/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

public class TransformUtil {

    public static final String BeforePattern = "this-should-be-transformed";

    public static final String AfterPattern  = "this-has-been--transformed";

    public static final String ParentCheckPattern = "parent-transform-check: ";

    public static final String ChildCheckPattern = "child-transform-check: ";

    /**

     * @return the number of occurrences of the <code>from</code> string that

     * have been replaced.

     */

    public static int replace(byte buff[], String from, String to) {

        if (to.length() != from.length()) {

            throw new RuntimeException("bad strings");

        }

        byte f[] = asciibytes(from);

        byte t[] = asciibytes(to);

        byte f0 = f[0];

        int numReplaced = 0;

        int max = buff.length - f.length;

        for (int i = 0; i < max; ) {

            if (buff[i] == f0 && replace(buff, f, t, i)) {

                i += f.length;

                numReplaced++;

            } else {

                i++;

            }

        }

        return numReplaced;

    }

    public static boolean replace(byte buff[], byte f[], byte t[], int i) {

        for (int x = 0; x < f.length; x++) {

            if (buff[x+i] != f[x]) {

                return false;

            }

        }

        for (int x = 0; x < f.length; x++) {

            buff[x+i] = t[x];

        }

        return true;

    }

    static byte[] asciibytes(String s) {

        byte b[] = new byte[s.length()];

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

            b[i] = (byte)s.charAt(i);

        }

        return b;

    }

}