/*

 * 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.

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 *     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

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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) = delete;

    void operator=(const HRTFKernel& other) = 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