/*

 * 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

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package jdk.nashorn.internal.runtime.linker;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import static jdk.nashorn.internal.runtime.ECMAErrors.typeError;

import static jdk.nashorn.internal.runtime.ScriptRuntime.UNDEFINED;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.util.HashMap;

import java.util.Map;

import java.util.function.Supplier;

import jdk.dynalink.CallSiteDescriptor;

import jdk.dynalink.NamedOperation;

import jdk.dynalink.Operation;

import jdk.dynalink.beans.BeansLinker;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.GuardingDynamicLinker;

import jdk.dynalink.linker.GuardingTypeConverterFactory;

import jdk.dynalink.linker.LinkRequest;

import jdk.dynalink.linker.LinkerServices;

import jdk.dynalink.linker.support.Lookup;

import jdk.nashorn.internal.codegen.types.Type;

import jdk.nashorn.internal.runtime.ECMAException;

import jdk.nashorn.internal.runtime.JSType;

import jdk.nashorn.internal.runtime.ScriptRuntime;

import jdk.nashorn.internal.runtime.UnwarrantedOptimismException;

/**

 * Nashorn bottom linker; used as a last-resort catch-all linker for all linking requests that fall through all other

 * linkers (see how {@link Bootstrap} class configures the dynamic linker in its static initializer). It will throw

 * appropriate ECMAScript errors for attempts to invoke operations on {@code null}, link no-op property getters and

 * setters for Java objects that couldn't be linked by any other linker, and throw appropriate ECMAScript errors for

 * attempts to invoke arbitrary Java objects as functions or constructors.

 */

final class NashornBottomLinker implements GuardingDynamicLinker, GuardingTypeConverterFactory {

    @Override

    public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices)

            throws Exception {

        final Object self = linkRequest.getReceiver();

        if (self == null) {

            return linkNull(linkRequest);

        }

        // None of the objects that can be linked by NashornLinker should ever reach here. Basically, anything below

        // this point is a generic Java bean. Therefore, reaching here with a ScriptObject is a Nashorn bug.

        assert isExpectedObject(self) : "Couldn't link " + linkRequest.getCallSiteDescriptor() + " for " + self.getClass().getName();

        return linkBean(linkRequest);

    }

    private static final MethodHandle EMPTY_PROP_GETTER =

            MH.dropArguments(MH.constant(Object.class, UNDEFINED), 0, Object.class);

    private static final MethodHandle EMPTY_ELEM_GETTER =

            MH.dropArguments(EMPTY_PROP_GETTER, 0, Object.class);

    private static final MethodHandle EMPTY_PROP_SETTER =

            MH.asType(EMPTY_ELEM_GETTER, EMPTY_ELEM_GETTER.type().changeReturnType(void.class));

    private static final MethodHandle EMPTY_ELEM_SETTER =

            MH.dropArguments(EMPTY_PROP_SETTER, 0, Object.class);

    private static final MethodHandle THROW_STRICT_PROPERTY_SETTER;

    private static final MethodHandle THROW_OPTIMISTIC_UNDEFINED;

    static {

        final Lookup lookup = new Lookup(MethodHandles.lookup());

        THROW_STRICT_PROPERTY_SETTER = lookup.findOwnStatic("throwStrictPropertySetter", void.class, Object.class, Object.class);

        THROW_OPTIMISTIC_UNDEFINED = lookup.findOwnStatic("throwOptimisticUndefined", Object.class, int.class);

    }

    private static GuardedInvocation linkBean(final LinkRequest linkRequest) throws Exception {

        final CallSiteDescriptor desc = linkRequest.getCallSiteDescriptor();

        final Object self = linkRequest.getReceiver();

        switch (NashornCallSiteDescriptor.getStandardOperation(desc)) {

        case NEW:

            if(BeansLinker.isDynamicConstructor(self)) {

                throw typeError("no.constructor.matches.args", ScriptRuntime.safeToString(self));

            }

            if(BeansLinker.isDynamicMethod(self)) {

                throw typeError("method.not.constructor", ScriptRuntime.safeToString(self));

            }

            throw typeError("not.a.function", NashornCallSiteDescriptor.getFunctionErrorMessage(desc, self));

        case CALL:

            if(BeansLinker.isDynamicConstructor(self)) {

                throw typeError("constructor.requires.new", ScriptRuntime.safeToString(self));

            }

            if(BeansLinker.isDynamicMethod(self)) {

                throw typeError("no.method.matches.args", ScriptRuntime.safeToString(self));

            }

            throw typeError("not.a.function", NashornCallSiteDescriptor.getFunctionErrorMessage(desc, self));

        default:

            // Everything else is supposed to have been already handled by Bootstrap.beansLinker

            // delegating to linkNoSuchBeanMember

            throw new AssertionError("unknown call type " + desc);

        }

    }

    static MethodHandle linkMissingBeanMember(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {

        final CallSiteDescriptor desc = linkRequest.getCallSiteDescriptor();

        final String operand = NashornCallSiteDescriptor.getOperand(desc);

        switch (NashornCallSiteDescriptor.getStandardOperation(desc)) {

        case GET:

            if (NashornCallSiteDescriptor.isOptimistic(desc)) {

                return adaptThrower(MethodHandles.insertArguments(THROW_OPTIMISTIC_UNDEFINED, 0, NashornCallSiteDescriptor.getProgramPoint(desc)), desc);

            } else if (operand != null) {

                return getInvocation(EMPTY_PROP_GETTER, linkerServices, desc);

            }

            return getInvocation(EMPTY_ELEM_GETTER, linkerServices, desc);

        case SET:

            if (strict) {

                return adaptThrower(bindOperand(THROW_STRICT_PROPERTY_SETTER, operand), desc);

            } else if (operand != null) {

                return getInvocation(EMPTY_PROP_SETTER, linkerServices, desc);

            }

            return getInvocation(EMPTY_ELEM_SETTER, linkerServices, desc);

        default:

            throw new AssertionError("unknown call type " + desc);

        }

    }

    private static MethodHandle bindOperand(final MethodHandle handle, final String operand) {

        return operand == null ? handle : MethodHandles.insertArguments(handle, 1, operand);

    }

    private static MethodHandle adaptThrower(final MethodHandle handle, final CallSiteDescriptor desc) {

        final MethodType targetType = desc.getMethodType();

        final int paramCount = handle.type().parameterCount();

        return MethodHandles

                .dropArguments(handle, paramCount, targetType.parameterList().subList(paramCount, targetType.parameterCount()))

                .asType(targetType);

    }

    @SuppressWarnings("unused")

    private static void throwStrictPropertySetter(final Object self, final Object name) {

        throw createTypeError(self, name, "cant.set.property");

    }

    private static ECMAException createTypeError(final Object self, final Object name, final String msg) {

        return typeError(msg, String.valueOf(name), ScriptRuntime.safeToString(self));

    }

    @SuppressWarnings("unused")

    private static Object throwOptimisticUndefined(final int programPoint) {

        throw new UnwarrantedOptimismException(UNDEFINED, programPoint, Type.OBJECT);

    }

    @Override

    public GuardedInvocation convertToType(final Class<?> sourceType, final Class<?> targetType, final Supplier<MethodHandles.Lookup> lookupSupplier) throws Exception {

        final GuardedInvocation gi = convertToTypeNoCast(sourceType, targetType);

        return gi == null ? null : gi.asType(MH.type(targetType, sourceType));

    }

    /**

     * Main part of the implementation of {@link GuardingTypeConverterFactory#convertToType} that doesn't

     * care about adapting the method signature; that's done by the invoking method. Returns conversion

     * from Object to String/number/boolean (JS primitive types).

     * @param sourceType the source type

     * @param targetType the target type

     * @return a guarded invocation that converts from the source type to the target type.

     * @throws Exception if something goes wrong

     */

    private static GuardedInvocation convertToTypeNoCast(final Class<?> sourceType, final Class<?> targetType) throws Exception {

        final MethodHandle mh = CONVERTERS.get(targetType);

        if (mh != null) {

            return new GuardedInvocation(mh);

        }

        return null;

    }

    private static MethodHandle getInvocation(final MethodHandle handle, final LinkerServices linkerServices, final CallSiteDescriptor desc) {

        return linkerServices.asTypeLosslessReturn(handle, desc.getMethodType());

    }

    // Used solely in an assertion to figure out if the object we get here is something we in fact expect. Objects

    // linked by NashornLinker should never reach here.

    private static boolean isExpectedObject(final Object obj) {

        return !(NashornLinker.canLinkTypeStatic(obj.getClass()));

    }

    private static GuardedInvocation linkNull(final LinkRequest linkRequest) {

        final CallSiteDescriptor desc = linkRequest.getCallSiteDescriptor();

        switch (NashornCallSiteDescriptor.getStandardOperation(desc)) {

        case NEW:

        case CALL:

            throw typeError("not.a.function", "null");

        case GET:

            throw typeError(NashornCallSiteDescriptor.isMethodFirstOperation(desc) ? "no.such.function" : "cant.get.property", getArgument(linkRequest), "null");

        case SET:

            throw typeError("cant.set.property", getArgument(linkRequest), "null");

        default:

            throw new AssertionError("unknown call type " + desc);

        }

    }

    private static final Map<Class<?>, MethodHandle> CONVERTERS = new HashMap<>();

    static {

        CONVERTERS.put(boolean.class, JSType.TO_BOOLEAN.methodHandle());

        CONVERTERS.put(double.class, JSType.TO_NUMBER.methodHandle());

        CONVERTERS.put(int.class, JSType.TO_INTEGER.methodHandle());

        CONVERTERS.put(long.class, JSType.TO_LONG.methodHandle());

        CONVERTERS.put(String.class, JSType.TO_STRING.methodHandle());

    }

    private static String getArgument(final LinkRequest linkRequest) {

        final Operation op = linkRequest.getCallSiteDescriptor().getOperation();

        if (op instanceof NamedOperation) {

            return ((NamedOperation)op).getName().toString();

        }

        return ScriptRuntime.safeToString(linkRequest.getArguments()[1]);

    }

}