package org.kuali.ole.docstore.discovery.service;
   
   import java.io.File;
   import java.io.IOException;
   import java.net.MalformedURLException;
   import java.util.HashMap;
   import java.util.Map;
   
   import javax.xml.parsers.ParserConfigurationException;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.solr.client.solrj.SolrServer;
  import org.apache.solr.client.solrj.SolrServerException;
  import org.apache.solr.client.solrj.embedded.EmbeddedSolrServer;
  import org.apache.solr.client.solrj.impl.CommonsHttpSolrServer;
  import org.apache.solr.client.solrj.impl.StreamingUpdateSolrServer;
  import org.apache.solr.client.solrj.impl.XMLResponseParser;
  import org.apache.solr.core.CoreContainer;
  import org.kuali.ole.docstore.discovery.util.PropertyUtil;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.xml.sax.SAXException;
  
  /**
   * This class handles the creation of solr server object, used for connecting to solr server (core).
   * User: tirumalesh.b
   * Date: 23/12/11 Time: 12:32 PM
   */
  public class SolrServerManager {
  
      private static final Logger LOG = LoggerFactory.getLogger(SolrServerManager.class);
  
      public static final String SOLR_HOME = "solr.solr.home";
      public static final String SOLR_CORE_MAIN = "bib";
      public static final String SOLR_SERVER_EMBEDDED = "solr.server.embedded";
      public static final String SOLR_SERVER_STREAMING = "solr.server.streaming";
  
      private static SolrServerManager solrServerMgr = null;
      private static String docSearchUrl = null;
      public static Map<String, SolrServer> serverMap = null;
  
      public static SolrServerManager getInstance() {
          if (null == solrServerMgr) {
              solrServerMgr = new SolrServerManager();
          }
          return solrServerMgr;
      }
  
      private SolrServerManager() {
          init();
      }
  
      protected void init() {
          LOG.debug("SolrServerManager.init()");
          docSearchUrl = PropertyUtil.getPropertyUtil().getProperty("docSearchURL");
          if ((null != docSearchUrl) && !docSearchUrl.endsWith("/")) {
              docSearchUrl = docSearchUrl + "/";
          }
          LOG.info("Actual Document Search URL being used docSearchURL=" + docSearchUrl);
          serverMap = new HashMap<String, SolrServer>();
      }
  
      /**
       * Simplest method to get a solr server for the default core.
       *
       * @return Returns solr server object.
       * @throws Exception Throws an exception on error.
       */
      public SolrServer getSolrServer() throws SolrServerException {
          return getSolrServer(SOLR_CORE_MAIN);
      }
  
      /**
       * Get a solr server for the given core.
       *
       * @param solrCore Solr core for which server is required.
       * @return Returns solr server object.
       * @throws Exception Throws an exception on error.
       */
      public SolrServer getSolrServer(String solrCore) throws SolrServerException {
          boolean isStreaming = false;
          boolean isEmbedded = false;
          String embedPropValue = System.getProperty(SOLR_SERVER_EMBEDDED);
          if (StringUtils.isNotEmpty(embedPropValue)) {
              isEmbedded = Boolean.parseBoolean(embedPropValue);
          }
          String streamingPropValue = System.getProperty(SOLR_SERVER_STREAMING);
          if (StringUtils.isNotEmpty(streamingPropValue)) {
              isStreaming = Boolean.parseBoolean(streamingPropValue);
          }
          return getSolrServer(solrCore, isStreaming, isEmbedded);
      }
  
      /**
       * Get a solr server for the given core, with the specified options for streaming or embedded.
       * The streaming and embedded options are considered only for the first time, for the sake of simplicity.
       * The server objects are saved in a map and reused.
       *
       * @param solrCore Solr core for which server is required.
      * @param isStreaming Indicates whether a streaming server is needed.
      * @param isEmbedded Indicates whether an embedded server is needed.
      * @return Returns solr server object.
      * @throws Exception Throws an exception on error.
      */
     public SolrServer getSolrServer(String solrCore, boolean isStreaming, boolean isEmbedded)
             throws SolrServerException {
         SolrServer solr = null;
         try {
             if (null == serverMap) {
                 serverMap = new HashMap<String, SolrServer>();
             }
             solr = serverMap.get(solrCore);
             if (null != solr) {
                 return solr;
             }
             if (isEmbedded) {
                 solr = getEmbeddedSolrServer(solrCore);
             }
             else if (isStreaming) {
                 solr = new StreamingUpdateSolrServer(docSearchUrl + solrCore, 100, 5);
             }
             else {
                 solr = getCommonsHttpSolrServer(docSearchUrl + solrCore);
             }
             serverMap.put(solrCore, solr);
         }
         catch (SolrServerException sse) {
             throw sse;
         }
         catch (Exception e) {
             throw new SolrServerException(e);
         }
         return solr;
     }
 
     public String getSolrCoreURL() {
         return docSearchUrl + SOLR_CORE_MAIN;
     }
 
     protected static CommonsHttpSolrServer getCommonsHttpSolrServer(String solrUrl) throws MalformedURLException {
         CommonsHttpSolrServer server = new CommonsHttpSolrServer(solrUrl);
         server.setConnectionTimeout(100);
         server.setDefaultMaxConnectionsPerHost(100);
         server.setMaxTotalConnections(100);
         server.setFollowRedirects(false);
         server.setAllowCompression(true);
         server.setMaxRetries(1);
         server.setParser(new XMLResponseParser());
         return server;
     }
 
     protected SolrServer getEmbeddedSolrServer(String solrCore) throws IOException, ParserConfigurationException, SAXException, SolrServerException {
         String solrHomeDir = System.getProperty(SOLR_HOME);
         File home = new File(solrHomeDir);
         File f = new File(home, "solr.xml");
         CoreContainer container = new CoreContainer();
         container.load(solrHomeDir, f);
         return new EmbeddedSolrServer(container, solrCore);
     }
 
 }