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.inbox.server;
  
  import static java.util.Collections.emptyMap;
  
  import com.google.common.collect.Iterators;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import lombok.extern.slf4j.Slf4j;
  
  @Slf4j
  public final class InboxFetcherRegistry implements IInboxFetcherRegistry {
      private final ConcurrentMap<String, Map<String, Map<String, IInboxFetcher>>> fetchers = new ConcurrentHashMap<>();
  
      @Override
      public void reg(IInboxFetcher fetcher) {
          fetchers.compute(fetcher.tenantId(), (key, val) -> {
              if (val == null) {
                  val = new ConcurrentHashMap<>();
              }
              IInboxFetcher prevFetcher = val.computeIfAbsent(fetcher.delivererKey(), k -> new ConcurrentHashMap<>())
                  .put(fetcher.id(), fetcher);
              if (prevFetcher != null) {
                  prevFetcher.close();
              }
              return val;
          });
      }
  
      @Override
      public void unreg(IInboxFetcher fetcher) {
          fetchers.compute(fetcher.tenantId(), (tenantId, m) -> {
              if (m != null) {
                  m.computeIfPresent(fetcher.delivererKey(), (k, v) -> {
                      v.remove(fetcher.id(), fetcher);
                      if (v.isEmpty()) {
                          return null;
                      }
                      return v;
                  });
                  if (m.isEmpty()) {
                      return null;
                  }
              }
              return m;
          });
      }
  
      @Override
      public Collection<IInboxFetcher> get(String tenantId, String delivererKey) {
          return fetchers.getOrDefault(tenantId, emptyMap()).getOrDefault(delivererKey, emptyMap()).values();
      }
  
      @Override
      public Iterator<IInboxFetcher> iterator() {
          return Iterators.concat(
              Iterators.transform(
                  Iterators.concat(
                      fetchers.values().stream().map(m -> m.values().iterator()).iterator()
                  ),
                  e -> e.values().iterator()
              )
          );
      }
  }
  