/*

 * Copyright (C) 2009 Apple 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:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions 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.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#ifndef ArrayBufferView_h

#define ArrayBufferView_h

#include <algorithm>

#include "ExceptionCode.h"

#include <limits.h>

#include <wtf/PassRefPtr.h>

#include <wtf/RefCounted.h>

#include <wtf/RefPtr.h>

#include "ArrayBuffer.h"

namespace WebCore {

class ArrayBufferView : public RefCounted<ArrayBufferView> {

  public:

    virtual bool isByteArray() const { return false; }

    virtual bool isUnsignedByteArray() const { return false; }

    virtual bool isShortArray() const { return false; }

    virtual bool isUnsignedShortArray() const { return false; }

    virtual bool isIntArray() const { return false; }

    virtual bool isUnsignedIntArray() const { return false; }

    virtual bool isFloatArray() const { return false; }

    PassRefPtr<ArrayBuffer> buffer() const

    {

        return m_buffer;

    }

    void* baseAddress() const

    {

        return m_baseAddress;

    }

    unsigned byteOffset() const

    {

        return m_byteOffset;

    }

    virtual unsigned length() const = 0;

    virtual unsigned byteLength() const = 0;

    virtual PassRefPtr<ArrayBufferView> slice(int start, int end) const = 0;

    virtual ~ArrayBufferView();

  protected:

    ArrayBufferView(PassRefPtr<ArrayBuffer> buffer, unsigned byteOffset);

    void setImpl(ArrayBufferView* array, unsigned byteOffset, ExceptionCode& ec);

    static void calculateOffsetAndLength(int start, int end, unsigned arraySize,

                                         unsigned* offset, unsigned* length);

    // Helper to verify that a given sub-range of an ArrayBuffer is

    // within range.

    template <typename T>

    static bool verifySubRange(PassRefPtr<ArrayBuffer> buffer,

                               unsigned byteOffset,

                               unsigned numElements)

    {

        if (!buffer)

            return false;

        if (sizeof(T) > 1 && byteOffset % sizeof(T))

            return false;

        if (byteOffset > buffer->byteLength())

            return false;

        unsigned remainingElements = (buffer->byteLength() - byteOffset) / sizeof(T);

        if (numElements > remainingElements)

            return false;

        return true;

    }

    // Input offset is in number of elements from this array's view;

    // output offset is in number of bytes from the underlying buffer's view.

    template <typename T>

    static void clampOffsetAndNumElements(PassRefPtr<ArrayBuffer> buffer,

                                          unsigned arrayByteOffset,

                                          unsigned *offset,

                                          unsigned *numElements)

    {

        unsigned maxOffset = (UINT_MAX - arrayByteOffset) / sizeof(T);

        if (*offset > maxOffset) {

            *offset = buffer->byteLength();

            *numElements = 0;

            return;

        }

        *offset = arrayByteOffset + *offset * sizeof(T);

        *offset = std::min(buffer->byteLength(), *offset);

        unsigned remainingElements = (buffer->byteLength() - *offset) / sizeof(T);

        *numElements = std::min(remainingElements, *numElements);

    }

    // This is the address of the ArrayBuffer's storage, plus the byte offset.

    void* m_baseAddress;

    unsigned m_byteOffset;

  private:

    RefPtr<ArrayBuffer> m_buffer;

};

} // namespace WebCore

#endif // ArrayBufferView_h