/*

 * Copyright (c) 2012, 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.

 */

package java.lang.invoke;

import java.lang.reflect.Constructor;

import java.lang.reflect.Method;

import java.security.ProtectionDomain;

import java.util.concurrent.atomic.AtomicInteger;

import jdk.internal.org.objectweb.asm.*;

import static jdk.internal.org.objectweb.asm.Opcodes.*;

import sun.misc.Unsafe;

import java.security.AccessController;

import java.security.PrivilegedAction;

/**

 * Lambda metafactory implementation which dynamically creates an inner-class-like class per lambda callsite.

 *

 * @see LambdaMetafactory

 */

/* package */ final class InnerClassLambdaMetafactory extends AbstractValidatingLambdaMetafactory {

    private static final int CLASSFILE_VERSION = 51;

    private static final String METHOD_DESCRIPTOR_VOID = Type.getMethodDescriptor(Type.VOID_TYPE);

    private static final String NAME_MAGIC_ACCESSOR_IMPL = "java/lang/invoke/MagicLambdaImpl";

    private static final String NAME_CTOR = "<init>";

    //Serialization support

    private static final String NAME_SERIALIZED_LAMBDA = "java/lang/invoke/SerializedLambda";

    private static final String DESCR_METHOD_WRITE_REPLACE = "()Ljava/lang/Object;";

    private static final String NAME_METHOD_WRITE_REPLACE = "writeReplace";

    private static final String NAME_OBJECT = "java/lang/Object";

    private static final String DESCR_CTOR_SERIALIZED_LAMBDA

            = MethodType.methodType(void.class,

                                    Class.class,

                                    int.class, String.class, String.class, String.class,

                                    int.class, String.class, String.class, String.class,

                                    String.class,

                                    Object[].class).toMethodDescriptorString();

    // Used to ensure that each spun class name is unique

    private static final AtomicInteger counter = new AtomicInteger(0);

    // See context values in AbstractValidatingLambdaMetafactory

    private final String implMethodClassName;        // Name of type containing implementation "CC"

    private final String implMethodName;             // Name of implementation method "impl"

    private final String implMethodDesc;             // Type descriptor for implementation methods "(I)Ljava/lang/String;"

    private final Type[] implMethodArgumentTypes;    // ASM types for implementaion method parameters

    private final Type implMethodReturnType;         // ASM type for implementaion method return type "Ljava/lang/String;"

    private final MethodType constructorType;        // Generated class constructor type "(CC)void"

    private final String constructorDesc;            // Type descriptor for constructor "(LCC;)V"

    private final ClassWriter cw;                    // ASM class writer

    private final Type[] argTypes;                   // ASM types for the constructor arguments

    private final String[] argNames;                 // Generated names for the constructor arguments

    private final String lambdaClassName;            // Generated name for the generated class "X$$Lambda$1"

    private final Type[] instantiatedArgumentTypes;  // ASM types for the functional interface arguments

    /**

     * General meta-factory constructor, standard cases and allowing for uncommon options such as serialization.

     *

     * @param caller Stacked automatically by VM; represents a lookup context with the accessibility privileges

     *               of the caller.

     * @param invokedType Stacked automatically by VM; the signature of the invoked method, which includes the

     *                    expected static type of the returned lambda object, and the static types of the captured

     *                    arguments for the lambda.  In the event that the implementation method is an instance method,

     *                    the first argument in the invocation signature will correspond to the receiver.

     * @param samMethod The primary method in the functional interface to which the lambda or method reference is

     *                  being converted, represented as a method handle.

     * @param implMethod The implementation method which should be called (with suitable adaptation of argument

     *                   types, return types, and adjustment for captured arguments) when methods of the resulting

     *                   functional interface instance are invoked.

     * @param instantiatedMethodType The signature of the primary functional interface method after type variables

     *                               are substituted with their instantiation from the capture site

     * @param flags A bitmask containing flags that may influence the translation of this lambda expression.  Defined

     *              fields include FLAG_SERIALIZABLE.

     * @param markerInterfaces Additional interfaces which the lambda object should implement.

     * @throws ReflectiveOperationException

     * @throws LambdaConversionException If any of the meta-factory protocol invariants are violated

     */

    public InnerClassLambdaMetafactory(MethodHandles.Lookup caller,

                                       MethodType invokedType,

                                       MethodHandle samMethod,

                                       MethodHandle implMethod,

                                       MethodType instantiatedMethodType,

                                       int flags,

                                       Class<?>[] markerInterfaces)

            throws ReflectiveOperationException, LambdaConversionException {

        super(caller, invokedType, samMethod, implMethod, instantiatedMethodType, flags, markerInterfaces);

        implMethodClassName = implDefiningClass.getName().replace('.', '/');

        implMethodName = implInfo.getName();

        implMethodDesc = implMethodType.toMethodDescriptorString();

        Type implMethodAsmType = Type.getMethodType(implMethodDesc);

        implMethodArgumentTypes = implMethodAsmType.getArgumentTypes();

        implMethodReturnType = (implKind == MethodHandleInfo.REF_newInvokeSpecial)

                ? Type.getObjectType(implMethodClassName)

                : implMethodAsmType.getReturnType();

        constructorType = invokedType.changeReturnType(Void.TYPE);

        constructorDesc = constructorType.toMethodDescriptorString();

        lambdaClassName = targetClass.getName().replace('.', '/') + "$$Lambda$" + counter.incrementAndGet();

        cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);

        argTypes = Type.getArgumentTypes(constructorDesc);

        argNames = new String[argTypes.length];

        for (int i = 0; i < argTypes.length; i++) {

            argNames[i] = "arg$" + (i + 1);

        }

        instantiatedArgumentTypes = Type.getArgumentTypes(instantiatedMethodType.toMethodDescriptorString());

    }

    /**

     * Build the CallSite. Generate a class file which implements the functional

     * interface, define the class, if there are no parameters create an instance

     * of the class which the CallSite will return, otherwise, generate handles

     * which will call the class' constructor.

     *

     * @return a CallSite, which, when invoked, will return an instance of the

     * functional interface

     * @throws ReflectiveOperationException

     * @throws LambdaConversionException If properly formed functional interface is not found

     */

    @Override

    CallSite buildCallSite() throws ReflectiveOperationException, LambdaConversionException {

        final Class<?> innerClass = spinInnerClass();

        if (invokedType.parameterCount() == 0) {

            final Constructor[] ctrs = AccessController.doPrivileged(

                    new PrivilegedAction<Constructor[]>() {

                @Override

                public Constructor[] run() {

                    return innerClass.getDeclaredConstructors();

                }

            });

            if (ctrs.length != 1) {

                throw new ReflectiveOperationException("Expected one lambda constructor for "

                        + innerClass.getCanonicalName() + ", got " + ctrs.length);

            }

            // The lambda implementing inner class constructor is private, set

            // it accessible (by us) before creating the constant sole instance

            AccessController.doPrivileged(new PrivilegedAction<Void>() {

                @Override

                public Void run() {

                    ctrs[0].setAccessible(true);

                    return null;

                }

            });

            Object inst = ctrs[0].newInstance();

            return new ConstantCallSite(MethodHandles.constant(samBase, inst));

        } else {

            return new ConstantCallSite(

                    MethodHandles.Lookup.IMPL_LOOKUP

                                        .findConstructor(innerClass, constructorType)

                                        .asType(constructorType.changeReturnType(samBase)));

        }

    }

    /**

     * Generate a class file which implements the functional

     * interface, define and return the class.

     *

     * @return a Class which implements the functional interface

     * @throws LambdaConversionException If properly formed functional interface is not found

     */

    private Class<?> spinInnerClass() throws LambdaConversionException {

        String samName = samBase.getName().replace('.', '/');

        String[] interfaces = new String[markerInterfaces.length + 1];

        interfaces[0] = samName;

        for (int i=0; i<markerInterfaces.length; i++) {

            interfaces[i+1] = markerInterfaces[i].getName().replace('.', '/');

        }

        cw.visit(CLASSFILE_VERSION, ACC_SUPER + ACC_FINAL + ACC_SYNTHETIC,

                 lambdaClassName, null,

                 NAME_MAGIC_ACCESSOR_IMPL, interfaces);

        // Generate final fields to be filled in by constructor

        for (int i = 0; i < argTypes.length; i++) {

            FieldVisitor fv = cw.visitField(ACC_PRIVATE + ACC_FINAL, argNames[i], argTypes[i].getDescriptor(),

                                            null, null);

            fv.visitEnd();

        }

        generateConstructor();

        MethodAnalyzer ma = new MethodAnalyzer();

        // Forward the SAM method

        if (ma.getSamMethod() == null) {

            throw new LambdaConversionException(String.format("Functional interface method not found: %s", samMethodType));

        } else {

            generateForwardingMethod(ma.getSamMethod(), false);

        }

        // Forward the bridges

        // @@@ The commented-out code is temporary, pending the VM's ability to bridge all methods on request

        // @@@ Once the VM can do fail-over, uncomment the !ma.wasDefaultMethodFound() test, and emit the appropriate

        // @@@ classfile attribute to request custom bridging.  See 8002092.

        if (!ma.getMethodsToBridge().isEmpty() /* && !ma.conflictFoundBetweenDefaultAndBridge() */ ) {

            for (Method m : ma.getMethodsToBridge()) {

                generateForwardingMethod(m, true);

            }

        }

        if (isSerializable) {

            generateWriteReplace();

        }

        cw.visitEnd();

        // Define the generated class in this VM.

        final byte[] classBytes = cw.toByteArray();

        /*** Uncomment to dump the generated file

            System.out.printf("Loaded: %s (%d bytes) %n", lambdaClassName, classBytes.length);

            try (FileOutputStream fos = new FileOutputStream(lambdaClassName.replace('/', '.') + ".class")) {

                fos.write(classBytes);

            } catch (IOException ex) {

                PlatformLogger.getLogger(InnerClassLambdaMetafactory.class.getName()).severe(ex.getMessage(), ex);

            }

        ***/

        ClassLoader loader = targetClass.getClassLoader();

        ProtectionDomain pd = (loader == null)

            ? null

            : AccessController.doPrivileged(

            new PrivilegedAction<ProtectionDomain>() {

                @Override

                public ProtectionDomain run() {

                    return targetClass.getProtectionDomain();

                }

            }

        );

        return (Class<?>) Unsafe.getUnsafe().defineClass(lambdaClassName, classBytes, 0, classBytes.length,

                                                                   loader, pd);

    }

    /**

     * Generate the constructor for the class

     */

    private void generateConstructor() {

        // Generate constructor

        MethodVisitor ctor = cw.visitMethod(ACC_PRIVATE, NAME_CTOR, constructorDesc, null, null);

        ctor.visitCode();

        ctor.visitVarInsn(ALOAD, 0);

        ctor.visitMethodInsn(INVOKESPECIAL, NAME_MAGIC_ACCESSOR_IMPL, NAME_CTOR, METHOD_DESCRIPTOR_VOID);

        int lvIndex = 0;

        for (int i = 0; i < argTypes.length; i++) {

            ctor.visitVarInsn(ALOAD, 0);

            ctor.visitVarInsn(argTypes[i].getOpcode(ILOAD), lvIndex + 1);

            lvIndex += argTypes[i].getSize();

            ctor.visitFieldInsn(PUTFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());

        }

        ctor.visitInsn(RETURN);

        ctor.visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored

        ctor.visitEnd();

    }

    /**

     * Generate the writeReplace method (if needed for serialization)

     */

    private void generateWriteReplace() {

        TypeConvertingMethodAdapter mv

                = new TypeConvertingMethodAdapter(cw.visitMethod(ACC_PRIVATE + ACC_FINAL,

                                                                 NAME_METHOD_WRITE_REPLACE, DESCR_METHOD_WRITE_REPLACE,

                                                                 null, null));

        mv.visitCode();

        mv.visitTypeInsn(NEW, NAME_SERIALIZED_LAMBDA);

        mv.visitInsn(DUP);;

        mv.visitLdcInsn(Type.getType(targetClass));

        mv.visitLdcInsn(samInfo.getReferenceKind());

        mv.visitLdcInsn(invokedType.returnType().getName().replace('.', '/'));

        mv.visitLdcInsn(samInfo.getName());

        mv.visitLdcInsn(samInfo.getMethodType().toMethodDescriptorString());

        mv.visitLdcInsn(implInfo.getReferenceKind());

        mv.visitLdcInsn(implInfo.getDeclaringClass().getName().replace('.', '/'));

        mv.visitLdcInsn(implInfo.getName());

        mv.visitLdcInsn(implInfo.getMethodType().toMethodDescriptorString());

        mv.visitLdcInsn(instantiatedMethodType.toMethodDescriptorString());

        mv.iconst(argTypes.length);

        mv.visitTypeInsn(ANEWARRAY, NAME_OBJECT);

        for (int i = 0; i < argTypes.length; i++) {

            mv.visitInsn(DUP);

            mv.iconst(i);

            mv.visitVarInsn(ALOAD, 0);

            mv.visitFieldInsn(GETFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());

            mv.boxIfTypePrimitive(argTypes[i]);

            mv.visitInsn(AASTORE);

        }

        mv.visitMethodInsn(INVOKESPECIAL, NAME_SERIALIZED_LAMBDA, NAME_CTOR,

                DESCR_CTOR_SERIALIZED_LAMBDA);

        mv.visitInsn(ARETURN);

        mv.visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored

        mv.visitEnd();

    }

    /**

     * Generate a method which calls the lambda implementation method,

     * converting arguments, as needed.

     * @param m The method whose signature should be generated

     * @param isBridge True if this methods should be flagged as a bridge

     */

    private void generateForwardingMethod(Method m, boolean isBridge) {

        Class<?>[] exceptionTypes = m.getExceptionTypes();

        String[] exceptionNames = new String[exceptionTypes.length];

        for (int i = 0; i < exceptionTypes.length; i++) {

            exceptionNames[i] = exceptionTypes[i].getName().replace('.', '/');

        }

        String methodDescriptor = Type.getMethodDescriptor(m);

        int access = isBridge? ACC_PUBLIC | ACC_BRIDGE : ACC_PUBLIC;

        MethodVisitor mv = cw.visitMethod(access, m.getName(), methodDescriptor, null, exceptionNames);

        new ForwardingMethodGenerator(mv).generate(m);

    }

    /**

     * This class generates a method body which calls the lambda implementation

     * method, converting arguments, as needed.

     */

    private class ForwardingMethodGenerator extends TypeConvertingMethodAdapter {

        ForwardingMethodGenerator(MethodVisitor mv) {

            super(mv);

        }

        void generate(Method m) throws InternalError {

            visitCode();

            if (implKind == MethodHandleInfo.REF_newInvokeSpecial) {

                visitTypeInsn(NEW, implMethodClassName);

                visitInsn(DUP);;

            }

            for (int i = 0; i < argTypes.length; i++) {

                visitVarInsn(ALOAD, 0);

                visitFieldInsn(GETFIELD, lambdaClassName, argNames[i], argTypes[i].getDescriptor());

            }

            convertArgumentTypes(Type.getArgumentTypes(m));

            // Invoke the method we want to forward to

            visitMethodInsn(invocationOpcode(), implMethodClassName, implMethodName, implMethodDesc);

            // Convert the return value (if any) and return it

            // Note: if adapting from non-void to void, the 'return' instruction will pop the unneeded result

            Type samReturnType = Type.getReturnType(m);

            convertType(implMethodReturnType, samReturnType, samReturnType);

            visitInsn(samReturnType.getOpcode(Opcodes.IRETURN));

            visitMaxs(-1, -1); // Maxs computed by ClassWriter.COMPUTE_MAXS, these arguments ignored

            visitEnd();

        }

        private void convertArgumentTypes(Type[] samArgumentTypes) {

            int lvIndex = 0;

            boolean samIncludesReceiver = implIsInstanceMethod && argTypes.length == 0;

            int samReceiverLength = samIncludesReceiver ? 1 : 0;

            if (samIncludesReceiver) {

                // push receiver

                Type rcvrType = samArgumentTypes[0];

                Type instantiatedRcvrType = instantiatedArgumentTypes[0];

                visitVarInsn(rcvrType.getOpcode(ILOAD), lvIndex + 1);

                lvIndex += rcvrType.getSize();

                convertType(rcvrType, Type.getType(implDefiningClass), instantiatedRcvrType);

            }

            int argOffset = implMethodArgumentTypes.length - samArgumentTypes.length;

            for (int i = samReceiverLength; i < samArgumentTypes.length; i++) {

                Type argType = samArgumentTypes[i];

                Type targetType = implMethodArgumentTypes[argOffset + i];

                Type instantiatedArgType = instantiatedArgumentTypes[i];

                visitVarInsn(argType.getOpcode(ILOAD), lvIndex + 1);

                lvIndex += argType.getSize();

                convertType(argType, targetType, instantiatedArgType);

            }

        }

        private void convertType(Type argType, Type targetType, Type functionalType) {

            convertType(argType.getDescriptor(), targetType.getDescriptor(), functionalType.getDescriptor());

        }

        private int invocationOpcode() throws InternalError {

            switch (implKind) {

                case MethodHandleInfo.REF_invokeStatic:

                    return INVOKESTATIC;

                case MethodHandleInfo.REF_newInvokeSpecial:

                    return INVOKESPECIAL;

                 case MethodHandleInfo.REF_invokeVirtual:

                    return INVOKEVIRTUAL;

                case MethodHandleInfo.REF_invokeInterface:

                    return INVOKEINTERFACE;

                case MethodHandleInfo.REF_invokeSpecial:

                    return INVOKESPECIAL;

                default:

                    throw new InternalError("Unexpected invocation kind: " + implKind);

            }

        }

    }

}