/*
 * JBoss, a division of Red Hat
 * Copyright 2011, Red Hat Middleware, LLC, and individual
 * contributors as indicated by the @authors tag. See the
 * copyright.txt in the distribution for a full listing of
 * individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.gatein.pc.federation.impl;

import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;
import org.gatein.pc.api.InvokerUnavailableException;
import org.gatein.pc.api.NoSuchPortletException;
import org.gatein.pc.api.Portlet;
import org.gatein.pc.api.PortletContext;
import org.gatein.pc.api.PortletInvoker;
import org.gatein.pc.api.PortletInvokerException;
import org.gatein.pc.api.PortletStateType;
import org.gatein.pc.api.PortletStatus;
import org.gatein.pc.api.invocation.PortletInvocation;
import org.gatein.pc.api.invocation.response.PortletInvocationResponse;
import org.gatein.pc.api.state.DestroyCloneFailure;
import org.gatein.pc.api.state.PropertyChange;
import org.gatein.pc.api.state.PropertyMap;
import org.gatein.pc.federation.FederatedPortletInvoker;
import org.gatein.pc.federation.FederatingPortletInvoker;
import org.gatein.pc.federation.PortletInvokerResolver;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * @author <a href="mailto:julien@jboss.org">Julien Viet</a>
 * @author <a href="mailto:chris.laprun@jboss.com">Chris Laprun</a>
 * @version $Revision: 5918 $
 * @since 2.4
 */
public class FederatingPortletInvokerService implements FederatingPortletInvoker
{

   /** . */
   private static final Log                             log             =
                                                            ExoLogger.getLogger(FederatingPortletInvokerService.class);

   /** The registred FederatedPortletInvokers. */
   private volatile Map<String, FederatedPortletInvoker> invokerCache = new HashMap<String, FederatedPortletInvoker>();

   private PortletInvokerResolver portletResolver = PortletInvokerResolver.DEFAULT_RESOLVER;

   public synchronized FederatedPortletInvoker registerInvoker(String federatedId, PortletInvoker federatedInvoker)
   {
      if (federatedId == null)
      {
         throw new IllegalArgumentException("No null id");
      }
      if (federatedInvoker == null)
      {
         throw new IllegalArgumentException("No null invoker");
      }
      if (invokerCache.containsKey(federatedId))
      {
         throw new IllegalArgumentException("Attempting dual registration of " + federatedId);
      }

      Map<String, FederatedPortletInvoker> copy = new HashMap<String, FederatedPortletInvoker>(invokerCache);
      FederatedPortletInvokerService invoker = new FederatedPortletInvokerService(this, federatedId, federatedInvoker);
      copy.put(federatedId, invoker);
      invokerCache = copy;
      return invoker;
   }

   public synchronized void unregisterInvoker(String federatedId)
   {
      if (federatedId == null)
      {
         throw new IllegalArgumentException("No null id accepted");
      }
      if (!invokerCache.containsKey(federatedId) && !portletResolver.knows(federatedId))
      {
         throw new IllegalArgumentException("Attempting to unregister unknown invoker " + federatedId);
      }
      Map<String, FederatedPortletInvoker> copy = new HashMap<String, FederatedPortletInvoker>(invokerCache);
      copy.remove(federatedId);
      invokerCache = copy;
   }

   public FederatedPortletInvoker getFederatedInvoker(String federatedId) throws IllegalArgumentException
   {
      if (federatedId == null)
      {
         throw new IllegalArgumentException("No null id provided");
      }

      try
      {
         return getOrResolveFederatedInvoker(federatedId, null);
      }
      catch (NoSuchPortletException e)
      {
         return null;
      }
   }

   private FederatedPortletInvoker getOrResolveFederatedInvoker(String federatedId, String compoundPortletId) throws NoSuchPortletException
   {
      // check cache first and then see if we can resolve the invoker if we didn't hit the cache
      FederatedPortletInvoker federatedPortletInvoker = invokerCache.get(federatedId);
      if (federatedPortletInvoker == null)
      {
         federatedPortletInvoker = portletResolver.resolvePortletInvokerFor(federatedId, this, compoundPortletId);
         if (federatedPortletInvoker != null)
         {
            synchronized (this)
            {
               Map<String, FederatedPortletInvoker> copy = new HashMap<String, FederatedPortletInvoker>(invokerCache);
               copy.put(federatedId, federatedPortletInvoker); // put newly resolved invoker in cache
               invokerCache = copy;
            }
         }
      }
      return federatedPortletInvoker;
   }

   public Collection<String> getFederatedInvokerIds()
   {
      final Collection<String> resolvedIds = getResolvedInvokerIds();
      final Collection<String> resolvableIds = portletResolver.getKnownInvokerIds();
      final HashSet<String> ids = new HashSet<String>(resolvedIds.size() + resolvableIds.size());
      ids.addAll(resolvedIds);
      ids.addAll(resolvableIds);

      return ids;
   }

   public Collection<String> getResolvedInvokerIds()
   {
      return invokerCache.keySet();
   }

   public boolean isResolved(String federatedId) throws IllegalArgumentException
   {
      return invokerCache.containsKey(federatedId);
   }

   // PortletInvoker implementation ************************************************************************************

   public Set<Portlet> getPortlets() throws PortletInvokerException
   {
      return getPortlets(true, true);
   }

   private Set<Portlet> getPortlets(boolean includeRemotePortlets, boolean includeLocalPortlets) throws PortletInvokerException
   {
      LinkedHashSet<Portlet> portlets = new LinkedHashSet<Portlet>();
      for (String invokerId : getFederatedInvokerIds())
      {
         if (LOCAL_PORTLET_INVOKER_ID.equals(invokerId))
         {
            // skip invoker if it's local and we don't want local portlets
            if (!includeLocalPortlets)
            {
               continue;
            }
         }
         else
         {
            // skip invoker if it's remote and we don't want remote portlets
            if (!includeRemotePortlets)
            {
               continue;
            }
         }

         final FederatedPortletInvoker federated = getFederatedInvoker(invokerId);

         // skip the invoker if it isn't active
         if(!federated.isActive())
         {
            log.info("PortletInvoker with id: " + invokerId + " was skipped because it isn't active.");
            continue;
         }

         try
         {
            Set<Portlet> offeredPortlets = federated.getPortlets();
            portlets.addAll(offeredPortlets);
         }
         catch (InvokerUnavailableException e)
         {
            Throwable cause = e.getCause();
            log.debug(e.fillInStackTrace());
            log.warn("PortletInvoker with id: " + invokerId + " is not available.\nReason: " + e.getMessage()
               + "\nCaused by:\n" + (cause == null ? e : cause));
         }
      }

      return portlets;
   }

   public Set<Portlet> getLocalPortlets() throws PortletInvokerException
   {
      return getPortlets(false, true);
   }

   public Set<Portlet> getRemotePortlets() throws PortletInvokerException
   {
      return getPortlets(true, false);
   }

   public Portlet getPortlet(PortletContext compoundPortletContext) throws IllegalArgumentException, PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.getPortlet(compoundPortletContext);
   }

   public PortletStatus getStatus(PortletContext portletContext) throws IllegalArgumentException, PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(portletContext);
      return federated.getStatus(portletContext);
   }

   public PortletInvocationResponse invoke(PortletInvocation invocation) throws PortletInvokerException
   {
      PortletContext compoundPortletContext = invocation.getTarget();
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.invoke(invocation);
   }

   public PortletContext createClone(PortletStateType stateType, PortletContext compoundPortletContext) throws PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.createClone(stateType, compoundPortletContext);
   }

   public List<DestroyCloneFailure> destroyClones(List<PortletContext> portletContexts) throws IllegalArgumentException, PortletInvokerException, UnsupportedOperationException
   {
      if (portletContexts == null)
      {
         throw new IllegalArgumentException("No null list accepted");
      }
      if (portletContexts.size() == 0)
      {
         return Collections.emptyList();
      }

      // Get the invoker and check that we address only one invoker (for now)
      PortletInvoker invoker = null;
      for (PortletContext compoundPortletContext : portletContexts)
      {
         PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
         if (invoker == null)
         {
            invoker = federated;
         }
         else if (!invoker.equals(federated))
         {
            throw new PortletInvokerException("Cannot destroy portlet lists that requires more than one federated invoker");
         }
      }

      //
      return invoker.destroyClones(portletContexts);
   }

   public PropertyMap getProperties(PortletContext compoundPortletContext, Set<String> keys) throws PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.getProperties(compoundPortletContext, keys);
   }

   public PropertyMap getProperties(PortletContext compoundPortletContext) throws PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.getProperties(compoundPortletContext);
   }

   public PortletContext setProperties(PortletContext compoundPortletContext, PropertyChange[] changes) throws IllegalArgumentException, PortletInvokerException, UnsupportedOperationException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.setProperties(compoundPortletContext, changes);
   }

   public PortletContext exportPortlet(PortletStateType stateType, PortletContext compoundPortletContext)
      throws PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.exportPortlet(stateType, compoundPortletContext);
   }

   public PortletContext importPortlet(PortletStateType stateType, PortletContext compoundPortletContext)
      throws PortletInvokerException
   {
      PortletInvoker federated = getFederatedPortletInvokerFor(compoundPortletContext);
      return federated.importPortlet(stateType, compoundPortletContext);
   }

   public boolean isActive()
   {
      return true;
   }

   public synchronized void setPortletInvokerResolver(PortletInvokerResolver portletResolver)
   {
      if (portletResolver == null)
      {
         this.portletResolver = PortletInvokerResolver.DEFAULT_RESOLVER;
      }
      else
      {
         this.portletResolver = portletResolver;
      }
   }

   // Support methods **************************************************************************************************

   /**
    * Retrieves the portlet invoker associated with the specified compound portlet id or null if it is not found.
    *
    * @param compoundPortletContext the portlet context for which the invoker is to be retrieved
    * @return the portlet invoker associated with the specified compound portlet id
    * @throws IllegalArgumentException if the compound portlet id is not well formed or null
    * @throws NoSuchPortletException   if not such portlet exist
    */
   protected FederatedPortletInvoker getFederatedPortletInvokerFor(PortletContext compoundPortletContext) throws IllegalArgumentException, NoSuchPortletException
   {
      if (compoundPortletContext == null)
      {
         throw new IllegalArgumentException("No null portlet id accepted");
      }

      PortletContext.PortletContextComponents components = compoundPortletContext.getComponents();
      final String compoundPortletId = compoundPortletContext.getId();
      if (components == null)
      {
         // force intepretation
         compoundPortletContext = PortletContext.createPortletContext(compoundPortletId, true);
         components = compoundPortletContext.getComponents();
      }

      final String invokerId = components.getInvokerName();
      if (invokerId == null)
      {
         throw new IllegalArgumentException("Bad portlet id format " + compoundPortletId);
      }

      return getOrResolveFederatedInvoker(invokerId, compoundPortletId);
   }
}
