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id codec

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/*
 * Copyright 2012 Jin Kwon .
 *
 * 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 com.github.jinahya.codec;


import java.security.SecureRandom;
import java.util.Random;
import java.util.UUID;


/**
 * A class for encoding identifiers.
 *
 * @author Jin Kwon <jinahya_at_gmail.com>
 */
public class IdEncoder extends IdCodecBase {


    @Override
    public IdEncoder scale(int scale) {

        return super.scale(scale);
    }


    @Override
    public IdEncoder radix(int radix) {

        return super.radix(radix);
    }


    private String block(final long decoded) {

        final StringBuilder builder = new StringBuilder(Long.toString(decoded));

        final Random random = new SecureRandom();
        builder.ensureCapacity(builder.length() + getScale());
        for (int i = 0; i < getScale() - 1; i++) {
            builder.append(Integer.toString(random.nextInt(10)));
        }
        builder.append(Integer.toString(random.nextInt(9) + 1));
        builder.reverse();

        return Long.toString(Long.parseLong(builder.toString()), getRadix());
    }


    /**
     * Encodes given value.
     *
     * @param decoded the value to encode.
     *
     * @return encoded output.
     */
    public String encode(final long decoded) {

        return block(decoded >>> Integer.SIZE) + "-"
               + block(decoded & 0xFFFFFFFFL);
    }


    /**
     * Encodes given value.
     *
     * @param decoded the value to encode
     *
     * @return encoded output.
     */
    public String encodeUuid(final UUID decoded) {

        return encode(decoded.getMostSignificantBits()) + "-"
               + encode(decoded.getLeastSignificantBits());
    }

}