/**
    * This file Copyright (c) 2009-2010 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.link;
  
  import info.magnolia.cms.beans.config.ContentRepository;
  import info.magnolia.cms.beans.config.URI2RepositoryManager;
  import info.magnolia.cms.core.Content;
  import info.magnolia.cms.core.HierarchyManager;
  import info.magnolia.cms.core.NodeData;
  import info.magnolia.context.MgnlContext;
  
  import java.io.UnsupportedEncodingException;
  import java.net.URLEncoder;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import javax.jcr.RepositoryException;
  
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Utility methods for various operations necessary for link transformations and handling.
   * @author had
   *
   */
  public class LinkUtil {
  
      /**
       * Pattern that matches external and mailto: links.
       */
      public static final Pattern EXTERNAL_LINK_PATTERN = Pattern.compile("^(\\w*://|mailto:|javascript:).*");
  
      public static final String DEFAULT_EXTENSION = "html";
  
      public static final String DEFAULT_REPOSITORY = ContentRepository.WEBSITE;
  
      // is this proxied or not? Tests says no.
      //private static final LinkTransformerManager linkManager = LinkTransformerManager.getInstance();
  
      /**
       * Pattern to find a link.
       */
      public static final Pattern LINK_OR_IMAGE_PATTERN = Pattern.compile(
          "(<(a|img|embed) " + // start <a or <img
          "[^>]*" +  // some attributes
          "(href|src)[ ]*=[ ]*\")" + // start href or src
          "([^\"]*)" + // the link
          "(\"" + // ending "
          "[^>]*" + // any attributes
          ">)"); // end the tag
  
      /**
       * Logger.
       */
      private static final Logger log = LoggerFactory.getLogger(LinkUtil.class);
  
  
      //-- conversions from UUID - singles
      /**
       * Transforms a uuid to a handle beginning with a /. This path is used to get the page from the repository.
       * The editor needs this kind of links.
       */
      public static String convertUUIDtoHandle(String uuid, String repository) throws LinkException {
          return LinkFactory.createLink(repository, uuid).getHandle();
      }
  
     /**
      * Transforms a uuid to an uri. It does not add the context path. In difference from {@link Link#getHandle()},
      * this method will apply all uri to repository mappings as well as i18n.
      */
     public static String convertUUIDtoURI(String uuid, String repository) throws LinkException {
         return LinkTransformerManager.getInstance().getAbsolute(false).transform(LinkFactory.createLink(repository, uuid));
     }
 
     //-- conversions to UUID - bulk
     /**
      * Parses provided html and transforms all the links to the magnolia format. Used during storing.
      * @param html html code with links to be converted
      * @return html with changed hrefs
      */
     public static String convertAbsoluteLinksToUUIDs(String html) {
         // get all link tags
         Matcher matcher = LINK_OR_IMAGE_PATTERN.matcher(html);
         StringBuffer res = new StringBuffer();
         while (matcher.find()) {
             final String href = matcher.group(4);
             if (!isExternalLinkOrAnchor(href)) {
                 try {
                     Link link = LinkFactory.parseLink(href);
                     String linkStr = LinkFactory.toPattern(link);
                     linkStr = StringUtils.replace(linkStr, "\\", "\\\\");
                     linkStr = StringUtils.replace(linkStr, "$", "\\$");
                     matcher.appendReplacement(res, "$1" + linkStr + "$5");
                 }
                 catch (LinkException e) {
                     // this is expected if the link is an absolute path to something else
                     // than content stored in the repository
                     matcher.appendReplacement(res, "$0");
                     log.debug("can't parse link", e);
                 }
             }
             else{
                 matcher.appendReplacement(res, "$0");
             }
         }
         matcher.appendTail(res);
         return res.toString();
     }
 
     //-- conversions from UUID - bulk
 
     /**
      * Converts provided html with links in UUID pattern format to any other kind of links based on provided link transformer.
      * @param str Html with UUID links
      * @param transformer Link transformer
      * @return converted html with links as created by provided transformer.
      * @see LinkTransformerManager
      */
     public static String convertLinksFromUUIDPattern(String str, LinkTransformer transformer) throws LinkException {
         Matcher matcher = LinkFactory.UUID_PATTERN.matcher(str);
         StringBuffer res = new StringBuffer();
         while (matcher.find()) {
             Link link = LinkFactory.createLink(matcher.group(1), matcher.group(2), matcher.group(5), matcher.group(7), matcher.group(8), matcher.group(10), matcher.group(12));
             String replacement = transformer.transform(link);
             // Replace "\" with "\\" and "$" with "\$" since Matcher.appendReplacement treats these characters specially
             replacement = StringUtils.replace(replacement, "\\", "\\\\");
             replacement = StringUtils.replace(replacement,"$", "\\$");
             matcher.appendReplacement(res, replacement);
         }
         matcher.appendTail(res);
         return res.toString();
     }
 
     public static String convertLinksFromUUIDPattern(String str) throws LinkException {
         LinkTransformer transformer = LinkTransformerManager.getInstance().getBrowserLink(null);
         return convertLinksFromUUIDPattern(str, transformer);
     }
     /**
      * Determines if the given link is internal and relative.
      */
     public static boolean isInternalRelativeLink(String href) {
         // TODO : this could definitely be improved
         return !isExternalLinkOrAnchor(href) && !href.startsWith("/");
     }
 
     /**
      * Determines whether the given link is external link or anchor (i.e. returns true for all non translatable links).
      */
     public static boolean isExternalLinkOrAnchor(String href) {
        return LinkUtil.EXTERNAL_LINK_PATTERN.matcher(href).matches() || href.startsWith("#");
     }
 
     /**
      * Make a absolute path relative. It adds ../ until the root is reached
      * @param absolutePath absolute path
      * @param url page to be relative to
      * @return relative path
      */
     public static String makePathRelative(String url, String absolutePath){
         String fromPath = StringUtils.substringBeforeLast(url, "/");
         String toPath = StringUtils.substringBeforeLast(absolutePath, "/");
 
         // reference to parent folder
         if (StringUtils.equals(fromPath, toPath) && StringUtils.endsWith(absolutePath, "/")) {
             return ".";
         }
 
         String[] fromDirectories = StringUtils.split(fromPath, "/");
         String[] toDirectories = StringUtils.split(toPath, "/");
 
         int pos=0;
         while(pos < fromDirectories.length && pos < toDirectories.length && fromDirectories[pos].equals(toDirectories[pos])){
             pos++;
         }
 
         String rel = "";
         for(int i=pos; i < fromDirectories.length; i++ ){
             rel += "../";
         }
 
         for(int i=pos; i < toDirectories.length; i++ ){
             rel = rel + toDirectories[i] + "/";
         }
 
         rel += StringUtils.substringAfterLast(absolutePath, "/");
 
         return rel;
     }
 
     /**
      * Maps a path to a repository.
      * @param path URI
      * @return repository denoted by the provided URI.
      */
     public static String mapPathToRepository(String path) {
         String repository = URI2RepositoryManager.getInstance().getRepository(path);
         if(StringUtils.isEmpty(repository)){
             repository = DEFAULT_REPOSITORY;
         }
         return repository;
     }
 
     /**
      * Appends a parameter to the given url, using ?, or & if there are already
      * parameters in the given url. <strong>Warning:</strong> It does not
      * <strong>replace</strong> an existing parameter with the same name.
      */
     public static void addParameter(StringBuffer uri, String name, String value) {
         if (uri.indexOf("?") < 0) {
             uri.append('?');
         } else {
             uri.append('&');
         }
         uri.append(name).append('=');
         try {
             uri.append(URLEncoder.encode(value, "UTF-8"));
         } catch (UnsupportedEncodingException e) {
             throw new RuntimeException("It seems your system does not support UTF-8 !?", e);
         }
     }
 
     /**
      * Creates absolute link including context path for provided node data.
      * @param nodedata Node data to create link for.
      * @return Absolute link to the provided node data.
      * @see AbstractI18nContentSupport
      */
     public static String createAbsoluteLink(NodeData nodedata) throws LinkException {
         if(nodedata == null || !nodedata.isExist()){
             return null;
         }
         return LinkTransformerManager.getInstance().getAbsolute().transform(LinkFactory.createLink(nodedata));
     }
 
     /**
      * Creates absolute link including context path to the provided content and performing all URI2Repository mappings and applying locales.
      * @param uuid UUID of content to create link to.
      * @param repository Name of the repository where content is located.
      * @return Absolute link to the provided content.
      * @see AbstractI18nContentSupport
      */
     public static String createAbsoluteLink(String repository, String uuid) throws RepositoryException {
         HierarchyManager hm = MgnlContext.getHierarchyManager(repository);
         Content node = hm.getContentByUUID(uuid);
         return createAbsoluteLink(node);
     }
 
     /**
      * Creates absolute link including context path to the provided content and performing all URI2Repository mappings and applying locales.
      * @param content content to create link to.
      * @return Absolute link to the provided content.
      * @see AbstractI18nContentSupport
      */
     public static String createAbsoluteLink(Content content) {
         if(content == null){
             return null;
         }
         return LinkTransformerManager.getInstance().getAbsolute().transform(LinkFactory.createLink(content));
     }
 
     /**
      * Creates a complete url to access given content from external systems applying all the URI2Repository mappings and locales.
      * @param content
      * @return
      */
     public static String createExternalLink(Content content) {
         if(content == null){
             return null;
         }
         return LinkTransformerManager.getInstance().getCompleteUrl().transform(LinkFactory.createLink(content));
     }
 
     /**
      * Creates link guessing best possible link format from current site and provided node.
      * @param nodedata Node data to create link for.
      * @return Absolute link to the provided node data.
      * @see AbstractI18nContentSupport
      */
     public static String createLink(Content node) {
         if(node == null){
             return null;
         }
         return LinkTransformerManager.getInstance().getBrowserLink(node.getHandle()).transform(LinkFactory.createLink(node));
     }
 
     /**
      * Creates link guessing best possible link format from current site and provided node data.
      * @param nodedata Node data to create link for.
      * @return Absolute link to the provided node data.
      * @see AbstractI18nContentSupport
      */
     public static String createLink(NodeData nodedata) throws LinkException {
         if(nodedata == null || !nodedata.isExist()){
             return null;
         }
         try {
             return LinkTransformerManager.getInstance().getBrowserLink(nodedata.getParent().getHandle()).transform(LinkFactory.createLink(nodedata));
         } catch (RepositoryException e) {
             throw new LinkException(e.getMessage(), e);
         }
     }
 
     /**
      * Creates link guessing best possible link format from current site and provided content.
      * @param uuid UUID of content to create link to.
      * @param repository Name of the repository where content is located.
      * @return Absolute link to the provided content.
      * @see AbstractI18nContentSupport
      */
     public static String createLink(String repository, String uuid) throws RepositoryException {
         HierarchyManager hm = MgnlContext.getHierarchyManager(repository);
         Content node = hm.getContentByUUID(uuid);
         return createLink(node);
     }
 }