/*
 * 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.remoting.support;

import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import org.aopalliance.intercept.MethodInvocation;

import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * Encapsulates a remote invocation, providing core method invocation properties
 * in a serializable fashion. Used for RMI and HTTP-based serialization invokers.
 *
 * <p>This is an SPI class, typically not used directly by applications.
 * Can be subclassed for additional invocation parameters.
 *
 * <p>Both {@link RemoteInvocation} and {@link RemoteInvocationResult} are designed
 * for use with standard Java serialization as well as JavaBean-style serialization.
 *
 * @author Juergen Hoeller
 * @since 25.02.2004
 * @see RemoteInvocationResult
 * @see RemoteInvocationFactory
 * @see RemoteInvocationExecutor
 * @see org.springframework.remoting.rmi.RmiProxyFactoryBean
 * @see org.springframework.remoting.rmi.RmiServiceExporter
 * @see org.springframework.remoting.httpinvoker.HttpInvokerProxyFactoryBean
 * @see org.springframework.remoting.httpinvoker.HttpInvokerServiceExporter
 */
public class RemoteInvocation implements Serializable {

        /** use serialVersionUID from Spring 1.1 for interoperability. */
        private static final long serialVersionUID = 6876024250231820554L;


        private String methodName;

        private Class<?>[] parameterTypes;

        private Object[] arguments;

        private Map<String, Serializable> attributes;


        /**
         * Create a new RemoteInvocation for the given AOP method invocation.
         * @param methodInvocation the AOP invocation to convert
         */
        public RemoteInvocation(MethodInvocation methodInvocation) {
                this.methodName = methodInvocation.getMethod().getName();
                this.parameterTypes = methodInvocation.getMethod().getParameterTypes();
                this.arguments = methodInvocation.getArguments();
        }

        /**
         * Create a new RemoteInvocation for the given parameters.
         * @param methodName the name of the method to invoke
         * @param parameterTypes the parameter types of the method
         * @param arguments the arguments for the invocation
         */
        public RemoteInvocation(String methodName, Class<?>[] parameterTypes, Object[] arguments) {
                this.methodName = methodName;
                this.parameterTypes = parameterTypes;
                this.arguments = arguments;
        }

        /**
         * Create a new RemoteInvocation for JavaBean-style deserialization
         * (e.g. with Jackson).
         */
        public RemoteInvocation() {
        }


        /**
         * Set the name of the target method.
         * <p>This setter is intended for JavaBean-style deserialization.
         */
        public void setMethodName(String methodName) {
                this.methodName = methodName;
        }

        /**
         * Return the name of the target method.
         */
        public String getMethodName() {
                return this.methodName;
        }

        /**
         * Set the parameter types of the target method.
         * <p>This setter is intended for JavaBean-style deserialization.
         */
        public void setParameterTypes(Class<?>[] parameterTypes) {
                this.parameterTypes = parameterTypes;
        }

        /**
         * Return the parameter types of the target method.
         */
        public Class<?>[] getParameterTypes() {
                return this.parameterTypes;
        }

        /**
         * Set the arguments for the target method call.
         * <p>This setter is intended for JavaBean-style deserialization.
         */
        public void setArguments(Object[] arguments) {
                this.arguments = arguments;
        }

        /**
         * Return the arguments for the target method call.
         */
        public Object[] getArguments() {
                return this.arguments;
        }


        /**
         * Add an additional invocation attribute. Useful to add additional
         * invocation context without having to subclass RemoteInvocation.
         * <p>Attribute keys have to be unique, and no overriding of existing
         * attributes is allowed.
         * <p>The implementation avoids to unnecessarily create the attributes
         * Map, to minimize serialization size.
         * @param key the attribute key
         * @param value the attribute value
         * @throws IllegalStateException if the key is already bound
         */
        public void addAttribute(String key, Serializable value) throws IllegalStateException {
                if (this.attributes == null) {
                        this.attributes = new HashMap<>();
                }
                if (this.attributes.containsKey(key)) {
                        throw new IllegalStateException("There is already an attribute with key '" + key + "' bound");
                }
                this.attributes.put(key, value);
        }

        /**
         * Retrieve the attribute for the given key, if any.
         * <p>The implementation avoids to unnecessarily create the attributes
         * Map, to minimize serialization size.
         * @param key the attribute key
         * @return the attribute value, or {@code null} if not defined
         */
        @Nullable
        public Serializable getAttribute(String key) {
                if (this.attributes == null) {
                        return null;
                }
                return this.attributes.get(key);
        }

        /**
         * Set the attributes Map. Only here for special purposes:
         * Preferably, use {@link #addAttribute} and {@link #getAttribute}.
         * @param attributes the attributes Map
         * @see #addAttribute
         * @see #getAttribute
         */
        public void setAttributes(@Nullable Map<String, Serializable> attributes) {
                this.attributes = attributes;
        }

        /**
         * Return the attributes Map. Mainly here for debugging purposes:
         * Preferably, use {@link #addAttribute} and {@link #getAttribute}.
         * @return the attributes Map, or {@code null} if none created
         * @see #addAttribute
         * @see #getAttribute
         */
        @Nullable
        public Map<String, Serializable> getAttributes() {
                return this.attributes;
        }


        /**
         * Perform this invocation on the given target object.
         * Typically called when a RemoteInvocation is received on the server.
         * @param targetObject the target object to apply the invocation to
         * @return the invocation result
         * @throws NoSuchMethodException if the method name could not be resolved
         * @throws IllegalAccessException if the method could not be accessed
         * @throws InvocationTargetException if the method invocation resulted in an exception
         * @see java.lang.reflect.Method#invoke
         */
        public Object invoke(Object targetObject)
                        throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {

                Method method = targetObject.getClass().getMethod(this.methodName, this.parameterTypes);
                return method.invoke(targetObject, this.arguments);
        }


        @Override
        public String toString() {
                return "RemoteInvocation: method name '" + this.methodName + "'; parameter types " +
                                ClassUtils.classNamesToString(this.parameterTypes);
        }

}