package com.atlassian.plugins.rest.common.expand.interceptor;
   
   import com.atlassian.plugins.rest.common.interceptor.ResourceInterceptor;
   import com.atlassian.plugins.rest.common.interceptor.MethodInvocation;
   import com.atlassian.plugins.rest.common.expand.resolver.EntityExpanderResolver;
   import com.atlassian.plugins.rest.common.expand.parameter.ExpandParameter;
   import com.atlassian.plugins.rest.common.expand.parameter.DefaultExpandParameter;
   import com.atlassian.plugins.rest.common.expand.EntityCrawler;
   import com.google.common.base.Preconditions;
  import com.sun.jersey.api.core.HttpRequestContext;
  import com.sun.jersey.api.core.HttpResponseContext;
  
  import java.lang.reflect.InvocationTargetException;
  
  /**
   * Expands the entity returned from the resource method
   *
   * @since 2.0
   */
  public class ExpandInterceptor implements ResourceInterceptor {
      private final EntityExpanderResolver expanderResolver;
      private final String expandParameterName;
  
      public ExpandInterceptor(EntityExpanderResolver expanderResolver) {
          this("expand", expanderResolver);
      }
  
      public ExpandInterceptor(String expandParameterName, EntityExpanderResolver expanderResolver) {
          this.expanderResolver = expanderResolver;
          this.expandParameterName = Preconditions.checkNotNull(expandParameterName);
      }
  
      public void intercept(MethodInvocation invocation) throws IllegalAccessException, InvocationTargetException {
          invocation.invoke();
          HttpRequestContext request = invocation.getHttpContext().getRequest();
          HttpResponseContext response = invocation.getHttpContext().getResponse();
          final ExpandParameter expandParameter = new DefaultExpandParameter(request.getQueryParameters().get(expandParameterName));
          new EntityCrawler().crawl(response.getEntity(), expandParameter, expanderResolver);
      }
  }