/*

 * 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 sun.invoke.util;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodHandles.Lookup;

import java.lang.invoke.MethodType;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.EnumMap;

import java.util.List;

public class ValueConversions {

    private static final Class<?> THIS_CLASS = ValueConversions.class;

    // Do not adjust this except for special platforms:

    private static final int MAX_ARITY;

    static {

        final Object[] values = { 255 };

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

                public Void run() {

                    values[0] = Integer.getInteger(THIS_CLASS.getName()+".MAX_ARITY", 255);

                    return null;

                }

            });

        MAX_ARITY = (Integer) values[0];

    }

    private static final Lookup IMPL_LOOKUP = MethodHandles.lookup();

    private static EnumMap<Wrapper, MethodHandle>[] newWrapperCaches(int n) {

        @SuppressWarnings("unchecked")

        EnumMap<Wrapper, MethodHandle>[] caches

                = (EnumMap<Wrapper, MethodHandle>[]) new EnumMap[n];  // unchecked warning expected here

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

            caches[i] = new EnumMap<>(Wrapper.class);

        return caches;

    }

    /// Converting references to values.

    // There are several levels of this unboxing conversions:

    //   no conversions:  exactly Integer.valueOf, etc.

    //   implicit conversions sanctioned by JLS 5.1.2, etc.

    //   explicit conversions as allowed by explicitCastArguments

    static int unboxInteger(Object x, boolean cast) {

        if (x instanceof Integer)

            return ((Integer) x).intValue();

        return primitiveConversion(Wrapper.INT, x, cast).intValue();

    }

    static byte unboxByte(Object x, boolean cast) {

        if (x instanceof Byte)

            return ((Byte) x).byteValue();

        return primitiveConversion(Wrapper.BYTE, x, cast).byteValue();

    }

    static short unboxShort(Object x, boolean cast) {

        if (x instanceof Short)

            return ((Short) x).shortValue();

        return primitiveConversion(Wrapper.SHORT, x, cast).shortValue();

    }

    static boolean unboxBoolean(Object x, boolean cast) {

        if (x instanceof Boolean)

            return ((Boolean) x).booleanValue();

        return (primitiveConversion(Wrapper.BOOLEAN, x, cast).intValue() & 1) != 0;

    }

    static char unboxCharacter(Object x, boolean cast) {

        if (x instanceof Character)

            return ((Character) x).charValue();

        return (char) primitiveConversion(Wrapper.CHAR, x, cast).intValue();

    }

    static long unboxLong(Object x, boolean cast) {

        if (x instanceof Long)

            return ((Long) x).longValue();

        return primitiveConversion(Wrapper.LONG, x, cast).longValue();

    }

    static float unboxFloat(Object x, boolean cast) {

        if (x instanceof Float)

            return ((Float) x).floatValue();

        return primitiveConversion(Wrapper.FLOAT, x, cast).floatValue();

    }

    static double unboxDouble(Object x, boolean cast) {

        if (x instanceof Double)

            return ((Double) x).doubleValue();

        return primitiveConversion(Wrapper.DOUBLE, x, cast).doubleValue();

    }

    /// Converting references to "raw" values.

    /// A raw primitive value is always an int or long.

    static int unboxByteRaw(Object x, boolean cast) {

        return unboxByte(x, cast);

    }

    static int unboxShortRaw(Object x, boolean cast) {

        return unboxShort(x, cast);

    }

    static int unboxBooleanRaw(Object x, boolean cast) {

        return unboxBoolean(x, cast) ? 1 : 0;

    }

    static int unboxCharacterRaw(Object x, boolean cast) {

        return unboxCharacter(x, cast);

    }

    static int unboxFloatRaw(Object x, boolean cast) {

        return Float.floatToIntBits(unboxFloat(x, cast));

    }

    static long unboxDoubleRaw(Object x, boolean cast) {

        return Double.doubleToRawLongBits(unboxDouble(x, cast));

    }

    private static MethodType unboxType(Wrapper wrap, boolean raw) {

        return MethodType.methodType(rawWrapper(wrap, raw).primitiveType(), Object.class, boolean.class);

    }

    private static final EnumMap<Wrapper, MethodHandle>[]

            UNBOX_CONVERSIONS = newWrapperCaches(4);

    private static MethodHandle unbox(Wrapper wrap, boolean raw, boolean cast) {

        EnumMap<Wrapper, MethodHandle> cache = UNBOX_CONVERSIONS[(cast?1:0)+(raw?2:0)];

        MethodHandle mh = cache.get(wrap);

        if (mh != null) {

            return mh;

        }

        // slow path

        switch (wrap) {

            case OBJECT:

                mh = IDENTITY; break;

            case VOID:

                mh = raw ? ALWAYS_ZERO : IGNORE; break;

            case INT: case LONG:

                // these guys don't need separate raw channels

                if (raw)  mh = unbox(wrap, false, cast);

                break;

        }

        if (mh != null) {

            cache.put(wrap, mh);

            return mh;

        }

        // look up the method

        String name = "unbox" + wrap.simpleName() + (raw ? "Raw" : "");

        MethodType type = unboxType(wrap, raw);

        try {

            mh = IMPL_LOOKUP.findStatic(THIS_CLASS, name, type);

        } catch (ReflectiveOperationException ex) {

            mh = null;

        }

        if (mh != null) {

            mh = MethodHandles.insertArguments(mh, 1, cast);

            cache.put(wrap, mh);

            return mh;

        }

        throw new IllegalArgumentException("cannot find unbox adapter for " + wrap

                + (cast ? " (cast)" : "") + (raw ? " (raw)" : ""));

    }

    public static MethodHandle unboxCast(Wrapper type) {

        return unbox(type, false, true);

    }

    public static MethodHandle unboxRaw(Wrapper type) {

        return unbox(type, true, false);

    }

    public static MethodHandle unbox(Class<?> type) {

        return unbox(Wrapper.forPrimitiveType(type), false, false);

    }

    public static MethodHandle unboxCast(Class<?> type) {

        return unbox(Wrapper.forPrimitiveType(type), false, true);

    }

    public static MethodHandle unboxRaw(Class<?> type) {

        return unbox(Wrapper.forPrimitiveType(type), true, false);

    }

    static private final Integer ZERO_INT = 0, ONE_INT = 1;

    /// Primitive conversions

    public static Number primitiveConversion(Wrapper wrap, Object x, boolean cast) {

        // Maybe merge this code with Wrapper.convert/cast.

        Number res = null;

        if (x == null) {

            if (!cast)  return null;

            return ZERO_INT;

        }

        if (x instanceof Number) {

            res = (Number) x;

        } else if (x instanceof Boolean) {

            res = ((boolean)x ? ONE_INT : ZERO_INT);

        } else if (x instanceof Character) {

            res = (int)(char)x;

        } else {

            // this will fail with the required ClassCastException:

            res = (Number) x;

        }

        Wrapper xwrap = Wrapper.findWrapperType(x.getClass());

        if (xwrap == null || !cast && !wrap.isConvertibleFrom(xwrap))

            // this will fail with the required ClassCastException:

            return (Number) wrap.wrapperType().cast(x);

        return res;

    }

    /// Converting primitives to references

    static Integer boxInteger(int x) {

        return x;

    }

    static Byte boxByte(byte x) {

        return x;

    }

    static Short boxShort(short x) {

        return x;

    }

    static Boolean boxBoolean(boolean x) {

        return x;

    }

    static Character boxCharacter(char x) {

        return x;

    }

    static Long boxLong(long x) {

        return x;

    }

    static Float boxFloat(float x) {

        return x;

    }

    static Double boxDouble(double x) {

        return x;

    }

    /// Converting raw primitives to references

    static Byte boxByteRaw(int x) {

        return boxByte((byte)x);

    }

    static Short boxShortRaw(int x) {

        return boxShort((short)x);

    }

    static Boolean boxBooleanRaw(int x) {

        return boxBoolean(x != 0);

    }

    static Character boxCharacterRaw(int x) {

        return boxCharacter((char)x);

    }

    static Float boxFloatRaw(int x) {

        return boxFloat(Float.intBitsToFloat(x));

    }

    static Double boxDoubleRaw(long x) {

        return boxDouble(Double.longBitsToDouble(x));

    }

    // a raw void value is (arbitrarily) a garbage int

    static Void boxVoidRaw(int x) {

        return null;

    }

    private static MethodType boxType(Wrapper wrap, boolean raw) {

        // be exact, since return casts are hard to compose

        Class<?> boxType = wrap.wrapperType();

        return MethodType.methodType(boxType, rawWrapper(wrap, raw).primitiveType());

    }

    private static Wrapper rawWrapper(Wrapper wrap, boolean raw) {

        if (raw)  return wrap.isDoubleWord() ? Wrapper.LONG : Wrapper.INT;

        return wrap;

    }

    private static final EnumMap<Wrapper, MethodHandle>[]

            BOX_CONVERSIONS = newWrapperCaches(4);

    private static MethodHandle box(Wrapper wrap, boolean exact, boolean raw) {

        EnumMap<Wrapper, MethodHandle> cache = BOX_CONVERSIONS[(exact?1:0)+(raw?2:0)];

        MethodHandle mh = cache.get(wrap);

        if (mh != null) {

            return mh;

        }

        // slow path

        switch (wrap) {

            case OBJECT:

                mh = IDENTITY; break;

            case VOID:

                if (!raw)  mh = ZERO_OBJECT;

                break;

            case INT: case LONG:

                // these guys don't need separate raw channels

                if (raw)  mh = box(wrap, exact, false);

                break;

        }

        if (mh != null) {

            cache.put(wrap, mh);

            return mh;

        }

        // look up the method

        String name = "box" + wrap.simpleName() + (raw ? "Raw" : "");

        MethodType type = boxType(wrap, raw);

        if (exact) {

            try {

                mh = IMPL_LOOKUP.findStatic(THIS_CLASS, name, type);

            } catch (ReflectiveOperationException ex) {

                mh = null;

            }

        } else {

            mh = box(wrap, !exact, raw).asType(type.erase());

        }

        if (mh != null) {

            cache.put(wrap, mh);

            return mh;

        }

        throw new IllegalArgumentException("cannot find box adapter for "

                + wrap + (exact ? " (exact)" : "") + (raw ? " (raw)" : ""));

    }

    public static MethodHandle box(Class<?> type) {

        boolean exact = false;

        // e.g., boxShort(short)Short if exact,

        // e.g., boxShort(short)Object if !exact

        return box(Wrapper.forPrimitiveType(type), exact, false);

    }

    public static MethodHandle boxRaw(Class<?> type) {

        boolean exact = false;

        // e.g., boxShortRaw(int)Short if exact

        // e.g., boxShortRaw(int)Object if !exact

        return box(Wrapper.forPrimitiveType(type), exact, true);

    }

    public static MethodHandle box(Wrapper type) {

        boolean exact = false;

        return box(type, exact, false);

    }

    public static MethodHandle boxRaw(Wrapper type) {

        boolean exact = false;

        return box(type, exact, true);

    }

    /// Kludges for when raw values get accidentally boxed.

    static int unboxRawInteger(Object x) {

        if (x instanceof Integer)

            return (int) x;

        else

            return (int) unboxLong(x, false);

    }

    static Integer reboxRawInteger(Object x) {

        if (x instanceof Integer)

            return (Integer) x;

        else

            return (int) unboxLong(x, false);

    }

    static Byte reboxRawByte(Object x) {

        if (x instanceof Byte)  return (Byte) x;

        return boxByteRaw(unboxRawInteger(x));

    }

    static Short reboxRawShort(Object x) {

        if (x instanceof Short)  return (Short) x;

        return boxShortRaw(unboxRawInteger(x));

    }

    static Boolean reboxRawBoolean(Object x) {

        if (x instanceof Boolean)  return (Boolean) x;

        return boxBooleanRaw(unboxRawInteger(x));

    }

    static Character reboxRawCharacter(Object x) {

        if (x instanceof Character)  return (Character) x;

        return boxCharacterRaw(unboxRawInteger(x));

    }

    static Float reboxRawFloat(Object x) {

        if (x instanceof Float)  return (Float) x;

        return boxFloatRaw(unboxRawInteger(x));

    }

    static Long reboxRawLong(Object x) {

        return (Long) x;  //never a rebox

    }

    static Double reboxRawDouble(Object x) {

        if (x instanceof Double)  return (Double) x;

        return boxDoubleRaw(unboxLong(x, true));

    }

    private static MethodType reboxType(Wrapper wrap) {

        Class<?> boxType = wrap.wrapperType();

        return MethodType.methodType(boxType, Object.class);

    }

    private static final EnumMap<Wrapper, MethodHandle>[]

            REBOX_CONVERSIONS = newWrapperCaches(1);

    /**

     * Because we normalize primitive types to reduce the number of signatures,

     * primitives are sometimes manipulated under an "erased" type,

     * either int (for types other than long/double) or long (for all types).

     * When the erased primitive value is then boxed into an Integer or Long,

     * the final boxed primitive is sometimes required.  This transformation

     * is called a "rebox".  It takes an Integer or Long and produces some

     * other boxed value, typed (inexactly) as an Object

     */

    public static MethodHandle rebox(Wrapper wrap) {

        EnumMap<Wrapper, MethodHandle> cache = REBOX_CONVERSIONS[0];

        MethodHandle mh = cache.get(wrap);

        if (mh != null) {

            return mh;

        }

        // slow path

        switch (wrap) {

            case OBJECT:

                mh = IDENTITY; break;

            case VOID:

                throw new IllegalArgumentException("cannot rebox a void");

        }

        if (mh != null) {

            cache.put(wrap, mh);

            return mh;

        }

        // look up the method

        String name = "reboxRaw" + wrap.simpleName();

        MethodType type = reboxType(wrap);

        try {

            mh = IMPL_LOOKUP.findStatic(THIS_CLASS, name, type);

            mh = mh.asType(IDENTITY.type());

        } catch (ReflectiveOperationException ex) {

            mh = null;

        }

        if (mh != null) {

            cache.put(wrap, mh);

            return mh;

        }

        throw new IllegalArgumentException("cannot find rebox adapter for " + wrap);

    }

    public static MethodHandle rebox(Class<?> type) {

        return rebox(Wrapper.forPrimitiveType(type));

    }

    /// Width-changing conversions between int and long.

    static long widenInt(int x) {

        return (long) x;

    }

    static Long widenBoxedInt(Integer x) {

        return (long)(int)x;

    }

    static int narrowLong(long x) {

        return (int) x;

    }

    static Integer narrowBoxedLong(Long x) {

        return (int)(long) x;

    }