// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package io.v.syncbase.v23.services.syncbase.util;

import java.io.UnsupportedEncodingException;

/**
 * Various syncbase utility methods.
 */
public class Util {
    /**
     * Returns the start of the row range for the given prefix.
     */
    public static String prefixRangeStart(String prefix) {
        return prefix;
    }

    /**
     * Returns the limit of the row range for the given prefix.
     */
    public static String prefixRangeLimit(String prefix) {
        // We convert a string to a byte[] array, which can be thought of as a base-256
        // number.  The code below effectively adds 1 to this number, then chops off any
        // trailing 0x00 bytes. If the input string consists entirely of 0xFF, an empty string
        // will be returned.
        try {
            byte[] bytes = prefix.getBytes("ISO8859-1");
            int last = bytes.length - 1;
            for (; last >= 0 && bytes[last] == (byte) 0xFF; --last);
            if (last < 0) {
                return "";
            }
            bytes[last] += 1;
            return new String(bytes, 0, last + 1, "ISO8859-1");
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException("JVM must support ISO8859-1 char encoding", e);
        }
    }

    private Util() {}
}