/**************************************************************************************
 * Copyright (c) Jonas Bonér, Alexandre Vasseur. All rights reserved.                 *
 * http://aspectwerkz.codehaus.org                                                    *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the LGPL license      *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package org.codehaus.aspectwerkz.aspect;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

import org.codehaus.aspectwerkz.exception.WrappedRuntimeException;
import org.codehaus.aspectwerkz.joinpoint.JoinPoint;
import org.codehaus.aspectwerkz.transform.TransformationUtil;
import org.codehaus.aspectwerkz.CrossCuttingInfo;
import org.codehaus.aspectwerkz.DeploymentModel;

/**
 * Implements the default aspect container strategy.
 *
 * @author <a href="mailto:jboner@codehaus.org">Jonas Bonér</a>
 */
public class DefaultAspectContainerStrategy implements AspectContainer {

    private static final int ASPECT_CONSTRUCTION_TYPE_UNKNOWN = 0;
    private static final int ASPECT_CONSTRUCTION_TYPE_DEFAULT = 1;
    private static final int ASPECT_CONSTRUCTION_TYPE_CROSS_CUTTING_INFO = 2;

    private static final Object[] EMPTY_OBJECT_ARRAY = new Object[]{};

    /**
     * Introduction container containing introduction declared by this aspect, keys by introduction names
     */
    private final Map m_introductionContainers = new HashMap();

    /**
     * The cross-cutting info prototype.
     */
    private final CrossCuttingInfo m_infoPrototype;

    /**
     * An array with the single cross-cutting info, needed to save one array creation per invocation.
     */
    private final Object[] arrayWithSingleCrossCuttingInfo = new Object[1];

    /**
     * The aspect instance prototype.
     */
    private final Object m_aspectPrototype;

    /**
     * The constructor for the aspect.
     */
    private final Constructor m_aspectConstructor;

    /**
     * Holds a reference to the sole per JVM aspect instance.
     */
    private Object m_perJvm;

    /**
     * Holds references to the per class aspect instances.
     */
    private final Map m_perClass = new WeakHashMap();

    /**
     * Holds references to the per instance aspect instances.
     */
    private final Map m_perInstance = new WeakHashMap();

    /**
     * Holds references to the per thread aspect instances.
     */
    private final Map m_perThread = new WeakHashMap();

    /**
     * The advice repository.
     */
    private Method[] m_adviceRepository = new Method[0];

    /**
     * The aspect construction type.
     */
    private int m_aspectConstructionType = ASPECT_CONSTRUCTION_TYPE_UNKNOWN;

    /**
     * Creates a new aspect container strategy.
     *
     * @param crossCuttingInfo the cross-cutting info
     */
    public DefaultAspectContainerStrategy(final CrossCuttingInfo crossCuttingInfo) {
        if (crossCuttingInfo == null) {
            throw new IllegalArgumentException("cross-cutting info can not be null");
        }
        m_infoPrototype = crossCuttingInfo;

        arrayWithSingleCrossCuttingInfo[0] = m_infoPrototype;

        m_aspectConstructor = findConstructor();
        m_aspectPrototype = createAspect();

        createAdviceRepository();
    }

    /**
     * Invokes an introduced method with the index specified.
     *
     * @param methodIndex the method index
     * @param joinPoint   the join point
     * @return the result from the invocation
     */
    public Object invokeAdvice(final int methodIndex, final JoinPoint joinPoint) {
        Object result = null;
        switch (m_infoPrototype.getDeploymentModel()) {

            case DeploymentModel.PER_JVM:
                result = invokeAdvicePerJvm(methodIndex, joinPoint);
                break;

            case DeploymentModel.PER_CLASS:
                result = invokeAdvicePerClass(methodIndex, joinPoint);
                break;

            case DeploymentModel.PER_INSTANCE:
                result = invokeAdvicePerInstance(methodIndex, joinPoint);
                break;

            case DeploymentModel.PER_THREAD:
                result = invokeAdvicePerThread(methodIndex, joinPoint);
                break;

            default:
                throw new RuntimeException("invalid deployment model: " + m_infoPrototype.getDeploymentModel());
        }
        return result;
    }

    /**
     * Returns a specific advice by index.
     *
     * @param index the index
     * @return the advice
     */
    public Method getAdvice(final int index) {
        if (index < 0) {
            throw new IllegalArgumentException("advice index can not be less than 0");
        }
        return m_adviceRepository[index];
    }

    /**
     * Returns the cross-cutting info.
     *
     * @return the cross-cutting info
     */
    public CrossCuttingInfo getCrossCuttingInfo() {
        return m_infoPrototype;
    }

    /**
     * Invokes the advice method on a per JVM basis.
     *
     * @param methodIndex the method index
     * @param joinPoint   the join point
     * @return the result from the method invocation
     */
    private Object invokeAdvicePerJvm(final int methodIndex, final JoinPoint joinPoint) {
        Object result = null;
        try {
            createPerJvmAspect();
            Method method = m_adviceRepository[methodIndex];
            result = method.invoke(m_perJvm, new Object[]{joinPoint});
        }
        catch (InvocationTargetException e) {
            throw new WrappedRuntimeException(e.getTargetException());
        }
        catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the advice method on a per class basis.
     *
     * @param methodIndex the method index
     * @param joinPoint   the join point
     * @return the result from the method invocation
     */
    private Object invokeAdvicePerClass(final int methodIndex, final JoinPoint joinPoint) {
        final Class targetClass = joinPoint.getTargetClass();
        Object result = null;
        try {
            createPerClassAspect(targetClass);
            result = m_adviceRepository[methodIndex].invoke(m_perClass.get(targetClass), new Object[]{joinPoint});
        }
        catch (InvocationTargetException e) {
            throw new WrappedRuntimeException(e.getTargetException());
        }
        catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the advice method on a per instance basis.
     *
     * @param methodIndex the method index
     * @param joinPoint   the join point
     * @return the result from the method invocation
     */
    private Object invokeAdvicePerInstance(final int methodIndex, final JoinPoint joinPoint) {
        Object result = null;
        Object targetInstance = joinPoint.getTargetInstance();

        if (targetInstance == null) { // can be null if f.e. an aspect has deployment model perInstance and has caller side pointcuts defined
            return invokeAdvicePerClass(methodIndex, joinPoint);
        }
        try {
            createPerInstanceAspect(targetInstance);
            result =
            m_adviceRepository[methodIndex].invoke(m_perInstance.get(targetInstance), new Object[]{joinPoint});
        }
        catch (InvocationTargetException e) {
            throw new WrappedRuntimeException(e.getTargetException());
        }
        catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the advice method on a per thread basis.
     *
     * @param methodIndex the method index
     * @param joinPoint   the join point
     * @return the result from the method invocation
     */
    private Object invokeAdvicePerThread(final int methodIndex, final JoinPoint joinPoint) {
        Object result;
        try {
            final Thread currentThread = Thread.currentThread();
            createPerThreadAspect(currentThread);
            Method method = m_adviceRepository[methodIndex];
            result = method.invoke(m_perThread.get(currentThread), new Object[]{joinPoint});
        }
        catch (InvocationTargetException e) {
            throw new WrappedRuntimeException(e.getTargetException());
        }
        catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Creates a new perJVM cross-cutting instance, if it already exists then return it.
     *
     * @return the cross-cutting instance
     */
    public Object createPerJvmAspect() {
        if (m_perJvm == null) {
            m_perJvm = createAspect();
        }
        return m_perJvm;
    }

    /**
     * Creates a new perClass cross-cutting instance, if it already exists then return it.
     *
     * @param callingClass
     * @return the cross-cutting instance
     */
    public Object createPerClassAspect(final Class callingClass) {
        if (!m_perClass.containsKey(callingClass)) {
            synchronized (m_perClass) {
                m_perClass.put(callingClass, createAspect());
            }
        }
        return m_perClass.get(callingClass);
    }

    /**
     * Creates a new perInstance cross-cutting instance, if it already exists then return it.
     *
     * @param callingInstance
     * @return the cross-cutting instance
     */
    public Object createPerInstanceAspect(final Object callingInstance) {
        if (callingInstance == null) {
            return createPerClassAspect(callingInstance.getClass());
        }
        if (!m_perInstance.containsKey(callingInstance)) {
            synchronized (m_perInstance) {
                m_perInstance.put(callingInstance, createAspect());
            }
        }
        return m_perInstance.get(callingInstance);
    }

    /**
     * Creates a new perThread cross-cutting instance, if it already exists then return it.
     *
     * @param thread the thread for the aspect
     * @return the cross-cutting instance
     */
    public Object createPerThreadAspect(final Thread thread) {
        if (!m_perThread.containsKey(thread)) {
            synchronized (m_perThread) {
                m_perThread.put(thread, createAspect());
            }
        }
        return m_perThread.get(thread);
    }

    /**
     * Grabs the correct constructor for the aspect.
     *
     * @return the constructor for the aspect
     */
    private Constructor findConstructor() {
        Constructor aspectConstructor = null;
        Class aspectClass = m_infoPrototype.getAspectClass();
        Constructor[] constructors = aspectClass.getDeclaredConstructors();
        for (int i = 0; i < constructors.length; i++) {
            Constructor constructor = constructors[i];
            Class[] parameterTypes = constructor.getParameterTypes();
            if (parameterTypes.length == 0) {
                m_aspectConstructionType = ASPECT_CONSTRUCTION_TYPE_DEFAULT;
                aspectConstructor = constructor;
            }
            else if (parameterTypes.length == 1 && parameterTypes[0].equals(CrossCuttingInfo.class)) {
                m_aspectConstructionType = ASPECT_CONSTRUCTION_TYPE_CROSS_CUTTING_INFO;
                aspectConstructor = constructor;
                break;
            }
        }
        if (m_aspectConstructionType == ASPECT_CONSTRUCTION_TYPE_UNKNOWN) {
            throw new RuntimeException(
                    "aspect [" + aspectClass.getName() +
                    "] does not have a valid constructor (either default no-arg or one that takes a CrossCuttingInfo type as its only parameter)"
            );
        }
        return aspectConstructor;
    }

    /**
     * Creates a new aspect instance.
     *
     * @return the new aspect instance
     */
    private Object createAspect() {
        try {
            switch (m_aspectConstructionType) {
                case ASPECT_CONSTRUCTION_TYPE_DEFAULT:
                    return m_aspectConstructor.newInstance(EMPTY_OBJECT_ARRAY);

                case ASPECT_CONSTRUCTION_TYPE_CROSS_CUTTING_INFO:
                    return m_aspectConstructor.newInstance(arrayWithSingleCrossCuttingInfo);

                default:
                    throw new RuntimeException(
                            "aspect [" + m_aspectPrototype.getClass().getName() +
                            "] does not have a valid constructor (either default no-arg or one that takes a CrossCuttingInfo type as its only parameter)"
                    );
            }
        }
        catch (InstantiationException e) {
            throw new WrappedRuntimeException(e);
        }
        catch (IllegalAccessException e) {
            throw new WrappedRuntimeException(e);
        }
        catch (InvocationTargetException e) {
            throw new WrappedRuntimeException(e.getTargetException());
        }
    }

    /**
     * Creates a repository for the advice methods.
     */
    private void createAdviceRepository() {
        synchronized (m_adviceRepository) {
            List methodList = TransformationUtil.createSortedMethodList(m_infoPrototype.getAspectClass());
            m_adviceRepository = new Method[methodList.size()];
            for (int i = 0; i < m_adviceRepository.length; i++) {
                Method method = (Method)methodList.get(i);
                method.setAccessible(true);
                m_adviceRepository[i] = method;
            }
        }
    }

    /**
     * Attach the introduction container to this aspect container to mirror the "aspect contains 0-n introduction"
     *
     * @param name           of the introduction
     * @param introContainer introduction container
     */
    public void addIntroductionContainer(final String name, final IntroductionContainer introContainer) {
        m_introductionContainers.put(name, introContainer);
    }

    /**
     * Returns the introduction container of given name (introduction name) or null if not linked.
     *
     * @param name of the introduction
     * @return introduction container
     */
    public IntroductionContainer getIntroductionContainer(final String name) {
        return (IntroductionContainer)m_introductionContainers.get(name);
    }
}
