/*
 * Copyright 2002-2018 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.validation.beanvalidation;

import java.lang.reflect.Method;
import java.util.Set;
import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.hibernate.validator.HibernateValidator;

import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.SmartFactoryBean;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
import org.springframework.validation.annotation.Validated;

/**
 * An AOP Alliance {@link MethodInterceptor} implementation that delegates to a
 * JSR-303 provider for performing method-level validation on annotated methods.
 *
 * <p>Applicable methods have JSR-303 constraint annotations on their parameters
 * and/or on their return value (in the latter case specified at the method level,
 * typically as inline annotation).
 *
 * <p>E.g.: {@code public @NotNull Object myValidMethod(@NotNull String arg1, @Max(10) int arg2)}
 *
 * <p>Validation groups can be specified through Spring's {@link Validated} annotation
 * at the type level of the containing target class, applying to all public service methods
 * of that class. By default, JSR-303 will validate against its default group only.
 *
 * <p>As of Spring 4.0, this functionality requires either a Bean Validation 1.1 provider
 * (such as Hibernate Validator 5.x) or the Bean Validation 1.0 API with Hibernate Validator
 * 4.3. The actual provider will be autodetected and automatically adapted.
 *
 * @author Juergen Hoeller
 * @since 3.1
 * @see MethodValidationPostProcessor
 * @see javax.validation.executable.ExecutableValidator
 * @see org.hibernate.validator.method.MethodValidator
 */
public class MethodValidationInterceptor implements MethodInterceptor {

        private static Method forExecutablesMethod;

        private static Method validateParametersMethod;

        private static Method validateReturnValueMethod;

        static {
                try {
                        forExecutablesMethod = Validator.class.getMethod("forExecutables");
                        Class<?> executableValidatorClass = forExecutablesMethod.getReturnType();
                        validateParametersMethod = executableValidatorClass.getMethod(
                                        "validateParameters", Object.class, Method.class, Object[].class, Class[].class);
                        validateReturnValueMethod = executableValidatorClass.getMethod(
                                        "validateReturnValue", Object.class, Method.class, Object.class, Class[].class);
                }
                catch (Exception ex) {
                        // Bean Validation 1.1 ExecutableValidator API not available
                }
        }


        private volatile Validator validator;


        /**
         * Create a new MethodValidationInterceptor using a default JSR-303 validator underneath.
         */
        public MethodValidationInterceptor() {
                this(forExecutablesMethod != null ? Validation.buildDefaultValidatorFactory() :
                                HibernateValidatorDelegate.buildValidatorFactory());
        }

        /**
         * Create a new MethodValidationInterceptor using the given JSR-303 ValidatorFactory.
         * @param validatorFactory the JSR-303 ValidatorFactory to use
         */
        public MethodValidationInterceptor(ValidatorFactory validatorFactory) {
                this(validatorFactory.getValidator());
        }

        /**
         * Create a new MethodValidationInterceptor using the given JSR-303 Validator.
         * @param validator the JSR-303 Validator to use
         */
        public MethodValidationInterceptor(Validator validator) {
                this.validator = validator;
        }


        @Override
        @SuppressWarnings("unchecked")
        public Object invoke(MethodInvocation invocation) throws Throwable {
                // Avoid Validator invocation on FactoryBean.getObjectType/isSingleton
                if (isFactoryBeanMetadataMethod(invocation.getMethod())) {
                        return invocation.proceed();
                }

                Class<?>[] groups = determineValidationGroups(invocation);

                if (forExecutablesMethod != null) {
                        // Standard Bean Validation 1.1 API
                        Object execVal;
                        try {
                                execVal = ReflectionUtils.invokeMethod(forExecutablesMethod, this.validator);
                        }
                        catch (AbstractMethodError err) {
                                // Probably an adapter (maybe a lazy-init proxy) without BV 1.1 support
                                Validator nativeValidator = this.validator.unwrap(Validator.class);
                                execVal = ReflectionUtils.invokeMethod(forExecutablesMethod, nativeValidator);
                                // If successful, store native Validator for further use
                                this.validator = nativeValidator;
                        }

                        Method methodToValidate = invocation.getMethod();
                        Set<ConstraintViolation<?>> result;

                        try {
                                result = (Set<ConstraintViolation<?>>) ReflectionUtils.invokeMethod(validateParametersMethod,
                                                execVal, invocation.getThis(), methodToValidate, invocation.getArguments(), groups);
                        }
                        catch (IllegalArgumentException ex) {
                                // Probably a generic type mismatch between interface and impl as reported in SPR-12237 / HV-1011
                                // Let's try to find the bridged method on the implementation class...
                                methodToValidate = BridgeMethodResolver.findBridgedMethod(
                                                ClassUtils.getMostSpecificMethod(invocation.getMethod(), invocation.getThis().getClass()));
                                result = (Set<ConstraintViolation<?>>) ReflectionUtils.invokeMethod(validateParametersMethod,
                                                execVal, invocation.getThis(), methodToValidate, invocation.getArguments(), groups);
                        }
                        if (!result.isEmpty()) {
                                throw new ConstraintViolationException(result);
                        }

                        Object returnValue = invocation.proceed();
                        result = (Set<ConstraintViolation<?>>) ReflectionUtils.invokeMethod(validateReturnValueMethod,
                                        execVal, invocation.getThis(), methodToValidate, returnValue, groups);
                        if (!result.isEmpty()) {
                                throw new ConstraintViolationException(result);
                        }
                        return returnValue;
                }

                else {
                        // Hibernate Validator 4.3's native API
                        return HibernateValidatorDelegate.invokeWithinValidation(invocation, this.validator, groups);
                }
        }

        private boolean isFactoryBeanMetadataMethod(Method method) {
                Class<?> clazz = method.getDeclaringClass();

                // Call from interface-based proxy handle, allowing for an efficient check?
                if (clazz.isInterface()) {
                        return ((clazz == FactoryBean.class || clazz == SmartFactoryBean.class) &&
                                        !method.getName().equals("getObject"));
                }

                // Call from CGLIB proxy handle, potentially implementing a FactoryBean method?
                Class<?> factoryBeanType = null;
                if (SmartFactoryBean.class.isAssignableFrom(clazz)) {
                        factoryBeanType = SmartFactoryBean.class;
                }
                else if (FactoryBean.class.isAssignableFrom(clazz)) {
                        factoryBeanType = FactoryBean.class;
                }
                return (factoryBeanType != null && !method.getName().equals("getObject") &&
                                ClassUtils.hasMethod(factoryBeanType, method.getName(), method.getParameterTypes()));
        }

        /**
         * Determine the validation groups to validate against for the given method invocation.
         * <p>Default are the validation groups as specified in the {@link Validated} annotation
         * on the containing target class of the method.
         * @param invocation the current MethodInvocation
         * @return the applicable validation groups as a Class array
         */
        protected Class<?>[] determineValidationGroups(MethodInvocation invocation) {
                Validated validatedAnn = AnnotationUtils.findAnnotation(invocation.getMethod(), Validated.class);
                if (validatedAnn == null) {
                        validatedAnn = AnnotationUtils.findAnnotation(invocation.getThis().getClass(), Validated.class);
                }
                return (validatedAnn != null ? validatedAnn.value() : new Class<?>[0]);
        }


        /**
         * Inner class to avoid a hard-coded Hibernate Validator 4.3 dependency.
         */
        private static class HibernateValidatorDelegate {

                public static ValidatorFactory buildValidatorFactory() {
                        return Validation.byProvider(HibernateValidator.class).configure().buildValidatorFactory();
                }

                @SuppressWarnings("deprecation")
                public static Object invokeWithinValidation(MethodInvocation invocation, Validator validator, Class<?>[] groups)
                                throws Throwable {

                        org.hibernate.validator.method.MethodValidator methodValidator =
                                        validator.unwrap(org.hibernate.validator.method.MethodValidator.class);
                        Set<org.hibernate.validator.method.MethodConstraintViolation<Object>> result =
                                        methodValidator.validateAllParameters(
                                                        invocation.getThis(), invocation.getMethod(), invocation.getArguments(), groups);
                        if (!result.isEmpty()) {
                                throw new org.hibernate.validator.method.MethodConstraintViolationException(result);
                        }
                        Object returnValue = invocation.proceed();
                        result = methodValidator.validateReturnValue(
                                        invocation.getThis(), invocation.getMethod(), returnValue, groups);
                        if (!result.isEmpty()) {
                                throw new org.hibernate.validator.method.MethodConstraintViolationException(result);
                        }
                        return returnValue;
                }
        }

}