/*

 * Copyright (c) 2008, 2011, 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 java.lang.invoke;

import sun.invoke.util.VerifyType;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import sun.invoke.empty.Empty;

import sun.invoke.util.ValueConversions;

import sun.invoke.util.Wrapper;

import sun.misc.Unsafe;

import static java.lang.invoke.MethodHandleStatics.*;

import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

/**

 * Trusted implementation code for MethodHandle.

 * @author jrose

 */

/*non-public*/ abstract class MethodHandleImpl {

    /// Factory methods to create method handles:

    private static final MemberName.Factory LOOKUP = MemberName.Factory.INSTANCE;

    static void initStatics() {

        // Trigger preceding sequence.

    }

    /** Look up a given method.

     * Callable only from sun.invoke and related packages.

     * <p>

     * The resulting method handle type will be of the given type,

     * with a receiver type {@code rcvc} prepended if the member is not static.

     * <p>

     * Access checks are made as of the given lookup class.

     * In particular, if the method is protected and {@code defc} is in a

     * different package from the lookup class, then {@code rcvc} must be

     * the lookup class or a subclass.

     * @param token Proof that the lookup class has access to this package.

     * @param member Resolved method or constructor to call.

     * @param name Name of the desired method.

     * @param rcvc Receiver type of desired non-static method (else null)

     * @param doDispatch whether the method handle will test the receiver type

     * @param lookupClass access-check relative to this class

     * @return a direct handle to the matching method

     * @throws IllegalAccessException if the given method cannot be accessed by the lookup class

     */

    static

    MethodHandle findMethod(MemberName method,

                            boolean doDispatch, Class<?> lookupClass) throws IllegalAccessException {

        MethodType mtype = method.getMethodType();

        if (!method.isStatic()) {

            // adjust the advertised receiver type to be exactly the one requested

            // (in the case of invokespecial, this will be the calling class)

            Class<?> recvType = method.getDeclaringClass();

            mtype = mtype.insertParameterTypes(0, recvType);

        }

        DirectMethodHandle mh = new DirectMethodHandle(mtype, method, doDispatch, lookupClass);

        if (!mh.isValid())

            throw method.makeAccessException("no direct method handle", lookupClass);

        assert(mh.type() == mtype);

        if (!method.isVarargs())

            return mh;

        int argc = mtype.parameterCount();

        if (argc != 0) {

            Class<?> arrayType = mtype.parameterType(argc-1);

            if (arrayType.isArray())

                return AdapterMethodHandle.makeVarargsCollector(mh, arrayType);

        }

        throw method.makeAccessException("cannot make variable arity", null);

    }

    static

    MethodHandle makeAllocator(MethodHandle rawConstructor) {

        MethodType rawConType = rawConstructor.type();

        Class<?> allocateClass = rawConType.parameterType(0);

        // Wrap the raw (unsafe) constructor with the allocation of a suitable object.

        assert(AdapterMethodHandle.canCollectArguments(rawConType, MethodType.methodType(allocateClass), 0, true));

        // allocator(arg...)

        // [fold]=> cookedConstructor(obj=allocate(C), arg...)

        // [dup,collect]=> identity(obj, void=rawConstructor(obj, arg...))

        MethodHandle returner = MethodHandles.identity(allocateClass);

        MethodType ctype = rawConType.insertParameterTypes(0, allocateClass).changeReturnType(allocateClass);

        MethodHandle  cookedConstructor = AdapterMethodHandle.makeCollectArguments(returner, rawConstructor, 1, false);

        assert(cookedConstructor.type().equals(ctype));

        ctype = ctype.dropParameterTypes(0, 1);

        cookedConstructor = AdapterMethodHandle.makeCollectArguments(cookedConstructor, returner, 0, true);

        AllocateObject allocator = new AllocateObject(allocateClass);

        // allocate() => new C(void)

        assert(allocator.type().equals(MethodType.methodType(allocateClass)));

        ctype = ctype.dropParameterTypes(0, 1);

        MethodHandle fold = foldArguments(cookedConstructor, ctype, 0, allocator);

        return fold;

    }

    static final class AllocateObject /*<C>*/ extends BoundMethodHandle {

        private static final Unsafe unsafe = Unsafe.getUnsafe();

        private final Class<?> /*<C>*/ allocateClass;

        // for allocation only:

        private AllocateObject(Class<?> /*<C>*/ allocateClass) {

            super(ALLOCATE.asType(MethodType.methodType(allocateClass, AllocateObject.class)));

            this.allocateClass = allocateClass;

        }

        @SuppressWarnings("unchecked")

        private Object /*C*/ allocate() throws InstantiationException {

            return unsafe.allocateInstance(allocateClass);

        }

        static final MethodHandle ALLOCATE;

        static {

            try {

                ALLOCATE = IMPL_LOOKUP.findVirtual(AllocateObject.class, "allocate", MethodType.genericMethodType(0));

            } catch (ReflectiveOperationException ex) {

                throw uncaughtException(ex);

            }

        }

    }

    static

    MethodHandle accessField(MemberName member, boolean isSetter,

                             Class<?> lookupClass) {

        // Use sun. misc.Unsafe to dig up the dirt on the field.

        FieldAccessor accessor = new FieldAccessor(member, isSetter);

        return accessor;

    }

    static

    MethodHandle accessArrayElement(Class<?> arrayClass, boolean isSetter) {

        if (!arrayClass.isArray())

            throw newIllegalArgumentException("not an array: "+arrayClass);

        Class<?> elemClass = arrayClass.getComponentType();

        MethodHandle[] mhs = FieldAccessor.ARRAY_CACHE.get(elemClass);

        if (mhs == null) {

            if (!FieldAccessor.doCache(elemClass))

                return FieldAccessor.ahandle(arrayClass, isSetter);

            mhs = new MethodHandle[] {

                FieldAccessor.ahandle(arrayClass, false),

                FieldAccessor.ahandle(arrayClass, true)

            };

            if (mhs[0].type().parameterType(0) == Class.class) {

                mhs[0] = mhs[0].bindTo(elemClass);

                mhs[1] = mhs[1].bindTo(elemClass);

            }

            synchronized (FieldAccessor.ARRAY_CACHE) {}  // memory barrier

            FieldAccessor.ARRAY_CACHE.put(elemClass, mhs);

        }

        return mhs[isSetter ? 1 : 0];

    }

    static final class FieldAccessor /*<C,V>*/ extends BoundMethodHandle {

        private static final Unsafe unsafe = Unsafe.getUnsafe();

        final Object base;  // for static refs only

        final long offset;

        final String name;

        FieldAccessor(MemberName field, boolean isSetter) {

            super(fhandle(field.getDeclaringClass(), field.getFieldType(), isSetter, field.isStatic()));

            this.offset = (long) field.getVMIndex();

            this.name = field.getName();

            this.base = staticBase(field);

        }

        @Override

        String debugString() { return addTypeString(name, this); }

        static Object staticBase(final MemberName field) {

            if (!field.isStatic())  return null;

            return AccessController.doPrivileged(new PrivilegedAction<Object>() {

                    public Object run() {

                        try {

                            // FIXME:  Should not have to create 'f' to get this value.

                            java.lang.reflect.Field f = c.getDeclaredField(field.getName());

                            return unsafe.staticFieldBase(f);

                        } catch (NoSuchFieldException ee) {

                            throw uncaughtException(ee);

                        }

                    }

                });

        }

        int getStaticI() { return unsafe.getInt(base, offset); }

        void setStaticI(int x) { unsafe.putInt(base, offset, x); }

        long getStaticJ() { return unsafe.getLong(base, offset); }

        void setStaticJ(long x) { unsafe.putLong(base, offset, x); }

        float getStaticF() { return unsafe.getFloat(base, offset); }

        void setStaticF(float x) { unsafe.putFloat(base, offset, x); }

        double getStaticD() { return unsafe.getDouble(base, offset); }

        void setStaticD(double x) { unsafe.putDouble(base, offset, x); }

        boolean getStaticZ() { return unsafe.getBoolean(base, offset); }

        void setStaticZ(boolean x) { unsafe.putBoolean(base, offset, x); }

        byte getStaticB() { return unsafe.getByte(base, offset); }

        void setStaticB(byte x) { unsafe.putByte(base, offset, x); }

        short getStaticS() { return unsafe.getShort(base, offset); }

        void setStaticS(short x) { unsafe.putShort(base, offset, x); }

        char getStaticC() { return unsafe.getChar(base, offset); }

        void setStaticC(char x) { unsafe.putChar(base, offset, x); }

        Object /*V*/ getStaticL() { return unsafe.getObject(base, offset); }

        void setStaticL(Object /*V*/ x) { unsafe.putObject(base, offset, x); }

        static String fname(Class<?> vclass, boolean isSetter, boolean isStatic) {

            String stem;

            if (!isStatic)

                stem = (!isSetter ? "getField" : "setField");

            else

                stem = (!isSetter ? "getStatic" : "setStatic");

            return stem + Wrapper.basicTypeChar(vclass);

        }

        static MethodType ftype(Class<?> cclass, Class<?> vclass, boolean isSetter, boolean isStatic) {

            MethodType type;

            if (!isStatic) {

                if (!isSetter)

                    return MethodType.methodType(vclass, cclass);

                else

                    return MethodType.methodType(void.class, cclass, vclass);

            } else {

                if (!isSetter)

                    return MethodType.methodType(vclass);

                else

                    return MethodType.methodType(void.class, vclass);

            }

        }

        static MethodHandle fhandle(Class<?> cclass, Class<?> vclass, boolean isSetter, boolean isStatic) {

            String name = FieldAccessor.fname(vclass, isSetter, isStatic);

            if (cclass.isPrimitive())  throw newIllegalArgumentException("primitive "+cclass);

            Class<?> ecclass = Object.class;  //erase this type

            Class<?> evclass = vclass;

            if (!evclass.isPrimitive())  evclass = Object.class;

            MethodType type = FieldAccessor.ftype(ecclass, evclass, isSetter, isStatic);

            MethodHandle mh;

            try {

                mh = IMPL_LOOKUP.findVirtual(FieldAccessor.class, name, type);

            } catch (ReflectiveOperationException ex) {

                throw uncaughtException(ex);

            }

            if (evclass != vclass || (!isStatic && ecclass != cclass)) {

                MethodType strongType = FieldAccessor.ftype(cclass, vclass, isSetter, isStatic);

                strongType = strongType.insertParameterTypes(0, FieldAccessor.class);

                mh = convertArguments(mh, strongType, 0);

            }

            return mh;

        }

        /// Support for array element access

        static final HashMap<Class<?>, MethodHandle[]> ARRAY_CACHE =

                new HashMap<Class<?>, MethodHandle[]>();

        // FIXME: Cache on the classes themselves, not here.

        static boolean doCache(Class<?> elemClass) {

            if (elemClass.isPrimitive())  return true;

            ClassLoader cl = elemClass.getClassLoader();

            return cl == null || cl == ClassLoader.getSystemClassLoader();

        }

        static int getElementI(int[] a, int i) { return a[i]; }

        static void setElementI(int[] a, int i, int x) { a[i] = x; }

        static long getElementJ(long[] a, int i) { return a[i]; }

        static void setElementJ(long[] a, int i, long x) { a[i] = x; }

        static float getElementF(float[] a, int i) { return a[i]; }

        static void setElementF(float[] a, int i, float x) { a[i] = x; }

        static double getElementD(double[] a, int i) { return a[i]; }

        static void setElementD(double[] a, int i, double x) { a[i] = x; }

        static boolean getElementZ(boolean[] a, int i) { return a[i]; }

        static void setElementZ(boolean[] a, int i, boolean x) { a[i] = x; }

        static byte getElementB(byte[] a, int i) { return a[i]; }

        static void setElementB(byte[] a, int i, byte x) { a[i] = x; }

        static short getElementS(short[] a, int i) { return a[i]; }

        static void setElementS(short[] a, int i, short x) { a[i] = x; }

        static char getElementC(char[] a, int i) { return a[i]; }

        static void setElementC(char[] a, int i, char x) { a[i] = x; }

        static Object getElementL(Object[] a, int i) { return a[i]; }

        static void setElementL(Object[] a, int i, Object x) { a[i] = x; }

        static <V> V getElementL(Class<V[]> aclass, V[] a, int i) { return aclass.cast(a)[i]; }

        static <V> void setElementL(Class<V[]> aclass, V[] a, int i, V x) { aclass.cast(a)[i] = x; }

        static String aname(Class<?> aclass, boolean isSetter) {

            Class<?> vclass = aclass.getComponentType();

            if (vclass == null)  throw new IllegalArgumentException();

            return (!isSetter ? "getElement" : "setElement") + Wrapper.basicTypeChar(vclass);

        }

        static MethodType atype(Class<?> aclass, boolean isSetter) {

            Class<?> vclass = aclass.getComponentType();

            if (!isSetter)

                return MethodType.methodType(vclass, aclass, int.class);

            else

                return MethodType.methodType(void.class, aclass, int.class, vclass);

        }

        static MethodHandle ahandle(Class<?> aclass, boolean isSetter) {

            Class<?> vclass = aclass.getComponentType();

            String name = FieldAccessor.aname(aclass, isSetter);

            Class<?> caclass = null;

            if (!vclass.isPrimitive() && vclass != Object.class) {

                caclass = aclass;

                aclass = Object[].class;

                vclass = Object.class;

            }

            MethodType type = FieldAccessor.atype(aclass, isSetter);

            if (caclass != null)

                type = type.insertParameterTypes(0, Class.class);

            MethodHandle mh;

            try {

                mh = IMPL_LOOKUP.findStatic(FieldAccessor.class, name, type);

            } catch (ReflectiveOperationException ex) {

                throw uncaughtException(ex);

            }

            if (caclass != null) {

                MethodType strongType = FieldAccessor.atype(caclass, isSetter);

                mh = mh.bindTo(caclass);

                mh = convertArguments(mh, strongType, 0);

            }

            return mh;

        }

    }

    /** Bind a predetermined first argument to the given direct method handle.

     * Callable only from MethodHandles.

     * @param token Proof that the caller has access to this package.

     * @param target Any direct method handle.

     * @param receiver Receiver (or first static method argument) to pre-bind.

     * @return a BoundMethodHandle for the given DirectMethodHandle, or null if it does not exist

     */

    static

    MethodHandle bindReceiver(MethodHandle target, Object receiver) {

        if (receiver == null)  return null;

        if (target instanceof AdapterMethodHandle &&

            ((AdapterMethodHandle)target).conversionOp() == MethodHandleNatives.Constants.OP_RETYPE_ONLY

            ) {

            Object info = MethodHandleNatives.getTargetInfo(target);

            if (info instanceof DirectMethodHandle) {

                DirectMethodHandle dmh = (DirectMethodHandle) info;

                if (dmh.type().parameterType(0).isAssignableFrom(receiver.getClass())) {

                    MethodHandle bmh = new BoundMethodHandle(dmh, receiver, 0);

                    MethodType newType = target.type().dropParameterTypes(0, 1);

                    return convertArguments(bmh, newType, bmh.type(), 0);

                }

            }

        }

        if (target instanceof DirectMethodHandle)

            return new BoundMethodHandle((DirectMethodHandle)target, receiver, 0);

        return null;   // let caller try something else

    }

    /** Bind a predetermined argument to the given arbitrary method handle.

     * Callable only from MethodHandles.

     * @param token Proof that the caller has access to this package.

     * @param target Any method handle.

     * @param receiver Argument (which can be a boxed primitive) to pre-bind.

     * @return a suitable BoundMethodHandle

     */

    static

    MethodHandle bindArgument(MethodHandle target, int argnum, Object receiver) {

        return new BoundMethodHandle(target, receiver, argnum);

    }

    static MethodHandle permuteArguments(MethodHandle target,

                                                MethodType newType,

                                                MethodType oldType,

                                                int[] permutationOrNull) {

        assert(oldType.parameterCount() == target.type().parameterCount());

        int outargs = oldType.parameterCount(), inargs = newType.parameterCount();

        if (permutationOrNull.length != outargs)

            throw newIllegalArgumentException("wrong number of arguments in permutation");

        // Make the individual outgoing argument types match up first.

        Class<?>[] callTypeArgs = new Class<?>[outargs];

        for (int i = 0; i < outargs; i++)

            callTypeArgs[i] = newType.parameterType(permutationOrNull[i]);

        MethodType callType = MethodType.methodType(oldType.returnType(), callTypeArgs);

        target = convertArguments(target, callType, oldType, 0);

        assert(target != null);

        oldType = target.type();

        List<Integer> goal = new ArrayList<Integer>();  // i*TOKEN

        List<Integer> state = new ArrayList<Integer>(); // i*TOKEN

        List<Integer> drops = new ArrayList<Integer>(); // not tokens

        List<Integer> dups = new ArrayList<Integer>();  // not tokens

        final int TOKEN = 10; // to mark items which are symbolic only

        // state represents the argument values coming into target

        for (int i = 0; i < outargs; i++) {

            state.add(permutationOrNull[i] * TOKEN);

        }

        // goal represents the desired state

        for (int i = 0; i < inargs; i++) {

            if (state.contains(i * TOKEN)) {

                goal.add(i * TOKEN);

            } else {

                // adapter must initially drop all unused arguments

                drops.add(i);

            }

        }

        // detect duplications

        while (state.size() > goal.size()) {

            for (int i2 = 0; i2 < state.size(); i2++) {

                int arg1 = state.get(i2);

                int i1 = state.indexOf(arg1);

                if (i1 != i2) {

                    // found duplicate occurrence at i2

                    int arg2 = (inargs++) * TOKEN;

                    state.set(i2, arg2);

                    dups.add(goal.indexOf(arg1));

                    goal.add(arg2);

                }

            }

        }

        assert(state.size() == goal.size());

        int size = goal.size();

        while (!state.equals(goal)) {

            // Look for a maximal sequence of adjacent misplaced arguments,

            // and try to rotate them into place.

            int bestRotArg = -10 * TOKEN, bestRotLen = 0;

            int thisRotArg = -10 * TOKEN, thisRotLen = 0;

            for (int i = 0; i < size; i++) {

                int arg = state.get(i);

                // Does this argument match the current run?

                if (arg == thisRotArg + TOKEN) {

                    thisRotArg = arg;

                    thisRotLen += 1;

                    if (bestRotLen < thisRotLen) {

                        bestRotLen = thisRotLen;

                        bestRotArg = thisRotArg;

                    }

                } else {

                    // The old sequence (if any) stops here.

                    thisRotLen = 0;

                    thisRotArg = -10 * TOKEN;

                    // But maybe a new one starts here also.

                    int wantArg = goal.get(i);

                    final int MAX_ARG_ROTATION = AdapterMethodHandle.MAX_ARG_ROTATION;

                    if (arg != wantArg &&

                        arg >= wantArg - TOKEN * MAX_ARG_ROTATION &&

                        arg <= wantArg + TOKEN * MAX_ARG_ROTATION) {

                        thisRotArg = arg;

                        thisRotLen = 1;

                    }

                }

            }

            if (bestRotLen >= 2) {

                // Do a rotation if it can improve argument positioning

                // by at least 2 arguments.  This is not always optimal,

                // but it seems to catch common cases.

                int dstEnd = state.indexOf(bestRotArg);

                int srcEnd = goal.indexOf(bestRotArg);

                int rotBy = dstEnd - srcEnd;

                int dstBeg = dstEnd - (bestRotLen - 1);

                int srcBeg = srcEnd - (bestRotLen - 1);

                assert((dstEnd | dstBeg | srcEnd | srcBeg) >= 0); // no negs