/*
 * Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 */

package com.sun.opengl.impl;

import java.lang.reflect.*;
import java.nio.*;

/** Internal copy of selected routines from BufferUtil to avoid
    outward dependencies on com.sun.opengl.util package. */
public class InternalBufferUtil {
    public static final int SIZEOF_BYTE = 1;
    public static final int SIZEOF_SHORT = 2;
    public static final int SIZEOF_INT = 4;
    public static final int SIZEOF_FLOAT = 4;
    public static final int SIZEOF_LONG = 8;
    public static final int SIZEOF_DOUBLE = 8;

    //----------------------------------------------------------------------
    // Allocation routines
    //

    /** Allocates a new direct ByteBuffer with the specified number of
        elements. The returned buffer will have its byte order set to
        the host platform's native byte order. */
    public static ByteBuffer newByteBuffer(int numElements) {
        ByteBuffer bb = ByteBuffer.allocateDirect(numElements);
        nativeOrder(bb);
        return bb;
    }
    
    /** Allocates a new direct DoubleBuffer with the specified number of
        elements. The returned buffer will have its byte order set to
        the host platform's native byte order. */
    public static DoubleBuffer newDoubleBuffer(int numElements) {
        ByteBuffer bb = newByteBuffer(numElements * SIZEOF_DOUBLE);
        return bb.asDoubleBuffer();
    }

    /** Allocates a new direct IntBuffer with the specified number of
        elements. The returned buffer will have its byte order set to
        the host platform's native byte order. */
    public static IntBuffer newIntBuffer(int numElements) {
        ByteBuffer bb = newByteBuffer(numElements * SIZEOF_INT);
        return bb.asIntBuffer();
    }
    
    /** Allocates a new direct FloatBuffer with the specified number of
        elements. The returned buffer will have its byte order set to
        the host platform's native byte order. */
    public static FloatBuffer newFloatBuffer(int numElements) {
        ByteBuffer bb = newByteBuffer(numElements * SIZEOF_FLOAT);
        return bb.asFloatBuffer();
    }
    
    //----------------------------------------------------------------------
    // Copy routines (type-to-type)
    //

    /** Copies the <i>remaining</i> elements (as defined by
        <code>limit() - position()</code>) in the passed ByteBuffer into
        a newly-allocated direct ByteBuffer. The returned buffer will
        have its byte order set to the host platform's native byte
        order. The position of the newly-allocated buffer will be zero,
        and the position of the passed buffer is unchanged (though its
        mark is changed). */
    public static ByteBuffer copyByteBuffer(ByteBuffer orig) {
        ByteBuffer dest = newByteBuffer(orig.remaining());
        dest.put(orig);
        dest.rewind();
        return dest;
    }

    //----------------------------------------------------------------------
    // Copy routines (type-to-ByteBuffer)
    //

    /** Copies the <i>remaining</i> elements (as defined by
        <code>limit() - position()</code>) in the passed FloatBuffer
        into a newly-allocated direct ByteBuffer. The returned buffer
        will have its byte order set to the host platform's native byte
        order. The position of the newly-allocated buffer will be zero,
        and the position of the passed buffer is unchanged (though its
        mark is changed). */
    public static ByteBuffer copyFloatBufferAsByteBuffer(FloatBuffer orig) {
        ByteBuffer dest = newByteBuffer(orig.remaining() * SIZEOF_FLOAT);
        dest.asFloatBuffer().put(orig);
        dest.rewind();
        return dest;
    }
  
    /** Copies the <i>remaining</i> elements (as defined by
        <code>limit() - position()</code>) in the passed IntBuffer into
        a newly-allocated direct ByteBuffer. The returned buffer will
        have its byte order set to the host platform's native byte
        order. The position of the newly-allocated buffer will be zero,
        and the position of the passed buffer is unchanged (though its
        mark is changed). */
    public static ByteBuffer copyIntBufferAsByteBuffer(IntBuffer orig) {
        ByteBuffer dest = newByteBuffer(orig.remaining() * SIZEOF_INT);
        dest.asIntBuffer().put(orig);
        dest.rewind();
        return dest;
    }
  
    /** Copies the <i>remaining</i> elements (as defined by
        <code>limit() - position()</code>) in the passed ShortBuffer
        into a newly-allocated direct ByteBuffer. The returned buffer
        will have its byte order set to the host platform's native byte
        order. The position of the newly-allocated buffer will be zero,
        and the position of the passed buffer is unchanged (though its
        mark is changed). */
    public static ByteBuffer copyShortBufferAsByteBuffer(ShortBuffer orig) {
        ByteBuffer dest = newByteBuffer(orig.remaining() * SIZEOF_SHORT);
        dest.asShortBuffer().put(orig);
        dest.rewind();
        return dest;
    }

    //----------------------------------------------------------------------
    // Conversion routines 
    //

    public static float[] getFloatArray(double[] source) {
        int i=source.length;
        float[] dest = new float[i--];
        while(i>=0) { dest[i]=(float)source[i]; i--; }
        return dest;
    }

    public static ByteBuffer nativeOrder(ByteBuffer buf) {
        if (!isCDCFP) {
            try {
                if (byteOrderClass == null) {
                    byteOrderClass = Class.forName("java.nio.ByteOrder");
                    orderMethod = ByteBuffer.class.getMethod("order", new Class[] { byteOrderClass });
                    Method nativeOrderMethod = byteOrderClass.getMethod("nativeOrder", null);
                    nativeOrderObject = nativeOrderMethod.invoke(null, null);
                }
            } catch (Throwable t) {
                // Must be running on CDC / FP
                isCDCFP = true;
            }

            if (!isCDCFP) {
                try {
                    orderMethod.invoke(buf, new Object[] { nativeOrderObject });
                } catch (Throwable t) {
                }
            }
        }
        return buf;
    }

    //----------------------------------------------------------------------
    // Internals only below this point
    //

    // NOTE that this work must be done reflectively at the present time
    // because this code must compile and run correctly on both CDC/FP and J2SE
    private static boolean isCDCFP;
    private static Class byteOrderClass;
    private static Object nativeOrderObject;
    private static Method orderMethod;
}