package org.trails.record;

 import java.util.Arrays;

 import java.util.List;

 import org.apache.tapestry.record.PersistentPropertyDataEncoder;

 import org.apache.tapestry.services.DataSqueezer;

 /**

  * Responsible for squeezing lists of {@link org.apache.tapestry.record.PropertyChange}s back and

  * forth to a URL safe encoded string.

  */

 public class SqueezerDataEncoder implements PersistentPropertyDataEncoder

 {

         DataSqueezer dataSqueezer;

         public void setDataSqueezer(DataSqueezer dataSqueezer)

         {

                 this.dataSqueezer = dataSqueezer;

         }

         public String encodePageChanges(List list)

         {

                 Object[] objects = new Object[list.size()];

                 objects = list.toArray(objects);

                 String[] results = dataSqueezer.squeeze(objects);

                 return arrayToString(results);

         }

         public List decodePageChanges(String s)

         {

                 String[] strings = s.trim().substring(1, s.length() - 1).split(",");

                 Object[] objects = dataSqueezer.unsqueeze(strings);

                 return Arrays.asList(objects);

         }

         public String arrayToString(Object[] a)

         {

                 if (a == null)

                         return "null";

                 int iMax = a.length - 1;

                 if (iMax == -1)

                         return "{}";

                 StringBuilder b = new StringBuilder();

                 b.append('{');

                 for (int i = 0; ; i++)

                 {

                         b.append(String.valueOf(a[i]));

                         if (i == iMax)

                                 return b.append('}').toString();

                         b.append(",");

                 }

         }

 }