package org.apache.maven.doxia.util;

 /*

  * 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.

  */

 /*

  * Originally from org.apache.doxia.module.apt.AptReaderSource. It was modified

  * to get unget support

  */

 import java.io.IOException;

 import java.io.LineNumberReader;

 import java.io.Reader;

 import org.apache.maven.doxia.parser.ParseException;

 import org.codehaus.plexus.util.IOUtil;

 /**

  * {@link ByLineSource} default implementation

  *

  * @version $Id: ByLineReaderSource.java 775115 2009-05-15 12:54:18Z ltheussl $

  */

 public class ByLineReaderSource implements ByLineSource

 {

     /**

      * reader

      */

     private LineNumberReader reader;

     /**

      * current line number

      */

     private int lineNumber;

     /**

      * holds the last line returned by getNextLine()

      */

     private String lastLine;

     /**

      * <code>true</code> if ungetLine() was called and no getNextLine() was

      * called

      */

     private boolean ungetted = false;

     /**

      * Creates the ByLineReaderSource.

      *

      * @param in real source :)

      */

     public ByLineReaderSource( final Reader in )

     {

         reader = new LineNumberReader( in );

         lineNumber = -1;

     }

     /** {@inheritDoc} */

     public final String getNextLine() throws ParseException

     {

         if ( reader == null )

         {

             return null;

         }

         if ( ungetted )

         {

             ungetted = false;

             return lastLine;

         }

         String line;

         try

         {

             line = reader.readLine();

             if ( line == null )

             {

                 reader.close();

                 reader = null;

             }

             else

             {

                 lineNumber = reader.getLineNumber();

             }

         }

         catch ( IOException e )

         {

             throw new ParseException( e, lineNumber, 0 );

         }

         lastLine = line;

         return line;

     }

     /** {@inheritDoc} */

     public final String getName()

     {

         return "";

     }

     /** {@inheritDoc} */

     public final int getLineNumber()

     {

         return lineNumber;

     }

     /** {@inheritDoc} */

     public final void close()

     {

         IOUtil.close( reader );

         reader = null;

     }

     /** {@inheritDoc} */

     public final void ungetLine()

     {

         if ( ungetted )

         {

             throw new IllegalStateException( "we support only one level of ungetLine()" );

         }

         ungetted = true;

     }

     /** {@inheritDoc} */

     public final void unget( final String s )

     {

         if ( s == null )

         {

             throw new IllegalArgumentException( "argument can't be null" );

         }

         if ( s.length() != 0 )

         {

             ungetLine();

             lastLine = s;

         }

     }

 }