/*
 * Copyright 2002-2020 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.aop.framework;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.aopalliance.aop.Advice;

import org.springframework.aop.Advisor;
import org.springframework.aop.DynamicIntroductionAdvice;
import org.springframework.aop.IntroductionAdvisor;
import org.springframework.aop.IntroductionInfo;
import org.springframework.aop.TargetSource;
import org.springframework.aop.support.DefaultIntroductionAdvisor;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.aop.target.EmptyTargetSource;
import org.springframework.aop.target.SingletonTargetSource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CollectionUtils;

Base class for AOP proxy configuration managers.
These are not themselves AOP proxies, but subclasses of this class are
normally factories from which AOP proxy instances are obtained directly.
This class frees subclasses of the housekeeping of Advices
and Advisors, but doesn't actually implement proxy creation
methods, which are provided by subclasses.
This class is serializable; subclasses need not be.
This class is used to hold snapshots of proxies.
Author:
Rod Johnson, Juergen Hoeller
See Also:
AopProxy/**
 * Base class for AOP proxy configuration managers.
 * These are not themselves AOP proxies, but subclasses of this class are
 * normally factories from which AOP proxy instances are obtained directly.
 *
 * <p>This class frees subclasses of the housekeeping of Advices
 * and Advisors, but doesn't actually implement proxy creation
 * methods, which are provided by subclasses.
 *
 * <p>This class is serializable; subclasses need not be.
 * This class is used to hold snapshots of proxies.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see org.springframework.aop.framework.AopProxy
 */
public class AdvisedSupport extends ProxyConfig implements Advised {

	
use serialVersionUID from Spring 2.0 for interoperability. /** use serialVersionUID from Spring 2.0 for interoperability. */
	private static final long serialVersionUID = 2651364800145442165L;


	
Canonical TargetSource when there's no target, and behavior is
supplied by the advisors.
/**
	 * Canonical TargetSource when there's no target, and behavior is
	 * supplied by the advisors.
	 */
	public static final TargetSource EMPTY_TARGET_SOURCE = EmptyTargetSource.INSTANCE;


	
Package-protected to allow direct access for efficiency. /** Package-protected to allow direct access for efficiency. */
	TargetSource targetSource = EMPTY_TARGET_SOURCE;

	
Whether the Advisors are already filtered for the specific target class. /** Whether the Advisors are already filtered for the specific target class. */
	private boolean preFiltered = false;

	
The AdvisorChainFactory to use. /** The AdvisorChainFactory to use. */
	AdvisorChainFactory advisorChainFactory = new DefaultAdvisorChainFactory();

	
Cache with Method as key and advisor chain List as value. /** Cache with Method as key and advisor chain List as value. */
	private transient Map<MethodCacheKey, List<Object>> methodCache;

	
Interfaces to be implemented by the proxy. Held in List to keep the order
of registration, to create JDK proxy with specified order of interfaces.
/**
	 * Interfaces to be implemented by the proxy. Held in List to keep the order
	 * of registration, to create JDK proxy with specified order of interfaces.
	 */
	private List<Class<?>> interfaces = new ArrayList<>();

	
List of Advisors. If an Advice is added, it will be wrapped
in an Advisor before being added to this List.
/**
	 * List of Advisors. If an Advice is added, it will be wrapped
	 * in an Advisor before being added to this List.
	 */
	private List<Advisor> advisors = new ArrayList<>();


	
No-arg constructor for use as a JavaBean.
/**
	 * No-arg constructor for use as a JavaBean.
	 */
	public AdvisedSupport() {
		this.methodCache = new ConcurrentHashMap<>(32);
	}

	
Create a AdvisedSupport instance with the given parameters.
Params:
interfaces – the proxied interfaces/**
	 * Create a AdvisedSupport instance with the given parameters.
	 * @param interfaces the proxied interfaces
	 */
	public AdvisedSupport(Class<?>... interfaces) {
		this();
		setInterfaces(interfaces);
	}


	
Set the given object as target.
Will create a SingletonTargetSource for the object.
See Also:
setTargetSource
SingletonTargetSource/**
	 * Set the given object as target.
	 * Will create a SingletonTargetSource for the object.
	 * @see #setTargetSource
	 * @see org.springframework.aop.target.SingletonTargetSource
	 */
	public void setTarget(Object target) {
		setTargetSource(new SingletonTargetSource(target));
	}

	@Override
	public void setTargetSource(@Nullable TargetSource targetSource) {
		this.targetSource = (targetSource != null ? targetSource : EMPTY_TARGET_SOURCE);
	}

	@Override
	public TargetSource getTargetSource() {
		return this.targetSource;
	}

	
Set a target class to be proxied, indicating that the proxy
should be castable to the given class.
Internally, an EmptyTargetSource for the given target class will be used. The kind of proxy needed will be determined on actual creation of the proxy. 
This is a replacement for setting a "targetSource" or "target",
for the case where we want a proxy based on a target class
(which can be an interface or a concrete class) without having
a fully capable TargetSource available.
See Also:
setTargetSource
setTarget/**
	 * Set a target class to be proxied, indicating that the proxy
	 * should be castable to the given class.
	 * <p>Internally, an {@link org.springframework.aop.target.EmptyTargetSource}
	 * for the given target class will be used. The kind of proxy needed
	 * will be determined on actual creation of the proxy.
	 * <p>This is a replacement for setting a "targetSource" or "target",
	 * for the case where we want a proxy based on a target class
	 * (which can be an interface or a concrete class) without having
	 * a fully capable TargetSource available.
	 * @see #setTargetSource
	 * @see #setTarget
	 */
	public void setTargetClass(@Nullable Class<?> targetClass) {
		this.targetSource = EmptyTargetSource.forClass(targetClass);
	}

	@Override
	@Nullable
	public Class<?> getTargetClass() {
		return this.targetSource.getTargetClass();
	}

	@Override
	public void setPreFiltered(boolean preFiltered) {
		this.preFiltered = preFiltered;
	}

	@Override
	public boolean isPreFiltered() {
		return this.preFiltered;
	}

	
Set the advisor chain factory to use.
Default is a DefaultAdvisorChainFactory. /**
	 * Set the advisor chain factory to use.
	 * <p>Default is a {@link DefaultAdvisorChainFactory}.
	 */
	public void setAdvisorChainFactory(AdvisorChainFactory advisorChainFactory) {
		Assert.notNull(advisorChainFactory, "AdvisorChainFactory must not be null");
		this.advisorChainFactory = advisorChainFactory;
	}

	
Return the advisor chain factory to use (never null). /**
	 * Return the advisor chain factory to use (never {@code null}).
	 */
	public AdvisorChainFactory getAdvisorChainFactory() {
		return this.advisorChainFactory;
	}


	
Set the interfaces to be proxied.
/**
	 * Set the interfaces to be proxied.
	 */
	public void setInterfaces(Class<?>... interfaces) {
		Assert.notNull(interfaces, "Interfaces must not be null");
		this.interfaces.clear();
		for (Class<?> ifc : interfaces) {
			addInterface(ifc);
		}
	}

	
Add a new proxied interface.
Params:
intf – the additional interface to proxy/**
	 * Add a new proxied interface.
	 * @param intf the additional interface to proxy
	 */
	public void addInterface(Class<?> intf) {
		Assert.notNull(intf, "Interface must not be null");
		if (!intf.isInterface()) {
			throw new IllegalArgumentException("[" + intf.getName() + "] is not an interface");
		}
		if (!this.interfaces.contains(intf)) {
			this.interfaces.add(intf);
			adviceChanged();
		}
	}

	
Remove a proxied interface.
Does nothing if the given interface isn't proxied.
Params:
intf – the interface to remove from the proxy
Returns:
true if the interface was removed; false if the interface was not found and hence could not be removed/**
	 * Remove a proxied interface.
	 * <p>Does nothing if the given interface isn't proxied.
	 * @param intf the interface to remove from the proxy
	 * @return {@code true} if the interface was removed; {@code false}
	 * if the interface was not found and hence could not be removed
	 */
	public boolean removeInterface(Class<?> intf) {
		return this.interfaces.remove(intf);
	}

	@Override
	public Class<?>[] getProxiedInterfaces() {
		return ClassUtils.toClassArray(this.interfaces);
	}

	@Override
	public boolean isInterfaceProxied(Class<?> intf) {
		for (Class<?> proxyIntf : this.interfaces) {
			if (intf.isAssignableFrom(proxyIntf)) {
				return true;
			}
		}
		return false;
	}


	@Override
	public final Advisor[] getAdvisors() {
		return this.advisors.toArray(new Advisor[0]);
	}

	@Override
	public int getAdvisorCount() {
		return this.advisors.size();
	}

	@Override
	public void addAdvisor(Advisor advisor) {
		int pos = this.advisors.size();
		addAdvisor(pos, advisor);
	}

	@Override
	public void addAdvisor(int pos, Advisor advisor) throws AopConfigException {
		if (advisor instanceof IntroductionAdvisor) {
			validateIntroductionAdvisor((IntroductionAdvisor) advisor);
		}
		addAdvisorInternal(pos, advisor);
	}

	@Override
	public boolean removeAdvisor(Advisor advisor) {
		int index = indexOf(advisor);
		if (index == -1) {
			return false;
		}
		else {
			removeAdvisor(index);
			return true;
		}
	}

	@Override
	public void removeAdvisor(int index) throws AopConfigException {
		if (isFrozen()) {
			throw new AopConfigException("Cannot remove Advisor: Configuration is frozen.");
		}
		if (index < 0 || index > this.advisors.size() - 1) {
			throw new AopConfigException("Advisor index " + index + " is out of bounds: " +
					"This configuration only has " + this.advisors.size() + " advisors.");
		}

		Advisor advisor = this.advisors.remove(index);
		if (advisor instanceof IntroductionAdvisor) {
			IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
			// We need to remove introduction interfaces.
			for (Class<?> ifc : ia.getInterfaces()) {
				removeInterface(ifc);
			}
		}

		adviceChanged();
	}

	@Override
	public int indexOf(Advisor advisor) {
		Assert.notNull(advisor, "Advisor must not be null");
		return this.advisors.indexOf(advisor);
	}

	@Override
	public boolean replaceAdvisor(Advisor a, Advisor b) throws AopConfigException {
		Assert.notNull(a, "Advisor a must not be null");
		Assert.notNull(b, "Advisor b must not be null");
		int index = indexOf(a);
		if (index == -1) {
			return false;
		}
		removeAdvisor(index);
		addAdvisor(index, b);
		return true;
	}

	
Add all of the given advisors to this proxy configuration.
Params:
advisors – the advisors to register/**
	 * Add all of the given advisors to this proxy configuration.
	 * @param advisors the advisors to register
	 */
	public void addAdvisors(Advisor... advisors) {
		addAdvisors(Arrays.asList(advisors));
	}

	
Add all of the given advisors to this proxy configuration.
Params:
advisors – the advisors to register/**
	 * Add all of the given advisors to this proxy configuration.
	 * @param advisors the advisors to register
	 */
	public void addAdvisors(Collection<Advisor> advisors) {
		if (isFrozen()) {
			throw new AopConfigException("Cannot add advisor: Configuration is frozen.");
		}
		if (!CollectionUtils.isEmpty(advisors)) {
			for (Advisor advisor : advisors) {
				if (advisor instanceof IntroductionAdvisor) {
					validateIntroductionAdvisor((IntroductionAdvisor) advisor);
				}
				Assert.notNull(advisor, "Advisor must not be null");
				this.advisors.add(advisor);
			}
			adviceChanged();
		}
	}

	private void validateIntroductionAdvisor(IntroductionAdvisor advisor) {
		advisor.validateInterfaces();
		// If the advisor passed validation, we can make the change.
		Class<?>[] ifcs = advisor.getInterfaces();
		for (Class<?> ifc : ifcs) {
			addInterface(ifc);
		}
	}

	private void addAdvisorInternal(int pos, Advisor advisor) throws AopConfigException {
		Assert.notNull(advisor, "Advisor must not be null");
		if (isFrozen()) {
			throw new AopConfigException("Cannot add advisor: Configuration is frozen.");
		}
		if (pos > this.advisors.size()) {
			throw new IllegalArgumentException(
					"Illegal position " + pos + " in advisor list with size " + this.advisors.size());
		}
		this.advisors.add(pos, advisor);
		adviceChanged();
	}

	
Allows uncontrolled access to the List of Advisors. 
Use with care, and remember to fire advice changed events when making any modifications. /**
	 * Allows uncontrolled access to the {@link List} of {@link Advisor Advisors}.
	 * <p>Use with care, and remember to {@link #adviceChanged() fire advice changed events}
	 * when making any modifications.
	 */
	protected final List<Advisor> getAdvisorsInternal() {
		return this.advisors;
	}

	@Override
	public void addAdvice(Advice advice) throws AopConfigException {
		int pos = this.advisors.size();
		addAdvice(pos, advice);
	}

	
Cannot add introductions this way unless the advice implements IntroductionInfo.
/**
	 * Cannot add introductions this way unless the advice implements IntroductionInfo.
	 */
	@Override
	public void addAdvice(int pos, Advice advice) throws AopConfigException {
		Assert.notNull(advice, "Advice must not be null");
		if (advice instanceof IntroductionInfo) {
			// We don't need an IntroductionAdvisor for this kind of introduction:
			// It's fully self-describing.
			addAdvisor(pos, new DefaultIntroductionAdvisor(advice, (IntroductionInfo) advice));
		}
		else if (advice instanceof DynamicIntroductionAdvice) {
			// We need an IntroductionAdvisor for this kind of introduction.
			throw new AopConfigException("DynamicIntroductionAdvice may only be added as part of IntroductionAdvisor");
		}
		else {
			addAdvisor(pos, new DefaultPointcutAdvisor(advice));
		}
	}

	@Override
	public boolean removeAdvice(Advice advice) throws AopConfigException {
		int index = indexOf(advice);
		if (index == -1) {
			return false;
		}
		else {
			removeAdvisor(index);
			return true;
		}
	}

	@Override
	public int indexOf(Advice advice) {
		Assert.notNull(advice, "Advice must not be null");
		for (int i = 0; i < this.advisors.size(); i++) {
			Advisor advisor = this.advisors.get(i);
			if (advisor.getAdvice() == advice) {
				return i;
			}
		}
		return -1;
	}

	
Is the given advice included in any advisor within this proxy configuration?
Params:
advice – the advice to check inclusion of
Returns:
whether this advice instance is included/**
	 * Is the given advice included in any advisor within this proxy configuration?
	 * @param advice the advice to check inclusion of
	 * @return whether this advice instance is included
	 */
	public boolean adviceIncluded(@Nullable Advice advice) {
		if (advice != null) {
			for (Advisor advisor : this.advisors) {
				if (advisor.getAdvice() == advice) {
					return true;
				}
			}
		}
		return false;
	}

	
Count advices of the given class.
Params:
adviceClass – the advice class to check
Returns:
the count of the interceptors of this class or subclasses/**
	 * Count advices of the given class.
	 * @param adviceClass the advice class to check
	 * @return the count of the interceptors of this class or subclasses
	 */
	public int countAdvicesOfType(@Nullable Class<?> adviceClass) {
		int count = 0;
		if (adviceClass != null) {
			for (Advisor advisor : this.advisors) {
				if (adviceClass.isInstance(advisor.getAdvice())) {
					count++;
				}
			}
		}
		return count;
	}


	
Determine a list of MethodInterceptor objects for the given method, based on this configuration. 
Params:
method – the proxied method
targetClass – the target class
Returns:
a List of MethodInterceptors (may also include InterceptorAndDynamicMethodMatchers)/**
	 * Determine a list of {@link org.aopalliance.intercept.MethodInterceptor} objects
	 * for the given method, based on this configuration.
	 * @param method the proxied method
	 * @param targetClass the target class
	 * @return a List of MethodInterceptors (may also include InterceptorAndDynamicMethodMatchers)
	 */
	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, @Nullable Class<?> targetClass) {
		MethodCacheKey cacheKey = new MethodCacheKey(method);
		List<Object> cached = this.methodCache.get(cacheKey);
		if (cached == null) {
			cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
					this, method, targetClass);
			this.methodCache.put(cacheKey, cached);
		}
		return cached;
	}

	
Invoked when advice has changed.
/**
	 * Invoked when advice has changed.
	 */
	protected void adviceChanged() {
		this.methodCache.clear();
	}

	
Call this method on a new instance created by the no-arg constructor
to create an independent copy of the configuration from the given object.
Params:
other – the AdvisedSupport object to copy configuration from/**
	 * Call this method on a new instance created by the no-arg constructor
	 * to create an independent copy of the configuration from the given object.
	 * @param other the AdvisedSupport object to copy configuration from
	 */
	protected void copyConfigurationFrom(AdvisedSupport other) {
		copyConfigurationFrom(other, other.targetSource, new ArrayList<>(other.advisors));
	}

	
Copy the AOP configuration from the given AdvisedSupport object,
but allow substitution of a fresh TargetSource and a given interceptor chain.
Params:
other – the AdvisedSupport object to take proxy configuration from
targetSource – the new TargetSource
advisors – the Advisors for the chain/**
	 * Copy the AOP configuration from the given AdvisedSupport object,
	 * but allow substitution of a fresh TargetSource and a given interceptor chain.
	 * @param other the AdvisedSupport object to take proxy configuration from
	 * @param targetSource the new TargetSource
	 * @param advisors the Advisors for the chain
	 */
	protected void copyConfigurationFrom(AdvisedSupport other, TargetSource targetSource, List<Advisor> advisors) {
		copyFrom(other);
		this.targetSource = targetSource;
		this.advisorChainFactory = other.advisorChainFactory;
		this.interfaces = new ArrayList<>(other.interfaces);
		for (Advisor advisor : advisors) {
			if (advisor instanceof IntroductionAdvisor) {
				validateIntroductionAdvisor((IntroductionAdvisor) advisor);
			}
			Assert.notNull(advisor, "Advisor must not be null");
			this.advisors.add(advisor);
		}
		adviceChanged();
	}

	
Build a configuration-only copy of this AdvisedSupport,
replacing the TargetSource.
/**
	 * Build a configuration-only copy of this AdvisedSupport,
	 * replacing the TargetSource.
	 */
	AdvisedSupport getConfigurationOnlyCopy() {
		AdvisedSupport copy = new AdvisedSupport();
		copy.copyFrom(this);
		copy.targetSource = EmptyTargetSource.forClass(getTargetClass(), getTargetSource().isStatic());
		copy.advisorChainFactory = this.advisorChainFactory;
		copy.interfaces = this.interfaces;
		copy.advisors = this.advisors;
		return copy;
	}


	//---------------------------------------------------------------------
	// Serialization support
	//---------------------------------------------------------------------

	private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
		// Rely on default serialization; just initialize state after deserialization.
		ois.defaultReadObject();

		// Initialize transient fields.
		this.methodCache = new ConcurrentHashMap<>(32);
	}

	@Override
	public String toProxyConfigString() {
		return toString();
	}

	
For debugging/diagnostic use.
/**
	 * For debugging/diagnostic use.
	 */
	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder(getClass().getName());
		sb.append(": ").append(this.interfaces.size()).append(" interfaces ");
		sb.append(ClassUtils.classNamesToString(this.interfaces)).append("; ");
		sb.append(this.advisors.size()).append(" advisors ");
		sb.append(this.advisors).append("; ");
		sb.append("targetSource [").append(this.targetSource).append("]; ");
		sb.append(super.toString());
		return sb.toString();
	}


	
Simple wrapper class around a Method. Used as the key when
caching methods, for efficient equals and hashCode comparisons.
/**
	 * Simple wrapper class around a Method. Used as the key when
	 * caching methods, for efficient equals and hashCode comparisons.
	 */
	private static final class MethodCacheKey implements Comparable<MethodCacheKey> {

		private final Method method;

		private final int hashCode;

		public MethodCacheKey(Method method) {
			this.method = method;
			this.hashCode = method.hashCode();
		}

		@Override
		public boolean equals(@Nullable Object other) {
			return (this == other || (other instanceof MethodCacheKey &&
					this.method == ((MethodCacheKey) other).method));
		}

		@Override
		public int hashCode() {
			return this.hashCode;
		}

		@Override
		public String toString() {
			return this.method.toString();
		}

		@Override
		public int compareTo(MethodCacheKey other) {
			int result = this.method.getName().compareTo(other.method.getName());
			if (result == 0) {
				result = this.method.toString().compareTo(other.method.toString());
			}
			return result;
		}
	}

}