/*

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file, and Oracle licenses the original version of this file under the BSD

 * license:

 */

/*

   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")

   and the BSD License (the "BSD License"), with licensee being free to

   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache

   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the

   following notice applies to you:

       You may obtain a copy of the Apache 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.

   If you choose to use this file in compliance with the BSD License, the

   following notice applies to you:

       Redistribution and use in source and binary forms, with or without

       modification, are permitted provided that the following conditions are

       met:

       * Redistributions of source code must retain the above copyright

         notice, this list of conditions and the following disclaimer.

       * Redistributions in binary form must reproduce the above copyright

         notice, this list of conditions and the following disclaimer in the

         documentation and/or other materials provided with the distribution.

       * Neither the name of the copyright holder nor the names of

         contributors may be used to endorse or promote products derived from

         this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER

       BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

package jdk.internal.dynalink.beans;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.lang.reflect.AccessibleObject;

import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Member;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import jdk.internal.dynalink.CallSiteDescriptor;

import jdk.internal.dynalink.beans.GuardedInvocationComponent.ValidationType;

import jdk.internal.dynalink.linker.GuardedInvocation;

import jdk.internal.dynalink.linker.GuardingDynamicLinker;

import jdk.internal.dynalink.linker.LinkRequest;

import jdk.internal.dynalink.linker.LinkerServices;

import jdk.internal.dynalink.support.CallSiteDescriptorFactory;

import jdk.internal.dynalink.support.Guards;

import jdk.internal.dynalink.support.Lookup;

/**

 * A base class for both {@link StaticClassLinker} and {@link BeanLinker}. Deals with common aspects of property

 * exposure and method calls for both static and instance facets of a class.

 *

 * @author Attila Szegedi

 */

abstract class AbstractJavaLinker implements GuardingDynamicLinker {

    final Class<?> clazz;

    private final MethodHandle classGuard;

    private final MethodHandle assignableGuard;

    private final Map<String, AnnotatedDynamicMethod> propertyGetters = new HashMap<>();

    private final Map<String, DynamicMethod> propertySetters = new HashMap<>();

    private final Map<String, DynamicMethod> methods = new HashMap<>();

    AbstractJavaLinker(Class<?> clazz, MethodHandle classGuard) {

        this(clazz, classGuard, classGuard);

    }

    AbstractJavaLinker(Class<?> clazz, MethodHandle classGuard, MethodHandle assignableGuard) {

        this.clazz = clazz;

        this.classGuard = classGuard;

        this.assignableGuard = assignableGuard;

        final FacetIntrospector introspector = createFacetIntrospector();

        // Add methods and properties

        for(Method method: introspector.getMethods()) {

            final String name = method.getName();

            // Add method

            addMember(name, method, methods);

            // Add the method as a property getter and/or setter

            if(name.startsWith("get") && name.length() > 3 && method.getParameterTypes().length == 0) {

                // Property getter

                setPropertyGetter(method, 3);

            } else if(name.startsWith("is") && name.length() > 2 && method.getParameterTypes().length == 0 &&

                    method.getReturnType() == boolean.class) {

                // Boolean property getter

                setPropertyGetter(method, 2);

            } else if(name.startsWith("set") && name.length() > 3 && method.getParameterTypes().length == 1) {

                // Property setter

                addMember(decapitalize(name.substring(3)), method, propertySetters);

            }

        }

        // Add field getter/setters as property getters/setters.

        for(Field field: introspector.getFields()) {

            final String name = field.getName();

            // Only add a property getter when one is not defined already as a getXxx()/isXxx() method.

            if(!propertyGetters.containsKey(name)) {

                setPropertyGetter(name, introspector.unreflectGetter(field), ValidationType.EXACT_CLASS);

            }

            if(!(Modifier.isFinal(field.getModifiers()) || propertySetters.containsKey(name))) {

                addMember(name, new SimpleDynamicMethod(introspector.unreflectSetter(field), clazz, name),

                        propertySetters);

            }

        }

        // Add inner classes, but only those for which we don't hide a property with it

        for(Map.Entry<String, MethodHandle> innerClassSpec: introspector.getInnerClassGetters().entrySet()) {

            final String name = innerClassSpec.getKey();

            if(!propertyGetters.containsKey(name)) {

                setPropertyGetter(name, innerClassSpec.getValue(), ValidationType.EXACT_CLASS);

            }

        }

    }

    private static String decapitalize(String str) {

        assert str != null;

        if(str.isEmpty()) {

            return str;

        }

        final char c0 = str.charAt(0);

        if(Character.isLowerCase(c0)) {

            return str;

        }

        // If it has two consecutive upper-case characters, i.e. "URL", don't decapitalize

        if(str.length() > 1 && Character.isUpperCase(str.charAt(1))) {

            return str;

        }

        final char c[] = str.toCharArray();

        c[0] = Character.toLowerCase(c0);

        return new String(c);

    }

    abstract FacetIntrospector createFacetIntrospector();

    /**

     * Sets the specified dynamic method to be the property getter for the specified property. Note that you can only

     * use this when you're certain that the method handle does not belong to a caller-sensitive method. For properties

     * that are caller-sensitive, you must use {@link #setPropertyGetter(String, SingleDynamicMethod, ValidationType)}

     * instead.

     * @param name name of the property

     * @param handle the method handle that implements the property getter

     * @param validationType the validation type for the property

     */

    private void setPropertyGetter(String name, SingleDynamicMethod handle, ValidationType validationType) {

        propertyGetters.put(name, new AnnotatedDynamicMethod(handle, validationType));

    }

    /**

     * Sets the specified reflective method to be the property getter for the specified property.

     * @param getter the getter method

     * @param prefixLen the getter prefix in the method name; should be 3 for getter names starting with "get" and 2 for

     * names starting with "is".

     */

    private void setPropertyGetter(Method getter, int prefixLen) {

        setPropertyGetter(decapitalize(getter.getName().substring(prefixLen)), createDynamicMethod(

                getMostGenericGetter(getter)), ValidationType.INSTANCE_OF);

    }

    /**

     * Sets the specified method handle to be the property getter for the specified property. Note that you can only

     * use this when you're certain that the method handle does not belong to a caller-sensitive method. For properties

     * that are caller-sensitive, you must use {@link #setPropertyGetter(String, SingleDynamicMethod, ValidationType)}

     * instead.

     * @param name name of the property

     * @param handle the method handle that implements the property getter

     * @param validationType the validation type for the property

     */

    void setPropertyGetter(String name, MethodHandle handle, ValidationType validationType) {

        setPropertyGetter(name, new SimpleDynamicMethod(handle, clazz, name), validationType);

    }

    private void addMember(String name, AccessibleObject ao, Map<String, DynamicMethod> methodMap) {

        addMember(name, createDynamicMethod(ao), methodMap);

    }

    private void addMember(String name, SingleDynamicMethod method, Map<String, DynamicMethod> methodMap) {

        final DynamicMethod existingMethod = methodMap.get(name);

        final DynamicMethod newMethod = mergeMethods(method, existingMethod, clazz, name);

        if(newMethod != existingMethod) {

            methodMap.put(name, newMethod);

        }

    }

    /**

     * Given one or more reflective methods or constructors, creates a dynamic method that represents them all. The

     * methods should represent all overloads of the same name (or all constructors of the class).

     * @param members the reflective members

     * @param clazz the class declaring the reflective members

     * @param name the common name of the reflective members.

     * @return a dynamic method representing all the specified reflective members.

     */

    static DynamicMethod createDynamicMethod(Iterable<? extends AccessibleObject> members, Class<?> clazz, String name) {

        DynamicMethod dynMethod = null;

        for(AccessibleObject method: members) {

            dynMethod = mergeMethods(createDynamicMethod(method), dynMethod, clazz, name);

        }

        return dynMethod;

    }

    /**

     * Given a reflective method or a constructor, creates a dynamic method that represents it. This method will

     * distinguish between caller sensitive and ordinary methods/constructors, and create appropriate caller sensitive

     * dynamic method when needed.

     * @param m the reflective member

     * @return the single dynamic method representing the reflective member

     */

    private static SingleDynamicMethod createDynamicMethod(AccessibleObject m) {

        if(CallerSensitiveDetector.isCallerSensitive(m)) {

            return new CallerSensitiveDynamicMethod(m);

        }

        final Member member = (Member)m;

        return new SimpleDynamicMethod(unreflectSafely(m), member.getDeclaringClass(), member.getName());

    }

    /**

     * Unreflects a method handle from a Method or a Constructor using safe (zero-privilege) unreflection. Should be

     * only used for methods and constructors that are not caller sensitive. If a caller sensitive method were

     * unreflected through this mechanism, it would not be a security issue, but would be bound to the zero-privilege

     * unreflector as its caller, and thus completely useless.

     * @param m the method or constructor

     * @return the method handle

     */

    private static MethodHandle unreflectSafely(AccessibleObject m) {

        if(m instanceof Method) {

            final Method reflMethod = (Method)m;

            final MethodHandle handle = SafeUnreflector.unreflect(reflMethod);

            if(Modifier.isStatic(reflMethod.getModifiers())) {

                return StaticClassIntrospector.editStaticMethodHandle(handle);

            }

            return handle;

        }

        return StaticClassIntrospector.editConstructorMethodHandle(SafeUnreflector.unreflectConstructor(

                (Constructor<?>)m));

    }

    private static DynamicMethod mergeMethods(SingleDynamicMethod method, DynamicMethod existing, Class<?> clazz, String name) {

        if(existing == null) {

            return method;

        } else if(existing.contains(method)) {

            return existing;

        } else if(existing instanceof SingleDynamicMethod) {

            final OverloadedDynamicMethod odm = new OverloadedDynamicMethod(clazz, name);

            odm.addMethod(((SingleDynamicMethod)existing));

            odm.addMethod(method);

            return odm;

        } else if(existing instanceof OverloadedDynamicMethod) {

            ((OverloadedDynamicMethod)existing).addMethod(method);

            return existing;

        }

        throw new AssertionError();

    }

    @Override

    public GuardedInvocation getGuardedInvocation(LinkRequest request, final LinkerServices linkerServices)

            throws Exception {

        final LinkRequest ncrequest = request.withoutRuntimeContext();

        // BeansLinker already checked that the name is at least 2 elements long and the first element is "dyn".

        final CallSiteDescriptor callSiteDescriptor = ncrequest.getCallSiteDescriptor();

        final String op = callSiteDescriptor.getNameToken(CallSiteDescriptor.OPERATOR);

        // Either dyn:callMethod:name(this[,args]) or dyn:callMethod(this,name[,args]).

        if("callMethod" == op) {

            return getCallPropWithThis(callSiteDescriptor, linkerServices);

        }

        List<String> operations = CallSiteDescriptorFactory.tokenizeOperators(callSiteDescriptor);

        while(!operations.isEmpty()) {

            final GuardedInvocationComponent gic = getGuardedInvocationComponent(callSiteDescriptor, linkerServices,

                    operations);

            if(gic != null) {

                return gic.getGuardedInvocation();

            }

            operations = pop(operations);

        }

        return null;

    }

    protected GuardedInvocationComponent getGuardedInvocationComponent(CallSiteDescriptor callSiteDescriptor,

            LinkerServices linkerServices, List<String> operations) throws Exception {

        if(operations.isEmpty()) {

            return null;

        }

        final String op = operations.get(0);

        // Either dyn:getProp:name(this) or dyn:getProp(this, name)

        if("getProp".equals(op)) {

            return getPropertyGetter(callSiteDescriptor, linkerServices, pop(operations));

        }

        // Either dyn:setProp:name(this, value) or dyn:setProp(this, name, value)

        if("setProp".equals(op)) {

            return getPropertySetter(callSiteDescriptor, linkerServices, pop(operations));

        }

        // Either dyn:getMethod:name(this), or dyn:getMethod(this, name)

        if("getMethod".equals(op)) {

            return getMethodGetter(callSiteDescriptor, linkerServices, pop(operations));

        }

        return null;

    }

    static final <T> List<T> pop(List<T> l) {

        return l.subList(1, l.size());

    }

    MethodHandle getClassGuard(CallSiteDescriptor desc) {

        return getClassGuard(desc.getMethodType());

    }

    MethodHandle getClassGuard(MethodType type) {

        return Guards.asType(classGuard, type);

    }

    GuardedInvocationComponent getClassGuardedInvocationComponent(MethodHandle invocation, MethodType type) {

        return new GuardedInvocationComponent(invocation, getClassGuard(type), clazz, ValidationType.EXACT_CLASS);

    }

    private MethodHandle getAssignableGuard(MethodType type) {

        return Guards.asType(assignableGuard, type);

    }

    private GuardedInvocation getCallPropWithThis(CallSiteDescriptor callSiteDescriptor, LinkerServices linkerServices) {

        switch(callSiteDescriptor.getNameTokenCount()) {

            case 3: {

                return createGuardedDynamicMethodInvocation(callSiteDescriptor, linkerServices,

                        callSiteDescriptor.getNameToken(CallSiteDescriptor.NAME_OPERAND), methods);

            }

            default: {

                return null;

            }

        }

    }

    private GuardedInvocation createGuardedDynamicMethodInvocation(CallSiteDescriptor callSiteDescriptor,

            LinkerServices linkerServices, String methodName, Map<String, DynamicMethod> methodMap){

        final MethodHandle inv = getDynamicMethodInvocation(callSiteDescriptor, linkerServices, methodName, methodMap);

        return inv == null ? null : new GuardedInvocation(inv, getClassGuard(callSiteDescriptor.getMethodType()));

    }

    private static MethodHandle getDynamicMethodInvocation(CallSiteDescriptor callSiteDescriptor,

            LinkerServices linkerServices, String methodName, Map<String, DynamicMethod> methodMap) {

        final DynamicMethod dynaMethod = getDynamicMethod(methodName, methodMap);

        return dynaMethod != null ? dynaMethod.getInvocation(callSiteDescriptor, linkerServices) : null;

    }

    private static DynamicMethod getDynamicMethod(String methodName, Map<String, DynamicMethod> methodMap) {

        final DynamicMethod dynaMethod = methodMap.get(methodName);

        return dynaMethod != null ? dynaMethod : getExplicitSignatureDynamicMethod(methodName, methodMap);

    }

    private static SingleDynamicMethod getExplicitSignatureDynamicMethod(String methodName,

            Map<String, DynamicMethod> methodsMap) {

        // What's below is meant to support the "name(type, type, ...)" syntax that programmers can use in a method name

        // to manually pin down an exact overloaded variant. This is not usually required, as the overloaded method

        // resolution works correctly in almost every situation. However, in presence of many language-specific

        // conversions with a radically dynamic language, most overloaded methods will end up being constantly selected

        // at invocation time, so a programmer knowledgeable of the situation might choose to pin down an exact overload

        // for performance reasons.

        // Is the method name lexically of the form "name(types)"?

        final int lastChar = methodName.length() - 1;

        if(methodName.charAt(lastChar) != ')') {

            return null;

        }

        final int openBrace = methodName.indexOf('(');

        if(openBrace == -1) {

            return null;

        }

        // Find an existing method for the "name" part

        final DynamicMethod simpleNamedMethod = methodsMap.get(methodName.substring(0, openBrace));

        if(simpleNamedMethod == null) {

            return null;

        }

        // Try to get a narrowed dynamic method for the explicit parameter types.

        return simpleNamedMethod.getMethodForExactParamTypes(methodName.substring(openBrace + 1, lastChar));

    }

    private static final MethodHandle IS_METHOD_HANDLE_NOT_NULL = Guards.isNotNull().asType(MethodType.methodType(

            boolean.class, MethodHandle.class));

    private static final MethodHandle CONSTANT_NULL_DROP_METHOD_HANDLE = MethodHandles.dropArguments(

            MethodHandles.constant(Object.class, null), 0, MethodHandle.class);

    private GuardedInvocationComponent getPropertySetter(CallSiteDescriptor callSiteDescriptor,

            LinkerServices linkerServices, List<String> operations) throws Exception {

        final MethodType type = callSiteDescriptor.getMethodType();

        switch(callSiteDescriptor.getNameTokenCount()) {

            case 2: {

                // Must have three arguments: target object, property name, and property value.

                assertParameterCount(callSiteDescriptor, 3);

                // What's below is basically:

                //   foldArguments(guardWithTest(isNotNull, invoke, null|nextComponent.invocation),

                //     get_setter_handle(type, linkerServices))

                // only with a bunch of method signature adjustments. Basically, retrieve method setter

                // MethodHandle; if it is non-null, invoke it, otherwise either return null, or delegate to next

                // component's invocation.

                // Call site type is "ret_type(object_type,property_name_type,property_value_type)", which we'll

                // abbreviate to R(O, N, V) going forward.

                // We want setters that conform to "R(O, V)"

                final MethodType setterType = type.dropParameterTypes(1, 2);

                // Bind property setter handle to the expected setter type and linker services. Type is

                // MethodHandle(Object, String, Object)

                final MethodHandle boundGetter = MethodHandles.insertArguments(getPropertySetterHandle, 0,

                        CallSiteDescriptorFactory.dropParameterTypes(callSiteDescriptor, 1, 2), linkerServices);

                // Cast getter to MethodHandle(O, N, V)

                final MethodHandle typedGetter = linkerServices.asType(boundGetter, type.changeReturnType(

                        MethodHandle.class));

                // Handle to invoke the setter R(MethodHandle, O, V)

                final MethodHandle invokeHandle = MethodHandles.exactInvoker(setterType);

                // Handle to invoke the setter, dropping unnecessary fold arguments R(MethodHandle, O, N, V)

                final MethodHandle invokeHandleFolded = MethodHandles.dropArguments(invokeHandle, 2, type.parameterType(

                        1));

                final GuardedInvocationComponent nextComponent = getGuardedInvocationComponent(callSiteDescriptor,

                        linkerServices, operations);

                final MethodHandle fallbackFolded;

                if(nextComponent == null) {

                    // Object(MethodHandle)->R(MethodHandle, O, N, V); returns constant null

                    fallbackFolded = MethodHandles.dropArguments(CONSTANT_NULL_DROP_METHOD_HANDLE, 1,

                            type.parameterList()).asType(type.insertParameterTypes(0, MethodHandle.class));

                } else {

                    // R(O, N, V)->R(MethodHandle, O, N, V); adapts the next component's invocation to drop the

                    // extra argument resulting from fold

                    fallbackFolded = MethodHandles.dropArguments(nextComponent.getGuardedInvocation().getInvocation(),

                            0, MethodHandle.class);

                }

                // fold(R(MethodHandle, O, N, V), MethodHandle(O, N, V))

                final MethodHandle compositeSetter = MethodHandles.foldArguments(MethodHandles.guardWithTest(

                            IS_METHOD_HANDLE_NOT_NULL, invokeHandleFolded, fallbackFolded), typedGetter);

                if(nextComponent == null) {

                    return getClassGuardedInvocationComponent(compositeSetter, type);