package com.ctrip.framework.apollo.biz.utils;

 import com.google.common.base.Joiner;

 import com.ctrip.framework.apollo.biz.entity.Namespace;

 import com.ctrip.framework.apollo.core.utils.ByteUtil;

 import com.ctrip.framework.apollo.core.utils.MachineUtil;

 import java.security.SecureRandom;

 import java.text.DateFormat;

 import java.text.SimpleDateFormat;

 import java.util.Date;

 import java.util.Objects;

 import java.util.concurrent.atomic.AtomicInteger;

 /**

  * @author Jason Song(song_s@ctrip.com)

  */

 public class ReleaseKeyGenerator {

   private static final DateFormat TIMESTAMP_FORMAT = new SimpleDateFormat("yyyyMMddHHmmss");

   private static final AtomicInteger releaseCounter = new AtomicInteger(new SecureRandom().nextInt());

   private static final Joiner KEY_JOINER = Joiner.on("-");

   /**

    * Generate the release key in the format: timestamp+appId+cluster+namespace+hash(ipAsInt+counter)

    *

    * @param namespace the namespace of the release

    * @return the unique release key

    */

   public static String generateReleaseKey(Namespace namespace) {

     String hexIdString =

         ByteUtil.toHexString(

             toByteArray(Objects.hash(namespace.getAppId(), namespace.getClusterName(),

                 namespace.getNamespaceName()), MachineUtil.getMachineIdentifier(),

                         releaseCounter.incrementAndGet()));

     return KEY_JOINER.join(TIMESTAMP_FORMAT.format(new Date()), hexIdString);

   }

   /**

    * Concat machine id, counter and key to byte array

    * Only retrieve lower 3 bytes of the id and counter and 2 bytes of the keyHashCode

    */

   private static byte[] toByteArray(int keyHashCode, int machineIdentifier, int counter) {

     byte[] bytes = new byte[8];

     bytes[0] = ByteUtil.int1(keyHashCode);

     bytes[1] = ByteUtil.int0(keyHashCode);

     bytes[2] = ByteUtil.int2(machineIdentifier);

     bytes[3] = ByteUtil.int1(machineIdentifier);

     bytes[4] = ByteUtil.int0(machineIdentifier);

     bytes[5] = ByteUtil.int2(counter);

     bytes[6] = ByteUtil.int1(counter);

     bytes[7] = ByteUtil.int0(counter);

     return bytes;

   }

 }