content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.bifromq.mqtt.inbox.util;
  
  import org.apache.bifromq.sysprops.props.DeliverersPerMqttServer;
  
  public class DelivererKeyUtil {
      private static final String DELIMITER = ":";
      private static final int MAX_DELIVERER_NUM = DeliverersPerMqttServer.INSTANCE.get();
  
      public static String toDelivererKey(String tenantId, String inboxId, String serverId) {
          assert !serverId.contains(DELIMITER) : "serverId SHOULD NOT contain '" + DELIMITER + "'";
          return serverId + DELIMITER + tenantId + DELIMITER + groupIdx(inboxId);
      }
  
      public static String parseTenantId(String delivererKey) {
          int firstIdx = delivererKey.indexOf(DELIMITER);
          int secondIdx = delivererKey.lastIndexOf(DELIMITER);
          return delivererKey.substring(firstIdx + 1, secondIdx);
      }
  
      public static String parseServerId(String delivererKey) {
          return delivererKey.substring(0, delivererKey.indexOf(DELIMITER));
      }
  
      private static int groupIdx(String inboxId) {
          int idx = inboxId.hashCode() % MAX_DELIVERER_NUM;
          if (idx < 0) {
              idx = (idx + MAX_DELIVERER_NUM) % MAX_DELIVERER_NUM;
          }
          return idx;
      }
  }
  