
      * @param schemaDescription The SchemaObject description
      * @return A SchemaObject instance
      * @throws ParseException If the parsing failed
      */
     public synchronized T parse( String schemaDescription ) throws ParseException
     {
         LOG.debug( "Parsing a {} : {}", schemaObjectType.getClass().getSimpleName(), schemaDescription );
 
         if ( schemaDescription == null )
         {
             LOG.error( I18n.err( errorCodeOnNull ) );
             throw new ParseException( "Null", 0 );
         }
 
         // reset and initialize the parser / lexer pair
         reset( schemaDescription );
 
         try
         {
             T schemaObject = doParse();
             schemaObject.setSpecification( schemaDescription );
 
             // Update the schemaName
             updateSchemaName( schemaObject );
 
             return schemaObject;
         }
         catch ( RecognitionException re )
         {
             throw wrapRecognitionException( schemaDescription, re );
         }
         catch ( TokenStreamRecognitionException tsre )
         {
             if ( tsre.recog != null )
             {
                 throw wrapRecognitionException( schemaDescription, tsre.recog );
             }
             else
             {
                 throw wrapTokenStreamException( schemaDescription, tsre );
             }
         }
         catch ( TokenStreamException tse )
         {
             throw wrapTokenStreamException( schemaDescription, tse );
         }
     }
 
 
     private ParseException wrapRecognitionException( String schemaDescription, RecognitionException re )
     {
         String msg = I18n.err( errorCodeOnParseExceptionWithPosition, schemaDescription, re.getMessage(),
             re.getColumn() );
         LOG.error( msg );
         ParseException parseException = new ParseException( msg, re.getColumn() );
         parseException.initCause( re );
         return parseException;
     }
 
 
     private ParseException wrapTokenStreamException( String schemaDescription, TokenStreamException tse )
     {
         String msg = I18n.err( errorCodeOnParseException, schemaDescription, tse.getMessage() );
         LOG.error( msg );
         ParseException parseException = new ParseException( msg, 0 );
         parseException.initCause( tse );
         return parseException;
     }
 
 
     /**
      * Parse a SchemaObject description and returns back an instance of SchemaObject.
      * 
      * @return A SchemaObject instance
      * @throws RecognitionException the native antlr exception
      * @throws TokenStreamException the native antlr exception
      */
     protected abstract T doParse() throws RecognitionException, TokenStreamException;
 
 
     /**
      * Update the schemaName for the given SchemaObject, accordingly to the X-SCHEMA parameter. If
      * not present, default to 'other'
      *
      * @param schemaObject the schema object where the name should be updated
      */
     private void updateSchemaName( SchemaObject schemaObject )
     {
         // Update the Schema if we have the X-SCHEMA extension
         List<String> schemaExtension = schemaObject.getExtension( MetaSchemaConstants.X_SCHEMA_AT );
 
         if ( schemaExtension != null )
         {
             String schemaName = schemaExtension.get( 0 );
 
             if ( Strings.isEmpty( schemaName ) )
             {
                 schemaObject.setSchemaName( MetaSchemaConstants.SCHEMA_OTHER );
             }
             else
             {
                 schemaObject.setSchemaName( schemaName );
             }
         }
         else
         {
             schemaObject.setSchemaName( MetaSchemaConstants.SCHEMA_OTHER );
         }
     }
 }