/*
 * Copyright 2002-2017 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
 *
 *      https://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.Map;

import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.ui.Model;
import org.springframework.ui.ModelMap;
import org.springframework.util.Assert;
import org.springframework.validation.DataBinder;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
import org.springframework.web.servlet.mvc.support.RedirectAttributesModelMap;

Resolves method arguments of type RedirectAttributes. 
This resolver must be listed ahead of ModelMethodProcessor and MapMethodProcessor, which support Map and Model arguments both of which are "super" types of RedirectAttributes and would also attempt to resolve a RedirectAttributes argument. 
Author:
Rossen Stoyanchev
Since:
3.1/**
 * Resolves method arguments of type {@link RedirectAttributes}.
 *
 * <p>This resolver must be listed ahead of
 * {@link org.springframework.web.method.annotation.ModelMethodProcessor} and
 * {@link org.springframework.web.method.annotation.MapMethodProcessor},
 * which support {@link Map} and {@link Model} arguments both of which are
 * "super" types of {@code RedirectAttributes} and would also attempt to
 * resolve a {@code RedirectAttributes} argument.
 *
 * @author Rossen Stoyanchev
 * @since 3.1
 */
public class RedirectAttributesMethodArgumentResolver implements HandlerMethodArgumentResolver {

	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		return RedirectAttributes.class.isAssignableFrom(parameter.getParameterType());
	}

	@Override
	public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
			NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

		Assert.state(mavContainer != null, "RedirectAttributes argument only supported on regular handler methods");

		ModelMap redirectAttributes;
		if (binderFactory != null) {
			DataBinder dataBinder = binderFactory.createBinder(webRequest, null, DataBinder.DEFAULT_OBJECT_NAME);
			redirectAttributes = new RedirectAttributesModelMap(dataBinder);
		}
		else {
			redirectAttributes  = new RedirectAttributesModelMap();
		}
		mavContainer.setRedirectModel(redirectAttributes);
		return redirectAttributes;
	}

}