package org.jboss.resteasy.core;

import org.jboss.resteasy.resteasy_jaxrs.i18n.Messages;

import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.container.PreMatching;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MultivaluedMap;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.List;

Enables content negotiation through a query parameter, instead of the Accept Header.
To enable this feature, use the context-param in web.xml:


<context-param>

    <param-name>resteasy.media.type.param.mapping</param-name>

    <param-value>someName</param-value>

</context-param>


So, in a request like
http://service.foo.com/resouce?someName=application/xml
the application/xml media type will received the highest priority in the content negotiation.
In the cases where the request contains both the parameter and the Accept header, the parameter will be more relevant.
It is possible to left the param-value empty, what will cause the processor to look for an accept parameter.
Author:
Leandro Ferro Luzia
Version:
$Revision: 1.2 $/**
 * <p>Enables content negotiation through a query parameter, instead of the Accept Header.</p>
 * <p>To enable this feature, use the context-param in web.xml:</p>
 * <p>
 * <code>
 * &lt;context-param&gt;<br>
 * &nbsp;&nbsp;&nbsp;&nbsp;&lt;param-name&gt;<strong>resteasy.media.type.param.mapping</strong>&lt;/param-name&gt;<br>
 * &nbsp;&nbsp;&nbsp;&nbsp;&lt;param-value&gt;<i>someName</i>&lt;/param-value&gt;<br>
 * &lt;/context-param&gt;<br>
 * </code>
 * <p>So, in a request like
 * <code>http://service.foo.com/resouce?someName=application/xml</code>
 * the application/xml media type will received the highest priority in the content negotiation.
 * <p>In the cases where the request contains both the parameter and the Accept header, the parameter will be more relevant.
 * <p>It is possible to left the <code>param-value</code> empty, what will cause the processor to look for an <strong>accept</strong> parameter.
 *
 * @author <a href="leandro.ferro@gmail.com">Leandro Ferro Luzia</a>
 * @version $Revision: 1.2 $
 */
@PreMatching
public class AcceptParameterHttpPreprocessor implements ContainerRequestFilter
{

   private final String paramMapping;

   
Create a new AcceptParameterHttpPreprocessor.
Params:
paramMapping – The name of query parameter that will be used to do the content negotiation/**
    * Create a new AcceptParameterHttpPreprocessor.
    *
    * @param paramMapping The name of query parameter that will be used to do the content negotiation
    */
   public AcceptParameterHttpPreprocessor(final String paramMapping)
   {
      if (paramMapping == null || paramMapping.matches("\\s+"))
         throw new IllegalArgumentException(Messages.MESSAGES.constructorMappingInvalid());
      this.paramMapping = paramMapping;
   }

   @Override
   public void filter(ContainerRequestContext request) throws IOException
   {
      MultivaluedMap<String, String> params = request.getUriInfo().getQueryParameters(false);

      if (params != null)
      {
         List<String> accepts = params.get(paramMapping);

         if (accepts != null && !accepts.isEmpty())
         {
            for (String accept : accepts)
            {
               try
               {
                  accept = URLDecoder.decode(accept, StandardCharsets.UTF_8.name());
                  request.getHeaders().add(HttpHeaders.ACCEPT, accept);
               }
               catch (UnsupportedEncodingException e)
               {
                  throw new RuntimeException(e);
               }
            }

         }
      }

   }

}