/**
    * This file Copyright (c) 2003-2015 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.cms.beans.config;
  
  import info.magnolia.cms.core.Content;
  import info.magnolia.cms.core.HierarchyManager;
  import info.magnolia.cms.core.ItemType;
  import info.magnolia.cms.util.NodeDataUtil;
  import info.magnolia.cms.util.ObservationUtil;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.repository.RepositoryConstants;
  
  import java.util.Collection;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.Map;
  
  import javax.jcr.PathNotFoundException;
  import javax.jcr.RepositoryException;
  import javax.jcr.observation.EventIterator;
  import javax.jcr.observation.EventListener;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Manages mappings of file extensions with their MIME types and icon.
   */
  public class MIMEMapping {
      private static final Logger log = LoggerFactory.getLogger(MIMEMapping.class);
  
      public static final String ICONS_PATH = "/.resources/file-icons/";
      public static final String DEFAULT_ICON = ICONS_PATH + "general.png";
      private static final String NODEPATH = "/server/MIMEMapping";
      public static final String DEFAULT_ICON_STYLE = "icon-file";
  
      private static Map<String, MIMEMappingItem> cachedContent = new Hashtable<String, MIMEMappingItem>();
      private static final String DEFAULT_CHAR_ENCODING = "UTF-8";
  
      /**
       * Used to keep the configuration in memory.
       */
      protected static class MIMEMappingItem {
  
          protected String ext;
  
          protected String mime;
  
          protected String icon;
  
          protected String iconStyle;
      }
  
  
      /**
       * Utility class, don't instantiate.
       */
      private MIMEMapping() {
          // unused
      }
  
      /**
       * Reads all configured mime mapping (config/server/MIMEMapping).
       */
      public static void init() {
          log.info("Initializing MIMEMapping from {}", NODEPATH);
          load();
         registerEventListener();
     }
 
     /**
      * Reads all configured mime mapping (config/server/MIMEMapping).
      */
     public static void load() {
         MIMEMapping.cachedContent.clear();
         try {
             final HierarchyManager hm = MgnlContext.getSystemContext().getHierarchyManager(RepositoryConstants.CONFIG);
 
             Collection<Content> mimeList = hm.getContent(NODEPATH).getChildren(ItemType.CONTENTNODE);
             MIMEMapping.cacheContent(mimeList);
             log.debug("MIMEMapping loaded from {}", NODEPATH);
         } catch (PathNotFoundException e) {
             log.warn("No MIMEMapping info configured at {}", NODEPATH);
         } catch (RepositoryException e) {
             log.error("Failed to load MIMEMapping: {}", e.getMessage(), e);
         }
     }
 
     public static void reload() {
         log.info("Reloading MIMEMapping from {}", NODEPATH);
         MIMEMapping.load();
     }
 
     /**
      * Register an event listener: reload cache configuration when something changes.
      */
     private static void registerEventListener() {
         log.info("Registering event listener for MIMEMapping");
 
         ObservationUtil.registerChangeListener(RepositoryConstants.CONFIG, NODEPATH, new EventListener() {
             @Override
             public void onEvent(EventIterator iterator) {
                 // reload everything
                 reload();
             }
         });
     }
 
     /**
      * Cache all MIME types configured.
      */
     private static void cacheContent(Collection<Content> mimeList) {
         Iterator<Content> iterator = mimeList.iterator();
         while (iterator.hasNext()) {
             Content c = iterator.next();
             try {
                 MIMEMappingItem item = new MIMEMappingItem();
                 item.ext = NodeDataUtil.getString(c, "extension", c.getName());
                 item.mime = c.getNodeData("mime-type").getString();
                 item.icon = NodeDataUtil.getString(c, "icon");
                 item.iconStyle = NodeDataUtil.getString(c, "iconStyle");
 
                 MIMEMapping.cachedContent.put(item.ext, item);
             } catch (Exception e) {
                 log.error("Failed to cache MIMEMapping");
             }
         }
     }
 
     /**
      * Get MIME type String.
      *
      * @param key extension for which MIME type is requested
      * @return MIME type
      */
     public static String getMIMEType(String key) {
         if (StringUtils.isEmpty(key)) {
             return StringUtils.EMPTY;
         }
         // check that the cached content contains the key first to avoid NPE when accessing 'mime'
         String loweredKey = key.toLowerCase();
         if (MIMEMapping.cachedContent.containsKey(loweredKey)) {
             return MIMEMapping.cachedContent.get(loweredKey).mime;
         }
 
         // this is expected by the caller
         return null;
 
     }
 
     /**
      * Returns the mime-type associated with this extension, or the server's default.
      */
     public static String getMIMETypeOrDefault(String extension) {
         String mimeType = getMIMEType(extension);
 
         if (StringUtils.isNotEmpty(mimeType)) {
             return mimeType;
         }
 
         if (StringUtils.isNotEmpty(extension)) {
             log.info("Cannot find MIME type for extension \"{}\"", extension);
         }
 
         String defaultExtension = ServerConfiguration.getInstance().getDefaultExtension();
         if (StringUtils.isBlank(defaultExtension)) {
             defaultExtension = "html";
         }
         return getMIMEType(defaultExtension);
     }
 
     public static String getContentEncoding(String contentType) {
         if (contentType != null) {
             int index = contentType.lastIndexOf(";");
             if (index > -1) {
                 String encoding = contentType.substring(index + 1).toLowerCase().trim();
                 encoding = encoding.replaceAll("charset=", StringUtils.EMPTY);
                 return encoding;
             }
         }
         return StringUtils.EMPTY;
     }
 
     public static String getContentEncodingOrDefault(String contentType) {
         final String characterEncoding = getContentEncoding(contentType);
 
         return (StringUtils.isEmpty(characterEncoding)) ? DEFAULT_CHAR_ENCODING : characterEncoding;
     }
 
     /**
      * Returns the icon used for rendering this type.
      *
      * @return the icon name
      */
     public static String getMIMETypeIcon(String extension) {
         MIMEMappingItem item = MIMEMapping.cachedContent.get(extension.toLowerCase());
         if (item != null) {
             return StringUtils.defaultIfEmpty(item.icon, DEFAULT_ICON);
         }
 
         return DEFAULT_ICON;
 
     }
 
     /**
      * Returns the icon css style name.
      *
      * @return icon css style name.
      */
     public static String getMIMETypeIconStyle(String mimeType) {
         String genericMimeType = StringUtils.substringBefore(mimeType, "/");
         MIMEMappingItem mimeMappingItem = null;
         for (MIMEMappingItem item : cachedContent.values()) {
             if (item.mime != null && item.mime.equals(mimeType) && StringUtils.isNotBlank(item.iconStyle)) {
                 mimeMappingItem = item;
                 break;
             }
             if (item.mime != null && item.mime.equals(genericMimeType) && StringUtils.isNotBlank(item.iconStyle)) {
                 mimeMappingItem = item;
             }
         }
         if (mimeMappingItem != null && StringUtils.isNotBlank(mimeMappingItem.iconStyle)) {
             return mimeMappingItem.iconStyle;
         }
         return DEFAULT_ICON_STYLE;
     }
 }