/**************************************************************************************
 * Copyright (c) Jonas BonŽr, 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 org.codehaus.aspectwerkz.DeploymentModel;
import org.codehaus.aspectwerkz.definition.IntroductionDefinition;
import org.codehaus.aspectwerkz.exception.DefinitionException;
import org.codehaus.aspectwerkz.exception.WrappedRuntimeException;
import org.codehaus.aspectwerkz.transform.ReflectHelper;
import org.codehaus.aspectwerkz.transform.TransformationUtil;

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

/**
 * Container for Introductions.
 * 
 * @author <a href="mailto:alex@gnilux.com">Alexandre Vasseur </a>
 * @author <a href="mailto:jboner@codehaus.org">Jonas BonŽr </a>
 */
public class IntroductionContainer {
    /**
     * Holds a reference to the sole per JVM introduction.
     */
    protected Introduction m_perJvm;

    /**
     * Holds references to the per class introductions.
     */
    protected Map m_perClass = new WeakHashMap();

    /**
     * Holds references to the per instance introductions.
     */
    protected Map m_perInstance = new WeakHashMap();

    /**
     * Holds references to the per thread introductions.
     */
    protected Map m_perThread = new WeakHashMap();

    /**
     * The introduction prototype.
     */
    protected Introduction m_prototype;

    /**
     * The methods repository.
     */
    protected Method[] m_methodRepository = new Method[0];

    /**
     * The aspect container for the introduction.
     */
    protected AspectContainer m_definingAspectContainer;

    /**
     * Creates a new container strategy.
     * 
     * @param definingAspectContainer the aspect container
     */
    public IntroductionContainer(final Introduction prototype, final AspectContainer definingAspectContainer) {
        if (prototype == null) {
            throw new IllegalArgumentException("introduction prototype can not be null");
        }
        m_definingAspectContainer = definingAspectContainer;
        m_prototype = prototype;
        createMethodRepository();
    }

    /**
     * Invokes the method on a per JVM basis.
     * 
     * @param methodIndex the method index
     * @param parameters the parameters for the invocation
     * @return the result from the method invocation
     */
    public Object invokeIntroductionPerJvm(final int methodIndex, final Object[] parameters) throws Throwable {
        Object result = null;
        try {
            if (m_perJvm == null) {
                // only compatible aspect deployment is perJVM
                m_perJvm = Introduction.newInstance(m_prototype, m_prototype.getCrossCuttingInfo());
                m_perJvm.createMixin();
            }
            result = m_methodRepository[methodIndex].invoke(m_perJvm.getImplementation(), parameters);
        } catch (InvocationTargetException e) {
            if (e.getTargetException() instanceof ClassCastException) {
                System.err
                        .println("WARNING: ClassCastException has been thrown from introduced method - this can occur if you cast 'this' to CrossCutting instead of casting 'OuterAspectClass.this'");
            }
            throw e.getTargetException();
        } catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the method on a per class basis.
     * 
     * @param targetInstance a reference to the calling object
     * @param methodIndex the method index
     * @param parameters the parameters for the invocation
     * @return the result from the method invocation
     */
    public Object invokeIntroductionPerClass(
        final Object targetInstance,
        final int methodIndex,
        final Object[] parameters) throws Throwable {
        final Class targetClass = targetInstance.getClass();
        Object result = null;
        try {
            if (!m_perClass.containsKey(targetClass)) {
                synchronized (m_perClass) {
                    // only compatible aspect deployments are perJVM and perClass
                    Introduction perClassIntroduction = Introduction.newInstance(m_prototype, m_prototype
                            .getCrossCuttingInfo());
                    m_perClass.put(targetClass, perClassIntroduction);
                    perClassIntroduction.createMixin();
                }
            }
            result = m_methodRepository[methodIndex].invoke(((Introduction) m_perClass.get(targetClass))
                    .getImplementation(), parameters);
        } catch (InvocationTargetException e) {
            if (e.getTargetException() instanceof ClassCastException) {
                System.err
                        .println("WARNING: ClassCastException has been thrown from introduced method - this can occur if you cast 'this' to CrossCutting instead of casting 'OuterAspectClass.this'");
            }
            throw e.getTargetException();
        } catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the method on a per instance basis.
     * 
     * @param targetInstance a reference to the target instance
     * @param methodIndex the method index
     * @param parameters the parameters for the invocation
     * @return the result from the method invocation
     */
    public Object invokeIntroductionPerInstance(
        final Object targetInstance,
        final int methodIndex,
        final Object[] parameters) throws Throwable {
        Object result = null;
        try {
            if (!m_perInstance.containsKey(targetInstance)) {
                synchronized (m_perInstance) {
                    // only compatible aspect deployments are perJVM and perClass
                    Introduction perInstanceIntroduction = Introduction.newInstance(m_prototype, m_prototype
                            .getCrossCuttingInfo());
                    m_perInstance.put(targetInstance, perInstanceIntroduction);

                    //TODO
                    //AW-207
                    //even with createMixin called after this is not fixed
                    // System.out.println(" added " + targetInstance + " / " +
                    // perInstanceIntroduction.getImplementation());
                    // since getImplementation is not yet set (since createMixin not yet called)
                    // and the getTargetInstance call is looping thru based on matching on
                    // getImplementation
                    // ie cannot be used as long as the mixin instance is not created
                    // ..
                    perInstanceIntroduction.createMixin();
                }
            }
            result = m_methodRepository[methodIndex].invoke(((Introduction) m_perInstance.get(targetInstance))
                    .getImplementation(), parameters);
        } catch (InvocationTargetException e) {
            if (e.getTargetException() instanceof ClassCastException) {
                System.err
                        .println("WARNING: ClassCastException has been thrown from introduced method - this can occur if you cast 'this' to CrossCutting instead of casting 'OuterAspectClass.this'");
            }
            throw e.getTargetException();
        } catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Invokes the method on a per thread basis.
     * 
     * @param methodIndex the method index
     * @param parameters the parameters for the invocation
     * @return the result from the method invocation
     */
    public Object invokeIntroductionPerThread(final int methodIndex, final Object[] parameters) throws Throwable {
        Object result;
        try {
            final Thread currentThread = Thread.currentThread();
            if (!m_perThread.containsKey(currentThread)) {
                synchronized (m_perThread) {
                    // only compatible aspect deployments is perThread
                    Introduction perThreadIntroduction = Introduction.newInstance(m_prototype, m_prototype
                            .getCrossCuttingInfo());
                    m_perThread.put(currentThread, perThreadIntroduction);
                    perThreadIntroduction.createMixin();
                }
            }
            result = m_methodRepository[methodIndex].invoke(((Introduction) m_perThread.get(currentThread))
                    .getImplementation(), parameters);
        } catch (InvocationTargetException e) {
            if (e.getTargetException() instanceof ClassCastException) {
                System.err
                        .println("WARNING: ClassCastException has been thrown from introduced method - this can occur if you cast 'this' to CrossCutting instead of casting 'OuterAspectClass.this'");
            }
            throw e.getTargetException();
        } catch (Exception e) {
            throw new WrappedRuntimeException(e);
        }
        return result;
    }

    /**
     * Swaps the current mixin implementation.
     * 
     * @param newImplementationClass the class of the new implementation to use
     */
    public void swapImplementation(final Class newImplementationClass) {
        if (newImplementationClass == null) {
            throw new IllegalArgumentException("new implementation class class can not be null");
        }

        // check compatibility
        IntroductionDefinition def = m_prototype.getIntroductionDefinition();
        for (Iterator intfs = def.getInterfaceClassNames().iterator(); intfs.hasNext();) {
            if (!findInterfaceInHierarchy(newImplementationClass, (String) intfs.next())) {
                throw new DefinitionException("new implementation class is not compatible");
            }
        }
        synchronized (this) {
            try {
                // create the new introduction to replace the current one
                m_prototype.swapImplementation(newImplementationClass);
                createMethodRepository();

                // clear the current introduction storages
                m_perJvm = null;
                m_perClass = new HashMap(m_perClass.size());
                m_perInstance = new WeakHashMap(m_perClass.size());
                m_perThread = new WeakHashMap(m_perClass.size());
            } catch (Exception e) {
                new WrappedRuntimeException(e);
            }
        }
    }

    /**
     * Recursively traverse the interface hierarchy implemented by the given root class in order to find one that
     * matches the given name. Looks in the class hierarchy as well.
     * 
     * @param root is the class or interface to start the search at.
     * @param requiredInterface that we are looking for.
     * @return <code>true</code> if we found the interface, <code>false</code> otherwise.
     */
    private static boolean findInterfaceInHierarchy(final Class root, final String requiredInterface) {
        if (root == null) {
            return false;
        }

        // looks in directly implemented interface first
        Class[] interfaces = root.getInterfaces();
        for (int i = 0; i < interfaces.length; i++) {
            Class implemented = interfaces[i];
            if (implemented.getName().equals(requiredInterface)
                || findInterfaceInHierarchy(implemented, requiredInterface)) {
                return true;
            }
        }
        return findInterfaceInHierarchy(root.getSuperclass(), requiredInterface);
    }

    /**
     * Creates a method repository for the introduced methods.
     */
    private void createMethodRepository() {
        synchronized (m_methodRepository) {
            List methodList = ReflectHelper.createSortedMethodList(m_prototype.getImplementationClass());
            m_methodRepository = new Method[methodList.size()];
            for (int i = 0; i < m_methodRepository.length; i++) {
                Method method = (Method) methodList.get(i);
                method.setAccessible(true);
                m_methodRepository[i] = method;
            }
        }
    }

    /**
     * Returns the target instance from an introduction
     * 
     * @param mixinImpl aka "this" from the mixin impl
     * @return the target instance or null (if not perInstance deployed mixin)
     */
    public Object getTargetInstance(Object mixinImpl) {
        Object targetInstance = null;
        if (m_prototype.getDeploymentModel() == DeploymentModel.PER_INSTANCE) {
            for (Iterator i = m_perInstance.entrySet().iterator(); i.hasNext();) {
                Map.Entry entry = (Map.Entry) i.next();
                Object mixin = ((Introduction) entry.getValue()).getImplementation();
                if (mixinImpl.equals(mixin)) {
                    targetInstance = entry.getKey();
                    break;
                }
            }
        }
        return targetInstance;
    }

    /**
     * Returns the target class from an introduction
     * 
     * @param mixinImpl aka "this" from the mixin impl
     * @return the target instance or null (if not perInstance or perClas deployed mixin)
     */
    public Class getTargetClass(Object mixinImpl) {
        Class targetClass = null;
        if (m_prototype.getDeploymentModel() == DeploymentModel.PER_INSTANCE) {
            Object instance = getTargetInstance(mixinImpl);
            if (instance != null) {
                targetClass = instance.getClass();
            }
        } else if (m_prototype.getDeploymentModel() == DeploymentModel.PER_CLASS) {
            for (Iterator i = m_perClass.entrySet().iterator(); i.hasNext();) {
                Map.Entry entry = (Map.Entry) i.next();
                Object mixin = ((Introduction) entry.getValue()).getImplementation();
                if (mixinImpl.equals(mixin)) {
                    targetClass = (Class) entry.getKey();
                    break;
                }
            }
        }
        return targetClass;
    }
}