/*
    * Copyright 2016 the original author or authors.
    *
    * 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 org.openehealth.ipf.boot.hl7v2;
  
  import ca.uhn.hl7v2.model.Message;
  import org.openehealth.ipf.commons.ihe.hl7v2.storage.InteractiveContinuationStorage;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.cache.Cache;
  import org.springframework.cache.CacheManager;
  
  import java.io.Serializable;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * InteractiveContinuationStorage that uses a Spring cache abstraction
   *
   * @author Christian Ohr
   * @since 3.2
   */
  public class CachingInteractiveHl7v2ContinuationStorage implements InteractiveContinuationStorage {
  
      private static final transient Logger LOG = LoggerFactory.getLogger(CachingInteractiveHl7v2ContinuationStorage.class);
      private static final String INTERACTIVE_CONTINUATION_CACHE = "interactiveHl7v2ContinuationCache";
      private final Cache cache;
  
      public CachingInteractiveHl7v2ContinuationStorage(CacheManager cacheManager) {
          this.cache = cacheManager.getCache(INTERACTIVE_CONTINUATION_CACHE);
      }
  
      @Override
      public void put(String continuationPointer, String chainId, Message fragment) {
          InteractiveContinuationChain chain = cache.get(chainId, InteractiveContinuationChain.class);
          if (chain == null) {
              LOG.debug("Create chain for storage key {}", chainId);
              chain = new InteractiveContinuationChain();
              cache.put(chainId, chain);
          }
          chain.put(continuationPointer, fragment);
      }
  
      @Override
      public Message get(String continuationPointer, String chainId) {
          InteractiveContinuationChain chain = cache.get(chainId, InteractiveContinuationChain.class);
          if (chain != null) {
              return chain.get(continuationPointer);
          }
          return null;
      }
  
      @Override
      public boolean delete(String chainId) {
          if (cache.get(chainId) != null) {
              cache.evict(chainId);
              return true;
          }
          return false;
      }
  
      /**
       * Chain of interactive continuation fragments of a query's response.
       * <p>
       * Keys correspond to continuation pointers of the fragments;
       * the key of the first fragment is <code>null</code>.
       */
      private static class InteractiveContinuationChain implements Serializable {
          private final Map<String, Message> responseMessages =
                  Collections.synchronizedMap(new HashMap<>());
  
          public void put(String continuationPointer, Message message) {
              responseMessages.put(continuationPointer, message);
          }
  
          public Message get(String continuationPointer) {
              return responseMessages.get(continuationPointer);
          }
      }
  }