/*
    * Copyright 2000-2004 The Apache Software Foundation.
    * 
    * 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.apache.jetspeed.services.registry;
  
  // Java classes
  import java.io.Reader;
  import java.util.Hashtable;
  import java.util.Enumeration;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Vector;
  
  import javax.servlet.ServletConfig;
  
  //turbine stuff
  import org.apache.turbine.services.InitializationException;
  import org.apache.turbine.services.TurbineBaseService;
  import org.apache.turbine.services.TurbineServices;
  import org.apache.turbine.services.resources.ResourceService;
  import org.apache.turbine.services.servlet.ServletService;
  
  // Jetspeed classes
  import org.apache.jetspeed.om.registry.DBRegistry;
  import org.apache.jetspeed.om.registry.Registry;
  import org.apache.jetspeed.om.registry.RegistryEntry;
  import org.apache.jetspeed.om.registry.RegistryException;
  import org.apache.jetspeed.om.registry.base.BaseRegistry;
  import org.apache.jetspeed.om.registry.base.LocalRegistry;
  import org.apache.jetspeed.services.logging.JetspeedLogFactoryService;
  import org.apache.jetspeed.services.logging.JetspeedLogger;
  
  /***
   * <p>This is an implementation of the <code>RegistryService</code>
   * based on the Jetspeed Database Persistence Manager</p>
   *
   * @author <a href="mailto:taylor@apache.org">David Sean Taylor</a>
   * @author <a href="mailto:susinha@cisco.com">Suchisubhra Sinha</a>
   * @version $Id: DatabaseRegistryService.java,v 1.6 2004/02/23 03:31:50 jford Exp $
   */
  public class DatabaseRegistryService
      extends TurbineBaseService
      implements RegistryService , FileRegistry 
  {
      private static final JetspeedLogger logger = JetspeedLogFactoryService.getLogger(CastorRegistryService.class.getName());
          
      /*** The name of this service */
      public static String SERVICE_NAME = "DatabaseRegistry";
  
      public static final int DEFAULT_VERBOSE = 1;
  
      /*** regsitry type keyed list of entries */
      private Hashtable registries = new Hashtable();
  
      /*** The list of default fragments stores for newly created objects */
      private Hashtable defaults = new Hashtable();
  
      /*** The Castor generated RegsitryFragment objects */
      private Hashtable fragments = new Hashtable();
  
      /*** Associates entries with their fragments name for quick lookup */
      private Hashtable entryIndex = new Hashtable();
  
      /*** the Watcher object which monitors the regsitry directory */
      private DatabaseRegistryWatcher watcher = null;
  
      /*** Assign  the default  poolname */
      private final static String POOL_NAME = "database";
  
      
      /*** controls amount of debug output, the bigger the more output will be generated */
      private int verbose = DEFAULT_VERBOSE;
  
      /*** Base class to implement  */
      private static Hashtable baseClass = new Hashtable();
      
      /***
       * Returns a Registry object for further manipulation
       *
       * @param regName the name of the registry to fetch
       * @return a Registry object if found by the manager or null
       */
      public Registry get(String regName) 
      {
          return (Registry) registries.get(regName);
     }
 
     /***
      *  List all the registry currently available to this service
      *
      * @return an Enumeration of registry names.
      */
     public Enumeration getNames() 
     {
         return registries.keys();
     }
 
     /***
      * Creates a new RegistryEntry instance compatible with the current
      * Registry instance implementation
      *
      * @param regName the name of the registry to use
      * @return the newly created RegistryEntry
      */
     public RegistryEntry createEntry(String regName) 
     {
         RegistryEntry entry = null;
         Registry registry = (Registry) registries.get(regName);
 
         if (registry != null) 
         {
             entry = registry.createEntry();
         }
 
         return entry;
     }
 
     
     /***
      * Returns a RegistryEntry from the named Registry.
      * This is a convenience wrapper around {@link
      * org.apache.jetspeed.om.registry.Registry#getEntry }
      *
      * @param regName the name of the registry
      * @param entryName the name of the entry to retrieve from the registry.
      * @return a RegistryEntry object if the key is found or null
      */
     public RegistryEntry getEntry(String regName, String entryName) 
     {
         try 
         {
             return ((Registry) registries.get(regName)).getEntry(entryName);
         } 
         catch (RegistryException e) 
         {
             if (logger.isInfoEnabled()) 
             {
                 logger.info(
                     "RegistryService: Failed to retrieve "
                         + entryName
                         + " from "
                         + regName);
             }
         } 
         catch (NullPointerException e) 
         {
             logger.error(
                 "DatabaseRegistryService: "
                     + regName
                     + " registry is not known ");
             logger.error(e);
         }
 
         return null;
     }
             
     /***
      * Add a new RegistryEntry in the named Registry.
      * This is a convenience wrapper around {@link
      * org.apache.jetspeed.om.registry.Registry#addEntry }
      *
      * @param regName the name of the registry
      * @param entry the Registry entry to add
      * @exception Sends a RegistryException if the manager can't add
      *            the provided entry
      */
     public void addEntry(String regName, RegistryEntry entry)
         throws RegistryException 
     {
         if (entry == null) 
         {
             return;
         }
 
         LocalRegistry registry = (LocalRegistry) registries.get(regName);
 
         if (registry != null) 
         {
             String fragmentName = (String) entryIndex.get(entry.getName());
 
             if (fragmentName == null) 
             {
                 // either the entry was deleted or it does not exist
                 // in both cases, use the default fragment
                 fragmentName = (String) defaults.get(regName);
             }
 
             RegistryFragment fragment =
                 (RegistryFragment) fragments.get(fragmentName);
 
             //Fragment can be (and sometimes is, but should not be) null
             if (fragment == null) 
             {
                 fragment = new RegistryFragment();
                 fragment.put(regName, new Vector());
                 fragments.put(fragmentName, fragment);
             } 
             else 
             {
                 Vector vectRegistry = (Vector) fragment.get(regName);
                 if (vectRegistry == null) 
                 {
                     fragment.put(regName, new Vector());
                 }
             }
 
             synchronized (entryIndex) 
             {
                 if (registry.hasEntry(entry.getName())) 
                 {
                     fragment.setEntry(regName, entry);
                     registry.setLocalEntry(entry);
                 } 
                 else 
                 {
                     fragment.addEntry(regName, entry);
                     registry.addLocalEntry(entry);
                 }
 
                 entryIndex.put(entry.getName(), fragmentName);
                 // mark this fragment so that it's persisted next time
                 // the registry watcher is running
                 fragment.setDirty(true);
             }
         }
     }
     
    /***
     * Deletes a RegistryEntry from the named Registry
     * This is a convenience wrapper around {@link
     * org.apache.jetspeed.om.registry.Registry#removeEntry }
     *
     * @param regName the name of the registry
     * @param entryName the name of the entry to remove
     */
     public void removeEntry(String regName, String entryName) 
     {
         if (entryName == null) 
         {
             return;
         }
 
         LocalRegistry registry = (LocalRegistry) registries.get(regName);
 
         if (registry != null) 
         {
             String fragmentName = (String) entryIndex.get(entryName);
 
             if (fragmentName != null) 
             {
                 RegistryFragment fragment =
                     (RegistryFragment) fragments.get(fragmentName);
 
                 synchronized (entryIndex) 
                 {
                     fragment.removeEntry(regName, entryName);
                     entryIndex.remove(entryName);
 
                     // mark this fragment so that it's persisted next time
                     // the registry watcher is running
                     fragment.setDirty(true);
                 }
             }
 
             // the entry is physically removed, remove the dangling reference
             registry.removeLocalEntry(entryName);
         }
     }
     
     /***
      * This is the early initialization method called by the
      * Turbine <code>Service</code> framework
      */
     public synchronized void init(ServletConfig conf)
     throws InitializationException 
     {
         int refreshRate = 0;
         Vector names = new Vector();
     
         //Ensure that the servlet service is initialized
         TurbineServices.getInstance().initService(ServletService.SERVICE_NAME, conf);
 
         ResourceService serviceConf =
             ((TurbineServices) TurbineServices.getInstance()).getResources(SERVICE_NAME);
 
         //build the map of default fragments, eahc registry must be associated
         //with at least one fragment
         try 
         {            
             refreshRate = serviceConf.getInt("refreshRate", DEFAULT_REFRESH);
             ResourceService defaults = serviceConf.getResources("default");
             Iterator i = defaults.getKeys();
 
             while (i.hasNext()) 
             {
                 String name = (String) i.next();
                 // add this name in the list of available registries
                 
                 names.add(name);
                 try 
                 {
                     String registryClass =
                         "org.apache.jetspeed.om.registry.database.BaseJetspeed"
                             + name
                             + "Peer";
 
                     baseClass.put(
                         name,
                         (DBRegistry) Class
                             .forName(registryClass)
                             .newInstance());
                 } 
                 catch (Exception e) 
                 {
                     if (logger.isWarnEnabled()) 
                     {
                         logger.warn(
                             "DatabaseRegistryService: Class "
                                 + name
                                 + " not found");
                     }
 
                 }
 
             }
         } 
         catch (Throwable t) 
         {
             throw new InitializationException("Unable to initialize DatabaseRegistryService, missing config keys");
         }
     
         this.watcher = new DatabaseRegistryWatcher();
         this.watcher.setSubscriber(this);
 
         if (refreshRate == 0) 
         {
             this.watcher.setDone();
         } 
         else 
         {
             this.watcher.setRefreshRate(refreshRate);
         }
         // changing the base will trigger a synchronous loading of the fragments
         this.watcher.changeBase(names);
 
         //Mark that we are done
         setInit(true);
 
         // load the registries
         Enumeration en = names.elements();
 
         RegistryService localeService =
             (RegistryService) TurbineServices
                 .getInstance()
                 .getService(RegistryService.SERVICE_NAME);
 
         while (en.hasMoreElements()) 
         {
             String name = (String) en.nextElement();
             Registry registry = (Registry) registries.get(name);
 
             if (registry == null) 
             {
                 String registryClass = null;
                 try 
                 {
                     registry = localeService.get(name);
                 } 
                 catch (Exception e) 
                 {
                     if (logger.isWarnEnabled()) 
                     {
                         logger.warn(
                             "DatabaseRegistryService: Class "
                                 + registryClass
                                 + " not found, reverting to default Registry");
                     }
                     registry = new BaseRegistry();
                 }
                 registries.put(name, registry);
             }
 
             refresh(name);
         }
         
         // Start the directory watcher thread and rely on its refresh process
         // to completely load all registries
         if (this.watcher != null) 
         {
             this.watcher.start();
         }
 
         if (logger.isDebugEnabled()) 
         {
             logger.debug(
                 "DatabaseRegistryService: early init()....end!, this.getInit()= "
                     + getInit());
         }
     }
     /***
          * @return a Map of all fragments keyed by file names
          */
     public Map getFragmentMap() 
     {
         return (Map) fragments.clone();
     }
 
     /*** Late init method from Turbine Service model */
     public void init() throws InitializationException 
     {
         if (logger.isDebugEnabled()) 
         {
             logger.debug("DatabaseRegistryService: Late init called");
         }
         while (!getInit()) 
         {
             //Not yet...
             try 
             {
                 Thread.sleep(500);
                 if ((verbose > 2) && logger.isDebugEnabled()) 
                 {
                     logger.debug(
                         "DatabaseRegistryService: Waiting for init of Registry...");
                 }
             } 
             catch (InterruptedException ie) 
             {
                 logger.error(ie);
             }
         }
 
         if (logger.isDebugEnabled()) 
         {
             logger.debug("DatabaseRegistryService: We are done");
         }
     }
     
     /***
      * This is the shutdown method called by the
      * Turbine <code>Service</code> framework
      */
     public void shutdown() 
     {
         this.watcher.setDone();
 
         Iterator i = fragments.keySet().iterator();
         while (i.hasNext()) 
         {
             saveFragment((String) i.next());
         }
     }
 
     /***
      * Scan all the registry fragments for new entries relevant to
      * this registry and update its definition.
      *
      * @param regName the name of the Registry to refresh
      */
     protected void refresh(String regName) 
     {
         if (logger.isDebugEnabled()) 
         {
             logger.debug(
                 "DatabaseRegistryService: Updating the "
                     + regName
                     + " registry");
         }
 
         int count = 0;
         int counDeleted = 0;
         LocalRegistry registry = (LocalRegistry) get(regName);
 
         Vector toDelete = new Vector();
         Iterator i = registry.listEntryNames();
 
         while (i.hasNext()) 
         {
             toDelete.add(i.next());
         }
 
         if (registry == null) 
         {
             logger.error(
                 "DatabaseRegistryService: Null "
                     + name
                     + " registry in refresh");
             return;
         }
 
         // for each fragment...
         Enumeration en = fragments.keys();
         while (en.hasMoreElements()) 
         {
             String location = (String) en.nextElement();
             RegistryFragment fragment =
                 (RegistryFragment) fragments.get(location);
             int fragCount = 0;
 
             if (!fragment.hasChanged()) 
             {
                 if ((verbose > 2) && logger.isDebugEnabled()) 
                 {
                     logger.debug(
                         "DatabaseRegistryService: Skipping fragment "
                             + location);
                 }
 
                 //remove this fragment entries from the delete list
                 Vector entries = fragment.getEntries(regName);
                 i = entries.iterator();
                 while (i.hasNext()) 
                 {
                     toDelete.remove(((RegistryEntry) i.next()).getName());
                 }
                 continue;
             }
 
             //the fragment has some changes, iterate over its entries...
             Vector entries = fragment.getEntries(regName);
             //... if it has entries related to this regsistry,
             if (entries != null) 
             {
                 // for all these entries
                 Enumeration en2 = entries.elements();
                 while (en2.hasMoreElements()) 
                 {
                     RegistryEntry entry = (RegistryEntry) en2.nextElement();
                     // update or add the entry in the registry
                     try 
                     {
                         if (registry.hasEntry(entry.getName())) 
                         {
                             if (registry
                                 .getEntry(entry.getName())
                                 .equals(entry)) 
                             {
                                 if ((verbose > 2)
                                     && logger.isDebugEnabled()) 
                                 {
                                     logger.debug(
                                         "DatabaseRegistryService: No changes to entry "
                                             + entry.getName());
                                 }
                             } 
                             else 
                             {
                                 if ((verbose > 1)
                                     && logger.isDebugEnabled()) 
                                 {
                                     logger.debug(
                                         "DatabaseRegistryService: Updating entry "
                                             + entry.getName()
                                             + " of class "
                                             + entry.getClass()
                                             + " to registry "
                                             + name);
                                 }
                                 registry.setLocalEntry(entry);
                                 // Initialize the entry index
                                 this.entryIndex.put(entry.getName(), location);
                                 ++fragCount;
                             }
                         } 
                         else 
                         {
                             registry.addLocalEntry(entry);
                             // Initialize the entry index
                             this.entryIndex.put(entry.getName(), location);
                             ++fragCount;
 
                             if ((verbose > 1)
                                 && logger.isDebugEnabled()) 
                             {
                                 logger.debug(
                                     "DatabaseRegistryService: Adding entry "
                                         + entry.getName()
                                         + " of class "
                                         + entry.getClass()
                                         + " to registry "
                                         + name);
                             }
                         }
                     } 
                     catch (RegistryException e) 
                     {
                         logger.error(
                             "DatabaseRegistryService: RegistryException while adding "
                                 + entry.getName()
                                 + "from "
                                 + location,
                             e);
                     }
                     //remove this entry from the delete list
                     toDelete.remove(entry.getName());
                 }
             }
 
             count += fragCount;
         }
 
         //now delete the entries not found in any fragment
         i = toDelete.iterator();
         while (i.hasNext()) 
         {
             String entryName = (String) i.next();
 
             if ((verbose > 1) && logger.isDebugEnabled()) 
             {
                 logger.debug(
                     "DatabaseRegistryService: removing entry " + entryName);
             }
             //TODO may  be I will  do it later 
             //it should  delete only portlets which  is coming from  database
             
             //registry.removeLocalEntry(entryName);
         }
 
         if ((verbose > 1) && logger.isDebugEnabled()) 
         {
             logger.debug(
                 "DatabaseRegistryService: Merged "
                     + count
                     + " entries and deleted "
                     + toDelete.size()
                     + " in "
                     + name);
         }
     }
 
     // FileRegistry interface
 
     /*** Refresh the state of the registry implementation. Should be called
      *   whenever the underlying fragments are modified
      */
     public void refresh() 
     {
         synchronized (watcher) 
         {
             Enumeration en = getNames();
             while (en.hasMoreElements()) 
             {
                 refresh((String) en.nextElement());
             }
         }
     }
 
     /***
         * Load and unmarshal a RegistryFragment from the file
         * @param file the absolute file path storing this fragment
         */
     public void loadFragment(String file ) 
     {
         try 
         {            
             RegistryFragment fragment = createFragment(file);
             //mark this fragment as changed
             fragment.setChanged(true);
 
             // if we get here, we successfully loaded the new fragment
             updateFragment(file, fragment);
 
         } 
         catch (Throwable t) 
         {
             logger.error(
                 "DatabaseRegistryService: Could not unmarshal: " + file,
                 t);
         }
     }
 
     /***
         * Read and unmarshal a fragment in memory
         * @param name the name of this fragment
         * @param persistent whether this fragment should be persisted on disk in
         * the registry
         */
     public void createFragment(
         String name,
         Reader reader,
         boolean persistent)
     {
         String file = null;
 
         try 
         {
         } 
         catch (Throwable t) 
         {
             logger.error(
                 "DatabaseRegistryService: Could not create fragment: " + file, t);
         } 
         finally 
         {
             try 
             {
                 reader.close();
             } 
             catch (Exception e) 
             {
                 logger.error(e); // At least log the exception.
             }
         }
     }
     /***
      * Marshal and save a RegistryFragment to disk
      * @param file the absolute file path storing this fragment
      */
     public void saveFragment(String file) 
     {
 
         /***
          * TODO I will  implement this 
          * should go  to  database
          */
 
     }
     /***
      * Remove a fragment from storage
      * @param file the absolute file path storing this fragment
      */
     public void removeFragment(String file) 
     {
         RegistryFragment fragment = (RegistryFragment) fragments.get(file);
 
         if (fragment != null) 
         {
             synchronized (entryIndex) 
             {
                 // clear the entry index
                 Iterator i = entryIndex.keySet().iterator();
                 while (i.hasNext()) 
                 {
                     if (file.equals(entryIndex.get(i.next()))) 
                     {
                         i.remove();
                     }
                 }
 
                 // make sure the keys & entries are freed for this fragment
                 // only the entries not replaced by the next registry refresh will
                 // stay in memory
                 fragment.clear();
                 // remove the actual fragment from memory
                 fragments.remove(file);
             }
         }
     }
     
     /***
      * Updates a fragment in storage and the associated entryIndex
      */
     protected void updateFragment(String name, RegistryFragment fragment) 
     {
         synchronized (entryIndex) 
         {
             // remove the old keys
             Iterator i = entryIndex.keySet().iterator();
             while (i.hasNext()) 
             {
                 if (name.equals(entryIndex.get(i.next()))) 
                 {
                     i.remove();
                 }
             }
             // store the new fragment
             fragments.put(name, fragment);
 
             // recreate the index entries (only this fragment)
 
             Enumeration enum = fragment.keys();
             while (enum.hasMoreElements()) 
             {
                 String strReg = (String) enum.nextElement();
                 Vector v = fragment.getEntries(strReg);
                 for (int counter = 0; counter < v.size(); counter++) 
                 {
                     RegistryEntry str = (RegistryEntry) v.elementAt(counter);
                     entryIndex.put(str.getName(), name);
                 }
             }
         }
     }
 
     //class  specific implementation 
     private static List getData(String name) 
     {
         List list = null;
         try 
         {        
             DBRegistry BaseClass = (DBRegistry) baseClass.get(name);
             if (BaseClass != null) 
             {
                 list = BaseClass.getXREGDataFromDb();
             }
             else
             {
                 logger.warn(
                     "DatabaseRegistryService: Base class  for service " + name + " not found");
             }
         } 
         catch (Exception ex) 
         {
             logger.warn(
                 "DatabaseRegistryService: Base class  for service " + name + " not found");
         }
         return list;
     }
     
     private RegistryFragment createFragment(String regName) 
     {
         RegistryFragment fragment = (RegistryFragment) fragments.get(regName);
 
         //Fragment can be (and sometimes is, but should not be) null
         if (fragment == null) 
         {
             fragment = new RegistryFragment();
             fragment.put(regName, new Vector());
         } 
         else 
         {
             Vector vectRegistry = (Vector) fragment.get(regName);
             if (vectRegistry == null) 
             {
                 fragment.put(regName, new Vector());
             }
         }
         List entries = getData(regName);
         if (entries != null) 
         {
             for (int i = 0; i < entries.size(); i++) 
             {
                 fragment.setEntry(regName, (RegistryEntry) entries.get(i));
                 // mark this fragment so that it's persisted next time
                 // the registry watcher is running
                 fragment.setDirty(true);
             }
         }
         else
         {            
             logger.warn(
                 "DatabaseRegistryService:no data fouund for service " + name );
 
         }
         return fragment;
 
     }
 }