CacheControlHeaderParser.java

/*
 * Copyright 2014 cruxframework.org.
 * 
 * Licensed 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.cruxframework.crux.core.server.rest.util.header;

import java.util.List;

import org.cruxframework.crux.core.server.rest.core.CacheControl;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class CacheControlHeaderParser 
{
   public static CacheControl fromString(String value) throws IllegalArgumentException
   {
      if (value == null) throw new IllegalArgumentException("Cache-Control value is null");
      CacheControl result = new CacheControl();

      String[] directives = value.split(",");
      for (String directive : directives)
      {
         directive = directive.trim();

         String[] nv = directive.split("=");
         String name = nv[0].trim();
         String val = null;
         if (nv.length > 1)
         {
            val = nv[1].trim();
            if (val.startsWith("\"")) val = val.substring(1);
            if (val.endsWith("\"")) val = val.substring(0, val.length() - 1);
         }

         String lowercase = name.toLowerCase();
         if ("no-cache".equals(lowercase))
         {
            result.setNoCache(true);
            if (val != null && !"".equals(val))
            {
               result.getNoCacheFields().add(val);
            }
         }
         else if ("private".equals(lowercase))
         {
            result.setPrivate(true);
            if (val != null && !"".equals(val))
            {
               result.getPrivateFields().add(val);
            }
         }
         else if ("no-store".equals(lowercase))
         {
            result.setNoStore(true);
         }
         else if ("max-age".equals(lowercase))
         {
            if (val == null)
               throw new IllegalArgumentException("CacheControl max-age header does not have a value: " + value);
            result.setMaxAge(Integer.valueOf(val));
         }
         else if ("s-maxage".equals(lowercase))
         {
            if (val == null)
               throw new IllegalArgumentException("CacheControl s-maxage header does not have a value: " + value);
            result.setSMaxAge(Integer.valueOf(val));
         }
         else if ("no-transform".equals(lowercase))
         {
            result.setNoTransform(true);
         }
         else if ("must-revalidate".equals(lowercase))
         {
            result.setMustRevalidate(true);
         }
         else if ("proxy-revalidate".equals(lowercase))
         {
            result.setProxyRevalidate(true);
         }
         else if ("public".equals(lowercase))
         {
             result.setPublic(true);
         }
         else
         {
            if (val == null) val = "";
            result.getCacheExtension().put(name, val);
         }
      }
      return result;
   }

   private static StringBuffer addDirective(String directive, StringBuffer buffer)
   {
      if (buffer.length() > 0) buffer.append(", ");
      buffer.append(directive);
      return buffer;
   }

   public static String toString(CacheControl value)
   {
      StringBuffer buffer = new StringBuffer();
      if (value.isNoCache())
      {
         List<String> fields = value.getNoCacheFields();
         if (fields.size() < 1)
         {
            addDirective("no-cache", buffer);
         }
         else
         {
            for (String field : value.getNoCacheFields())
            {
               addDirective("no-cache", buffer).append("=\"").append(field).append("\"");
            }
         }
      }
      if (value.isPublic())
      {
    	  addDirective("public", buffer);
      }
      if (value.isMustRevalidate()) addDirective("must-revalidate", buffer);
      if (value.isNoTransform()) addDirective("no-transform", buffer);
      if (value.isNoStore()) addDirective("no-store", buffer);
      if (value.isProxyRevalidate()) addDirective("proxy-revalidate", buffer);
      if (value.getSMaxAge() > -1) addDirective("s-maxage", buffer).append("=").append(value.getSMaxAge());
      if (value.getMaxAge() > -1) addDirective("max-age", buffer).append("=").append(value.getMaxAge());
      if (value.isPrivate())
      {
         List<String> fields = value.getPrivateFields();
         if (fields.size() < 1) addDirective("private", buffer);
         else
         {
            for (String field : value.getPrivateFields())
            {
               addDirective("private", buffer).append("=\"").append(field).append("\"");
            }
         }
      }
      for (String key : value.getCacheExtension().keySet())
      {
         String val = value.getCacheExtension().get(key);
         addDirective(key, buffer);
         if (val != null && !"".equals(val))
         {
            buffer.append("=\"").append(val).append("\"");
         }
      }
      return buffer.toString();
   }

}