/*
 * Copyright (c) 2008, 2009, 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.dyn.util;

public enum Wrapper {
    INT(Integer.class, int.class, 'I', (Integer)(int)0, Format.signed(32)),
    LONG(Long.class, long.class, 'J', (Long)(long)0, Format.signed(64)),
    BYTE(Byte.class, byte.class, 'B', (Byte)(byte)0, Format.signed(8)),
    SHORT(Short.class, short.class, 'S', (Short)(short)0, Format.signed(16)),
    CHAR(Character.class, char.class, 'C', (Character)(char)0, Format.unsigned(16)),
    BOOLEAN(Boolean.class, boolean.class, 'Z', (Boolean)false, Format.unsigned(1)),
    FLOAT(Float.class, float.class, 'F', (Float)(float)0, Format.floating(32)),
    DOUBLE(Double.class, double.class, 'D', (Double)(double)0, Format.floating(64)),
    VOID(Void.class, void.class, 'V', null, Format.other(0)),
    //NULL(Null.class, null.class, 'N', null, Format.other(1)),
    OBJECT(Object.class, Object.class, 'L', null, Format.other(1)),
    ;

    private final Class<?> wrapperType;
    private final Class<?> primitiveType;
    private final char     basicTypeChar;
    private final Object   zero;
    private final int      format;
    private final String   simpleName;

    private Wrapper(Class<?> wtype, Class<?> ptype, char tchar, Object zero, int format) {
        this.wrapperType = wtype;
        this.primitiveType = ptype;
        this.basicTypeChar = tchar;
        this.zero = zero;
        this.format = format;
        this.simpleName = wtype.getSimpleName();
    }

    private static abstract class Format {
        static final int SLOT_SHIFT = 0, SIZE_SHIFT = 2, KIND_SHIFT = 12;
        static final int
                SIGNED   = (-1) << KIND_SHIFT,
                UNSIGNED = 0    << KIND_SHIFT,
                FLOATING = 1    << KIND_SHIFT;
        static final int
                SLOT_MASK = ((1<<(SIZE_SHIFT-SLOT_SHIFT))-1),
                SIZE_MASK = ((1<<(KIND_SHIFT-SIZE_SHIFT))-1);
        static int format(int kind, int size, int slots) {
            assert(((kind >> KIND_SHIFT) << KIND_SHIFT) == kind);
            assert((size & (size-1)) == 0); // power of two
            assert((kind == SIGNED)   ? (size > 0) :
                   (kind == UNSIGNED) ? (size > 0) :
                   (kind == FLOATING) ? (size == 32 || size == 64)  :
                   false);
            assert((slots == 2) ? (size == 64) :
                   (slots == 1) ? (size <= 32) :
                   false);
            return kind | (size << SIZE_SHIFT) | (slots << SLOT_SHIFT);
        }
        static int
                INT      = SIGNED   | (32 << SIZE_SHIFT) | (1 << SLOT_SHIFT),
                BOOLEAN  = UNSIGNED | (1  << SIZE_SHIFT) | (1 << SLOT_SHIFT),
                FLOAT    = FLOATING | (32 << SIZE_SHIFT) | (1 << SLOT_SHIFT),
                VOID     = UNSIGNED | (0  << SIZE_SHIFT) | (0 << SLOT_SHIFT),
                NUM_MASK = (-1) << SIZE_SHIFT;
        static int signed(int size)   { return format(SIGNED,   size, (size > 32 ? 2 : 1)); }
        static int unsigned(int size) { return format(UNSIGNED, size, (size > 32 ? 2 : 1)); }
        static int floating(int size) { return format(FLOATING, size, (size > 32 ? 2 : 1)); }
        static int other(int slots)   { return slots << SLOT_SHIFT; }
    }

    /// format queries:

    /** How many bits are in the wrapped value?  Returns 0 for OBJECT or VOID. */
    public int     bitWidth()      { return (format >> Format.SIZE_SHIFT) & Format.SIZE_MASK; }
    /** How many JVM stack slots occupied by the wrapped value?  Returns 0 for VOID. */
    public int     stackSlots()    { return (format >> Format.SLOT_SHIFT) & Format.SLOT_MASK; }
    /** Does the wrapped value occupy a single JVM stack slot? */
    public boolean isSingleWord()  { return (format & (1 << Format.SLOT_SHIFT)) != 0; }
    /** Does the wrapped value occupy two JVM stack slots? */
    public boolean isDoubleWord()  { return (format & (2 << Format.SLOT_SHIFT)) != 0; }
    /** Is the wrapped type numeric (not void or object)? */
    public boolean isNumeric()     { return (format & Format.NUM_MASK) != 0; }
    /** Is the wrapped type a primitive other than float, double, or void? */
    public boolean isIntegral()    { return isNumeric() && format < Format.FLOAT; }
    /** Is the wrapped type one of int, boolean, byte, char, or short? */
    public boolean isSubwordOrInt() { return isIntegral() && isSingleWord(); }
    /* Is the wrapped value a signed integral type (one of byte, short, int, or long)? */
    public boolean isSigned()      { return format < Format.VOID; }
    /* Is the wrapped value an unsigned integral type (one of boolean or char)? */
    public boolean isUnsigned()    { return format >= Format.BOOLEAN && format < Format.FLOAT; }
    /** Is the wrapped type either float or double? */
    public boolean isFloating()    { return format >= Format.FLOAT; }

    /** Produce a zero value for the given wrapper type.
     *  This will be a numeric zero for a number or character,
     *  false for a boolean, and null for a reference or void.
     *  The common thread is that this is what is contained
     *  in a default-initialized variable of the given primitive
     *  type.  (For void, it is what a reflective method returns
     *  instead of no value at all.)
     */
    public Object zero() { return zero; }

    /** Produce a zero value for the given wrapper type T.
     *  The optinoal argument must a type compatible with this wrapper.
     *  Equivalent to {@code this.cast(this.zero(), type)}.
     */
    public <T> T zero(Class<T> type) { return cast(zero, type); }

//    /** Produce a wrapper for the given wrapper or primitive type. */
//    public static Wrapper valueOf(Class<?> type) {
//        if (isPrimitiveType(type))
//            return forPrimitiveType(type);
//        else
//            return forWrapperType(type);
//    }

    /** Return the wrapper that wraps values of the given type.
     *  The type may be {@code Object}, meaning the {@code OBJECT} wrapper.
     *  Otherwise, the type must be a primitive.
     *  @throws IllegalArgumentException for unexpected types
     */
    public static Wrapper forPrimitiveType(Class<?> type) {
        Wrapper w = findPrimitiveType(type);
        if (w != null)  return w;
        if (type.isPrimitive())
            throw new InternalError(); // redo hash function
        throw newIllegalArgumentException("not primitive: "+type);
    }

    static Wrapper findPrimitiveType(Class<?> type) {
        Wrapper w = FROM_PRIM[hashPrim(type)];
        if (w != null && w.primitiveType == type) {
            return w;
        }
        return null;
    }

    /** Return the wrapper that wraps values into the given wrapper type.
     *  If it is {@code Object} or an interface, return {@code OBJECT}.
     *  Otherwise, it must be a wrapper type.
     *  The type must not be a primitive type.
     *  @throws IllegalArgumentException for unexpected types
     */
    public static Wrapper forWrapperType(Class<?> type) {
        Wrapper w = findWrapperType(type);
        if (w != null)  return w;
        for (Wrapper x : values())
            if (x.wrapperType == type)
                throw new InternalError(); // redo hash function
        throw newIllegalArgumentException("not wrapper: "+type);
    }

    static Wrapper findWrapperType(Class<?> type) {
        Wrapper w = FROM_WRAP[hashWrap(type)];
        if (w != null && w.wrapperType == type) {
            return w;
        }
        if (type.isInterface())
            return OBJECT;
        return null;
    }

    /** Return the wrapper that corresponds to the given bytecode
     *  signature character.  Return {@code OBJECT} for the character 'L'.
     *  @throws IllegalArgumentException for any non-signature character or {@code '['}.
     */
    public static Wrapper forBasicType(char type) {
        Wrapper w = FROM_CHAR[hashChar(type)];
        if (w != null && w.basicTypeChar == type) {
            return w;
        }
        for (Wrapper x : values())
            if (w.basicTypeChar == type)
                throw new InternalError(); // redo hash function
        throw newIllegalArgumentException("not basic type char: "+type);
    }

    /** Return the wrapper for the given type, if it is
     *  a primitive type, else return {@code OBJECT}.
     */
    public static Wrapper forBasicType(Class<?> type) {
        if (type.isPrimitive())
            return forPrimitiveType(type);
        return OBJECT;  // any reference, including wrappers or arrays
    }

    // Note on perfect hashes:
    //   for signature chars c, do (c + (c >> 1)) % 16
    //   for primitive type names n, do (n[0] + n[2]) % 16
    // The type name hash works for both primitive and wrapper names.
    // You can add "java/lang/Object" to the primitive names.
    // But you add the wrapper name Object, use (n[2] + (3*n[1])) % 16.
    private static final Wrapper[] FROM_PRIM = new Wrapper[16];
    private static final Wrapper[] FROM_WRAP = new Wrapper[16];
    private static final Wrapper[] FROM_CHAR = new Wrapper[16];
    private static int hashPrim(Class<?> x) {
        String xn = x.getName();
        if (xn.length() < 3)  return 0;
        return (xn.charAt(0) + xn.charAt(2)) % 16;
    }
    private static int hashWrap(Class<?> x) {
        String xn = x.getName();
        final int offset = 10; assert(offset == "java.lang.".length());
        if (xn.length() < offset+3)  return 0;
        return (3*xn.charAt(offset+1) + xn.charAt(offset+2)) % 16;
    }
    private static int hashChar(char x) {
        return (x + (x >> 1)) % 16;
    }
    static {
        for (Wrapper w : values()) {
            int pi = hashPrim(w.primitiveType);
            int wi = hashWrap(w.wrapperType);
            int ci = hashChar(w.basicTypeChar);
            assert(FROM_PRIM[pi] == null);
            assert(FROM_WRAP[wi] == null);
            assert(FROM_CHAR[ci] == null);
            FROM_PRIM[pi] = w;
            FROM_WRAP[wi] = w;
            FROM_CHAR[ci] = w;
        }
        //assert(jdk.sun.dyn.util.WrapperTest.test(false));
    }

    /** What is the primitive type wrapped by this wrapper? */
    public Class<?> primitiveType() { return primitiveType; }

    /** What is the wrapper type for this wrapper? */
    public Class<?> wrapperType() { return wrapperType; }

    /** What is the wrapper type for this wrapper?
     * Otherwise, the example type must be the wrapper type,
     * or the corresponding primitive type.
     * (For {@code OBJECT}, the example type can be any non-primitive,
     * and is normalized to {@code Object.class}.)
     * The resulting class type has the same type parameter.
     */
    public <T> Class<T> wrapperType(Class<T> exampleType) {
        if (exampleType == wrapperType) {
            return exampleType;
        } else if (exampleType == primitiveType ||
                   wrapperType == Object.class ||
                   exampleType.isInterface()) {
            return forceType(wrapperType, exampleType);
        }
        throw new ClassCastException(exampleType + " not <:" + wrapperType);
    }

    /** If {@code type} is a primitive type, return the corresponding
     *  wrapper type, else return {@code type} unchanged.
     */
    public static <T> Class<T> asWrapperType(Class<T> type) {
        if (type.isPrimitive()) {
            return forPrimitiveType(type).wrapperType(type);
        }
        return type;
    }

    /** If {@code type} is a wrapper type, return the corresponding
     *  primitive type, else return {@code type} unchanged.
     */
    public static <T> Class<T> asPrimitiveType(Class<T> type) {
        Wrapper w = findWrapperType(type);
        if (w != null) {
            return forceType(w.primitiveType(), type);
        }
        return type;
    }

    /** Query:  Is the given type a wrapper, such as {@code Integer} or {@code Void}? */
    public static boolean isWrapperType(Class<?> type) {
        return findWrapperType(type) != null;
    }

    /** Query:  Is the given type a primitive, such as {@code int} or {@code void}? */
    public static boolean isPrimitiveType(Class<?> type) {
        return type.isPrimitive();
    }

    /** What is the bytecode signature character for this type?
     *  All non-primitives, including array types, report as 'L', the signature character for references.
     */
    public static char basicTypeChar(Class<?> type) {
        if (!type.isPrimitive())
            return 'L';
        else
            return forPrimitiveType(type).basicTypeChar();
    }

    /** What is the bytecode signature character for this wrapper's
     *  primitive type?
     */
    public char basicTypeChar() { return basicTypeChar; }

    /** What is the simple name of the wrapper type?
     */
    public String simpleName() { return simpleName; }

//    /** Wrap a value in the given type, which may be either a primitive or wrapper type.
//     *  Performs standard primitive conversions, including truncation and float conversions.
//     */
//    public static <T> T wrap(Object x, Class<T> type) {
//        return Wrapper.valueOf(type).cast(x, type);
//    }

    /** Cast a wrapped value to the given type, which may be either a primitive or wrapper type.
     *  Performs standard primitive conversions, including truncation and float conversions.
     *  The given type must be compatible with this wrapper.  That is, it must either
     *  be the wrapper type (or a subtype, in the case of {@code OBJECT}) or else
     *  it must be the wrapper's primitive type.
     *  @throws ClassCastException if the given type is not compatible with this wrapper
     */
    public <T> T cast(Object x, Class<T> type) {
        Class<T> wtype = wrapperType(type);
        if (wtype.isInstance(x))
            return wtype.cast(x);
        return wtype.cast(wrap(x));
    }

    /** Cast a reference type to another reference type.
     * If the target type is an interface, perform no runtime check.
     * (This loophole is safe, and is allowed by the JVM verifier.)
     * If the target type is a primitive, change it to a wrapper.
     */
    static <T> Class<T> forceType(Class<?> type, Class<T> exampleType) {
        boolean z = (type == exampleType ||
               type.isPrimitive() && forPrimitiveType(type) == findWrapperType(exampleType) ||
               exampleType.isPrimitive() && forPrimitiveType(exampleType) == findWrapperType(type) ||
               type == Object.class && !exampleType.isPrimitive());
        if (!z)
            System.out.println(type+" <= "+exampleType);
        assert(type == exampleType ||
               type.isPrimitive() && forPrimitiveType(type) == findWrapperType(exampleType) ||
               exampleType.isPrimitive() && forPrimitiveType(exampleType) == findWrapperType(type) ||
               type == Object.class && !exampleType.isPrimitive());
        @SuppressWarnings("unchecked")
        Class<T> result = (Class<T>) type;  // unchecked warning is expected here
        return result;
    }

    /** Wrap a value in this wrapper's type.
     * Performs standard primitive conversions, including truncation and float conversions.
     * Performs returns the unchanged reference for {@code OBJECT}.
     * Returns null for {@code VOID}.
     * Returns a zero value for a null input.
     * @throws ClassCastException if this wrapper is numeric and the operand
     *                            is not a number, character, boolean, or null
     */
    public Object wrap(Object x) {
        // do non-numeric wrappers first
        switch (basicTypeChar) {
            case 'L': return x;
            case 'V': return null;
        }
        Number xn = numberValue(x);
        switch (basicTypeChar) {
            case 'I': return Integer.valueOf(xn.intValue());
            case 'J': return Long.valueOf(xn.longValue());
            case 'F': return Float.valueOf(xn.floatValue());
            case 'D': return Double.valueOf(xn.doubleValue());
            case 'S': return Short.valueOf((short) xn.intValue());
            case 'B': return Byte.valueOf((byte) xn.intValue());
            case 'C': return Character.valueOf((char) xn.intValue());
            case 'Z': return Boolean.valueOf(boolValue(xn.longValue()));
        }
        throw new InternalError("bad wrapper");
    }

    /** Wrap a value (an int or smaller value) in this wrapper's type.
     * Performs standard primitive conversions, including truncation and float conversions.
     * Produces an {@code Integer} for {@code OBJECT}, although the exact type
     * of the operand is not known.
     * Returns null for {@code VOID}.
     */
    public Object wrap(int x) {
        if (basicTypeChar == 'L')  return (Integer)x;
        switch (basicTypeChar) {
            case 'L': throw newIllegalArgumentException("cannot wrap to object type");
            case 'V': return null;
            case 'I': return Integer.valueOf((int)x);
            case 'J': return Long.valueOf(x);
            case 'F': return Float.valueOf(x);
            case 'D': return Double.valueOf(x);
            case 'S': return Short.valueOf((short) x);
            case 'B': return Byte.valueOf((byte) x);
            case 'C': return Character.valueOf((char) x);
            case 'Z': return Boolean.valueOf(boolValue(x));
        }
        throw new InternalError("bad wrapper");
    }

    /** Wrap a value (a long or smaller value) in this wrapper's type.
     * Does not perform floating point conversion.
     * Produces a {@code Long} for {@code OBJECT}, although the exact type
     * of the operand is not known.
     * Returns null for {@code VOID}.
     */
    public Object wrapRaw(long x) {
        switch (basicTypeChar) {
            case 'F':  return Float.valueOf(Float.intBitsToFloat((int)x));
            case 'D':  return Double.valueOf(Double.longBitsToDouble(x));
            case 'L':  // same as 'J':
            case 'J':  return (Long) x;
        }
        // Other wrapping operations are just the same, given that the
        // operand is already promoted to an int.
        return wrap((int)x);
    }

    /** Produce bitwise value which encodes the given wrapped value.
     * Does not perform floating point conversion.
     * Returns zero for {@code VOID}.
     */
    public long unwrapRaw(Object x) {
        switch (basicTypeChar) {
            case 'F':  return Float.floatToRawIntBits((Float) x);
            case 'D':  return Double.doubleToRawLongBits((Double) x);

            case 'L': throw newIllegalArgumentException("cannot unwrap from sobject type");
            case 'V': return 0;
            case 'I': return (int)(Integer) x;
            case 'J': return (long)(Long) x;
            case 'S': return (short)(Short) x;
            case 'B': return (byte)(Byte) x;
            case 'C': return (char)(Character) x;
            case 'Z': return (boolean)(Boolean) x ? 1 : 0;
        }
        throw new InternalError("bad wrapper");
    }

    /** Report what primitive type holds this guy's raw value. */
    public Class<?> rawPrimitiveType() {
        return rawPrimitive().primitiveType();
    }

    /** Report, as a wrapper, what primitive type holds this guy's raw value.
     *  Returns self for INT, LONG, OBJECT; returns LONG for DOUBLE,
     *  else returns INT.
     */
    public Wrapper rawPrimitive() {
        switch (basicTypeChar) {
            case 'S': case 'B':
            case 'C': case 'Z':
            case 'V':
            case 'F':
                return INT;
            case 'D':
                return LONG;
        }
        return this;
    }

    private static Number numberValue(Object x) {
        if (x instanceof Number)     return (Number)x;
        if (x instanceof Character)  return (int)(Character)x;
        if (x instanceof Boolean)    return (Boolean)x ? 1 : 0;
        // Remaining allowed case of void:  Must be a null reference.
        return (Number)x;
    }

    private static boolean boolValue(long bits) {
        //bits &= 1;  // simple 31-bit zero extension
        return (bits != 0);
    }

    private static RuntimeException newIllegalArgumentException(String message, Object x) {
        return newIllegalArgumentException(message + x);
    }
    private static RuntimeException newIllegalArgumentException(String message) {
        return new IllegalArgumentException(message);
    }
}