package org.codehaus.plexus.util.cli;

/*
 * Copyright The Codehaus Foundation.
 *
 * Licensed 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.
 */

import java.util.StringTokenizer;

/**
 * The java.util.StringTokenizer is horribly broken. Given the string 1,,,3,,4 (, delim) It will return 1,3,4 Which is
 * clearly wrong - 1,EMPTY,EMPTY,3,EMPTY,4 is what it should return
 * 
 * @version $Id$
 */
public final class EnhancedStringTokenizer
{
    private StringTokenizer cst = null;

    String cdelim;

    final boolean cdelimSingleChar;

    final char cdelimChar;

    boolean creturnDelims;

    String lastToken = null;

    boolean delimLast = true;

    public EnhancedStringTokenizer( String str )
    {
        this( str, " \t\n\r\f", false );
    }

    public EnhancedStringTokenizer( String str, String delim )
    {
        this( str, delim, false );
    }

    public EnhancedStringTokenizer( String str, String delim, boolean returnDelims )
    {
        cst = new StringTokenizer( str, delim, true );
        cdelim = delim;
        creturnDelims = returnDelims;
        cdelimSingleChar = ( delim.length() == 1 );
        cdelimChar = delim.charAt( 0 );
    }

    public boolean hasMoreTokens()
    {
        return cst.hasMoreTokens();
    }

    private String internalNextToken()
    {
        if ( lastToken != null )
        {
            String last = lastToken;
            lastToken = null;
            return last;
        }

        String token = cst.nextToken();
        if ( isDelim( token ) )
        {
            if ( delimLast )
            {
                lastToken = token;
                return "";
            }
            else
            {
                delimLast = true;
                return token;
            }
        }
        else
        {
            delimLast = false;
            return token;
        }
    }

    public String nextToken()
    {
        String token = internalNextToken();
        if ( creturnDelims )
        {
            return token;
        }
        if ( isDelim( token ) )
        {
            return hasMoreTokens() ? internalNextToken() : "";
        }
        else
        {
            return token;
        }
    }

    private boolean isDelim( String str )
    {
        if ( str.length() == 1 )
        {
            char ch = str.charAt( 0 );
            if ( cdelimSingleChar )
            {
                if ( cdelimChar == ch )
                {
                    return true;
                }
            }
            else
            {
                if ( cdelim.indexOf( ch ) >= 0 )
                {
                    return true;
                }
            }
        }
        return false;

    }
}
