/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.myfaces.trinidad.util;
  
  import java.io.File;
  import java.io.IOException;
  
  import java.io.UnsupportedEncodingException;
  
  import java.net.JarURLConnection;
  import java.net.URL;
  import java.net.URLConnection;
  
  import java.net.URLDecoder;
  
  import java.net.URLEncoder;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import javax.servlet.http.HttpServletResponse;
  
  public final class URLUtils
  {
    private URLUtils()
    {
    }
  
    public static long getLastModified(URL url) throws IOException
    {
      if ("file".equals(url.getProtocol()))
      {
        String externalForm = url.toExternalForm();
        // Remove the "file:"
        File file = new File(externalForm.substring(5));
  
        return file.lastModified();
      }
      else
      {
        return getLastModified(url.openConnection());
      }
    }
  
    public static long getLastModified(URLConnection connection) throws IOException
    {
      long modified;
      if (connection instanceof JarURLConnection)
      {
        // The following hack is required to work-around a JDK bug.
        // getLastModified() on a JAR entry URL delegates to the actual JAR file
        // rather than the JAR entry.
        // This opens internally, and does not close, an input stream to the JAR
        // file.
        // In turn, you cannot close it by yourself, because it's internal.
        // The work-around is to get the modification date of the JAR file
        // manually,
        // and then close that connection again.
  
        URL jarFileUrl = ((JarURLConnection) connection).getJarFileURL();
        URLConnection jarFileConnection = jarFileUrl.openConnection();
  
        try
        {
          modified = jarFileConnection.getLastModified();
        }
        finally
        {
          try
          {
            jarFileConnection.getInputStream().close();
          }
          catch (Exception exception)
          {
            // Ignored
          }
        }
      }
      else
      {
        modified = connection.getLastModified();
     }
 
     return modified;
   }
   
   /**
    * Takes a URL that is not escaped for javascript and escapes it   
    */
   public static String jsEncodeURL(String url, String charset)
     throws UnsupportedEncodingException
   {
     StringBuilder sb = new StringBuilder(url.length() * 2);
     for(char c: url.toCharArray())
     {
       if ((c >= 'A' && c <= 'Z') ||
             (c >= 'a' && c <= 'z') ||
             (c >= '0' && c <= '9') ||
             _JS_IMMUNE_CHARS.indexOf(c) > -1
          )
       {
         //Valid character.  Just append.
         sb.append(c);
       }
       else
       {        
         //This is an invalid character, so we encode need to get the bytes
         for(byte b: Character.toString(c).getBytes(charset))
         {
           sb.append("\\x")
             .append(String.format("%02X", b));
         }
       }
     }
     return sb.toString();
   }
     
   /**
    * Encodes a URL (with or without an existing query string) such that the value in the params map are added to them.
    * A valid character encoding must be provided to ensure the parameters are encoded properly.
    * 
    * @param url the base URL
    * @param params the map of parameters to add, or <code>null</code>
    * @param characterResponseEncoding the character response encoding
    * @return the properly encoded url
    * 
    * @throws UnsupportedOperationException if the encoding is not supported.
    */
   public static String encodeURL(String url, Map<String, List<String>> params, String characterResponseEncoding)
   {
     String fragment = null;
     String queryString = null;
     Map<String, List<String>> paramMap = null;
 
     //extract any URL fragment
     int index = url.indexOf(_URL_FRAGMENT_SEPERATOR);
     if (index != -1)
     {
       fragment = url.substring(index+1);
       url = url.substring(0,index);
     }
 
     //extract the current query string and add the params to the paramMap
     index = url.indexOf(_URL_QUERY_SEPERATOR);
     if (index != -1)
     {
       queryString = url.substring(index + 1);
       url = url.substring(0, index);
       String[] nameValuePairs = queryString.split(_URL_PARAM_SEPERATOR);
       for (int i = 0; i < nameValuePairs.length; i++)
       {
         String[] currentPair = nameValuePairs[i].split(_URL_NAME_VALUE_PAIR_SEPERATOR);
 
         ArrayList<String> value = new ArrayList<String>(1);
         try
         {
           value.add(currentPair.length > 1
                     ? URLDecoder.decode(currentPair[1], characterResponseEncoding)
                     : "");
         }
         catch (UnsupportedEncodingException e)
         {
           //shouldn't ever get here
           throw new UnsupportedOperationException("Encoding type=" + characterResponseEncoding
                                                           + " not supported", e);
         }
         if (paramMap == null)
         {
           paramMap = new HashMap<String, List<String>>();
         }
         paramMap.put(currentPair[0], value);
       }
     }
 
     //add/update with new params on the paramMap
     if (params != null && params.size() > 0)
     {
       for (Map.Entry<String, List<String>> pair : params.entrySet())
       {
         if (pair.getKey() != null && pair.getKey().trim().length() != 0)
         {
           if (paramMap == null)
           {
             paramMap = new HashMap<String, List<String>>();
           }
           paramMap.put(pair.getKey(), pair.getValue());
         }
       }
     }
 
     // start building the new URL
     StringBuilder newUrl = new StringBuilder(url);
 
     //now add the updated param list onto the url
     if (paramMap != null && paramMap.size()>0)
     {
       boolean isFirstPair = true;
       for (Map.Entry<String, List<String>> pair : paramMap.entrySet())
       {
         for (String value : pair.getValue())
         {
           if (!isFirstPair)
           {
             newUrl.append(_URL_PARAM_SEPERATOR);
           }
           else
           {
             newUrl.append(_URL_QUERY_SEPERATOR);
             isFirstPair = false;
           }
 
           newUrl.append(pair.getKey());
           newUrl.append(_URL_NAME_VALUE_PAIR_SEPERATOR);
           try
           {
             newUrl.append(URLEncoder.encode(value,characterResponseEncoding));
           }
           catch (UnsupportedEncodingException e)
           {
             //shouldn't ever get here
             throw new UnsupportedOperationException("Encoding type=" + characterResponseEncoding
                                                   + " not supported", e);
           }
         }
       }    
     }
     
     //add the fragment back on (if any)
     if (fragment != null)
     {
       newUrl.append(_URL_FRAGMENT_SEPERATOR + fragment);
     }
     
     return newUrl.toString();
   }
   
   private static final String _URL_PARAM_SEPERATOR="&";
   private static final String _URL_QUERY_SEPERATOR="?";
   private static final String _URL_FRAGMENT_SEPERATOR="#";
   private static final String _URL_NAME_VALUE_PAIR_SEPERATOR="=";
   private static final String _JS_IMMUNE_CHARS=",._";
 }