/*
    * Copyright 2002-2014 the original author or authors.
    *
    * 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.springframework.web.servlet.mvc.method.annotation;
  
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  import org.springframework.core.MethodParameter;
  import org.springframework.util.CollectionUtils;
  import org.springframework.util.StringUtils;
  import org.springframework.web.bind.annotation.PathVariable;
  import org.springframework.web.bind.support.WebDataBinderFactory;
  import org.springframework.web.context.request.NativeWebRequest;
  import org.springframework.web.context.request.RequestAttributes;
  import org.springframework.web.method.support.HandlerMethodArgumentResolver;
  import org.springframework.web.method.support.ModelAndViewContainer;
  import org.springframework.web.servlet.HandlerMapping;
  
  /**
   * Resolves {@link Map} method arguments annotated with an @{@link PathVariable}
   * where the annotation does not specify a path variable name. The created
   * {@link Map} contains all URI template name/value pairs.
   *
   * @author Rossen Stoyanchev
   * @since 3.2
   * @see PathVariableMethodArgumentResolver
   */
  public class PathVariableMapMethodArgumentResolver implements HandlerMethodArgumentResolver {
  
  	@Override
  	public boolean supportsParameter(MethodParameter parameter) {
  		PathVariable ann = parameter.getParameterAnnotation(PathVariable.class);
  		return (ann != null && (Map.class.isAssignableFrom(parameter.getParameterType()))
  				&& !StringUtils.hasText(ann.value()));
  	}
  
  	/**
  	 * Return a Map with all URI template variables or an empty map.
  	 */
  	@Override
  	public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
  			NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
  
  		@SuppressWarnings("unchecked")
  		Map<String, String> uriTemplateVars =
  				(Map<String, String>) webRequest.getAttribute(
  						HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
  
  		if (!CollectionUtils.isEmpty(uriTemplateVars)) {
  			return new LinkedHashMap<String, String>(uriTemplateVars);
  		}
  		else {
  			return Collections.emptyMap();
  		}
  	}
  
  }