/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat, Inc. and/or its affiliates, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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.jboss.weld.bean.proxy;

import static org.jboss.classfilewriter.util.DescriptorUtils.isPrimitive;
import static org.jboss.classfilewriter.util.DescriptorUtils.isWide;
import static org.jboss.weld.util.reflection.Reflections.cast;

import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;
import java.nio.file.Files;
import java.nio.file.StandardOpenOption;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import jakarta.enterprise.inject.spi.Bean;

import org.jboss.classfilewriter.AccessFlag;
import org.jboss.classfilewriter.ClassFile;
import org.jboss.classfilewriter.ClassMethod;
import org.jboss.classfilewriter.DuplicateMemberException;
import org.jboss.classfilewriter.code.BranchEnd;
import org.jboss.classfilewriter.code.CodeAttribute;
import org.jboss.classfilewriter.util.Boxing;
import org.jboss.classfilewriter.util.DescriptorUtils;
import org.jboss.weld.Container;
import org.jboss.weld.bean.AbstractProducerBean;
import org.jboss.weld.bean.builtin.AbstractBuiltInBean;
import org.jboss.weld.config.WeldConfiguration;
import org.jboss.weld.exceptions.DefinitionException;
import org.jboss.weld.exceptions.WeldException;
import org.jboss.weld.interceptor.proxy.LifecycleMixin;
import org.jboss.weld.interceptor.util.proxy.TargetInstanceProxy;
import org.jboss.weld.logging.BeanLogger;
import org.jboss.weld.proxy.WeldConstruct;
import org.jboss.weld.security.GetDeclaredConstructorsAction;
import org.jboss.weld.security.GetDeclaredMethodsAction;
import org.jboss.weld.security.GetProtectionDomainAction;
import org.jboss.weld.serialization.spi.BeanIdentifier;
import org.jboss.weld.serialization.spi.ContextualStore;
import org.jboss.weld.serialization.spi.ProxyServices;
import org.jboss.weld.util.Proxies;
import org.jboss.weld.util.Proxies.TypeInfo;
import org.jboss.weld.util.bytecode.BytecodeUtils;
import org.jboss.weld.util.bytecode.ConstructorUtils;
import org.jboss.weld.util.bytecode.DeferredBytecode;
import org.jboss.weld.util.bytecode.MethodInformation;
import org.jboss.weld.util.bytecode.RuntimeMethodInformation;
import org.jboss.weld.util.collections.ImmutableSet;
import org.jboss.weld.util.collections.Sets;
import org.jboss.weld.util.reflection.Reflections;

/**
 * Main factory to produce proxy classes and instances for Weld beans. This
 * implementation creates proxies which forward non-static method invocations to
 * a {@link BeanInstance}. All proxies implement the {@link Proxy} interface.
 *
 * @author David Allen
 * @author Stuart Douglas
 * @author Marius Bogoevici
 * @author Ales Justin
 */
public class ProxyFactory<T> implements PrivilegedAction<T> {

    // Default proxy class name suffix
    public static final String PROXY_SUFFIX = "$Proxy$";
    // choose different package from what we have in tests to distinguish it clearly
    public static final String WELD_PROXY_PREFIX = "org.jboss.weld.generated.proxies";
    public static final String DEFAULT_PROXY_PACKAGE = WELD_PROXY_PREFIX + ".default";
    public static final String CONSTRUCTED_FLAG_NAME = "constructed";
    protected static final BytecodeMethodResolver DEFAULT_METHOD_RESOLVER = new DefaultBytecodeMethodResolver();
    protected static final String LJAVA_LANG_REFLECT_METHOD = "Ljava/lang/reflect/Method;";
    protected static final String LJAVA_LANG_BYTE = "Ljava/lang/Byte;";
    protected static final String LJAVA_LANG_CLASS = "Ljava/lang/Class;";
    protected static final String LJAVA_LANG_OBJECT = "Ljava/lang/Object;";
    protected static final String LBEAN_IDENTIFIER = "Lorg/jboss/weld/serialization/spi/BeanIdentifier;";
    protected static final String LJAVA_LANG_STRING = "Ljava/lang/String;";
    protected static final String LJAVA_LANG_THREAD_LOCAL = "Ljava/lang/ThreadLocal;";
    protected static final String INIT_METHOD_NAME = "<init>";
    protected static final String INVOKE_METHOD_NAME = "invoke";
    protected static final String METHOD_HANDLER_FIELD_NAME = "methodHandler";
    static final String JAVA = "java";
    static final String JAKARTA = "jakarta";
    static final String NO_PACKAGE = "the class package is null or empty";
    static final String SIGNED = "the class is signed";
    private static final Set<ProxiedMethodFilter> METHOD_FILTERS;

    static {
        Set<ProxiedMethodFilter> filters = new HashSet<>();
        filters.add(CommonProxiedMethodFilters.NON_STATIC);
        filters.add(CommonProxiedMethodFilters.NON_FINAL);
        filters.add(CommonProxiedMethodFilters.OBJECT_TO_STRING);
        filters.add(CommonProxiedMethodFilters.NON_JDK_PACKAGE_PRIVATE);
        GroovyMethodFilter groovy = new GroovyMethodFilter();
        if (groovy.isEnabled()) {
            filters.add(groovy);
        }
        METHOD_FILTERS = ImmutableSet.copyOf(filters);
    }

    private final Class<?> beanType;
    private final Set<Class<?>> additionalInterfaces = new LinkedHashSet<Class<?>>();
    private final String baseProxyName;
    private final Bean<?> bean;
    private final Class<?> proxiedBeanType;
    private final String contextId;
    private final ProxyServices proxyServices;
    private final WeldConfiguration configuration;
    private final ProxyInstantiator proxyInstantiator;

    /**
     * created a new proxy factory from a bean instance. The proxy name is
     * generated from the bean id
     */
    public ProxyFactory(String contextId, Class<?> proxiedBeanType, Set<? extends Type> typeClosure, Bean<?> bean) {
        this(contextId, proxiedBeanType, typeClosure, bean, false);
    }

    public ProxyFactory(String contextId, Class<?> proxiedBeanType, Set<? extends Type> typeClosure, Bean<?> bean, boolean forceSuperClass) {
        this(contextId, proxiedBeanType, typeClosure, getProxyName(contextId, proxiedBeanType, typeClosure, bean), bean, forceSuperClass);
    }

    /**
     * Creates a new proxy factory when the name of the proxy class is already
     * known, such as during de-serialization
     *
     * @param proxiedBeanType the super-class for this proxy class
     * @param typeClosure     the bean types of the bean
     * @param proxyName       the name of the proxy class
     */
    public ProxyFactory(String contextId, Class<?> proxiedBeanType, Set<? extends Type> typeClosure, String proxyName, Bean<?> bean) {
        this(contextId, proxiedBeanType, typeClosure, proxyName, bean, false);
    }

    public ProxyFactory(String contextId, Class<?> proxiedBeanType, Set<? extends Type> typeClosure, String proxyName, Bean<?> bean, boolean forceSuperClass) {
        this.bean = bean;
        this.contextId = contextId;
        this.proxiedBeanType = proxiedBeanType;
        this.configuration = Container.instance(contextId).deploymentManager().getServices().get(WeldConfiguration.class);
        addInterfacesFromTypeClosure(typeClosure, proxiedBeanType);
        TypeInfo typeInfo = TypeInfo.of(typeClosure);
        Class<?> superClass = typeInfo.getSuperClass();
        superClass = superClass == null ? Object.class : superClass;
        if (forceSuperClass || (superClass.equals(Object.class) && additionalInterfaces.isEmpty())) {
            // No interface beans, must use the bean impl as superclass
            superClass = proxiedBeanType;
        }
        this.beanType = superClass;

        addDefaultAdditionalInterfaces();
        baseProxyName = proxyName;
        proxyServices = Container.instance(contextId).services().get(ProxyServices.class);
        // hierarchy order
        if (additionalInterfaces.size() > 1) {
            LinkedHashSet<Class<?>> sorted = Proxies.sortInterfacesHierarchy(additionalInterfaces);
            additionalInterfaces.clear();
            additionalInterfaces.addAll(sorted);
        }

        this.proxyInstantiator = Container.instance(contextId).services().get(ProxyInstantiator.class);
    }

    static String getProxyName(String contextId, Class<?> proxiedBeanType, Set<? extends Type> typeClosure, Bean<?> bean) {
        TypeInfo typeInfo = TypeInfo.of(typeClosure);
        final String className;
        ProxyNameHolder holder;
        if (typeInfo.getSuperClass() == Object.class) {
            final StringBuilder name = new StringBuilder();
            //interface only bean.
            holder = createCompoundProxyName(contextId, bean, typeInfo, name);
        } else {
            boolean typeModified = false;
            for (Class<?> iface : typeInfo.getInterfaces()) {
                if (!iface.isAssignableFrom(typeInfo.getSuperClass())) {
                    typeModified = true;
                    break;
                }
            }
            if (typeModified) {
                //this bean has interfaces that the base type is not assignable to
                //which can happen with some creative use of the SPI
                //interface only bean.
                StringBuilder name = new StringBuilder(typeInfo.getSuperClass().getSimpleName() + "$");
                holder = createCompoundProxyName(contextId, bean, typeInfo, name);
            } else {
                holder = new ProxyNameHolder(null, typeInfo.getSuperClass().getSimpleName(), bean);
            }
        }
        className = holder.getClassName() + PROXY_SUFFIX;
        String proxyPackage = holder.getPackageName();
        if (proxiedBeanType.equals(Object.class)) {
            Class<?> superInterface = typeInfo.getSuperInterface();
            if (superInterface == null) {
                throw new IllegalArgumentException("Proxied bean type cannot be java.lang.Object without an interface");
            } else {
                String reason = getDefaultPackageReason(superInterface);
                if (reason != null) {
                    proxyPackage = DEFAULT_PROXY_PACKAGE;
                    BeanLogger.LOG.generatingProxyToDefaultPackage(superInterface, DEFAULT_PROXY_PACKAGE, reason);
                }
            }
        } else {
            String reason = getDefaultPackageReason(proxiedBeanType);
            if (reason != null && reason.equals(NO_PACKAGE)) {
                proxyPackage = DEFAULT_PROXY_PACKAGE;
                BeanLogger.LOG.generatingProxyToDefaultPackage(proxiedBeanType, DEFAULT_PROXY_PACKAGE, reason);
            } else {
                if (proxyPackage == null) {
                    proxyPackage = proxiedBeanType.getPackage().getName();
                }
            }
        }
        return proxyPackage + '.' + getEnclosingPrefix(proxiedBeanType) + className;
    }

    private static ProxyNameHolder createCompoundProxyName(String contextId, Bean<?> bean, TypeInfo typeInfo, StringBuilder name) {
        String className;
        String proxyPackage = null;
        // we need a sorted collection without repetition, hence LinkedHashSet
        final Set<String> interfaces = new LinkedHashSet<>();
        // for producers, try to determine the most specific class and make sure the proxy starts with the same package and class
        if (bean != null && bean instanceof AbstractProducerBean) {
            Class<?> mostSpecificClass = ((AbstractProducerBean) bean).getType();
            proxyPackage = mostSpecificClass.getPackage().getName();
            if (mostSpecificClass.getDeclaringClass() != null) {
                interfaces.add(mostSpecificClass.getDeclaringClass().getSimpleName());
            }
            interfaces.add(mostSpecificClass.getSimpleName());
        }
        final Set<String> declaringClasses = new HashSet<>();
        for (Class<?> type : typeInfo.getInterfaces()) {
            Class<?> declaringClass = type.getDeclaringClass();
            if (declaringClass != null && declaringClasses.add(declaringClass.getSimpleName())) {
                interfaces.add(declaringClass.getSimpleName());
            }
            interfaces.add(type.getSimpleName());
            if (proxyPackage == null) {
                proxyPackage = typeInfo.getPackageNameForClass(type);
            }
        }
        // no need to sort the set, because we copied and already sorted one
        Iterator<String> iterator = interfaces.iterator();
        while (iterator.hasNext()) {
            name.append(iterator.next());
            if (iterator.hasNext()) {
                name.append("$");
            }

        }
        //there is a remote chance that this could generate the same
        //proxy name for two interfaces with the same simple name.
        //append the hash code of the bean id to be sure
        // However, it is safe to share a proxy class for built-in beans of the same type (e.g. Event)
        if (bean != null && !(bean instanceof AbstractBuiltInBean)) {
            final BeanIdentifier id = Container.instance(contextId).services().get(ContextualStore.class).putIfAbsent(bean);
            int idHash = id.hashCode();
            // add a separator so that WeldDefaultProxyServices can determine the correct full class name by first occurrence of "$"
            name.append("$");
            name.append(Math.abs(idHash == Integer.MIN_VALUE ? 0 : idHash));
        }
        className = name.toString();
        return new ProxyNameHolder(proxyPackage, className, bean);
    }

    private static String getEnclosingPrefix(Class<?> clazz) {
        Class<?> encl = clazz.getEnclosingClass();
        return encl == null ? "" : getEnclosingPrefix(encl) + encl.getSimpleName() + '$';
    }

    /**
     * Convenience method to set the underlying bean instance for a proxy.
     *
     * @param proxy        the proxy instance
     * @param beanInstance the instance of the bean
     */
    public static <T> void setBeanInstance(String contextId, T proxy, BeanInstance beanInstance, Bean<?> bean) {
        if (proxy instanceof ProxyObject) {
            ProxyObject proxyView = (ProxyObject) proxy;
            proxyView.weld_setHandler(new ProxyMethodHandler(contextId, beanInstance, bean));
        }
    }

    private static String getDefaultPackageReason(Class<?> clazz) {
        if (clazz.getPackage() == null || clazz.getPackage().getName().isEmpty()) {
            return NO_PACKAGE;
        }
        if (clazz.getSigners() != null) {
            return SIGNED;
        }
        return null;
    }

    public void addInterfacesFromTypeClosure(Set<? extends Type> typeClosure, Class<?> proxiedBeanType) {
        for (Type type : typeClosure) {
            Class<?> c = Reflections.getRawType(type);
            // Ignore no-interface views, they are dealt with proxiedBeanType
            // (pending redesign)
            if (c.isInterface()) {
                addInterface(c);
            }
        }
    }

    /**
     * Adds an additional interface that the proxy should implement. The default
     * implementation will be to forward invocations to the bean instance.
     *
     * @param newInterface an interface
     */
    public void addInterface(Class<?> newInterface) {
        if (!newInterface.isInterface()) {
            throw new IllegalArgumentException(newInterface + " is not an interface");
        }
        additionalInterfaces.add(newInterface);
    }

    /**
     * Method to create a new proxy that wraps the bean instance.
     *
     * @param beanInstance the bean instance
     * @return a new proxy object
     */
    public T create(BeanInstance beanInstance) {
        final T proxy = (System.getSecurityManager() == null) ? run() : AccessController.doPrivileged(this);
        ((ProxyObject) proxy).weld_setHandler(new ProxyMethodHandler(contextId, beanInstance, bean));
        return proxy;
    }

    @Override
    public T run() {
        try {
            Class<T> proxyClass = getProxyClass();
            boolean hasConstrutedField = SecurityActions.hasDeclaredField(proxyClass, CONSTRUCTED_FLAG_NAME);
            if (hasConstrutedField != useConstructedFlag()) {
                // The proxy class was created with a different type of ProxyInstantiator
                ProxyInstantiator newInstantiator = ProxyInstantiator.Factory.create(!hasConstrutedField);
                BeanLogger.LOG.creatingProxyInstanceUsingDifferentInstantiator(proxyClass, newInstantiator, proxyInstantiator);
                return newInstantiator.newInstance(proxyClass);
            }
            return proxyInstantiator.newInstance(proxyClass);
        } catch (InstantiationException e) {
            throw new DefinitionException(BeanLogger.LOG.proxyInstantiationFailed(this), e.getCause());
        } catch (IllegalAccessException e) {
            throw new DefinitionException(BeanLogger.LOG.proxyInstantiationBeanAccessFailed(this), e.getCause());
        }
    }

    /**
     * Produces or returns the existing proxy class. The operation is thread-safe.
     *
     * @return always the class of the proxy
     */
    public Class<T> getProxyClass() {
        String suffix = "_$$_Weld" + getProxyNameSuffix();
        String proxyClassName = getBaseProxyName();
        if (!proxyClassName.endsWith(suffix)) {
            proxyClassName = proxyClassName + suffix;
        }
        if (proxyClassName.startsWith(JAVA)) {
            proxyClassName = proxyClassName.replaceFirst(JAVA, WELD_PROXY_PREFIX);
        } else if (proxyClassName.startsWith(JAKARTA)) {
            proxyClassName = proxyClassName.replaceFirst(JAKARTA, WELD_PROXY_PREFIX);
        }
        Class<T> proxyClass = null;
        Class<?> originalClass = bean != null ? bean.getBeanClass() : proxiedBeanType;
        BeanLogger.LOG.generatingProxyClass(proxyClassName);
        try {
            // First check to see if we already have this proxy class
            proxyClass = cast(proxyServices.loadClass(originalClass, proxyClassName));
        } catch (ClassNotFoundException e) {
            // Create the proxy class for this instance
            try {
                proxyClass = createProxyClass(originalClass, proxyClassName);
            } catch (Throwable e1) {
                //attempt to load the class again, just in case another thread
                //defined it between the check and the create method
                try {
                    proxyClass = cast(proxyServices.loadClass(originalClass, proxyClassName));
                } catch (ClassNotFoundException e2) {
                    BeanLogger.LOG.catchingDebug(e1);
                    throw BeanLogger.LOG.unableToLoadProxyClass(bean, proxiedBeanType, e1);
                }
            }
        }
        return proxyClass;
    }

    /**
     * Returns the package and base name for the proxy class.
     *
     * @return base name without suffixes
     */
    protected String getBaseProxyName() {
        return baseProxyName;
    }

    /**
     * Returns a suffix to append to the name of the proxy class. The name
     * already consists of <class-name>_$$_Weld, to which the suffix is added.
     * This allows the creation of different types of proxies for the same class.
     *
     * @return a name suffix
     */
    protected String getProxyNameSuffix() {
        return PROXY_SUFFIX;
    }

    private void addDefaultAdditionalInterfaces() {
        additionalInterfaces.add(Serializable.class);
        // add a marker interface denoting that the resulting class uses weld internal contructs
        additionalInterfaces.add(WeldConstruct.class);
    }

    /**
     * Sub classes may override to specify additional interfaces the proxy should
     * implement
     */
    protected void addAdditionalInterfaces(Set<Class<?>> interfaces) {

    }

    private Class<T> createProxyClass(Class<?> originalClass, String proxyClassName) throws Exception {
        Set<Class<?>> specialInterfaces = Sets.newHashSet(LifecycleMixin.class, TargetInstanceProxy.class, ProxyObject.class);
        addAdditionalInterfaces(specialInterfaces);
        // Remove special interfaces from main set (deserialization scenario)
        additionalInterfaces.removeAll(specialInterfaces);

        ClassFile proxyClassType = null;
        final int accessFlags = AccessFlag.of(AccessFlag.PUBLIC, AccessFlag.SUPER, AccessFlag.SYNTHETIC);
        if (getBeanType().isInterface()) {
            proxyClassType = newClassFile(proxyClassName, accessFlags, Object.class.getName());
            proxyClassType.addInterface(getBeanType().getName());
        } else {
            proxyClassType = newClassFile(proxyClassName, accessFlags, getBeanType().getName());
        }
        // Add interfaces which require method generation
        for (Class<?> clazz : additionalInterfaces) {
            proxyClassType.addInterface(clazz.getName());
        }
        List<DeferredBytecode> initialValueBytecode = new ArrayList<DeferredBytecode>();

        // Workaround for IBM JVM - the ACC_STATIC flag should only be required for class file with version number 51.0 or above
        ClassMethod staticConstructor = proxyClassType.addMethod(AccessFlag.of(AccessFlag.PUBLIC, AccessFlag.STATIC), "<clinit>", "V");

        addFields(proxyClassType, initialValueBytecode);
        addConstructors(proxyClassType, initialValueBytecode);
        addMethods(proxyClassType, staticConstructor);

        staticConstructor.getCodeAttribute().returnInstruction();

        // Additional interfaces whose methods require special handling
        for (Class<?> specialInterface : specialInterfaces) {
            proxyClassType.addInterface(specialInterface.getName());
        }

        // Dump proxy type bytecode if necessary
        dumpToFile(proxyClassName, proxyClassType.toBytecode());

        ProtectionDomain domain = AccessController.doPrivileged(new GetProtectionDomainAction(proxiedBeanType));

        if (proxiedBeanType.getPackage() == null || proxiedBeanType.getPackage().getName().isEmpty() || proxiedBeanType.equals(Object.class)) {
            domain = ProxyFactory.class.getProtectionDomain();
        } else if (System.getSecurityManager() != null) {
            ProtectionDomainCache cache = Container.instance(contextId).services().get(ProtectionDomainCache.class);
            domain = cache.getProtectionDomainForProxy(domain);
        }
        Class<T> proxyClass = cast(toClass(proxyClassType, originalClass, proxyServices, domain));
        BeanLogger.LOG.createdProxyClass(proxyClass, Arrays.toString(proxyClass.getInterfaces()));
        return proxyClass;
    }

    private ClassFile newClassFile(String name, int accessFlags, String superclass, String... interfaces) {
        try {
            // We need to use a (non-deprecated) method that avoids instantiating DefaultClassFactory.INSTANCE
            // If that happens, we will have module accessibility issues and the need to use --add-opens clausules
            // NOTE: the CL and ClassFactory are never really used to define the class, see WeldDefaultProxyServices
            return new ClassFile(name, accessFlags, superclass, ProxyFactory.class.getClassLoader(), DummyClassFactoryImpl.INSTANCE, interfaces);
        } catch (Exception e) {
            throw BeanLogger.LOG.unableToCreateClassFile(name, e.getCause());
        }
    }

    private void dumpToFile(String fileName, byte[] data) {
        File proxyDumpFilePath = configuration.getProxyDumpFilePath();
        if (proxyDumpFilePath == null) {
            return;
        }
        File dumpFile = new File(proxyDumpFilePath, fileName + ".class");
        try {
            Files.write(dumpFile.toPath(), data, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
        } catch (IOException e) {
            BeanLogger.LOG.beanCannotBeDumped(fileName, e);
        }
    }

    /**
     * Adds a constructor for the proxy for each constructor declared by the base
     * bean type.
     *
     * @param proxyClassType       the Javassist class for the proxy
     * @param initialValueBytecode
     */
    protected void addConstructors(ClassFile proxyClassType, List<DeferredBytecode> initialValueBytecode) {
        try {
            if (getBeanType().isInterface()) {
                ConstructorUtils.addDefaultConstructor(proxyClassType, initialValueBytecode, !useConstructedFlag());
            } else {
                boolean constructorFound = false;
                for (Constructor<?> constructor : AccessController.doPrivileged(new GetDeclaredConstructorsAction(getBeanType()))) {
                    if ((constructor.getModifiers() & Modifier.PRIVATE) == 0) {
                        constructorFound = true;
                        String[] exceptions = new String[constructor.getExceptionTypes().length];
                        for (int i = 0; i < exceptions.length; ++i) {
                            exceptions[i] = constructor.getExceptionTypes()[i].getName();
                        }
                        ConstructorUtils.addConstructor(BytecodeUtils.VOID_CLASS_DESCRIPTOR, DescriptorUtils.parameterDescriptors(constructor.getParameterTypes()), exceptions, proxyClassType, initialValueBytecode, !useConstructedFlag());
                    }
                }
                if (!constructorFound) {
                    // the bean only has private constructors, we need to generate
                    // two fake constructors that call each other
                    addConstructorsForBeanWithPrivateConstructors(proxyClassType);
                }
            }
        } catch (Exception e) {
            throw new WeldException(e);
        }
    }

    protected void addFields(ClassFile proxyClassType, List<DeferredBytecode> initialValueBytecode) {
        // The field representing the underlying instance or special method
        // handling
        proxyClassType.addField(AccessFlag.PRIVATE, METHOD_HANDLER_FIELD_NAME, getMethodHandlerType());
        if (useConstructedFlag()) {
            // field used to indicate that super() has been called
            proxyClassType.addField(AccessFlag.PRIVATE, CONSTRUCTED_FLAG_NAME, BytecodeUtils.BOOLEAN_CLASS_DESCRIPTOR);
        }
    }

    protected Class<? extends MethodHandler> getMethodHandlerType() {
        return MethodHandler.class;
    }

    protected void addMethods(ClassFile proxyClassType, ClassMethod staticConstructor) {
        // Add all class methods for interception
        addMethodsFromClass(proxyClassType, staticConstructor);

        // Add special proxy methods
        addSpecialMethods(proxyClassType, staticConstructor);

        // Add serialization support methods
        addSerializationSupport(proxyClassType);
    }

    /**
     * Adds special serialization code. By default this is a nop
     *
     * @param proxyClassType the Javassist class for the proxy class
     */
    protected void addSerializationSupport(ClassFile proxyClassType) {
        //noop
    }

    protected void addMethodsFromClass(ClassFile proxyClassType, ClassMethod staticConstructor) {
        try {
            // Add all methods from the class hierarchy
            Class<?> cls = getBeanType();

            // First add equals/hashCode methods if required
            generateEqualsMethod(proxyClassType);
            generateHashCodeMethod(proxyClassType);

            // In rare cases, the bean class may be abstract - in this case we have to add methods from all interfaces implemented by any abstract class
            // from the hierarchy
            boolean isBeanClassAbstract = Modifier.isAbstract(cls.getModifiers());

            while (cls != null) {
                addMethods(cls, proxyClassType, staticConstructor);
                if (isBeanClassAbstract && Modifier.isAbstract(cls.getModifiers())) {
                    for (Class<?> implementedInterface : Reflections.getInterfaceClosure(cls)) {
                        if (!additionalInterfaces.contains(implementedInterface)) {
                            addMethods(implementedInterface, proxyClassType, staticConstructor);
                        }
                    }
                }
                cls = cls.getSuperclass();
            }
            for (Class<?> c : additionalInterfaces) {
                for (Method method : c.getMethods()) {
                    if (isMethodAccepted(method, getProxySuperclass())) {
                        try {
                            MethodInformation methodInfo = new RuntimeMethodInformation(method);
                            ClassMethod classMethod = proxyClassType.addMethod(method);
                            if (Reflections.isDefault(method)) {
                                addConstructedGuardToMethodBody(classMethod);
                                createForwardingMethodBody(classMethod, methodInfo, staticConstructor);
                            } else {
                                createSpecialMethodBody(classMethod, methodInfo, staticConstructor);
                            }
                            BeanLogger.LOG.addingMethodToProxy(method);
                        } catch (DuplicateMemberException e) {
                        }
                    }
                }
            }
        } catch (Exception e) {
            throw new WeldException(e);
        }
    }

    private void addMethods(Class<?> cls, ClassFile proxyClassType, ClassMethod staticConstructor) {
        for (Method method : AccessController.doPrivileged(new GetDeclaredMethodsAction(cls))) {
            if (isMethodAccepted(method, getProxySuperclass())) {
                try {
                    MethodInformation methodInfo = new RuntimeMethodInformation(method);
                    ClassMethod classMethod = proxyClassType.addMethod(method);
                    addConstructedGuardToMethodBody(classMethod);
                    createForwardingMethodBody(classMethod, methodInfo, staticConstructor);
                    BeanLogger.LOG.addingMethodToProxy(method);
                } catch (DuplicateMemberException e) {
                    // do nothing. This will happen if superclass methods
                    // have been overridden
                }
            }
        }
    }

    protected boolean isMethodAccepted(Method method, Class<?> proxySuperclass) {
        for (ProxiedMethodFilter filter : METHOD_FILTERS) {
            if (!filter.accept(method, proxySuperclass)) {
                return false;
            }
        }
        return true;
    }

    /**
     * Generate the body of the proxies hashCode method.
     * <p/>
     * If this method returns null, the method will not be added, and the
     * hashCode on the superclass will be used as per normal virtual method
     * resolution rules
     */
    protected void generateHashCodeMethod(ClassFile proxyClassType) {
    }

    /**
     * Generate the body of the proxies equals method.
     * <p/>
     * If this method returns null, the method will not be added, and the
     * hashCode on the superclass will be used as per normal virtual method
     * resolution rules
     *
     * @param proxyClassType The class file
     */
    protected void generateEqualsMethod(ClassFile proxyClassType) {

    }

    protected void createSpecialMethodBody(ClassMethod proxyClassType, MethodInformation method, ClassMethod staticConstructor) {
        createInterceptorBody(proxyClassType, method, staticConstructor);
    }

    protected void addConstructedGuardToMethodBody(final ClassMethod classMethod) {
        addConstructedGuardToMethodBody(classMethod, classMethod.getClassFile().getSuperclass());
    }

    /**
     * Adds the following code to a delegating method:
     * <p/>
     * <code>
     * if(!this.constructed) return super.thisMethod()
     * </code>
     * <p/>
     * This means that the proxy will not start to delegate to the underlying
     * bean instance until after the constructor has finished.
     */
    protected void addConstructedGuardToMethodBody(final ClassMethod classMethod, String className) {
        if (!useConstructedFlag()) {
            return;
        }
        // now create the conditional
        final CodeAttribute cond = classMethod.getCodeAttribute();
        cond.aload(0);
        cond.getfield(classMethod.getClassFile().getName(), CONSTRUCTED_FLAG_NAME, BytecodeUtils.BOOLEAN_CLASS_DESCRIPTOR);

        // jump if the proxy constructor has finished
        BranchEnd jumpMarker = cond.ifne();
        // generate the invokespecial call to the super class method
        // this is run when the proxy is being constructed
        cond.aload(0);
        cond.loadMethodParameters();
        cond.invokespecial(className, classMethod.getName(), classMethod.getDescriptor());
        cond.returnInstruction();
        cond.branchEnd(jumpMarker);
    }

    protected void createForwardingMethodBody(ClassMethod classMethod, MethodInformation method, ClassMethod staticConstructor) {
        createInterceptorBody(classMethod, method, staticConstructor);
    }

    /**
     * Creates the given method on the proxy class where the implementation
     * forwards the call directly to the method handler.
     * <p/>
     * the generated bytecode is equivalent to:
     * <p/>
     * return (RetType) methodHandler.invoke(this,param1,param2);
     *
     * @param classMethod the class method
     * @param method      any JLR method
     * @return the method byte code
     */
    protected void createInterceptorBody(ClassMethod classMethod, MethodInformation method, ClassMethod staticConstructor) {
        invokeMethodHandler(classMethod, method, true, DEFAULT_METHOD_RESOLVER, staticConstructor);
    }

    /**
     * calls methodHandler.invoke for a given method
     *
     * @param method                 The method information
     * @param addReturnInstruction   set to true you want to return the result of
     *                               the method invocation
     * @param bytecodeMethodResolver The resolver that returns the method to invoke
     */
    protected void invokeMethodHandler(ClassMethod classMethod, MethodInformation method, boolean addReturnInstruction, BytecodeMethodResolver bytecodeMethodResolver, ClassMethod staticConstructor) {
        // now we need to build the bytecode. The order we do this in is as
        // follows:
        // load methodHandler
        // load this
        // load the method object
        // load null
        // create a new array the same size as the number of parameters
        // push our parameter values into the array
        // invokeinterface the invoke method
        // add checkcast to cast the result to the return type, or unbox if
        // primitive
        // add an appropriate return instruction
        final CodeAttribute b = classMethod.getCodeAttribute();
        b.aload(0);
        getMethodHandlerField(classMethod.getClassFile(), b);
        b.aload(0);
        bytecodeMethodResolver.getDeclaredMethod(classMethod, method.getDeclaringClass(), method.getName(), method.getParameterTypes(), staticConstructor);
        b.aconstNull();

        b.iconst(method.getParameterTypes().length);
        b.anewarray("java.lang.Object");

        int localVariableCount = 1;

        for (int i = 0; i < method.getParameterTypes().length; ++i) {
            String typeString = method.getParameterTypes()[i];
            b.dup(); // duplicate the array reference
            b.iconst(i);
            // load the parameter value
            BytecodeUtils.addLoadInstruction(b, typeString, localVariableCount);
            // box the parameter if necessary
            Boxing.boxIfNessesary(b, typeString);
            // and store it in the array
            b.aastore();
            if (isWide(typeString)) {
                localVariableCount = localVariableCount + 2;
            } else {
                localVariableCount++;
            }
        }
        // now we have all our arguments on the stack
        // lets invoke the method
        b.invokeinterface(MethodHandler.class.getName(), INVOKE_METHOD_NAME, LJAVA_LANG_OBJECT, new String[]{LJAVA_LANG_OBJECT,
                LJAVA_LANG_REFLECT_METHOD, LJAVA_LANG_REFLECT_METHOD, "[" + LJAVA_LANG_OBJECT});
        if (addReturnInstruction) {
            // now we need to return the appropriate type
            if (method.getReturnType().equals(BytecodeUtils.VOID_CLASS_DESCRIPTOR)) {
                b.returnInstruction();
            } else if (isPrimitive(method.getReturnType())) {
                Boxing.unbox(b, method.getReturnType());
                b.returnInstruction();
            } else {
                b.checkcast(BytecodeUtils.getName(method.getReturnType()));
                b.returnInstruction();
            }
        }
    }

    /**
     * Adds methods requiring special implementations rather than just
     * delegation.
     *
     * @param proxyClassType the Javassist class description for the proxy type
     */
    protected void addSpecialMethods(ClassFile proxyClassType, ClassMethod staticConstructor) {
        try {
            // Add special methods for interceptors
            for (Method method : LifecycleMixin.class.getMethods()) {
                BeanLogger.LOG.addingMethodToProxy(method);
                MethodInformation methodInfo = new RuntimeMethodInformation(method);
                final ClassMethod classMethod = proxyClassType.addMethod(method);
                createInterceptorBody(classMethod, methodInfo, staticConstructor);
            }
            Method getInstanceMethod = TargetInstanceProxy.class.getMethod("weld_getTargetInstance");
            Method getInstanceClassMethod = TargetInstanceProxy.class.getMethod("weld_getTargetClass");

            MethodInformation getInstanceMethodInfo = new RuntimeMethodInformation(getInstanceMethod);
            createInterceptorBody(proxyClassType.addMethod(getInstanceMethod), getInstanceMethodInfo, staticConstructor);


            MethodInformation getInstanceClassMethodInfo = new RuntimeMethodInformation(getInstanceClassMethod);
            createInterceptorBody(proxyClassType.addMethod(getInstanceClassMethod), getInstanceClassMethodInfo, staticConstructor);

            Method setMethodHandlerMethod = ProxyObject.class.getMethod("weld_setHandler", MethodHandler.class);
            generateSetMethodHandlerBody(proxyClassType.addMethod(setMethodHandlerMethod));

            Method getMethodHandlerMethod = ProxyObject.class.getMethod("weld_getHandler");
            generateGetMethodHandlerBody(proxyClassType.addMethod(getMethodHandlerMethod));
        } catch (Exception e) {
            throw new WeldException(e);
        }
    }

    protected void generateSetMethodHandlerBody(ClassMethod method) {
        final CodeAttribute b = method.getCodeAttribute();
        b.aload(0);
        b.aload(1);
        b.checkcast(getMethodHandlerType());
        b.putfield(method.getClassFile().getName(), METHOD_HANDLER_FIELD_NAME, DescriptorUtils.makeDescriptor(getMethodHandlerType()));
        b.returnInstruction();
    }

    protected void generateGetMethodHandlerBody(ClassMethod method) {
        final CodeAttribute b = method.getCodeAttribute();
        b.aload(0);
        getMethodHandlerField(method.getClassFile(), b);
        b.returnInstruction();
    }

    /**
     * Adds two constructors to the class that call each other in order to bypass
     * the JVM class file verifier.
     * <p/>
     * This would result in a stack overflow if they were actually called,
     * however the proxy is directly created without calling the constructor
     */
    private void addConstructorsForBeanWithPrivateConstructors(ClassFile proxyClassType) {
        ClassMethod ctor = proxyClassType.addMethod(AccessFlag.PUBLIC, INIT_METHOD_NAME, BytecodeUtils.VOID_CLASS_DESCRIPTOR, LJAVA_LANG_BYTE);
        CodeAttribute b = ctor.getCodeAttribute();
        b.aload(0);
        b.aconstNull();
        b.aconstNull();
        b.invokespecial(proxyClassType.getName(), INIT_METHOD_NAME, "(" + LJAVA_LANG_BYTE + LJAVA_LANG_BYTE + ")" + BytecodeUtils.VOID_CLASS_DESCRIPTOR);
        b.returnInstruction();

        ctor = proxyClassType.addMethod(AccessFlag.PUBLIC, INIT_METHOD_NAME, BytecodeUtils.VOID_CLASS_DESCRIPTOR, LJAVA_LANG_BYTE, LJAVA_LANG_BYTE);
        b = ctor.getCodeAttribute();
        b.aload(0);
        b.aconstNull();
        b.invokespecial(proxyClassType.getName(), INIT_METHOD_NAME, "(" + LJAVA_LANG_BYTE + ")" + BytecodeUtils.VOID_CLASS_DESCRIPTOR);
        b.returnInstruction();
    }

    public Class<?> getBeanType() {
        return beanType;
    }

    public Set<Class<?>> getAdditionalInterfaces() {
        return additionalInterfaces;
    }

    public Bean<?> getBean() {
        return bean;
    }

    public String getContextId() {
        return contextId;
    }

    protected Class<?> getProxiedBeanType() {
        return proxiedBeanType;
    }

    protected void getMethodHandlerField(ClassFile file, CodeAttribute b) {
        b.getfield(file.getName(), METHOD_HANDLER_FIELD_NAME, DescriptorUtils.makeDescriptor(getMethodHandlerType()));
    }

    protected Class<?> getProxySuperclass() {
        return getBeanType().isInterface() ? Object.class : getBeanType();
    }

    /**
     * @return {@code true} if {@link ProxyInstantiator} is used to instantiate proxy instances
     */
    protected boolean isUsingProxyInstantiator() {
        return true;
    }

    /**
     * @return {@code true} if {@link #CONSTRUCTED_FLAG_NAME} should be used
     */
    private boolean useConstructedFlag() {
        return !isUsingProxyInstantiator() || proxyInstantiator.isUsingConstructor();
    }

    /**
     * Delegates proxy creation via {@link ProxyServices} to the integrator or to our own implementation.
     */
    protected Class<?> toClass(ClassFile ct, Class<?> originalClass, ProxyServices proxyServices, ProtectionDomain domain) {
        try {
            byte[] bytecode = ct.toBytecode();
            Class<?> result;
            if (domain == null) {
                result = proxyServices.defineClass(originalClass, ct.getName(), bytecode, 0, bytecode.length);
            } else {
                result = proxyServices.defineClass(originalClass, ct.getName(), bytecode, 0, bytecode.length, domain);
            }
            return result;
        } catch (RuntimeException e) {
            throw e;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * When creating a proxy class name we can sometimes determine it's package as well.
     */
    private static class ProxyNameHolder {
        private String packageName;
        private String className;

        private ProxyNameHolder(String packageName, String className, Bean<?> bean) {
            this.packageName = packageName;
            if (className == null) {
                throw BeanLogger.LOG.tryingToCreateProxyNameHolderWithoutClassName(bean.getBeanClass());
            }
            this.className = className;
        }

        /**
         * Class name, never null
         * @return class name, never null
         */
        public String getClassName() {
            return className;
        }

        /**
         * Package name, can be null
         * @return package name or null
         */
        public String getPackageName() {
            return packageName;
        }
    }
}
