/*
 * Copyright 2001-2004 The Apache Software 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.
 */

package org.apache.ws.security.util;

import java.util.ArrayList;
import java.util.List;

public class StringUtil {
    /**
     * An empty immutable <code>String</code> array.
     */
    public static final String[] EMPTY_STRING_ARRAY = new String[0];

    /**
     * Tests if this string starts with the specified prefix (Ignoring whitespaces)
     *
     * @param prefix
     * @param string
     * @return boolean
     */
    public static boolean startsWithIgnoreWhitespaces(String prefix, String string) {
        int index1 = 0;
        int index2 = 0;
        int length1 = prefix.length();
        int length2 = string.length();
        char ch1 = ' ';
        char ch2 = ' ';
        while (index1 < length1 && index2 < length2) {
            while (index1 < length1 && Character.isWhitespace(ch1 = prefix.charAt(index1))) {
                index1++;
            }
            while (index2 < length2 && Character.isWhitespace(ch2 = string.charAt(index2))) {
                index2++;
            }
            if (index1 == length1 && index2 == length2) {
                return true;
            }
            if (ch1 != ch2) {
                return false;
            }
            index1++;
            index2++;
        }
        if (index1 < length1 && index2 >= length2)
            return false;
        return true;
    }

    /**
     * <p>Splits the provided text into an array, separator specified.
     * This is an alternative to using StringTokenizer.</p>
     * <p/>
     * <p>The separator is not included in the returned String array.
     * Adjacent separators are treated as one separator.</p>
     * <p/>
     * <p>A <code>null</code> input String returns <code>null</code>.</p>
     * <p/>
     * <pre>
     * StringUtils.split(null, *)         = null
     * StringUtils.split("", *)           = []
     * StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
     * StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
     * StringUtils.split("a:b:c", '.')    = ["a:b:c"]
     * StringUtils.split("a\tb\nc", null) = ["a", "b", "c"]
     * StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
     * </pre>
     *
     * @param str           the String to parse, may be null
     * @param separatorChar the character used as the delimiter,
     *                      <code>null</code> splits on whitespace
     * @return an array of parsed Strings, <code>null</code> if null String input
     */
    public static String[] split(String str, char separatorChar) {
        if (str == null) {
            return null;
        }
        int len = str.length();
        if (len == 0) {
            return EMPTY_STRING_ARRAY;
        }
        List list = new ArrayList();
        int i = 0, start = 0;
        boolean match = false;
        while (i < len) {
            if (str.charAt(i) == separatorChar) {
                if (match) {
                    list.add(str.substring(start, i));
                    match = false;
                }
                start = ++i;
                continue;
            }
            match = true;
            i++;
        }
        if (match) {
            list.add(str.substring(start, i));
        }
        return (String[]) list.toArray(new String[list.size()]);
    }
}