/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.hc.client5.http.impl.cache;
  
  import java.util.LinkedHashMap;
  import java.util.LinkedList;
  import java.util.Map;
  import java.util.Queue;
  import java.util.function.Consumer;
  
  import org.apache.hc.client5.http.cache.HttpCacheEntry;
  import org.apache.hc.client5.http.cache.HttpCacheStorageEntry;
  import org.apache.hc.core5.annotation.Internal;
  
  @Internal
  final public class InternalCacheStorage {
  
      private final Map<String, HttpCacheEntry> map;
      private final Queue<HttpCacheStorageEntry> evictionQueue;
      private final Consumer<HttpCacheStorageEntry> evictionCallback;
  
      public InternalCacheStorage(final int maxEntries, final Consumer<HttpCacheStorageEntry> evictionCallback) {
          this.evictionCallback = evictionCallback;
          this.map = new LinkedHashMap<String, HttpCacheEntry>(20, 0.75f, true) {
  
              @Override
              protected boolean removeEldestEntry(final Map.Entry<String, HttpCacheEntry> eldest) {
                  if (size() > maxEntries) {
                      if (evictionCallback != null) {
                          evictionQueue.add(new HttpCacheStorageEntry(eldest.getKey(), eldest.getValue()));
                      }
                      return true;
                  } else {
                      return false;
                  }
              }
  
          };
          this.evictionQueue = new LinkedList<>();
      }
  
      public InternalCacheStorage(final int maxEntries) {
          this(maxEntries, null);
      }
  
      public InternalCacheStorage() {
          this(Integer.MAX_VALUE, null);
      }
  
      public void put(final String key, final HttpCacheEntry entry) {
          map.put(key, entry);
          HttpCacheStorageEntry evicted;
          while ((evicted = evictionQueue.poll()) != null) {
              if (evictionCallback != null) {
                  evictionCallback.accept(evicted);
              }
          }
      }
  
      public HttpCacheEntry get(final String key) {
          return map.get(key);
      }
  
      public HttpCacheEntry remove(final String key) {
          return map.remove(key);
      }
  
      public void clear() {
          map.clear();
      }
  
  }