/*
 * Copyright 2002-2007 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.aop.aspectj;

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

import org.aopalliance.aop.Advice;
import org.aopalliance.intercept.MethodInvocation;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.weaver.tools.JoinPointMatch;
import org.aspectj.weaver.tools.PointcutParameter;

import org.springframework.aop.AopInvocationException;
import org.springframework.aop.MethodMatcher;
import org.springframework.aop.Pointcut;
import org.springframework.aop.ProxyMethodInvocation;
import org.springframework.aop.interceptor.ExposeInvocationInterceptor;
import org.springframework.aop.support.ComposablePointcut;
import org.springframework.aop.support.MethodMatchers;
import org.springframework.aop.support.StaticMethodMatcher;
import org.springframework.core.JdkVersion;
import org.springframework.core.LocalVariableTableParameterNameDiscoverer;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.PrioritizedParameterNameDiscoverer;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;

/**
 * Base class for AOP Alliance {@link org.aopalliance.aop.Advice} classes
 * wrapping an AspectJ aspect or an AspectJ-annotated advice method.
 *
 * @author Rod Johnson
 * @author Adrian Colyer
 * @author Juergen Hoeller
 * @author Ramnivas Laddad
 * @since 2.0
 */
public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedenceInformation {

	/**
	 * Key used in ReflectiveMethodInvocation userAtributes map for the current joinpoint.
	 */
	protected static final String JOIN_POINT_KEY = JoinPoint.class.getName();


	/**
	 * Lazily instantiate joinpoint for the current invocation.
	 * Requires MethodInvocation to be bound with ExposeInvocationInterceptor.
	 * <p>Do not use if access is available to the current ReflectiveMethodInvocation
	 * (in an around advice).
	 * @return current AspectJ joinpoint, or through an exception if we're not in a
	 * Spring AOP invocation.
	 */
	public static JoinPoint currentJoinPoint() {
		MethodInvocation mi = ExposeInvocationInterceptor.currentInvocation();
		if (!(mi instanceof ProxyMethodInvocation)) {
			throw new IllegalStateException("MethodInvocation is not a Spring ProxyMethodInvocation: " + mi);
		}
		ProxyMethodInvocation pmi = (ProxyMethodInvocation) mi;
		JoinPoint jp = (JoinPoint) pmi.getUserAttribute(JOIN_POINT_KEY);
		if (jp == null) {
			jp = new MethodInvocationProceedingJoinPoint(pmi);
			pmi.setUserAttribute(JOIN_POINT_KEY, jp);
		}
		return jp;
	}


	protected final Method aspectJAdviceMethod;

	/** The total number of arguments we have to populate on advice dispatch */
	private final int adviceInvocationArgumentCount;

	private final AspectJExpressionPointcut pointcut;

	private final AspectInstanceFactory aspectInstanceFactory;

	/**
	 * The name of the aspect (ref bean) in which this advice was defined (used
	 * when determining advice precedence so that we can determine
	 * whether two pieces of advice come from the same aspect).
	 */
	private String aspectName;

	/**
	 * The order of declaration of this advice within the aspect.
	 */
	private int declarationOrder;

	/**
	 * This will be non-null if the creator of this advice object knows the argument names
	 * and sets them explicitly
	 */
	private String[] argumentNames = null;

	/** Non-null if after throwing advice binds the thrown value */
	private String throwingName = null;

	/** Non-null if after returning advice binds the return value */
	private String returningName = null;

	private Class discoveredReturningType = Object.class;

	private Class discoveredThrowingType = Object.class;

	/**
	 * Index for thisJoinPoint argument (currently only
	 * supported at index 0 if present at all)
	 */
	private int joinPointArgumentIndex = -1;

	/**
	 * Index for thisJoinPointStaticPart argument (currently only
	 * supported at index 0 if present at all)
	 */
	private int joinPointStaticPartArgumentIndex = -1;

	private Map argumentBindings = null;

	private boolean argumentsIntrospected = false;

	// The actual type is java.lang.reflect.Type,
	// but for JDK 1.4 compatibility we use Object as the static type.
	private Object discoveredReturningGenericType;
	// Note: Unlike return type, no such generic information is needed for the throwing type,
	// since Java doesn't allow exception types to be parameterized.


	/**
	 * Create a new AbstractAspectJAdvice for the given advice method.
	 * @param aspectJAdviceMethod the AspectJ-style advice method
	 * @param pointcut the AspectJ expression pointcut
	 * @param aspectInstanceFactory the factory for aspect instances
	 */
	public AbstractAspectJAdvice(
			Method aspectJAdviceMethod, AspectJExpressionPointcut pointcut, AspectInstanceFactory aspectInstanceFactory) {

		Assert.notNull(aspectJAdviceMethod, "Advice method must not be null");
		this.aspectJAdviceMethod = aspectJAdviceMethod;
		this.adviceInvocationArgumentCount = this.aspectJAdviceMethod.getParameterTypes().length;
		this.pointcut = pointcut;
		this.aspectInstanceFactory = aspectInstanceFactory;
	}


	/**
	 * Return the AspectJ-style advice method.
	 */
	public final Method getAspectJAdviceMethod() {
		return this.aspectJAdviceMethod;
	}

	/**
	 * Return the AspectJ expression pointcut.
	 */
	public final AspectJExpressionPointcut getPointcut() {
		calculateArgumentBindings();
		return this.pointcut;
	}

	/**
	 * Build a 'safe' pointcut that excludes the AspectJ advice method itself.
	 * @return a composable pointcut that builds on the original AspectJ expression pointcut
	 * @see #getPointcut()
	 */
	public final Pointcut buildSafePointcut() {
		Pointcut pc = getPointcut();
		MethodMatcher safeMethodMatcher = MethodMatchers.intersection(
				new AdviceExcludingMethodMatcher(this.aspectJAdviceMethod), pc.getMethodMatcher());
		return new ComposablePointcut(pc.getClassFilter(), safeMethodMatcher);
	}

	/**
	 * Return the factory for aspect instances.
	 */
	public final AspectInstanceFactory getAspectInstanceFactory() {
		return this.aspectInstanceFactory;
	}

	/**
	 * Return the ClassLoader for aspect instances.
	 */
	public final ClassLoader getAspectClassLoader() {
		return this.aspectInstanceFactory.getAspectClassLoader();
	}

	public int getOrder() {
		return this.aspectInstanceFactory.getOrder();
	}


	public void setAspectName(String name) {
		this.aspectName = name;
	}
	
	public String getAspectName() {
		return this.aspectName;
	}

	/**
	 * Sets the <b>declaration order</b> of this advice within the aspect
	 */
	public void setDeclarationOrder(int order) {
		this.declarationOrder = order;
	}

	public int getDeclarationOrder() {
		return this.declarationOrder;
	}

	/**
	 * Set by creator of this advice object if the argument names are known.
	 * <p>This could be for example because they have been explicitly specified in XML,
	 * or in an advice annotation.
	 * @param argNames comma delimited list of arg names
	 */
	public void setArgumentNames(String argNames) {
		String[] tokens = StringUtils.commaDelimitedListToStringArray(argNames);
		setArgumentNamesFromStringArray(tokens);
	}

	public void setArgumentNamesFromStringArray(String[] args) {
		this.argumentNames = new String[args.length];
		for (int i = 0; i < args.length; i++) {
			this.argumentNames[i] = StringUtils.trimWhitespace(args[i]);
			if (!isVariableName(this.argumentNames[i])) {
				throw new IllegalArgumentException(
						"'argumentNames' property of AbstractAspectJAdvice contains an argument name '" +
						this.argumentNames[i] + "' that is not a valid Java identifier");
			}
		}
		if (argumentNames != null) {
			if (aspectJAdviceMethod.getParameterTypes().length == argumentNames.length + 1) {
				// May need to add implicit join point arg name...
				Class firstArgType = aspectJAdviceMethod.getParameterTypes()[0];
				if (firstArgType == JoinPoint.class ||
						firstArgType == ProceedingJoinPoint.class ||
						firstArgType == JoinPoint.StaticPart.class) {
					String[] oldNames = argumentNames;
					argumentNames = new String[oldNames.length + 1];
					argumentNames[0] = "THIS_JOIN_POINT";
					System.arraycopy(oldNames, 0, argumentNames, 1, oldNames.length);
				}
			}
		}
	}

	public void setReturningName(String name) {
		throw new UnsupportedOperationException("Only afterReturning advice can be used to bind a return value");
	}

	/** 
	 * We need to hold the returning name at this level for argument binding calculations,
	 * this method allows the afterReturning advice subclass to set the name.
	 */
	protected void setReturningNameNoCheck(String name) {
		// name could be a variable or a type...
		if (isVariableName(name)) {
			this.returningName = name;
		}
		else {
			// assume a type
			try {
				this.discoveredReturningType = ClassUtils.forName(name, getAspectClassLoader());
			}
			catch (Throwable ex) {
				throw new IllegalArgumentException("Returning name '" + name  +
						"' is neither a valid argument name nor the fully-qualified name of a Java type on the classpath. " +
						"Root cause: " + ex);
			}
		}
	}

	protected Class getDiscoveredReturningType() {
		return this.discoveredReturningType;
	}

	protected Object getDiscoveredReturningGenericType() {
		return this.discoveredReturningGenericType;
	}

	public void setThrowingName(String name) {
		throw new UnsupportedOperationException("Only afterThrowing advice can be used to bind a thrown exception");
	}

	/** 
	 * We need to hold the throwing name at this level for argument binding calculations,
	 * this method allows the afterThrowing advice subclass to set the name.
	 */
	protected void setThrowingNameNoCheck(String name) {
		// name could be a variable or a type...
		if (isVariableName(name)) {
			this.throwingName = name;
		}
		else {
			// assume a type
			try {
				this.discoveredThrowingType = ClassUtils.forName(name, getAspectClassLoader());
			}
			catch (Throwable ex) {
				throw new IllegalArgumentException("Throwing name '" + name  +
						"' is neither a valid argument name nor the fully-qualified name of a Java type on the classpath. " +
						"Root cause: " + ex);
			}
		}
	}

	protected Class getDiscoveredThrowingType() {
		return this.discoveredThrowingType;
	}

	private boolean isVariableName(String name) {
		char[] chars = name.toCharArray();
		if (!Character.isJavaIdentifierStart(chars[0])) {
			return false;
		}
		for (int i = 1; i < chars.length; i++) {
			if (!Character.isJavaIdentifierPart(chars[i])) {
				return false;
			}
		}
		return true;
	}