/**************************************************************************************
 * 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.transform.delegation;

import org.codehaus.aspectwerkz.definition.SystemDefinition;
import org.codehaus.aspectwerkz.expression.ExpressionContext;
import org.codehaus.aspectwerkz.expression.PointcutType;
import org.codehaus.aspectwerkz.reflect.ClassInfo;
import org.codehaus.aspectwerkz.reflect.ConstructorInfo;
import org.codehaus.aspectwerkz.reflect.impl.javassist.JavassistClassInfo;
import org.codehaus.aspectwerkz.reflect.impl.javassist.JavassistConstructorInfo;
import org.codehaus.aspectwerkz.transform.Context;
import org.codehaus.aspectwerkz.transform.TransformationUtil;
import org.codehaus.aspectwerkz.transform.Transformer;

import java.util.Iterator;
import java.util.List;

import javassist.CannotCompileException;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.CtMethod;
import javassist.CtNewConstructor;
import javassist.NotFoundException;
import javassist.bytecode.CodeAttribute;

/**
 * Advises constructor EXECUTION join points.
 * 
 * @author <a href="mailto:alex@gnilux.com">Alexandre Vasseur </a>
 * @author <a href="mailto:jboner@codehaus.org">Jonas BonŽr </a>
 */
public class ConstructorExecutionTransformer implements Transformer {
    /**
     * The join point index.
     */

    //AXprivate int m_joinPointIndex;
    /**
     * Makes the member method transformations.
     * 
     * @param context the transformation context
     * @param klass the class set.
     */
    public void transform(final Context context, final Klass klass) throws Exception {
        List definitions = context.getDefinitions();

        //AXm_joinPointIndex =
        // TransformationUtil.getJoinPointIndex(klass.getCtClass()); //TODO
        // thread safe and reentrant
        for (Iterator it = definitions.iterator(); it.hasNext();) {
            SystemDefinition definition = (SystemDefinition) it.next();
            final CtClass ctClass = klass.getCtClass();
            ClassInfo classInfo = JavassistClassInfo.getClassInfo(ctClass, context.getLoader());
            if (classFilter(definition, new ExpressionContext(PointcutType.EXECUTION, classInfo, null), ctClass)) {
                continue;
            }
            final CtConstructor[] constructors = ctClass.getConstructors();
            for (int i = 0; i < constructors.length; i++) {
                CtConstructor constructor = constructors[i];
                ConstructorInfo constructorInfo = JavassistConstructorInfo.getConstructorInfo(constructor, context
                        .getLoader());
                ExpressionContext ctx = new ExpressionContext(PointcutType.EXECUTION, constructorInfo, null);
                if (constructorFilter(definition, ctx)) {
                    continue;
                }
                if (addPrefixToConstructor(ctClass, constructor)) {
                    context.markAsAdvised();
                    int constructorHash = JavassistHelper.calculateHash(constructor);
                    createWrapperConstructor(constructor, constructorHash, klass);
                }
            }
        }

        //AXTransformationUtil.setJoinPointIndex(klass.getCtClass(),
        // m_joinPointIndex);
        klass.flushJoinPointIndex();
    }

    /**
     * Creates a wrapper constructor for the original constructor specified. This constructor has the same signature as
     * the original constructor and catches the invocation for further processing by the framework before redirecting to
     * the original constructor.
     * 
     * @param originalConstructor the original constructor
     * @param constructorHash the constructor hash
     */
    private void createWrapperConstructor(
        final CtConstructor originalConstructor,
        final int constructorHash,
        final Klass klass) throws CannotCompileException, NotFoundException {
        StringBuffer body = new StringBuffer();
        body.append('{');
        if (originalConstructor.getParameterTypes().length > 0) {
            body.append("Object[] args = $args; ");
        } else {
            body.append("Object[] args = null; ");
        }
        body.append("Object nullObject = null;");
        body.append("return ($r)");
        body.append(TransformationUtil.JOIN_POINT_MANAGER_FIELD);
        body.append('.');
        body.append(TransformationUtil.PROCEED_WITH_EXECUTION_JOIN_POINT_METHOD);
        body.append('(');
        body.append(constructorHash);
        body.append(',');
        body.append(klass.getJoinPointIndex());
        body.append(',');
        body.append("args, this,");
        body.append(TransformationUtil.JOIN_POINT_TYPE_CONSTRUCTOR_EXECUTION);
        body.append("); }");
        klass.incrementJoinPointIndex();
        originalConstructor.setBody(body.toString());
    }

    /**
     * @param ctClass the class
     * @param constructor the current method
     * @return the new prefixed constructor
     */

    //    private void createStaticMethodWithConstructorBody(
    //            final CtClass ctClass,
    //            final CtConstructor constructor,
    //            final int methodSequence) throws NotFoundException,
    // CannotCompileException {
    //
    //        String prefixedMethodName = TransformationUtil.getPrefixedMethodName(
    //                constructor.getName(), methodSequence, ctClass.getName()
    //        );
    //
    //        CtMethod method = CtNewMethod.make(
    //                CtClass.voidType, prefixedMethodName, constructor.getParameterTypes(),
    //                constructor.getExceptionTypes(), null, ctClass
    //        );
    //        method.setModifiers(Modifier.STATIC | Modifier.FINAL);
    //
    //        CodeAttribute codeAttribute =
    // constructor.getMethodInfo().getCodeAttribute();
    //        method.getMethodInfo().setCodeAttribute(codeAttribute);
    //
    //// CodeAttribute codeAttribute =
    // method.getMethodInfo().getCodeAttribute();
    //// codeAttribute.setMaxLocals(codeAttribute.getMaxLocals() + 1);
    //
    //        ctClass.addMethod(method);
    //    }
    /**
     * Adds a prefix to the original constructor. To make it callable only from within the framework itself.
     * 
     * @param ctClass the class
     * @param constructor the current method
     * @return false if the prefixed constructor was already existing
     */
    private boolean addPrefixToConstructor(final CtClass ctClass, final CtConstructor constructor) throws NotFoundException,
            CannotCompileException {
        int accessFlags = constructor.getModifiers();
        CtClass[] parameterTypes = constructor.getParameterTypes();
        CtClass[] newParameterTypes = new CtClass[parameterTypes.length + 1];
        for (int i = 0; i < parameterTypes.length; i++) {
            newParameterTypes[i] = parameterTypes[i];
        }
        newParameterTypes[parameterTypes.length] = ctClass.getClassPool().get(
            TransformationUtil.JOIN_POINT_MANAGER_CLASS);
        if (!JavassistHelper.hasConstructor(ctClass, newParameterTypes)) {
            CtConstructor newConstructor = CtNewConstructor.make(
                newParameterTypes,
                constructor.getExceptionTypes(),
                CtNewConstructor.PASS_NONE,
                null,
                CtMethod.ConstParameter.string(constructor.getSignature()),
                ctClass);
            newConstructor.setBody(constructor, null);
            newConstructor.setModifiers(accessFlags);
            CodeAttribute codeAttribute = newConstructor.getMethodInfo().getCodeAttribute();
            codeAttribute.setMaxLocals(codeAttribute.getMaxLocals() + 1);
            ctClass.addConstructor(newConstructor);
            return true;
        } else {
            return false;
        }
    }

    /**
     * Filters the classes to be transformed.
     * 
     * @param definition the definition
     * @param ctx the context
     * @param ctClass the class to filter
     * @return boolean true if the method should be filtered away
     */
    public static boolean classFilter(
        final SystemDefinition definition,
        final ExpressionContext ctx,
        final CtClass ctClass) {
        if (ctClass.isInterface()) {
            return true;
        }
        String className = ctClass.getName().replace('/', '.');
        if (definition.inExcludePackage(className)) {
            return true;
        }
        if (!definition.inIncludePackage(className)) {
            return true;
        }
        if (definition.isAdvised(ctx)) {
            return false;
        }
        return true;
    }

    /**
     * Filters the methods to be transformed.
     * 
     * @param definition the definition
     * @param ctx the context
     * @return boolean
     */
    public static boolean constructorFilter(final SystemDefinition definition, final ExpressionContext ctx) {
        if (definition.hasPointcut(ctx)) {
            return false;
        } else {
            return true;
        }
    }
}