/**

  *  @author : Paul Taylor

  *  @author : Eric Farng

  *

  *  Version @version:$Id: AbstractFrameBodyUrlLink.java,v 1.13 2008/07/21 10:45:42 paultaylor Exp $

  *

  *  MusicTag Copyright (C)2003,2004

  *

  *  This library 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 library 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 library; if not,

  *  you can get a copy from http://www.opensource.org/licenses/lgpl-license.php or write to the Free Software

  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

  *

  *

  */

 package org.jaudiotagger.tag.id3.framebody;

 import org.jaudiotagger.logging.ErrorMessage;

 import org.jaudiotagger.tag.InvalidTagException;

 import org.jaudiotagger.tag.datatype.DataTypes;

 import org.jaudiotagger.tag.datatype.StringSizeTerminated;

 import org.jaudiotagger.tag.id3.valuepair.TextEncoding;

 import java.io.ByteArrayOutputStream;

 import java.io.UnsupportedEncodingException;

 import java.net.URLEncoder;

 import java.nio.ByteBuffer;

 import java.nio.charset.Charset;

 import java.nio.charset.CharsetEncoder;

 /**

  * Abstract superclass of all URL Frames

  */

 public abstract class AbstractFrameBodyUrlLink extends AbstractID3v2FrameBody

 {

     /**

      * Creates a new FrameBodyUrlLink datatype.

      */

     protected AbstractFrameBodyUrlLink()

     {

         super();

     }

     /**

      * Copy Constructor

      */

     protected AbstractFrameBodyUrlLink(AbstractFrameBodyUrlLink body)

     {

         super(body);

     }

     /**

      * Creates a new FrameBodyUrlLink datatype., set up with data.

      *

      * @param urlLink

      */

     public AbstractFrameBodyUrlLink(String urlLink)

     {

         setObjectValue(DataTypes.OBJ_URLLINK, urlLink);

     }

     /**

      * Creates a new FrameBodyUrlLink datatype.

      *

      * @throws InvalidTagException if unable to create framebody from buffer

      */

     protected AbstractFrameBodyUrlLink(ByteBuffer byteBuffer, int frameSize) throws InvalidTagException

     {

         super(byteBuffer, frameSize);

     }

     /**

      * Set URL Link

      *

      * @param urlLink

      */

     public void setUrlLink(String urlLink)

     {

         if (urlLink == null)

         {

             throw new IllegalArgumentException(ErrorMessage.GENERAL_INVALID_NULL_ARGUMENT.getMsg());

         }

         setObjectValue(DataTypes.OBJ_URLLINK, urlLink);

     }

     /**

      * Get URL Link

      *

      * @return the urllink

      */

     public String getUrlLink()

     {

         return (String) getObjectValue(DataTypes.OBJ_URLLINK);

     }

     /**

      * If the description cannot be encoded using the current encoding change the encoder

      */

     public void write(ByteArrayOutputStream tagBuffer)

     {

         CharsetEncoder encoder = Charset.forName(TextEncoding.CHARSET_ISO_8859_1).newEncoder();

         String origUrl = getUrlLink();

         if (!encoder.canEncode(origUrl))

         {

             //ALL W Frames only support ISO-8859-1 for the url itself, if unable to encode let us assume

             //the link just needs url encoding

             setUrlLink(encodeURL(origUrl));

             //We still cant convert so just set log error and set to blank to allow save to continue

             if (!encoder.canEncode(getUrlLink()))

             {

                 logger.warning(ErrorMessage.MP3_UNABLE_TO_ENCODE_URL.getMsg(origUrl));

                 setUrlLink("");

             }

             //it was ok, just note the modification made

             else

             {

                 logger.warning(ErrorMessage.MP3_URL_SAVED_ENCODED.getMsg(origUrl, getUrlLink()));

             }

         }

         super.write(tagBuffer);

     }

     /**

      *

      */

     protected void setupObjectList()

     {

         objectList.add(new StringSizeTerminated(DataTypes.OBJ_URLLINK, this));

     }

     /**

      * Encode url because may receive url already encoded or not, but we can only store as ISO8859-1

      *

      * @param url

      * @return

      */

     private String encodeURL(String url)

     {

         try

         {

             final String[] splitURL = url.split("(?<!/)/(?!/)", -1);

             final StringBuffer sb = new StringBuffer(splitURL[0]);

             for (int i = 1; i < splitURL.length; i++)

             {

                 sb.append("/").append(URLEncoder.encode(splitURL[i], "utf-8"));

             }

             return sb.toString();

         }

         catch (UnsupportedEncodingException uee)

         {

             //Should never happen as utf-8 is always availablebut in case it does we just return the utl

             //unmodified

             logger.warning("Uable to url encode because utf-8 charset not available:" + uee.getMessage());

             return url;

         }

     }

 }