/*

 * 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,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * 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.Collection;

import java.util.Collections;

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;

import jdk.internal.dynalink.support.TypeUtilities;

/**

 * 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(final Class<?> clazz, final MethodHandle classGuard) {

        this(clazz, classGuard, classGuard);

    }

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

        this.clazz = clazz;

        this.classGuard = classGuard;

        this.assignableGuard = assignableGuard;

        final FacetIntrospector introspector = createFacetIntrospector();

        // Add methods and properties

        for(final 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(final 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(final 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(final 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();

    Collection<String> getReadablePropertyNames() {

        return getUnmodifiableKeys(propertyGetters);

    }

    Collection<String> getWritablePropertyNames() {

        return getUnmodifiableKeys(propertySetters);

    }

    Collection<String> getMethodNames() {

        return getUnmodifiableKeys(methods);

    }

    private static Collection<String> getUnmodifiableKeys(final Map<String, ?> m) {

        return Collections.unmodifiableCollection(m.keySet());

    }

    /**

     * 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(final String name, final SingleDynamicMethod handle, final 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(final Method getter, final 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(final String name, final MethodHandle handle, final ValidationType validationType) {

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

    }

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

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

    }

    private void addMember(final String name, final SingleDynamicMethod method, final 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(final Iterable<? extends AccessibleObject> members, final Class<?> clazz, final String name) {

        DynamicMethod dynMethod = null;

        for(final 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(final AccessibleObject m) {

        if(CallerSensitiveDetector.isCallerSensitive(m)) {

            return new CallerSensitiveDynamicMethod(m);

        }

        final Member member = (Member)m;

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

    }

    /**

     * 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(final AccessibleObject m) {

        if(m instanceof Method) {

            final Method reflMethod = (Method)m;

            final MethodHandle handle = Lookup.PUBLIC.unreflect(reflMethod);

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

                return StaticClassIntrospector.editStaticMethodHandle(handle);

            }

            return handle;

        }

        return StaticClassIntrospector.editConstructorMethodHandle(Lookup.PUBLIC.unreflectConstructor((Constructor<?>)m));

    }

    private static DynamicMethod mergeMethods(final SingleDynamicMethod method, final DynamicMethod existing, final Class<?> clazz, final 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(final 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(final CallSiteDescriptor callSiteDescriptor,

            final LinkerServices linkerServices, final 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(final List<T> l) {

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

    }

    MethodHandle getClassGuard(final CallSiteDescriptor desc) {

        return getClassGuard(desc.getMethodType());

    }

    MethodHandle getClassGuard(final MethodType type) {

        return Guards.asType(classGuard, type);

    }

    GuardedInvocationComponent getClassGuardedInvocationComponent(final MethodHandle invocation, final MethodType type) {

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

    }

    SingleDynamicMethod getConstructorMethod(final String signature) {

        return null;

    }

    private MethodHandle getAssignableGuard(final MethodType type) {

        return Guards.asType(assignableGuard, type);

    }

    private GuardedInvocation getCallPropWithThis(final CallSiteDescriptor callSiteDescriptor, final LinkerServices linkerServices) {

        switch(callSiteDescriptor.getNameTokenCount()) {

            case 3: {

                return createGuardedDynamicMethodInvocation(callSiteDescriptor, linkerServices,

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

            }

            default: {

                return null;

            }

        }

    }

    private GuardedInvocation createGuardedDynamicMethodInvocation(final CallSiteDescriptor callSiteDescriptor,

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

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

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

    }

    private MethodHandle getDynamicMethodInvocation(final CallSiteDescriptor callSiteDescriptor,

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

        final DynamicMethod dynaMethod = getDynamicMethod(methodName, methodMap);

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

    }

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

        final DynamicMethod dynaMethod = methodMap.get(methodName);

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

    }

    private SingleDynamicMethod getExplicitSignatureDynamicMethod(final String fullName,

            final 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 = fullName.length() - 1;

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

            return null;

        }

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

        if(openBrace == -1) {

            return null;

        }

        final String name = fullName.substring(0, openBrace);

        final String signature = fullName.substring(openBrace + 1, lastChar);

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

        final DynamicMethod simpleNamedMethod = methodsMap.get(name);

        if(simpleNamedMethod == null) {

            // explicit signature constructor access

            // Java.type("java.awt.Color")["(int,int,int)"]

            // will get Color(int,int,int) constructor of Color class.

            if (name.isEmpty()) {

                return getConstructorMethod(signature);

            }

            return null;

        }

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

        return simpleNamedMethod.getMethodForExactParamTypes(signature);

    }

    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(final CallSiteDescriptor callSiteDescriptor,

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

        switch(callSiteDescriptor.getNameTokenCount()) {

            case 2: {

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

                assertParameterCount(callSiteDescriptor, 3);

                // We want setters that conform to "Object(O, V)". Note, we aren't doing "R(O, V)" as it might not be

                // valid for us to convert return values proactively. Also, since we don't know what setters will be

                // invoked, we'll conservatively presume Object return type.

                final MethodType type = callSiteDescriptor.getMethodType().changeReturnType(Object.class);

                // 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, although we don't really use R here (see above about using

                // Object return type).

                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));