/*
 * Copyright 2002-2016 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.rmi;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.SocketException;
import java.rmi.ConnectException;
import java.rmi.ConnectIOException;
import java.rmi.NoSuchObjectException;
import java.rmi.RemoteException;
import java.rmi.StubNotFoundException;
import java.rmi.UnknownHostException;

import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.lang.Nullable;
import org.springframework.remoting.RemoteAccessException;
import org.springframework.remoting.RemoteConnectFailureException;
import org.springframework.remoting.RemoteProxyFailureException;
import org.springframework.util.ReflectionUtils;

/**
 * Factored-out methods for performing invocations within an RMI client.
 * Can handle both RMI and non-RMI service interfaces working on an RMI stub.
 *
 * <p>Note: This is an SPI class, not intended to be used by applications.
 *
 * @author Juergen Hoeller
 * @since 1.1
 */
public abstract class RmiClientInterceptorUtils {

        private static final Log logger = LogFactory.getLog(RmiClientInterceptorUtils.class);


        /**
         * Perform a raw method invocation on the given RMI stub,
         * letting reflection exceptions through as-is.
         * @param invocation the AOP MethodInvocation
         * @param stub the RMI stub
         * @return the invocation result, if any
         * @throws InvocationTargetException if thrown by reflection
         */
        @Nullable
        public static Object invokeRemoteMethod(MethodInvocation invocation, Object stub)
                        throws InvocationTargetException {

                Method method = invocation.getMethod();
                try {
                        if (method.getDeclaringClass().isInstance(stub)) {
                                // directly implemented
                                return method.invoke(stub, invocation.getArguments());
                        }
                        else {
                                // not directly implemented
                                Method stubMethod = stub.getClass().getMethod(method.getName(), method.getParameterTypes());
                                return stubMethod.invoke(stub, invocation.getArguments());
                        }
                }
                catch (InvocationTargetException ex) {
                        throw ex;
                }
                catch (NoSuchMethodException ex) {
                        throw new RemoteProxyFailureException("No matching RMI stub method found for: " + method, ex);
                }
                catch (Throwable ex) {
                        throw new RemoteProxyFailureException("Invocation of RMI stub method failed: " + method, ex);
                }
        }

        /**
         * Wrap the given arbitrary exception that happened during remote access
         * in either a RemoteException or a Spring RemoteAccessException (if the
         * method signature does not support RemoteException).
         * <p>Only call this for remote access exceptions, not for exceptions
         * thrown by the target service itself!
         * @param method the invoked method
         * @param ex the exception that happened, to be used as cause for the
         * RemoteAccessException or RemoteException
         * @param message the message for the RemoteAccessException respectively
         * RemoteException
         * @return the exception to be thrown to the caller
         */
        public static Exception convertRmiAccessException(Method method, Throwable ex, String message) {
                if (logger.isDebugEnabled()) {
                        logger.debug(message, ex);
                }
                if (ReflectionUtils.declaresException(method, RemoteException.class)) {
                        return new RemoteException(message, ex);
                }
                else {
                        return new RemoteAccessException(message, ex);
                }
        }

        /**
         * Convert the given RemoteException that happened during remote access
         * to Spring's RemoteAccessException if the method signature does not
         * support RemoteException. Else, return the original RemoteException.
         * @param method the invoked method
         * @param ex the RemoteException that happened
         * @param serviceName the name of the service (for debugging purposes)
         * @return the exception to be thrown to the caller
         */
        public static Exception convertRmiAccessException(Method method, RemoteException ex, String serviceName) {
                return convertRmiAccessException(method, ex, isConnectFailure(ex), serviceName);
        }

        /**
         * Convert the given RemoteException that happened during remote access
         * to Spring's RemoteAccessException if the method signature does not
         * support RemoteException. Else, return the original RemoteException.
         * @param method the invoked method
         * @param ex the RemoteException that happened
         * @param isConnectFailure whether the given exception should be considered
         * a connect failure
         * @param serviceName the name of the service (for debugging purposes)
         * @return the exception to be thrown to the caller
         */
        public static Exception convertRmiAccessException(
                        Method method, RemoteException ex, boolean isConnectFailure, String serviceName) {

                if (logger.isDebugEnabled()) {
                        logger.debug("Remote service [" + serviceName + "] threw exception", ex);
                }
                if (ReflectionUtils.declaresException(method, ex.getClass())) {
                        return ex;
                }
                else {
                        if (isConnectFailure) {
                                return new RemoteConnectFailureException("Could not connect to remote service [" + serviceName + "]", ex);
                        }
                        else {
                                return new RemoteAccessException("Could not access remote service [" + serviceName + "]", ex);
                        }
                }
        }

        /**
         * Determine whether the given RMI exception indicates a connect failure.
         * <p>Treats RMI's ConnectException, ConnectIOException, UnknownHostException,
         * NoSuchObjectException and StubNotFoundException as connect failure.
         * @param ex the RMI exception to check
         * @return whether the exception should be treated as connect failure
         * @see java.rmi.ConnectException
         * @see java.rmi.ConnectIOException
         * @see java.rmi.UnknownHostException
         * @see java.rmi.NoSuchObjectException
         * @see java.rmi.StubNotFoundException
         */
        public static boolean isConnectFailure(RemoteException ex) {
                return (ex instanceof ConnectException || ex instanceof ConnectIOException ||
                                ex instanceof UnknownHostException || ex instanceof NoSuchObjectException ||
                                ex instanceof StubNotFoundException || ex.getCause() instanceof SocketException);
        }

}