/*
 * 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.bind.annotation.support;

import java.lang.annotation.Annotation;
import java.lang.reflect.Array;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.Conventions;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.ui.ExtendedModelMap;
import org.springframework.ui.Model;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ReflectionUtils;
import org.springframework.validation.BindException;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.web.HttpMediaTypeNotSupportedException;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.CookieValue;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ValueConstants;
import org.springframework.web.bind.support.DefaultSessionAttributeStore;
import org.springframework.web.bind.support.SessionAttributeStore;
import org.springframework.web.bind.support.SessionStatus;
import org.springframework.web.bind.support.SimpleSessionStatus;
import org.springframework.web.bind.support.WebArgumentResolver;
import org.springframework.web.bind.support.WebBindingInitializer;
import org.springframework.web.bind.support.WebRequestDataBinder;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartRequest;

/**
 * Support class for invoking an annotated handler method. Operates on the introspection results of a {@link
 * HandlerMethodResolver} for a specific handler type.
 *
 * <p>Used by {@link org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter} and {@link
 * org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter}.
 *
 * @author Juergen Hoeller
 * @author Arjen Poutsma
 * @since 2.5.2
 * @see #invokeHandlerMethod
 */
public class HandlerMethodInvoker {

	private static final String MODEL_KEY_PREFIX_STALE = SessionAttributeStore.class.getName() + ".STALE.";

	/** We'll create a lot of these objects, so we don't want a new logger every time. */
	private static final Log logger = LogFactory.getLog(HandlerMethodInvoker.class);

	private final HandlerMethodResolver methodResolver;

	private final WebBindingInitializer bindingInitializer;

	private final SessionAttributeStore sessionAttributeStore;

	private final ParameterNameDiscoverer parameterNameDiscoverer;

	private final WebArgumentResolver[] customArgumentResolvers;

	private final HttpMessageConverter<?>[] messageConverters;

	private final SimpleSessionStatus sessionStatus = new SimpleSessionStatus();


	public HandlerMethodInvoker(HandlerMethodResolver methodResolver) {
		this(methodResolver, null);
	}

	public HandlerMethodInvoker(HandlerMethodResolver methodResolver, WebBindingInitializer bindingInitializer) {
		this(methodResolver, bindingInitializer, new DefaultSessionAttributeStore(), null, null, null);
	}

	public HandlerMethodInvoker(HandlerMethodResolver methodResolver, WebBindingInitializer bindingInitializer,
			SessionAttributeStore sessionAttributeStore, ParameterNameDiscoverer parameterNameDiscoverer,
			WebArgumentResolver[] customArgumentResolvers, HttpMessageConverter<?>[] messageConverters) {

		this.methodResolver = methodResolver;
		this.bindingInitializer = bindingInitializer;
		this.sessionAttributeStore = sessionAttributeStore;
		this.parameterNameDiscoverer = parameterNameDiscoverer;
		this.customArgumentResolvers = customArgumentResolvers;
		this.messageConverters = messageConverters;
	}


	public final Object invokeHandlerMethod(Method handlerMethod, Object handler,
			NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {

		Method handlerMethodToInvoke = BridgeMethodResolver.findBridgedMethod(handlerMethod);
		try {
			boolean debug = logger.isDebugEnabled();
			for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
				Object attrValue = this.sessionAttributeStore.retrieveAttribute(webRequest, attrName);
				if (attrValue != null) {
					implicitModel.addAttribute(attrName, attrValue);
				}
			}
			for (Method attributeMethod : this.methodResolver.getModelAttributeMethods()) {
				Method attributeMethodToInvoke = BridgeMethodResolver.findBridgedMethod(attributeMethod);
				Object[] args = resolveHandlerArguments(attributeMethodToInvoke, handler, webRequest, implicitModel);
				if (debug) {
					logger.debug("Invoking model attribute method: " + attributeMethodToInvoke);
				}
				String attrName = AnnotationUtils.findAnnotation(attributeMethod, ModelAttribute.class).value();
				if (!"".equals(attrName) && implicitModel.containsAttribute(attrName)) {
					continue;
				}
				ReflectionUtils.makeAccessible(attributeMethodToInvoke);
				Object attrValue = attributeMethodToInvoke.invoke(handler, args);
				if ("".equals(attrName)) {
					Class<?> resolvedType = GenericTypeResolver.resolveReturnType(attributeMethodToInvoke, handler.getClass());
					attrName = Conventions.getVariableNameForReturnType(attributeMethodToInvoke, resolvedType, attrValue);
				}
				if (!implicitModel.containsAttribute(attrName)) {
					implicitModel.addAttribute(attrName, attrValue);
				}
			}
			Object[] args = resolveHandlerArguments(handlerMethodToInvoke, handler, webRequest, implicitModel);
			if (debug) {
				logger.debug("Invoking request handler method: " + handlerMethodToInvoke);
			}
			ReflectionUtils.makeAccessible(handlerMethodToInvoke);
			return handlerMethodToInvoke.invoke(handler, args);
		}
		catch (IllegalStateException ex) {
			// Internal assertion failed (e.g. invalid signature):
			// throw exception with full handler method context...
			throw new HandlerMethodInvocationException(handlerMethodToInvoke, ex);
		}
		catch (InvocationTargetException ex) {
			// User-defined @ModelAttribute/@InitBinder/@RequestMapping method threw an exception...
			ReflectionUtils.rethrowException(ex.getTargetException());
			return null;
		}
	}

	public final void updateModelAttributes(Object handler, Map<String, Object> mavModel,
			ExtendedModelMap implicitModel, NativeWebRequest webRequest) throws Exception {

		if (this.methodResolver.hasSessionAttributes() && this.sessionStatus.isComplete()) {
			for (String attrName : this.methodResolver.getActualSessionAttributeNames()) {
				this.sessionAttributeStore.cleanupAttribute(webRequest, attrName);
			}
		}

		// Expose model attributes as session attributes, if required.
		// Expose BindingResults for all attributes, making custom editors available.
		Map<String, Object> model = (mavModel != null ? mavModel : implicitModel);
		if (model != null) {
			try {
				String[] originalAttrNames = model.keySet().toArray(new String[model.size()]);
				for (String attrName : originalAttrNames) {
					Object attrValue = model.get(attrName);
					boolean isSessionAttr = this.methodResolver.isSessionAttribute(
							attrName, (attrValue != null ? attrValue.getClass() : null));
					if (isSessionAttr) {
						if (this.sessionStatus.isComplete()) {
							implicitModel.put(MODEL_KEY_PREFIX_STALE + attrName, Boolean.TRUE);
						}
						else if (!implicitModel.containsKey(MODEL_KEY_PREFIX_STALE + attrName)) {
							this.sessionAttributeStore.storeAttribute(webRequest, attrName, attrValue);
						}
					}
					if (!attrName.startsWith(BindingResult.MODEL_KEY_PREFIX) &&
							(isSessionAttr || isBindingCandidate(attrValue))) {
						String bindingResultKey = BindingResult.MODEL_KEY_PREFIX + attrName;
						if (mavModel != null && !model.containsKey(bindingResultKey)) {
							WebDataBinder binder = createBinder(webRequest, attrValue, attrName);
							initBinder(handler, attrName, binder, webRequest);
							mavModel.put(bindingResultKey, binder.getBindingResult());
						}
					}
				}
			}
			catch (InvocationTargetException ex) {
				// User-defined @InitBinder method threw an exception...
				ReflectionUtils.rethrowException(ex.getTargetException());
			}
		}
	}


	private Object[] resolveHandlerArguments(Method handlerMethod, Object handler,
			NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception {

		Class<?>[] paramTypes = handlerMethod.getParameterTypes();
		Object[] args = new Object[paramTypes.length];

		for (int i = 0; i < args.length; i++) {
			MethodParameter methodParam = new MethodParameter(handlerMethod, i);
			methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
			GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
			String paramName = null;
			String headerName = null;
			boolean requestBodyFound = false;
			String cookieName = null;
			String pathVarName = null;
			String attrName = null;
			boolean required = false;
			String defaultValue = null;
			boolean validate = false;
			Object[] validationHints = null;
			int annotationsFound = 0;
			Annotation[] paramAnns = methodParam.getParameterAnnotations();

			for (Annotation paramAnn : paramAnns) {
				if (RequestParam.class.isInstance(paramAnn)) {
					RequestParam requestParam = (RequestParam) paramAnn;
					paramName = requestParam.value();
					required = requestParam.required();
					defaultValue = parseDefaultValueAttribute(requestParam.defaultValue());
					annotationsFound++;
				}
				else if (RequestHeader.class.isInstance(paramAnn)) {
					RequestHeader requestHeader = (RequestHeader) paramAnn;
					headerName = requestHeader.value();
					required = requestHeader.required();
					defaultValue = parseDefaultValueAttribute(requestHeader.defaultValue());
					annotationsFound++;
				}
				else if (RequestBody.class.isInstance(paramAnn)) {
					requestBodyFound = true;
					annotationsFound++;
				}
				else if (CookieValue.class.isInstance(paramAnn)) {
					CookieValue cookieValue = (CookieValue) paramAnn;
					cookieName = cookieValue.value();
					required = cookieValue.required();
					defaultValue = parseDefaultValueAttribute(cookieValue.defaultValue());
					annotationsFound++;
				}
				else if (PathVariable.class.isInstance(paramAnn)) {
					PathVariable pathVar = (PathVariable) paramAnn;
					pathVarName = pathVar.value();
					annotationsFound++;
				}
				else if (ModelAttribute.class.isInstance(paramAnn)) {
					ModelAttribute attr = (ModelAttribute) paramAnn;
					attrName = attr.value();
					annotationsFound++;
				}
				else if (Value.class.isInstance(paramAnn)) {
					defaultValue = ((Value) paramAnn).value();
				}
				else if (paramAnn.annotationType().getSimpleName().startsWith("Valid")) {
					validate = true;
					Object value = AnnotationUtils.getValue(paramAnn);
					validationHints = (value instanceof Object[] ? (Object[]) value : new Object[] {value});
				}
			}

			if (annotationsFound > 1) {
				throw new IllegalStateException("Handler parameter annotations are exclusive choices - " +
						"do not specify more than one such annotation on the same parameter: " + handlerMethod);
			}

			if (annotationsFound == 0) {
				Object argValue = resolveCommonArgument(methodParam, webRequest);
				if (argValue != WebArgumentResolver.UNRESOLVED) {
					args[i] = argValue;
				}
				else if (defaultValue != null) {
					args[i] = resolveDefaultValue(defaultValue);
				}
				else {
					Class<?> paramType = methodParam.getParameterType();
					if (Model.class.isAssignableFrom(paramType) || Map.class.isAssignableFrom(paramType)) {
						if (!paramType.isAssignableFrom(implicitModel.getClass())) {
							throw new IllegalStateException("Argument [" + paramType.getSimpleName() + "] is of type " +
									"Model or Map but is not assignable from the actual model. You may need to switch " +
									"newer MVC infrastructure classes to use this argument.");
						}
						args[i] = implicitModel;
					}
					else if (SessionStatus.class.isAssignableFrom(paramType)) {
						args[i] = this.sessionStatus;
					}
					else if (HttpEntity.class.isAssignableFrom(paramType)) {
						args[i] = resolveHttpEntityRequest(methodParam, webRequest);
					}
					else if (Errors.class.isAssignableFrom(paramType)) {
						throw new IllegalStateException("Errors/BindingResult argument declared " +
								"without preceding model attribute. Check your handler method signature!");
					}
					else if (BeanUtils.isSimpleProperty(paramType)) {
						paramName = "";
					}
					else {
						attrName = "";
					}
				}
			}

			if (paramName != null) {
				args[i] = resolveRequestParam(paramName, required, defaultValue, methodParam, webRequest, handler);
			}
			else if (headerName != null) {
				args[i] = resolveRequestHeader(headerName, required, defaultValue, methodParam, webRequest, handler);
			}
			else if (requestBodyFound) {
				args[i] = resolveRequestBody(methodParam, webRequest, handler);
			}
			else if (cookieName != null) {
				args[i] = resolveCookieValue(cookieName, required, defaultValue, methodParam, webRequest, handler);
			}
			else if (pathVarName != null) {
				args[i] = resolvePathVariable(pathVarName, methodParam, webRequest, handler);
			}
			else if (attrName != null) {
				WebDataBinder binder =
						resolveModelAttribute(attrName, methodParam, implicitModel, webRequest, handler);
				boolean assignBindingResult = (args.length > i + 1 && Errors.class.isAssignableFrom(paramTypes[i + 1]));
				if (binder.getTarget() != null) {
					doBind(binder, webRequest, validate, validationHints, !assignBindingResult);
				}
				args[i] = binder.getTarget();
				if (assignBindingResult) {
					args[i + 1] = binder.getBindingResult();
					i++;
				}
				implicitModel.putAll(binder.getBindingResult().getModel());
			}
		}

		return args;
	}

	protected void initBinder(Object handler, String attrName, WebDataBinder binder, NativeWebRequest webRequest)
			throws Exception {

		if (this.bindingInitializer != null) {
			this.bindingInitializer.initBinder(binder, webRequest);
		}
		if (handler != null) {
			Set<Method> initBinderMethods = this.methodResolver.getInitBinderMethods();
			if (!initBinderMethods.isEmpty()) {
				boolean debug = logger.isDebugEnabled();
				for (Method initBinderMethod : initBinderMethods) {
					Method methodToInvoke = BridgeMethodResolver.findBridgedMethod(initBinderMethod);
					String[] targetNames = AnnotationUtils.findAnnotation(initBinderMethod, InitBinder.class).value();
					if (targetNames.length == 0 || Arrays.asList(targetNames).contains(attrName)) {
						Object[] initBinderArgs =
								resolveInitBinderArguments(handler, methodToInvoke, binder, webRequest);
						if (debug) {
							logger.debug("Invoking init-binder method: " + methodToInvoke);
						}
						ReflectionUtils.makeAccessible(methodToInvoke);
						Object returnValue = methodToInvoke.invoke(handler, initBinderArgs);
						if (returnValue != null) {
							throw new IllegalStateException(
									"InitBinder methods must not have a return value: " + methodToInvoke);
						}
					}
				}
			}
		}
	}

	private Object[] resolveInitBinderArguments(Object handler, Method initBinderMethod,
			WebDataBinder binder, NativeWebRequest webRequest) throws Exception {

		Class<?>[] initBinderParams = initBinderMethod.getParameterTypes();
		Object[] initBinderArgs = new Object[initBinderParams.length];

		for (int i = 0; i < initBinderArgs.length; i++) {
			MethodParameter methodParam = new MethodParameter(initBinderMethod, i);
			methodParam.initParameterNameDiscovery(this.parameterNameDiscoverer);
			GenericTypeResolver.resolveParameterType(methodParam, handler.getClass());
			String paramName = null;
			boolean paramRequired = false;
			String paramDefaultValue = null;
			String pathVarName = null;
			Annotation[] paramAnns = methodParam.getParameterAnnotations();

			for (Annotation paramAnn : paramAnns) {
				if (RequestParam.class.isInstance(paramAnn)) {
					RequestParam requestParam = (RequestParam) paramAnn;
					paramName = requestParam.value();
					paramRequired = requestParam.required();
					paramDefaultValue = parseDefaultValueAttribute(requestParam.defaultValue());
					break;
				}
				else if (ModelAttribute.class.isInstance(paramAnn)) {
					throw new IllegalStateException(
							"@ModelAttribute is not supported on @InitBinder methods: " + initBinderMethod);
				}
				else if (PathVariable.class.isInstance(paramAnn)) {
					PathVariable pathVar = (PathVariable) paramAnn;
					pathVarName = pathVar.value();
				}
			}

			if (paramName == null && pathVarName == null) {
				Object argValue = resolveCommonArgument(methodParam, webRequest);
				if (argValue != WebArgumentResolver.UNRESOLVED) {
					initBinderArgs[i] = argValue;
				}
				else {
					Class<?> paramType = initBinderParams[i];
					if (paramType.isInstance(binder)) {
						initBinderArgs[i] = binder;
					}
					else if (BeanUtils.isSimpleProperty(paramType)) {
						paramName = "";
					}
					else {
						throw new IllegalStateException("Unsupported argument [" + paramType.getName() +
								"] for @InitBinder method: " + initBinderMethod);
					}
				}
			}

			if (paramName != null) {
				initBinderArgs[i] =
						resolveRequestParam(paramName, paramRequired, paramDefaultValue, methodParam, webRequest, null);
			}
			else if (pathVarName != null) {
				initBinderArgs[i] = resolvePathVariable(pathVarName, methodParam, webRequest, null);
			}
		}

		return initBinderArgs;
	}

	@SuppressWarnings("unchecked")
	private Object resolveRequestParam(String paramName, boolean required, String defaultValue,
			MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
			throws Exception {

		Class<?> paramType = methodParam.getParameterType();
		if (Map.class.isAssignableFrom(paramType) && paramName.length() == 0) {
			return resolveRequestParamMap((Class<? extends Map<?, ?>>) paramType, webRequest);
		}
		if (paramName.length() == 0) {
			paramName = getRequiredParameterName(methodParam);
		}
		Object paramValue = null;
		MultipartRequest multipartRequest = webRequest.getNativeRequest(MultipartRequest.class);
		if (multipartRequest != null) {
			List<MultipartFile> files = multipartRequest.getFiles(paramName);
			if (!files.isEmpty()) {
				paramValue = (files.size() == 1 ? files.get(0) : files);
			}
		}
		if (paramValue == null) {
			String[] paramValues = webRequest.getParameterValues(paramName);
			if (paramValues != null) {
				paramValue = (paramValues.length == 1 ? paramValues[0] : paramValues);
			}
		}
		if (paramValue == null) {
			if (defaultValue != null) {
				paramValue = resolveDefaultValue(defaultValue);
			}
			else if (required) {
				raiseMissingParameterException(paramName, paramType);
			}
			paramValue = checkValue(paramName, paramValue, paramType);
		}
		WebDataBinder binder = createBinder(webRequest, null, paramName);
		initBinder(handlerForInitBinderCall, paramName, binder, webRequest);
		return binder.convertIfNecessary(paramValue, paramType, methodParam);
	}

	private Map<String, ?> resolveRequestParamMap(Class<? extends Map<?, ?>> mapType, NativeWebRequest webRequest) {
		Map<String, String[]> parameterMap = webRequest.getParameterMap();
		if (MultiValueMap.class.isAssignableFrom(mapType)) {
			MultiValueMap<String, String> result = new LinkedMultiValueMap<String, String>(parameterMap.size());
			for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
				for (String value : entry.getValue()) {
					result.add(entry.getKey(), value);
				}
			}
			return result;
		}
		else {
			Map<String, String> result = new LinkedHashMap<String, String>(parameterMap.size());
			for (Map.Entry<String, String[]> entry : parameterMap.entrySet()) {
				if (entry.getValue().length > 0) {
					result.put(entry.getKey(), entry.getValue()[0]);
				}
			}
			return result;
		}
	}

	@SuppressWarnings("unchecked")
	private Object resolveRequestHeader(String headerName, boolean required, String defaultValue,
			MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
			throws Exception {

		Class<?> paramType = methodParam.getParameterType();
		if (Map.class.isAssignableFrom(paramType)) {
			return resolveRequestHeaderMap((Class<? extends Map<?, ?>>) paramType, webRequest);
		}
		if (headerName.length() == 0) {
			headerName = getRequiredParameterName(methodParam);
		}
		Object headerValue = null;
		String[] headerValues = webRequest.getHeaderValues(headerName);
		if (headerValues != null) {
			headerValue = (headerValues.length == 1 ? headerValues[0] : headerValues);
		}
		if (headerValue == null) {
			if (defaultValue != null) {
				headerValue = resolveDefaultValue(defaultValue);
			}
			else if (required) {
				raiseMissingHeaderException(headerName, paramType);
			}
			headerValue = checkValue(headerName, headerValue, paramType);
		}
		WebDataBinder binder = createBinder(webRequest, null, headerName);
		initBinder(handlerForInitBinderCall, headerName, binder, webRequest);
		return binder.convertIfNecessary(headerValue, paramType, methodParam);
	}

	private Map<String, ?> resolveRequestHeaderMap(Class<? extends Map<?, ?>> mapType, NativeWebRequest webRequest) {
		if (MultiValueMap.class.isAssignableFrom(mapType)) {
			MultiValueMap<String, String> result;
			if (HttpHeaders.class.isAssignableFrom(mapType)) {
				result = new HttpHeaders();
			}
			else {
				result = new LinkedMultiValueMap<String, String>();
			}
			for (Iterator<String> iterator = webRequest.getHeaderNames(); iterator.hasNext();) {
				String headerName = iterator.next();
				for (String headerValue : webRequest.getHeaderValues(headerName)) {
					result.add(headerName, headerValue);
				}
			}
			return result;
		}
		else {
			Map<String, String> result = new LinkedHashMap<String, String>();
			for (Iterator<String> iterator = webRequest.getHeaderNames(); iterator.hasNext();) {
				String headerName = iterator.next();
				String headerValue = webRequest.getHeader(headerName);
				result.put(headerName, headerValue);
			}
			return result;
		}
	}

	/**
	 * Resolves the given {@link RequestBody @RequestBody} annotation.
	 */
	protected Object resolveRequestBody(MethodParameter methodParam, NativeWebRequest webRequest, Object handler)
			throws Exception {

		return readWithMessageConverters(methodParam, createHttpInputMessage(webRequest), methodParam.getParameterType());
	}

	private HttpEntity<?> resolveHttpEntityRequest(MethodParameter methodParam, NativeWebRequest webRequest)
			throws Exception {

		HttpInputMessage inputMessage = createHttpInputMessage(webRequest);
		Class<?> paramType = getHttpEntityType(methodParam);
		Object body = readWithMessageConverters(methodParam, inputMessage, paramType);
		return new HttpEntity<Object>(body, inputMessage.getHeaders());
	}

	@SuppressWarnings({ "unchecked", "rawtypes" })
	private Object readWithMessageConverters(MethodParameter methodParam, HttpInputMessage inputMessage, Class<?> paramType)
			throws Exception {

		MediaType contentType = inputMessage.getHeaders().getContentType();
		if (contentType == null) {
			StringBuilder builder = new StringBuilder(ClassUtils.getShortName(methodParam.getParameterType()));
			String paramName = methodParam.getParameterName();
			if (paramName != null) {
				builder.append(' ');
				builder.append(paramName);
			}
			throw new HttpMediaTypeNotSupportedException(
					"Cannot extract parameter (" + builder.toString() + "): no Content-Type found");
		}

		List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
		if (this.messageConverters != null) {
			for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
				allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
				if (messageConverter.canRead(paramType, contentType)) {
					if (logger.isDebugEnabled()) {
						logger.debug("Reading [" + paramType.getName() + "] as \"" + contentType
								+"\" using [" + messageConverter + "]");
					}
					return messageConverter.read((Class) paramType, inputMessage);
				}
			}
		}
		throw new HttpMediaTypeNotSupportedException(contentType, allSupportedMediaTypes);
	}

	private Class<?> getHttpEntityType(MethodParameter methodParam) {
		Assert.isAssignable(HttpEntity.class, methodParam.getParameterType());
		ParameterizedType type = (ParameterizedType) methodParam.getGenericParameterType();
		if (type.getActualTypeArguments().length == 1) {
			Type typeArgument = type.getActualTypeArguments()[0];
			if (typeArgument instanceof Class) {
				return (Class<?>) typeArgument;
			}
			else if (typeArgument instanceof GenericArrayType) {
				Type componentType = ((GenericArrayType) typeArgument).getGenericComponentType();
				if (componentType instanceof Class) {
					// Surely, there should be a nicer way to do this
					Object array = Array.newInstance((Class<?>) componentType, 0);
					return array.getClass();
				}
			}
		}
		throw new IllegalArgumentException(
				"HttpEntity parameter (" + methodParam.getParameterName() + ") is not parameterized");

	}

	private Object resolveCookieValue(String cookieName, boolean required, String defaultValue,
			MethodParameter methodParam, NativeWebRequest webRequest, Object handlerForInitBinderCall)
			throws Exception {

		Class<?> paramType = methodParam.getParameterType();
		if (cookieName.length() == 0) {
			cookieName = getRequiredParameterName(methodParam);
		}
		Object cookieValue = resolveCookieValue(cookieName, paramType, webRequest);
		if (cookieValue == null) {
			if (defaultValue != null) {
				cookieValue = resolveDefaultValue(defaultValue);
			}
			else if (required) {
				raiseMissingCookieException(cookieName, paramType);
			}
			cookieValue = checkValue(cookieName, cookieValue, paramType);
		}
		WebDataBinder binder = createBinder(webRequest, null, cookieName);
		initBinder(handlerForInitBinderCall, cookieName, binder, webRequest);
		return binder.convertIfNecessary(cookieValue, paramType, methodParam);
	}

	/**
	 * Resolves the given {@link CookieValue @CookieValue} annotation.
	 * <p>Throws an UnsupportedOperationException by default.
	 */
	protected Object resolveCookieValue(String cookieName, Class<?> paramType, NativeWebRequest webRequest)
			throws Exception {

		throw new UnsupportedOperationException("@CookieValue not supported");
	}

	private Object resolvePathVariable(String pathVarName, MethodParameter methodParam,
			NativeWebRequest webRequest, Object handlerForInitBinderCall) throws Exception {

		Class<?> paramType = methodParam.getParameterType();
		if (pathVarName.length() == 0) {
			pathVarName = getRequiredParameterName(methodParam);
		}
		String pathVarValue = resolvePathVariable(pathVarName, paramType, webRequest);
		WebDataBinder binder = createBinder(webRequest, null, pathVarName);
		initBinder(handlerForInitBinderCall, pathVarName, binder, webRequest);
		return binder.convertIfNecessary(pathVarValue, paramType, methodParam);
	}

	/**
	 * Resolves the given {@link PathVariable @PathVariable} annotation.
	 * <p>Throws an UnsupportedOperationException by default.
	 */
	protected String resolvePathVariable(String pathVarName, Class<?> paramType, NativeWebRequest webRequest)
			throws Exception {

		throw new UnsupportedOperationException("@PathVariable not supported");
	}

	private String getRequiredParameterName(MethodParameter methodParam) {
		String name = methodParam.getParameterName();
		if (name == null) {
			throw new IllegalStateException(
					"No parameter name specified for argument of type [" + methodParam.getParameterType().getName() +
							"], and no parameter name information found in class file either.");
		}
		return name;
	}

	private Object checkValue(String name, Object value, Class<?> paramType) {
		if (value == null) {
			if (boolean.class.equals(paramType)) {
				return Boolean.FALSE;
			}
			else if (paramType.isPrimitive()) {
				throw new IllegalStateException("Optional " + paramType + " parameter '" + name +
						"' is not present but cannot be translated into a null value due to being declared as a " +
						"primitive type. Consider declaring it as object wrapper for the corresponding primitive type.");
			}
		}
		return value;
	}

	private WebDataBinder resolveModelAttribute(String attrName, MethodParameter methodParam,
			ExtendedModelMap implicitModel, NativeWebRequest webRequest, Object handler) throws Exception {

		// Bind request parameter onto object...
		String name = attrName;
		if ("".equals(name)) {
			name = Conventions.getVariableNameForParameter(methodParam);
		}
		Class<?> paramType = methodParam.getParameterType();
		Object bindObject;
		if (implicitModel.containsKey(name)) {
			bindObject = implicitModel.get(name);
		}
		else if (this.methodResolver.isSessionAttribute(name, paramType)) {
			bindObject = this.sessionAttributeStore.retrieveAttribute(webRequest, name);
			if (bindObject == null) {
				raiseSessionRequiredException("Session attribute '" + name + "' required - not found in session");
			}
		}
		else {
			bindObject = BeanUtils.instantiateClass(paramType);
		}
		WebDataBinder binder = createBinder(webRequest, bindObject, name);
		initBinder(handler, name, binder, webRequest);
		return binder;
	}


	/**
	 * Determine whether the given value qualifies as a "binding candidate", i.e. might potentially be subject to
	 * bean-style data binding later on.
	 */
	protected boolean isBindingCandidate(Object value) {
		return (value != null && !value.getClass().isArray() && !(value instanceof Collection) &&
				!(value instanceof Map) && !BeanUtils.isSimpleValueType(value.getClass()));
	}

	protected void raiseMissingParameterException(String paramName, Class<?> paramType) throws Exception {
		throw new IllegalStateException("Missing parameter '" + paramName + "' of type [" + paramType.getName() + "]");
	}

	protected void raiseMissingHeaderException(String headerName, Class<?> paramType) throws Exception {
		throw new IllegalStateException("Missing header '" + headerName + "' of type [" + paramType.getName() + "]");
	}

	protected void raiseMissingCookieException(String cookieName, Class<?> paramType) throws Exception {
		throw new IllegalStateException(
				"Missing cookie value '" + cookieName + "' of type [" + paramType.getName() + "]");
	}

	protected void raiseSessionRequiredException(String message) throws Exception {
		throw new IllegalStateException(message);
	}

	protected WebDataBinder createBinder(NativeWebRequest webRequest, Object target, String objectName)
			throws Exception {

		return new WebRequestDataBinder(target, objectName);
	}

	private void doBind(WebDataBinder binder, NativeWebRequest webRequest, boolean validate,
			Object[] validationHints, boolean failOnErrors) throws Exception {

		doBind(binder, webRequest);
		if (validate) {
			binder.validate(validationHints);
		}
		if (failOnErrors && binder.getBindingResult().hasErrors()) {
			throw new BindException(binder.getBindingResult());
		}
	}

	protected void doBind(WebDataBinder binder, NativeWebRequest webRequest) throws Exception {
		((WebRequestDataBinder) binder).bind(webRequest);
	}

	/**
	 * Return a {@link HttpInputMessage} for the given {@link NativeWebRequest}.
	 * <p>Throws an UnsupportedOperation1Exception by default.
	 */
	protected HttpInputMessage createHttpInputMessage(NativeWebRequest webRequest) throws Exception {
		throw new UnsupportedOperationException("@RequestBody not supported");
	}

	/**
	 * Return a {@link HttpOutputMessage} for the given {@link NativeWebRequest}.
	 * <p>Throws an UnsupportedOperationException by default.
	 */
	protected HttpOutputMessage createHttpOutputMessage(NativeWebRequest webRequest) throws Exception {
		throw new UnsupportedOperationException("@Body not supported");
	}

	protected String parseDefaultValueAttribute(String value) {
		return (ValueConstants.DEFAULT_NONE.equals(value) ? null : value);
	}

	protected Object resolveDefaultValue(String value) {
		return value;
	}

	protected Object resolveCommonArgument(MethodParameter methodParameter, NativeWebRequest webRequest)
			throws Exception {

		// Invoke custom argument resolvers if present...
		if (this.customArgumentResolvers != null) {
			for (WebArgumentResolver argumentResolver : this.customArgumentResolvers) {
				Object value = argumentResolver.resolveArgument(methodParameter, webRequest);
				if (value != WebArgumentResolver.UNRESOLVED) {
					return value;
				}
			}
		}

		// Resolution of standard parameter types...
		Class<?> paramType = methodParameter.getParameterType();
		Object value = resolveStandardArgument(paramType, webRequest);
		if (value != WebArgumentResolver.UNRESOLVED && !ClassUtils.isAssignableValue(paramType, value)) {
			throw new IllegalStateException("Standard argument type [" + paramType.getName() +
					"] resolved to incompatible value of type [" + (value != null ? value.getClass() : null) +
					"]. Consider declaring the argument type in a less specific fashion.");
		}
		return value;
	}

	protected Object resolveStandardArgument(Class<?> parameterType, NativeWebRequest webRequest) throws Exception {
		if (WebRequest.class.isAssignableFrom(parameterType)) {
			return webRequest;
		}
		return WebArgumentResolver.UNRESOLVED;
	}

	protected final void addReturnValueAsModelAttribute(Method handlerMethod, Class<?> handlerType,
			Object returnValue, ExtendedModelMap implicitModel) {

		ModelAttribute attr = AnnotationUtils.findAnnotation(handlerMethod, ModelAttribute.class);
		String attrName = (attr != null ? attr.value() : "");
		if ("".equals(attrName)) {
			Class<?> resolvedType = GenericTypeResolver.resolveReturnType(handlerMethod, handlerType);
			attrName = Conventions.getVariableNameForReturnType(handlerMethod, resolvedType, returnValue);
		}
		implicitModel.addAttribute(attrName, returnValue);
	}

}
