/**
    * Copyright 2010 The Kuali Foundation Licensed under the
    * Educational Community 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.osedu.org/licenses/ECL-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.kuali.student.common.ui.server.gwt;
  
  import java.lang.ref.SoftReference;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.kuali.student.common.ui.client.service.SearchRpcService;
  import org.kuali.student.r1.common.assembly.transform.IdTranslatorFilter;
  import org.kuali.student.r2.common.exceptions.MissingParameterException;
  import org.kuali.student.r1.common.search.dto.SearchParam;
  import org.kuali.student.r1.common.search.dto.SearchRequest;
  import org.kuali.student.r1.common.search.dto.SearchResult;
  import org.kuali.student.r1.common.search.dto.SearchResultCell;
  import org.kuali.student.r1.common.search.dto.SearchResultRow;
  import org.kuali.student.r1.common.search.service.SearchDispatcher;
  import org.springframework.beans.factory.InitializingBean;
  
  import com.google.gwt.user.server.rpc.RemoteServiceServlet;
  
  public class SearchDispatchRpcGwtServlet extends RemoteServiceServlet implements SearchRpcService, InitializingBean {
  
      private static final long serialVersionUID = 1L;
  
      private IdTranslatorFilter idTranslatorFilter;
  
      private SearchDispatcher searchDispatcher;
  
      protected boolean cachingEnabled = false;
  	protected int searchCacheMaxSize = 20;
  	protected int searchCacheMaxAgeSeconds = 90;
  	protected Map<String,MaxAgeSoftReference<SearchResult>> searchCache;
  	
      
      public SearchDispatchRpcGwtServlet() {
          super();
      }
  
      /**
       * Delegates to the service responsible for the given search type key
       *
       * @param searchRequest
       * @return The searchResult from the delegated search or null
       * @throws MissingParameterException
       */
      @Override
      public SearchResult search(SearchRequest searchRequest) {
          try
          {
              SearchResult searchResult = searchDispatcher.dispatchSearch(searchRequest);
              List<SearchParam> params = searchRequest.getParams();
              if (params != null && params.size() > 0) {
                  SearchParam firstParam = params.get(0);
                  if (firstParam.getKey().equals("lu.queryParam.cluVersionIndId")) {//FIXME can this special case be handled after this call?
                      doIdTranslation(searchResult);
                  }
              }
              return searchResult;
          } catch (Exception ex) {
              // Log exception 
              ex.printStackTrace();
              throw new RuntimeException(ex);
          }
      }
  
      @Override
      public SearchResult cachingSearch(SearchRequest searchRequest) {
          try
          {
              String cacheKey = searchRequest.toString();
              if (cachingEnabled) {
  
                  //Get From Cache
                  MaxAgeSoftReference<SearchResult> ref = searchCache.get(cacheKey);
                  if (ref != null) {
                      SearchResult cachedSearchResult = ref.get();
                      if (cachedSearchResult != null) {
                          return cachedSearchResult;
                      }
                  }
              }
  
             //Perform the actual Search
             SearchResult searchResult = search(searchRequest);
 
             if (cachingEnabled) {
                 //Store to cache
                 searchCache
                         .put(cacheKey, new MaxAgeSoftReference<SearchResult>(searchCacheMaxAgeSeconds, searchResult));
             }
 
             return searchResult;
         } catch (Exception ex) {
             // Log exception 
             ex.printStackTrace();
             throw new RuntimeException(ex);
         }
     }
 
     private void doIdTranslation(SearchResult searchResult) {
         for (SearchResultRow searchResultRow : searchResult.getRows()) {
             for (SearchResultCell searchResultCell : searchResultRow.getCells()) {
                 String value = searchResultCell.getValue();
                 if (value != null && value.startsWith("kuali.atp")) {
                     String newValue = idTranslatorFilter.getTranslationForAtp(value);
                     if (newValue != null) {
                         searchResultCell.setValue(newValue);
                     }
                 }
             }
         }
     }
 
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		if(cachingEnabled){
 			searchCache = Collections.synchronizedMap( new MaxSizeMap<String,MaxAgeSoftReference<SearchResult>>( searchCacheMaxSize ) );
 		}
 	}
     
     public void setSearchDispatcher(SearchDispatcher searchDispatcher) {
         this.searchDispatcher = searchDispatcher;
     }
 
     public void setIdTranslatorFilter(IdTranslatorFilter idTranslatorFilter) {
         this.idTranslatorFilter = idTranslatorFilter;
     }
 
 	public void setCachingEnabled(boolean cachingEnabled) {
 		this.cachingEnabled = cachingEnabled;
 	}
 
 	public void setSearchCacheMaxSize(int searchCacheMaxSize) {
 		this.searchCacheMaxSize = searchCacheMaxSize;
 	}
 
 	public void setSearchCacheMaxAgeSeconds(int searchCacheMaxAgeSeconds) {
 		this.searchCacheMaxAgeSeconds = searchCacheMaxAgeSeconds;
 	}
 	
 	
 	//Added as inner classes to avoid huge dependency on rice-impl
 	/**
 	 * An extension to SoftReference that stores an expiration time for the 
 	 * value stored in the SoftReference. If no expiration time is passed in
 	 * the value will never be cached.  
 	 */
 	public class MaxAgeSoftReference<T> extends SoftReference<T> {
 		
 		private long expires;
 
 		public MaxAgeSoftReference(long expires, T referent) {
 			super(referent);
 			this.expires = System.currentTimeMillis() + expires * 1000;
 		}
 		
 		public boolean isValid() {
 			return System.currentTimeMillis() < expires;
 		}
 		
 		public T get() {			
 			return isValid() ? super.get() : null;
 		}		
 		
 	}
 	/**
 	 * This class acts like an LRU cache, automatically purging contents when it gets above a certain size. 
 	 * 
 	 * @author Kuali Rice Team (rice.collab@kuali.org)
 	 */
 	public class MaxSizeMap<K,V> extends LinkedHashMap<K,V> {
 		private static final long serialVersionUID = -5354227348838839919L;
 
 		private int maxSize;
 		
 		/**
 		 * @param maxSize
 		 */
 		public MaxSizeMap( int maxSize  ) {
 			this( maxSize, false );
 		}
 		/**
 		 * @param maxSize
 		 * @param accessOrder Whether to sort in the order accessed rather than the order inserted.
 		 */
 		public MaxSizeMap( int maxSize, boolean accessOrder ) {
 			super( maxSize / 2, 0.75f, accessOrder );
 			this.maxSize = maxSize;
 		}
 		
 		/**
 		 * @see java.util.LinkedHashMap#removeEldestEntry(java.util.Map.Entry)
 		 */
 		@Override
 		protected boolean removeEldestEntry(Entry<K,V> eldest) {
 			return size() > maxSize;
 		}
 		
 	}
 }