/*

 * 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

 * 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.InvocationTargetException;

import sun.invoke.util.ValueConversions;

import sun.invoke.util.Wrapper;

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

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

/**

 * Adapters which mediate between incoming calls which are not generic

 * and outgoing calls which are.  Any call can be represented generically

 * boxing up its arguments, and (on return) unboxing the return value.

 * <p>

 * A call is "generic" (in MethodHandle terms) if its MethodType features

 * only Object arguments.  A non-generic call therefore features

 * primitives and/or reference types other than Object.

 * An adapter has types for its incoming and outgoing calls.

 * The incoming call type is simply determined by the adapter's type

 * (the MethodType it presents to callers).  The outgoing call type

 * is determined by the adapter's target (a MethodHandle that the adapter

 * either binds internally or else takes as a leading argument).

 * (To stretch the term, adapter-like method handles may have multiple

 * targets or be polymorphic across multiple call types.)

 * @author jrose

 */

class ToGeneric {

    // type for the incoming call (may be erased)

    private final MethodType entryType;

    // incoming type with primitives moved to the end and turned to int/long

    private final MethodType rawEntryType;

    // adapter for the erased type

    private final Adapter adapter;

    // entry point for adapter (Adapter mh, a...) => ...

    private final MethodHandle entryPoint;

    // permutation of arguments for primsAtEndType

    private final int[] primsAtEndOrder;

    // optional final argument list conversions (at least, invokes the target)

    private final MethodHandle invoker;

    // conversion which unboxes a primitive return value

    private final MethodHandle returnConversion;

    /** Compute and cache information common to all generifying (boxing) adapters

     *  that implement members of the erasure-family of the given erased type.

     */

    private ToGeneric(MethodType entryType) {

        assert(entryType.erase() == entryType); // for now

        // incoming call will first "forget" all reference types except Object

        this.entryType = entryType;

        MethodHandle invoker0 = entryType.generic().invokers().exactInvoker();

        MethodType rawEntryTypeInit;

        Adapter ad = findAdapter(rawEntryTypeInit = entryType);

        if (ad != null) {

            // Immediate hit to exactly the adapter we want,

            // with no monkeying around with primitive types.

            this.returnConversion = computeReturnConversion(entryType, rawEntryTypeInit, false);

            this.rawEntryType = rawEntryTypeInit;

            this.adapter = ad;

            this.entryPoint = ad.prototypeEntryPoint();

            this.primsAtEndOrder = null;

            this.invoker = invoker0;

            return;

        }

        // next, it will reorder primitives after references

        MethodType primsAtEnd = entryType.form().primsAtEnd();

        // at the same time, it will "forget" all primitive types except int/long

        this.primsAtEndOrder = MethodTypeForm.primsAtEndOrder(entryType);

        if (primsAtEndOrder != null) {

            // reordering is required; build on top of a simpler ToGeneric

            ToGeneric va2 = ToGeneric.of(primsAtEnd);

            this.adapter = va2.adapter;

            if (true) throw new UnsupportedOperationException("NYI: primitive parameters must follow references; entryType = "+entryType);

            this.entryPoint = MethodHandleImpl.permuteArguments(

                    va2.entryPoint, primsAtEnd, entryType, primsAtEndOrder);

            // example: for entryType of (int,Object,Object), the reordered

            // type is (Object,Object,int) and the order is {1,2,0},

            // and putPAE is (mh,int0,obj1,obj2) => mh.invokeExact(obj1,obj2,int0)

            return;

        }

        // after any needed argument reordering, it will reinterpret

        // primitive arguments according to their "raw" types int/long

        MethodType intsAtEnd = primsAtEnd.form().primsAsInts();

        ad = findAdapter(rawEntryTypeInit = intsAtEnd);

        MethodHandle rawEntryPoint;

        if (ad != null) {

            rawEntryPoint = ad.prototypeEntryPoint();

        } else {

            // Perhaps the adapter is available only for longs.

            // If so, we can use it, but there will have to be a little

            // more stack motion on each call.

            MethodType longsAtEnd = primsAtEnd.form().primsAsLongs();

            ad = findAdapter(rawEntryTypeInit = longsAtEnd);

            if (ad != null) {

                MethodType eptWithLongs = longsAtEnd.insertParameterTypes(0, ad.getClass());

                MethodType eptWithInts  =  intsAtEnd.insertParameterTypes(0, ad.getClass());

                rawEntryPoint = ad.prototypeEntryPoint();

                MethodType midType = eptWithLongs;  // will change longs to ints

                for (int i = 0, nargs = midType.parameterCount(); i < nargs; i++) {

                    if (midType.parameterType(i) != eptWithInts.parameterType(i)) {

                        assert(midType.parameterType(i) == long.class);

                        assert(eptWithInts.parameterType(i) == int.class);

                        MethodType nextType = midType.changeParameterType(i, int.class);

                        rawEntryPoint = MethodHandleImpl.convertArguments(

                                rawEntryPoint, nextType, midType, 0);

                        midType = nextType;

                    }

                }

                assert(midType == eptWithInts);

            } else {

                // If there is no statically compiled adapter,

                // build one by means of dynamic bytecode generation.

                ad = buildAdapterFromBytecodes(rawEntryTypeInit = intsAtEnd);

                rawEntryPoint = ad.prototypeEntryPoint();

            }

        }

        MethodType tepType = entryType.insertParameterTypes(0, ad.getClass());

        this.entryPoint =

            AdapterMethodHandle.makeRetypeRaw(tepType, rawEntryPoint);

        if (this.entryPoint == null)

            throw new UnsupportedOperationException("cannot retype to "+entryType

                    +" from "+rawEntryPoint.type().dropParameterTypes(0, 1));

        this.returnConversion = computeReturnConversion(entryType, rawEntryTypeInit, false);

        this.rawEntryType = rawEntryTypeInit;

        this.adapter = ad;

        this.invoker = makeRawArgumentFilter(invoker0, rawEntryTypeInit, entryType);

    }

    static {

        assert(MethodHandleNatives.workaroundWithoutRicochetFrames());  // this class is deprecated

    }

    /** A generic argument list will be created by a call of type 'raw'.

     *  The values need to be reboxed for to match 'cooked'.

     *  Do this on the fly.

     */

    // TO DO: Use a generic argument converter in a different file

    static MethodHandle makeRawArgumentFilter(MethodHandle invoker,

            MethodType raw, MethodType cooked) {

        MethodHandle filteredInvoker = null;

        for (int i = 0, nargs = raw.parameterCount(); i < nargs; i++) {

            Class<?> src = raw.parameterType(i);

            Class<?> dst = cooked.parameterType(i);

            if (src == dst)  continue;

            assert(src.isPrimitive() && dst.isPrimitive());

            if (filteredInvoker == null) {

                filteredInvoker =

                        AdapterMethodHandle.makeCheckCast(

                            invoker.type().generic(), invoker, 0, MethodHandle.class);

                if (filteredInvoker == null)  throw new UnsupportedOperationException("NYI");

            }

            MethodHandle reboxer = ValueConversions.rebox(dst);

            filteredInvoker = FilterGeneric.makeArgumentFilter(1+i, reboxer, filteredInvoker);

            if (filteredInvoker == null)  throw new InternalError();

        }

        if (filteredInvoker == null)  return invoker;

        return AdapterMethodHandle.makeRetypeOnly(invoker.type(), filteredInvoker);

    }

    /**

     * Caller will be expecting a result from a call to {@code type},

     * while the internal adapter entry point is rawEntryType.

     * Also, the internal target method will be returning a boxed value,

     * as an untyped object.

     * <p>

     * Produce a value converter which will be typed to convert from

     * {@code Object} to the return value of {@code rawEntryType}, and will

     * in fact ensure that the value is compatible with the return type of

     * {@code type}.

     */

    private static MethodHandle computeReturnConversion(

            MethodType type, MethodType rawEntryType, boolean mustCast) {

        Class<?> tret = type.returnType();

        Class<?> rret = rawEntryType.returnType();

        if (mustCast || !tret.isPrimitive()) {

            assert(!tret.isPrimitive());

            assert(!rret.isPrimitive());

            if (rret == Object.class && !mustCast)

                return null;

            return ValueConversions.cast(tret);

        } else if (tret == rret) {

            return ValueConversions.unbox(tret);

        } else {

            assert(rret.isPrimitive());

            assert(tret == double.class ? rret == long.class : rret == int.class);

            return ValueConversions.unboxRaw(tret);

        }

    }

    Adapter makeInstance(MethodType type, MethodHandle genericTarget) {

        genericTarget.getClass();  // check for NPE

        MethodHandle convert = returnConversion;

        if (primsAtEndOrder != null)

            // reorder arguments passed to genericTarget, if primsAtEndOrder

            throw new UnsupportedOperationException("NYI");

        if (type == entryType) {

            if (convert == null)  convert = ValueConversions.identity();

            return adapter.makeInstance(entryPoint, invoker, convert, genericTarget);

        }

        // my erased-type is not exactly the same as the desired type

        assert(type.erase() == entryType);  // else we are busted

        if (convert == null)

            convert = computeReturnConversion(type, rawEntryType, true);

        // retype erased reference arguments (the cast makes it safe to do this)

        MethodType tepType = type.insertParameterTypes(0, adapter.getClass());

        MethodHandle typedEntryPoint =

            AdapterMethodHandle.makeRetypeRaw(tepType, entryPoint);

        return adapter.makeInstance(typedEntryPoint, invoker, convert, genericTarget);

    }

    /** Build an adapter of the given type, which invokes genericTarget

     *  on the incoming arguments, after boxing as necessary.

     *  The return value is unboxed if necessary.

     * @param type  the required type of the

     * @param genericTarget the target, which must accept and return only Object values

     * @return an adapter method handle

     */

    public static MethodHandle make(MethodType type, MethodHandle genericTarget) {

        MethodType gtype = genericTarget.type();

        if (type.generic() != gtype)

            throw newIllegalArgumentException("type must be generic");

        if (type == gtype)  return genericTarget;

        return ToGeneric.of(type).makeInstance(type, genericTarget);

    }

    /** Return the adapter information for this type's erasure. */

    static ToGeneric of(MethodType type) {

        MethodTypeForm form = type.form();

        ToGeneric toGen = form.toGeneric;

        if (toGen == null)

            form.toGeneric = toGen = new ToGeneric(form.erasedType());

        return toGen;

    }

    public String toString() {

        return "ToGeneric"+entryType

                +(primsAtEndOrder!=null?"[reorder]":"");

    }

    /* Create an adapter for the given incoming call type. */

    static Adapter findAdapter(MethodType entryPointType) {

        MethodTypeForm form = entryPointType.form();

        Class<?> rtype = entryPointType.returnType();

        int argc = form.parameterCount();

        int lac = form.longPrimitiveParameterCount();

        int iac = form.primitiveParameterCount() - lac;

        String intsAndLongs = (iac > 0 ? "I"+iac : "")+(lac > 0 ? "J"+lac : "");

        String rawReturn = String.valueOf(Wrapper.forPrimitiveType(rtype).basicTypeChar());

        String iname0 = "invoke_"+rawReturn;

        String iname1 = "invoke";

        String[] inames = { iname0, iname1 };

        String cname0 = rawReturn + argc;

        String cname1 = "A"       + argc;

        String[] cnames = { cname1, cname1+intsAndLongs, cname0, cname0+intsAndLongs };

        // e.g., D5I2, D5, L5I2, L5

        for (String cname : cnames) {

            Class<? extends Adapter> acls = Adapter.findSubClass(cname);

            if (acls == null)  continue;

            // see if it has the required invoke method

            for (String iname : inames) {

                MethodHandle entryPoint = null;

                try {

                    entryPoint = IMPL_LOOKUP.

                                    findSpecial(acls, iname, entryPointType, acls);

                } catch (ReflectiveOperationException ex) {

                }

                if (entryPoint == null)  continue;

                Constructor<? extends Adapter> ctor = null;

                try {

                    // Prototype builder:

                    ctor = acls.getDeclaredConstructor(MethodHandle.class);

                } catch (NoSuchMethodException ex) {

                } catch (SecurityException ex) {

                }

                if (ctor == null)  continue;

                try {

                    return ctor.newInstance(entryPoint);

                } catch (IllegalArgumentException ex) {

                } catch (InvocationTargetException wex) {

                    Throwable ex = wex.getTargetException();

                    if (ex instanceof Error)  throw (Error)ex;

                    if (ex instanceof RuntimeException)  throw (RuntimeException)ex;

                } catch (InstantiationException ex) {

                } catch (IllegalAccessException ex) {

                }

            }

        }

        return null;

    }

    static Adapter buildAdapterFromBytecodes(MethodType entryPointType) {

        throw new UnsupportedOperationException("NYI: "+entryPointType);

    }

    /**

     * The invoke method takes some particular but unconstrained spread

     * of raw argument types, and returns a raw return type (in L/I/J/F/D).

     * Internally, it converts the incoming arguments uniformly into objects.

     * This series of objects is then passed to the {@code target} method,

     * which returns a result object.  This result is finally converted,

     * via another method handle {@code convert}, which is responsible for

     * converting the object result into the raw return value.

     */

    static abstract class Adapter extends BoundMethodHandle {

        /*

         * class X<<R,A...>> extends Adapter {

         *   Object...=>Object target;

         *   Object=>R convert;

         *   R invoke(A... a...) = convert(invoker(target, a...)))

         * }

         */

        protected final MethodHandle invoker;  // (MH, Object...) -> Object

        protected final MethodHandle target;   // Object... -> Object

        protected final MethodHandle convert;  // Object -> R

        @Override

        public String toString() {

            return target == null ? "prototype:"+convert : addTypeString(target, this);

        }

        protected boolean isPrototype() { return target == null; }

        /* Prototype constructor. */

        protected Adapter(MethodHandle entryPoint) {

            super(entryPoint);

            this.invoker = null;

            this.convert = entryPoint;

            this.target = null;

            assert(isPrototype());

        }

        protected MethodHandle prototypeEntryPoint() {

            if (!isPrototype())  throw new InternalError();

            return convert;

        }

        protected Adapter(MethodHandle entryPoint, MethodHandle invoker, MethodHandle convert, MethodHandle target) {

            super(entryPoint);

            this.invoker = invoker;

            this.convert = convert;

            this.target = target;

        }

        /** Make a copy of self, with new fields. */

        protected abstract Adapter makeInstance(MethodHandle entryPoint,

                MethodHandle invoker, MethodHandle convert, MethodHandle target);

        // { return new ThisType(entryPoint, convert, target); }

        // Code to run when the arguments (<= 4) have all been boxed.

        protected Object target()               throws Throwable { return invoker.invokeExact(target); }

        protected Object target(Object a0)      throws Throwable { return invoker.invokeExact(target, a0); }

        protected Object target(Object a0, Object a1)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1); }

        protected Object target(Object a0, Object a1, Object a2)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1, a2); }

        protected Object target(Object a0, Object a1, Object a2, Object a3)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1, a2, a3); }

        /*

        protected Object target_0(Object... av) throws Throwable { return invoker.invokeExact(target, av); }

        protected Object target_1(Object a0, Object... av)

                                                throws Throwable { return invoker.invokeExact(target, a0, (Object)av); }

        protected Object target_2(Object a0, Object a1, Object... av)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1, (Object)av); }

        protected Object target_3(Object a0, Object a1, Object a2, Object... av)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1, a2, (Object)av); }

        protected Object target_4(Object a0, Object a1, Object a2, Object a3, Object... av)

                                                throws Throwable { return invoker.invokeExact(target, a0, a1, a2, a3, (Object)av); }

        // */

        // (For more than 4 arguments, generate the code in the adapter itself.)

        // Code to run when the generic target has finished and produced a value.

        protected Object return_L(Object res) throws Throwable { return (Object)convert.invokeExact(res); }

        protected int    return_I(Object res) throws Throwable { return (int)   convert.invokeExact(res); }

        protected long   return_J(Object res) throws Throwable { return (long)  convert.invokeExact(res); }

        protected float  return_F(Object res) throws Throwable { return (float) convert.invokeExact(res); }

        protected double return_D(Object res) throws Throwable { return (double)convert.invokeExact(res); }

        static private final String CLASS_PREFIX; // "java.lang.invoke.ToGeneric$"

        static {

            String aname = Adapter.class.getName();

            String sname = Adapter.class.getSimpleName();

            if (!aname.endsWith(sname))  throw new InternalError();

            CLASS_PREFIX = aname.substring(0, aname.length() - sname.length());

        }

        /** Find a sibing class of Adapter. */

        static Class<? extends Adapter> findSubClass(String name) {

            String cname = Adapter.CLASS_PREFIX + name;

            try {

                return Class.forName(cname).asSubclass(Adapter.class);

            } catch (ClassNotFoundException ex) {

                return null;

            } catch (ClassCastException ex) {

                return null;

            }

        }

    }

    /* generated classes follow this pattern:

    static class A1 extends Adapter {

        protected A1(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype

        protected A1(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t) { super(e, i, c, t); }

        protected A1 makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t) { return new A1(e, i, c, t); }

        protected Object target(Object a0)   throws Throwable { return invoker.invokeExact(target, a0); }

        protected Object targetA1(Object a0) throws Throwable { return target(a0); }

        protected Object targetA1(int    a0) throws Throwable { return target(a0); }

        protected Object targetA1(long   a0) throws Throwable { return target(a0); }

        protected Object invoke_L(Object a0) throws Throwable { return return_L(targetA1(a0)); }

        protected int    invoke_I(Object a0) throws Throwable { return return_I(targetA1(a0)); }

        protected long   invoke_J(Object a0) throws Throwable { return return_J(targetA1(a0)); }

        protected float  invoke_F(Object a0) throws Throwable { return return_F(targetA1(a0)); }

        protected double invoke_D(Object a0) throws Throwable { return return_D(targetA1(a0)); }

        protected Object invoke_L(int    a0) throws Throwable { return return_L(targetA1(a0)); }

        protected int    invoke_I(int    a0) throws Throwable { return return_I(targetA1(a0)); }

        protected long   invoke_J(int    a0) throws Throwable { return return_J(targetA1(a0)); }

        protected float  invoke_F(int    a0) throws Throwable { return return_F(targetA1(a0)); }

        protected double invoke_D(int    a0) throws Throwable { return return_D(targetA1(a0)); }

        protected Object invoke_L(long   a0) throws Throwable { return return_L(targetA1(a0)); }

        protected int    invoke_I(long   a0) throws Throwable { return return_I(targetA1(a0)); }

        protected long   invoke_J(long   a0) throws Throwable { return return_J(targetA1(a0)); }

        protected float  invoke_F(long   a0) throws Throwable { return return_F(targetA1(a0)); }

        protected double invoke_D(long   a0) throws Throwable { return return_D(targetA1(a0)); }

    }

    // */

/*

: SHELL; n=ToGeneric; cp -p $n.java $n.java-; sed < $n.java- > $n.java+ -e '/{{*{{/,/}}*}}/w /tmp/genclasses.java' -e '/}}*}}/q'; (cd /tmp; javac -d . genclasses.java; java -cp . genclasses) >> $n.java+; echo '}' >> $n.java+; mv $n.java+ $n.java; mv $n.java- $n.java~

//{{{

import java.util.*;

class genclasses {

    static String[] TYPES = { "Object", "int   ", "long  ", "float ", "double" };

    static String[] TCHARS = { "L",     "I",      "J",      "F",      "D",     "A" };

    static String[][] TEMPLATES = { {

        "@for@ arity=0..3   rcat<=4 nrefs<=99 nints<=99 nlongs<=99",

        "@for@ arity=4..4   rcat<=4 nrefs<=99 nints<=99 nlongs<=99",

        "@for@ arity=5..5   rcat<=2 nrefs<=99 nints<=99 nlongs<=99",

        "@for@ arity=6..10  rcat<=2 nrefs<=99 nints=0   nlongs<=99",

        "    //@each-cat@",

        "    static class @cat@ extends Adapter {",

        "        protected @cat@(MethodHandle entryPoint) { super(entryPoint); }  // to build prototype",

        "        protected @cat@(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t) { super(e, i, c, t); }",

        "        protected @cat@ makeInstance(MethodHandle e, MethodHandle i, MethodHandle c, MethodHandle t) { return new @cat@(e, i, c, t); }",

        "        protected Object target(@Ovav@)   throws Throwable { return invoker.invokeExact(target@comma@@av@); }",

        "        //@each-Tv@",

        "        protected Object target@cat@(@Tvav@) throws Throwable { return target(@av@); }",

        "        //@end-Tv@",

        "        //@each-Tv@",

        "        //@each-R@",

        "        protected @R@ invoke_@Rc@(@Tvav@) throws Throwable { return return_@Rc@(target@cat@(@av@)); }",

        "        //@end-R@",

        "        //@end-Tv@",

        "    }",

    } };

    enum VAR {

        cat, R, Rc, Tv, av, comma, Tvav, Ovav;

        public final String pattern = "@"+toString().replace('_','.')+"@";

        public String binding;

        static void makeBindings(boolean topLevel, int rcat, int nrefs, int nints, int nlongs) {

            int nargs = nrefs + nints + nlongs;

            if (topLevel)

                VAR.cat.binding = catstr(ALL_RETURN_TYPES ? TYPES.length : rcat, nrefs, nints, nlongs);

            VAR.R.binding = TYPES[rcat];

            VAR.Rc.binding = TCHARS[rcat];

            String[] Tv = new String[nargs];

            String[] av = new String[nargs];

            String[] Tvav = new String[nargs];

            String[] Ovav = new String[nargs];

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

                int tcat = (i < nrefs) ? 0 : (i < nrefs + nints) ? 1 : 2;

                Tv[i] = TYPES[tcat];

                av[i] = arg(i);

                Tvav[i] = param(Tv[i], av[i]);

                Ovav[i] = param("Object", av[i]);

            }

            VAR.Tv.binding = comma(Tv);

            VAR.av.binding = comma(av);

            VAR.comma.binding = (av.length == 0 ? "" : ", ");

            VAR.Tvav.binding = comma(Tvav);

            VAR.Ovav.binding = comma(Ovav);

        }

        static String arg(int i) { return "a"+i; }

        static String param(String t, String a) { return t+" "+a; }

        static String comma(String[] v) { return comma("", v); }

        static String comma(String sep, String[] v) {

            if (v.length == 0)  return "";

            String res = sep+v[0];

            for (int i = 1; i < v.length; i++)  res += ", "+v[i];

            return res;

        }