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 $Id$
 */
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;
    
    private String name;

    /**
     * Creates the ByLineReaderSource.
     *
     * @param in real source :)
     */
    public ByLineReaderSource( final Reader in )
    {
        this( in, "" );
    }
    
    public ByLineReaderSource( final Reader in, final String name )
    {
        this.reader = new LineNumberReader( in );
        
        this.name = name;

        this.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 name;
    }

    /** {@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;
        }
    }
}