/**
    * This file Copyright (c) 2011-2013 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.rendering.template.assignment;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import javax.inject.Inject;
  import javax.inject.Singleton;
  import javax.jcr.Node;
  import javax.jcr.RepositoryException;
  import javax.jcr.Session;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import info.magnolia.cms.i18n.Messages;
  import info.magnolia.cms.i18n.MessagesManager;
  import info.magnolia.cms.security.PermissionUtil;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.jcr.util.NodeTypes;
  import info.magnolia.jcr.util.NodeUtil;
  import info.magnolia.registry.RegistrationException;
  import info.magnolia.rendering.template.TemplateAvailability;
  import info.magnolia.rendering.template.TemplateDefinition;
  import info.magnolia.rendering.template.registry.TemplateDefinitionRegistry;
  
  
  /**
   * Uses the template id stored in the node's meta data.
   */
  @Singleton
  public class MetaDataBasedTemplateDefinitionAssignment implements TemplateDefinitionAssignment {
  
      private static final String DELETED_PAGE_TEMPLATE = "adminInterface:mgnlDeleted";
  
      private static final Logger log = LoggerFactory.getLogger(MetaDataBasedTemplateDefinitionAssignment.class);
  
      private TemplateDefinitionRegistry templateDefinitionRegistry;
  
      @Inject
      public MetaDataBasedTemplateDefinitionAssignment(TemplateDefinitionRegistry templateDefinitionRegistry) {
          this.templateDefinitionRegistry = templateDefinitionRegistry;
      }
  
      @Override
      public String getAssignedTemplate(Node content) throws RepositoryException {
          return NodeTypes.Renderable.getTemplate(content);
      }
  
      @Override
      public TemplateDefinition getAssignedTemplateDefinition(Node content) throws RegistrationException {
          final String templateId;
          try {
              templateId = getAssignedTemplate(content);
          } catch (RepositoryException e) {
              throw new RegistrationException("Could not determine assigned template", e);
          }
          if (templateId == null) {
              throw new RegistrationException("No template definition assigned");
          }
          return templateDefinitionRegistry.getTemplateDefinition(templateId);
      }
  
      /**
       * Get the Template that could be used for the provided content as a default.
       */
     @Override
     public TemplateDefinition getDefaultTemplate(Node content) {
 
         // try to use the same as the parent
         TemplateDefinition parentTemplate = null;
         try {
             parentTemplate = getAssignedTemplateDefinition(content.getParent());
         } catch (RepositoryException e) {
             log.error("Failed to determine template assigned to parent of node: " + NodeUtil.getNodePathIfPossible(content), e);
         } catch (RegistrationException e) {
             // No template assigned or the assigned template is missing
         }
 
         if (parentTemplate != null && isAvailable(content, parentTemplate)) {
             return parentTemplate;
         }
 
         // otherwise use the first available template
         Collection<TemplateDefinition> templates = getAvailableTemplates(content);
         if (templates.isEmpty()) {
             return null;
         }
 
         return templates.iterator().next();
     }
 
     @Override
     public Collection<TemplateDefinition> getAvailableTemplates(Node content) {
 
         try {
             if (content != null && NodeUtil.hasMixin(content, NodeTypes.Deleted.NAME)) {
                 return Collections.singleton(templateDefinitionRegistry.getTemplateDefinition(DELETED_PAGE_TEMPLATE));
             }
         } catch (RepositoryException e) {
             log.error("Failed to check node for deletion status.", e);
         } catch (RegistrationException e) {
             log.error("Deleted content template is not correctly registered.", e);
         }
 
         final ArrayList<TemplateDefinition> availableTemplateDefinitions = new ArrayList<TemplateDefinition>();
         final Collection<TemplateDefinition> templateDefinitions = templateDefinitionRegistry.getTemplateDefinitions();
         for (TemplateDefinition templateDefinition : templateDefinitions) {
             if (isTemplateAvailable(content, templateDefinition)) {
                 availableTemplateDefinitions.add(templateDefinition);
             }
         }
 
         Collections.sort(availableTemplateDefinitions, new Comparator<TemplateDefinition>() {
 
             @Override
             public int compare(TemplateDefinition lhs, TemplateDefinition rhs) {
                 return getI18nTitle(lhs).compareTo(getI18nTitle(rhs));
             }
 
             private String getI18nTitle(TemplateDefinition templateDefinition) {
                 Messages messages = MessagesManager.getMessages(templateDefinition.getI18nBasename());
                 return messages.getWithDefault(templateDefinition.getTitle(), templateDefinition.getTitle());
             }
         });
 
         return availableTemplateDefinitions;
     }
 
     protected boolean isTemplateAvailable(Node content, TemplateDefinition templateDefinition) {
         return hasReadAccess(content) &&
                 isVisible(templateDefinition) &&
                 isAvailable(content, templateDefinition);
     }
 
     protected boolean isVisible(TemplateDefinition templateDefinition) {
         return templateDefinition.getVisible() == null || templateDefinition.getVisible();
     }
 
     protected boolean isAvailable(Node content, TemplateDefinition templateDefinition) {
         TemplateAvailability templateAvailability = templateDefinition.getTemplateAvailability();
         return templateAvailability == null || templateAvailability.isAvailable(content, templateDefinition);
     }
 
     protected boolean hasReadAccess(Node content) {
         try {
             // should not fact that we are able to get path already show that we can read this node???
             // ... unless of course this "content" was created with system session ... so make sure we check using user session and not the node session
             return PermissionUtil.isGranted(
                     MgnlContext.getJCRSession(content.getSession().getWorkspace().getName()),
                     content.getPath(),
                     Session.ACTION_READ);
         } catch (RepositoryException e) {
             return false;
         }
     }
 }