/*
    * Copyright 2002-2012 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.Map;
  
  import org.springframework.core.MethodParameter;
  import org.springframework.util.CollectionUtils;
  import org.springframework.util.LinkedMultiValueMap;
  import org.springframework.util.MultiValueMap;
  import org.springframework.util.StringUtils;
  import org.springframework.web.bind.annotation.MatrixVariable;
  import org.springframework.web.bind.annotation.ValueConstants;
  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 method arguments of type Map annotated with
   * {@link MatrixVariable @MatrixVariable} where the annotation the does not
   * specify a name. If a name specified then the argument will by resolved by the
   * {@link MatrixVariableMethodArgumentResolver} instead.
   *
   * @author Rossen Stoyanchev
   * @since 3.2
   */
  public class MatrixVariableMapMethodArgumentResolver implements HandlerMethodArgumentResolver {
  
  	@Override
  	public boolean supportsParameter(MethodParameter parameter) {
  		MatrixVariable paramAnnot = parameter.getParameterAnnotation(MatrixVariable.class);
  		if (paramAnnot != null) {
  			if (Map.class.isAssignableFrom(parameter.getParameterType())) {
  				return !StringUtils.hasText(paramAnnot.value());
  			}
  		}
  		return false;
  	}
  
  	@Override
  	public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
  			NativeWebRequest request, WebDataBinderFactory binderFactory) throws Exception {
  
  		@SuppressWarnings("unchecked")
  		Map<String, MultiValueMap<String, String>> matrixVariables =
  				(Map<String, MultiValueMap<String, String>>) request.getAttribute(
  						HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);
  
  		if (CollectionUtils.isEmpty(matrixVariables)) {
  			return Collections.emptyMap();
  		}
  
  		String pathVariable = parameter.getParameterAnnotation(MatrixVariable.class).pathVar();
  
  		if (!pathVariable.equals(ValueConstants.DEFAULT_NONE)) {
  			MultiValueMap<String, String> map = matrixVariables.get(pathVariable);
  			return (map != null) ? map : Collections.emptyMap();
  		}
  
  		MultiValueMap<String, String> map = new LinkedMultiValueMap<String, String>();
  		for (MultiValueMap<String, String> vars : matrixVariables.values()) {
  			for (String name : vars.keySet()) {
  				for (String value : vars.get(name)) {
  					map.add(name, value);
  				}
  			}
  		}
  
  		return map;
  	}
  
  }