/*
 * Copyright (C) 2010 Google 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.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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
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 */

#ifndef HRTFKernel_h
#define HRTFKernel_h

#include "nsAutoPtr.h"
#include "nsAutoRef.h"
#include "nsTArray.h"
#include "mozilla/FFTBlock.h"
#include "mozilla/MemoryReporting.h"

namespace WebCore {

using mozilla::FFTBlock;

// HRTF stands for Head-Related Transfer Function.
// HRTFKernel is a frequency-domain representation of an impulse-response used as part of the spatialized panning system.
// For a given azimuth / elevation angle there will be one HRTFKernel for the left ear transfer function, and one for the right ear.
// The leading delay (average group delay) for each impulse response is extracted:
//      m_fftFrame is the frequency-domain representation of the impulse response with the delay removed
//      m_frameDelay is the leading delay of the original impulse response.
class HRTFKernel {
public:
    // Note: this is destructive on the passed in |impulseResponse|.
    // The |length| of |impulseResponse| must be a power of two.
    // The size of the DFT will be |2 * length|.
    static nsReturnRef<HRTFKernel> create(float* impulseResponse, size_t length, float sampleRate);

    static nsReturnRef<HRTFKernel> create(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate);

    // Given two HRTFKernels, and an interpolation factor x: 0 -> 1, returns an interpolated HRTFKernel.
    static nsReturnRef<HRTFKernel> createInterpolatedKernel(HRTFKernel* kernel1, HRTFKernel* kernel2, float x);
  
    FFTBlock* fftFrame() { return m_fftFrame.get(); }
    
    size_t fftSize() const { return m_fftFrame->FFTSize(); }
    float frameDelay() const { return m_frameDelay; }

    float sampleRate() const { return m_sampleRate; }
    double nyquist() const { return 0.5 * sampleRate(); }

    size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
    {
        size_t amount = aMallocSizeOf(this);
        amount += m_fftFrame->SizeOfIncludingThis(aMallocSizeOf);
        return amount;
    }

private:
    HRTFKernel(const HRTFKernel& other) MOZ_DELETE;
    void operator=(const HRTFKernel& other) MOZ_DELETE;

    // Note: this is destructive on the passed in |impulseResponse|.
    HRTFKernel(float* impulseResponse, size_t fftSize, float sampleRate);
    
    HRTFKernel(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate)
        : m_fftFrame(fftFrame)
        , m_frameDelay(frameDelay)
        , m_sampleRate(sampleRate)
    {
    }
    
    nsAutoPtr<FFTBlock> m_fftFrame;
    float m_frameDelay;
    float m_sampleRate;
};

typedef nsTArray<nsAutoRef<HRTFKernel> > HRTFKernelList;

} // namespace WebCore

template <>
class nsAutoRefTraits<WebCore::HRTFKernel> :
    public nsPointerRefTraits<WebCore::HRTFKernel> {
public:
    static void Release(WebCore::HRTFKernel* ptr) { delete(ptr); }
};

namespace WebCore {

inline nsReturnRef<HRTFKernel> HRTFKernel::create(float* impulseResponse, size_t length, float sampleRate)
{
    return nsReturnRef<HRTFKernel>(new HRTFKernel(impulseResponse, length, sampleRate));
}

inline nsReturnRef<HRTFKernel> HRTFKernel::create(nsAutoPtr<FFTBlock> fftFrame, float frameDelay, float sampleRate)
{
    return nsReturnRef<HRTFKernel>(new HRTFKernel(fftFrame, frameDelay, sampleRate));
}

} // namespace WebCore
#endif // HRTFKernel_h