/*
 * Copyright 2002-2013 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.io.IOException;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;

import org.springframework.core.MethodParameter;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.ResponseEntity;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.http.server.ServletServerHttpResponse;
import org.springframework.util.Assert;
import org.springframework.web.HttpMediaTypeNotSupportedException;
import org.springframework.web.accept.ContentNegotiationManager;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.ModelAndViewContainer;

/**
 * Resolves {@link HttpEntity} method argument values and also handles
 * both {@link HttpEntity} and {@link ResponseEntity} return values.
 *
 * <p>An {@link HttpEntity} return type has a set purpose. Therefore this
 * handler should be configured ahead of handlers that support any return
 * value type annotated with {@code @ModelAttribute} or {@code @ResponseBody}
 * to ensure they don't take over.
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @since 3.1
 */
public class HttpEntityMethodProcessor extends AbstractMessageConverterMethodProcessor {

	public HttpEntityMethodProcessor(List<HttpMessageConverter<?>> messageConverters) {
		super(messageConverters);
	}

	public HttpEntityMethodProcessor(List<HttpMessageConverter<?>> messageConverters,
			ContentNegotiationManager contentNegotiationManager) {

		super(messageConverters, contentNegotiationManager);
	}

	public boolean supportsParameter(MethodParameter parameter) {
		Class<?> parameterType = parameter.getParameterType();
		return HttpEntity.class.equals(parameterType);
	}

	public boolean supportsReturnType(MethodParameter returnType) {
		Class<?> parameterType = returnType.getParameterType();
		return HttpEntity.class.isAssignableFrom(parameterType) || ResponseEntity.class.isAssignableFrom(parameterType);
	}

	public Object resolveArgument(
			MethodParameter parameter, ModelAndViewContainer mavContainer,
			NativeWebRequest webRequest, WebDataBinderFactory binderFactory)
			throws IOException, HttpMediaTypeNotSupportedException {

		HttpInputMessage inputMessage = createInputMessage(webRequest);
		Type paramType = getHttpEntityType(parameter);

		Object body = readWithMessageConverters(webRequest, parameter, paramType);
		return new HttpEntity<Object>(body, inputMessage.getHeaders());
	}

	private Type getHttpEntityType(MethodParameter parameter) {
		Assert.isAssignable(HttpEntity.class, parameter.getParameterType());
		ParameterizedType type = (ParameterizedType) parameter.getGenericParameterType();
		if (type.getActualTypeArguments().length == 1) {
			return type.getActualTypeArguments()[0];
		}
		throw new IllegalArgumentException("HttpEntity parameter ("
				+ parameter.getParameterName() + ") in method " + parameter.getMethod()
				+ " is not parameterized or has more than one parameter");
	}

	public void handleReturnValue(
			Object returnValue, MethodParameter returnType,
			ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
			throws Exception {

		mavContainer.setRequestHandled(true);

		if (returnValue == null) {
			return;
		}

		ServletServerHttpRequest inputMessage = createInputMessage(webRequest);
		ServletServerHttpResponse outputMessage = createOutputMessage(webRequest);

		Assert.isInstanceOf(HttpEntity.class, returnValue);
		HttpEntity<?> responseEntity = (HttpEntity<?>) returnValue;
		if (responseEntity instanceof ResponseEntity) {
			outputMessage.setStatusCode(((ResponseEntity<?>) responseEntity).getStatusCode());
		}

		HttpHeaders entityHeaders = responseEntity.getHeaders();
		if (!entityHeaders.isEmpty()) {
			outputMessage.getHeaders().putAll(entityHeaders);
		}

		Object body = responseEntity.getBody();
		if (body != null) {
			writeWithMessageConverters(body, returnType, inputMessage, outputMessage);
		}
		else {
			// flush headers to the HttpServletResponse
			outputMessage.getBody();
		}
	}

}
