package org.apache.maven.jxr.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.
 */

import java.util.Collections;
import java.util.Vector;

/**
 * This is a small and fast word tokenizer. It has different characteristics
 * from the normal Java tokenizer. It only considers clear words that are only
 * ended with spaces as strings. EX: "Flight" would be a word but "Flight()"
 * would not.
 */
public class SimpleWordTokenizer
{

    /**
     * Description of the Field
     */
    public final static char[] BREAKERS = {'(', ')', '[', ' ', '{', '}'};

    /**
     * Break the given line into multiple StringUtils
     */
    public static StringEntry[] tokenize( String line )
    {

        /*
        determine where to start processing this String... this could
        either be the start of the line or just keep going until the first
        */
        int start = getStart( line );

        //find the first non-BREAKER char and assume that is where you want to start

        if ( line == null || line.length() == 0 || start == -1 )
        {
            return new StringEntry[0];
        }

        return tokenize( line, start );
    }


    /**
     * Tokenize the given line but only return StringUtils that match the parameter
     * find.
     *
     * @param line String to search in
     * @param find String to match.
     */
    public static StringEntry[] tokenize( String line, String find )
    {

        Vector v = new Vector();

        StringEntry[] se = tokenize( line );

        for ( int i = 0; i < se.length; ++i )
        {

            if ( se[i].toString().equals( find ) )
            {
                v.addElement( se[i] );
            }

        }

        StringEntry[] found = new StringEntry[v.size()];
        Collections.sort( v );
        v.copyInto( found );
        return found;
    }

    /**
     * Internal impl. Specify the start and end.
     */
    private static StringEntry[] tokenize( String line, int start )
    {

        Vector words = new Vector();

        //algorithm works like this... break the line out into segments
        //that are separated by spaces, and if the entire String doesn't contain
        //a non-Alpha char then assume it is a word.
        while ( true )
        {

            int next = getNextBreak( line, start );

            if ( next < 0 || next <= start )
            {
                break;
            }

            String word = line.substring( start, next );

            if ( isWord( word ) )
            {
                words.addElement( new StringEntry( word, start ) );
            }

            start = next + 1;
        }

        StringEntry[] found = new StringEntry[words.size()];
        words.copyInto( found );
        return found;
    }


    /**
     * Go through the entire String and if any character is not a Letter( a, b,
     * c, d, etc) then return false.
     */
    private static boolean isWord( String string )
    {

        if ( string == null || string.length() == 0 )
        {

            return false;
        }

        for ( int i = 0; i < string.length(); ++i )
        {

            char c = string.charAt( i );

            if ( Character.isLetter( c ) == false && c != '.' )
            {
                return false;
            }

        }

        return true;
    }

    /**
     * Go through the list of BREAKERS and find the closes one.
     */
    private static int getNextBreak( String string, int start )
    {

        int breakPoint = -1;

        for ( int i = 0; i < BREAKERS.length; ++i )
        {

            int next = string.indexOf( BREAKERS[i], start );

            if ( breakPoint == -1 || next < breakPoint && next != -1 )
            {

                breakPoint = next;

            }

        }

        //if the breakPoint is still -1 go to the end of the string
        if ( breakPoint == -1 )
        {
            breakPoint = string.length();
        }

        return breakPoint;
    }

    /**
     * Go through the list of BREAKERS and find the closes one.
     */
    private static int getStart( String string )
    {

        for ( int i = 0; i < string.length(); ++i )
        {

            if ( isBreaker( string.charAt( i ) ) == false )
            {
                return i;
            }

        }

        return -1;
    }


    /**
     * Return true if the given char is considered a breaker.
     */
    private static boolean isBreaker( char c )
    {

        for ( int i = 0; i < BREAKERS.length; ++i )
        {

            if ( BREAKERS[i] == c )
            {
                return true;
            }

        }

        return false;
    }

}