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 * 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.objects;

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

import java.nio.ByteBuffer;

import jdk.nashorn.internal.objects.annotations.Attribute;
import jdk.nashorn.internal.objects.annotations.Constructor;
import jdk.nashorn.internal.objects.annotations.Function;
import jdk.nashorn.internal.objects.annotations.Getter;
import jdk.nashorn.internal.objects.annotations.ScriptClass;
import jdk.nashorn.internal.objects.annotations.SpecializedFunction;
import jdk.nashorn.internal.objects.annotations.Where;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.PropertyMap;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.ScriptRuntime;

NativeArrayBuffer - ArrayBuffer as described in the JS typed
array spec
/**
 * NativeArrayBuffer - ArrayBuffer as described in the JS typed
 * array spec
 */
@ScriptClass("ArrayBuffer")
public final class NativeArrayBuffer extends ScriptObject {
    private final ByteBuffer nb;

    // initialized by nasgen
    private static PropertyMap $nasgenmap$;

    
Constructor
Params:
nb – native byte buffer to wrap
global – global instance/**
     * Constructor
     * @param nb native byte buffer to wrap
     * @param global global instance
     */
    protected NativeArrayBuffer(final ByteBuffer nb, final Global global) {
        super(global.getArrayBufferPrototype(), $nasgenmap$);
        this.nb = nb;
    }

    
Constructor
Params:
nb – native byte buffer to wrap/**
     * Constructor
     * @param nb native byte buffer to wrap
     */
    protected NativeArrayBuffer(final ByteBuffer nb) {
        this(nb, Global.instance());
    }

    
Constructor
Params:
byteLength – byteLength for buffer/**
     * Constructor
     * @param byteLength byteLength for buffer
     */
    protected NativeArrayBuffer(final int byteLength) {
        this(ByteBuffer.allocateDirect(byteLength));
    }

    
Clone constructor
Used only for slice
Params:
other – original buffer
begin – begin byte index
end –   end byte index/**
     * Clone constructor
     * Used only for slice
     * @param other original buffer
     * @param begin begin byte index
     * @param end   end byte index
     */
    protected NativeArrayBuffer(final NativeArrayBuffer other, final int begin, final int end) {
        this(cloneBuffer(other.getNioBuffer(), begin, end));
    }

    
Constructor
Params:
newObj – is this invoked with new
self –   self reference
args –   arguments to constructor
Returns:
new NativeArrayBuffer/**
     * Constructor
     * @param newObj is this invoked with new
     * @param self   self reference
     * @param args   arguments to constructor
     * @return new NativeArrayBuffer
     */
    @Constructor(arity = 1)
    public static NativeArrayBuffer constructor(final boolean newObj, final Object self, final Object... args) {
        if (!newObj) {
            throw typeError("constructor.requires.new", "ArrayBuffer");
        }

        if (args.length == 0) {
            return new NativeArrayBuffer(0);
        }

        final Object arg0 = args[0];
        if (arg0 instanceof ByteBuffer) {
            return new NativeArrayBuffer((ByteBuffer)arg0);
        } else {
            return new NativeArrayBuffer(JSType.toInt32(arg0));
        }
    }

    private static ByteBuffer cloneBuffer(final ByteBuffer original, final int begin, final int end) {
        final ByteBuffer clone = ByteBuffer.allocateDirect(original.capacity());
        original.rewind();//copy from the beginning
        clone.put(original);
        original.rewind();
        clone.flip();
        clone.position(begin);
        clone.limit(end);
        return clone.slice();
    }

    ByteBuffer getNioBuffer() {
        return nb;
    }

    @Override
    public String getClassName() {
        return "ArrayBuffer";
    }

    
Byte length for native array buffer
Params:
self – native array buffer
Returns:
byte length/**
     * Byte length for native array buffer
     * @param self native array buffer
     * @return byte length
     */
    @Getter(attributes = Attribute.NOT_ENUMERABLE | Attribute.NOT_WRITABLE | Attribute.NOT_CONFIGURABLE)
    public static int byteLength(final Object self) {
        return ((NativeArrayBuffer)self).getByteLength();
    }

    
Returns true if an object is an ArrayBufferView
Params:
self – self
obj –  object to check
Returns:
true if obj is an ArrayBufferView/**
     * Returns true if an object is an ArrayBufferView
     *
     * @param self self
     * @param obj  object to check
     *
     * @return true if obj is an ArrayBufferView
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE, where = Where.CONSTRUCTOR)
    public static boolean isView(final Object self, final Object obj) {
        return obj instanceof ArrayBufferView;
    }

    
Slice function
Params:
self –   native array buffer
begin0 – start byte index
end0 –   end byte index
Returns:
new array buffer, sliced/**
     * Slice function
     * @param self   native array buffer
     * @param begin0 start byte index
     * @param end0   end byte index
     * @return new array buffer, sliced
     */
    @Function(attributes = Attribute.NOT_ENUMERABLE)
    public static NativeArrayBuffer slice(final Object self, final Object begin0, final Object end0) {
        final NativeArrayBuffer arrayBuffer = (NativeArrayBuffer)self;
        final int               byteLength  = arrayBuffer.getByteLength();
        final int               begin       = adjustIndex(JSType.toInt32(begin0), byteLength);
        final int               end         = adjustIndex(end0 != ScriptRuntime.UNDEFINED ? JSType.toInt32(end0) : byteLength, byteLength);
        return new NativeArrayBuffer(arrayBuffer, begin, Math.max(end, begin));
    }

    
Specialized slice function
Params:
self –   native array buffer
begin –  start byte index
end –    end byte index
Returns:
new array buffer, sliced/**
     * Specialized slice function
     * @param self   native array buffer
     * @param begin  start byte index
     * @param end    end byte index
     * @return new array buffer, sliced
     */
    @SpecializedFunction
    public static Object slice(final Object self, final int begin, final int end) {
        final NativeArrayBuffer arrayBuffer = (NativeArrayBuffer)self;
        final int byteLength  = arrayBuffer.getByteLength();
        return new NativeArrayBuffer(arrayBuffer, adjustIndex(begin, byteLength), Math.max(adjustIndex(end, byteLength), begin));
    }

    
Specialized slice function
Params:
self –   native array buffer
begin –  start byte index
Returns:
new array buffer, sliced/**
     * Specialized slice function
     * @param self   native array buffer
     * @param begin  start byte index
     * @return new array buffer, sliced
     */
    @SpecializedFunction
    public static Object slice(final Object self, final int begin) {
        return slice(self, begin, ((NativeArrayBuffer)self).getByteLength());
    }

    
If index is negative, it refers to an index from the end of the array, as
opposed to from the beginning. The index is clamped to the valid index
range for the array.
Params:
index –  The index.
length – The length of the array.
Returns:
valid index index in the range [0, length)./**
     * If index is negative, it refers to an index from the end of the array, as
     * opposed to from the beginning. The index is clamped to the valid index
     * range for the array.
     *
     * @param index  The index.
     * @param length The length of the array.
     * @return valid index index in the range [0, length).
     */
    static int adjustIndex(final int index, final int length) {
        return index < 0 ? clamp(index + length, length) : clamp(index, length);
    }

    
Clamp index into the range [0, length).
/**
     * Clamp index into the range [0, length).
     */
    private static int clamp(final int index, final int length) {
        if (index < 0) {
            return 0;
        } else if (index > length) {
            return length;
        }
        return index;
    }

    int getByteLength() {
        return nb.limit();
    }

    ByteBuffer getBuffer() {
       return nb;
    }

    ByteBuffer getBuffer(final int offset) {
        return nb.duplicate().position(offset);
    }

    ByteBuffer getBuffer(final int offset, final int length) {
        return getBuffer(offset).limit(length);
    }
}