/*
    SPDX-FileCopyrightText: 2010 Simon Andreas Eugster <simon.eu@gmail.com>
    This file is part of kdenlive. See www.kdenlive.org.

SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/

#include "fftTools.h"

#include <cmath>
#include <iostream>

#include <QString>

// Uncomment for debugging, like writing a GNU Octave .m file to /tmp
//#define DEBUG_FFTTOOLS

#ifdef DEBUG_FFTTOOLS
#include "kdenlive_debug.h"
#include <QTime>
#include <fstream>
#endif

FFTTools::FFTTools()
    : m_fftCfgs()
    , m_windowFunctions()
{
}
FFTTools::~FFTTools()
{
    QHash<QString, kiss_fftr_cfg>::iterator i;
    for (i = m_fftCfgs.begin(); i != m_fftCfgs.end(); ++i) {
        free(*i);
    }
}

const QString FFTTools::windowSignature(const WindowType windowType, const int size, const float param)
{
    return QStringLiteral("s%1_t%2_p%3").arg(size).arg(windowType).arg(param, 0, 'f', 3);
}
const QString FFTTools::cfgSignature(const int size)
{
    return QStringLiteral("s%1").arg(size);
}

// https://cplusplus.syntaxerrors.info/index.php?title=Cannot_declare_member_function_%E2%80%98static_int_Foo::bar%28%29%E2%80%99_to_have_static_linkage
const QVector<float> FFTTools::window(const WindowType windowType, const int size, const float param)
{
    Q_ASSERT(size > 0);

    // Deliberately avoid converting size to a float
    // to keep mid an integer.
    int mid = (int(size - 1) / 2);
    int max = (size - 1);
    QVector<float> window;

    switch (windowType) {
    case Window_Rect:
        return QVector<float>(size + 1, 1);
    case Window_Triangle:
        window = QVector<float>(size + 1);

        for (int x = 0; x < mid; ++x) {
            window[x] = float(x) / mid + float(mid - x) / mid * param;
        }
        for (int x = mid; x < size; ++x) {
            window[x] = float(x - mid) / (max - mid) * param + float(max - x) / (max - mid);
        }
        window[size] = .5f + param / 2;

#ifdef DEBUG_FFTTOOLS
        qCDebug(KDENLIVE_LOG) << "Triangle window (factor " << window[size] << "):";
        for (int i = 0; i < size; ++i) {
            qCDebug(KDENLIVE_LOG) << window[i];
        }
        qCDebug(KDENLIVE_LOG) << "Triangle window end.";
#endif

        return window;
    case Window_Hamming:
        // Use a quick version of the Hamming window here: Instead of
        // interpolating values between (-max/2) and (max/2)
        // we use integer values instead, ranging from -mid to (max-mid).
        window = QVector<float>(size + 1);

        for (int x = 0; x < size; ++x) {
            window[x] = .54f + .46f * cosf(2.f * float(M_PI) * float(x - mid) / size);
        }

        // Integrating the cosine over the window function results in
        // an area of 0; So only the constant factor 0.54 counts.
        window[size] = .54f;

#ifdef DEBUG_FFTTOOLS
        qCDebug(KDENLIVE_LOG) << "Hanning window (factor " << window[size] << "):";
        for (int i = 0; i < size; ++i) {
            qCDebug(KDENLIVE_LOG) << window[i];
        }
        qCDebug(KDENLIVE_LOG) << "Hanning window end.";
#endif

        return window;
    }
    Q_ASSERT(false);
    return QVector<float>();
}

void FFTTools::fftNormalized(const audioShortVector &audioFrame, const uint channel, const uint numChannels, float *freqSpectrum, const WindowType windowType,
                             const uint windowSize, const float param)
{
#ifdef DEBUG_FFTTOOLS
    QTime start = QTime::currentTime();
#endif

    const uint numSamples = uint(audioFrame.size()) / numChannels;

    if (((windowSize & 1) != 0u) || windowSize < 2) {
        return;
    }

    const QString cfgSig = cfgSignature(int(windowSize));
    const QString winSig = windowSignature(windowType, int(windowSize), param);

    // Get the kiss_fft configuration from the config cache
    // or build a new configuration if the requested one is not available.
    kiss_fftr_cfg myCfg;
    if (m_fftCfgs.contains(cfgSig)) {
#ifdef DEBUG_FFTTOOLS
        qCDebug(KDENLIVE_LOG) << "Re-using FFT configuration with size " << windowSize;
#endif
        myCfg = m_fftCfgs.value(cfgSig);
    } else {
#ifdef DEBUG_FFTTOOLS
        qCDebug(KDENLIVE_LOG) << "Creating FFT configuration with size " << windowSize;
#endif
        myCfg = kiss_fftr_alloc(int(windowSize), 0, nullptr, nullptr);
        m_fftCfgs.insert(cfgSig, myCfg);
    }

    // Get the window function from the cache
    // (except for a rectangular window; nothing to do there).
    QVector<float> window;
    float windowScaleFactor = 1;
    if (windowType != FFTTools::Window_Rect) {

        if (m_windowFunctions.contains(winSig)) {
#ifdef DEBUG_FFTTOOLS
            qCDebug(KDENLIVE_LOG) << "Re-using window function with signature " << winSig;
#endif
            window = m_windowFunctions.value(winSig);
        } else {
#ifdef DEBUG_FFTTOOLS
            qCDebug(KDENLIVE_LOG) << "Building new window function with signature " << winSig;
#endif
            window = FFTTools::window(windowType, int(windowSize), 0);
            m_windowFunctions.insert(winSig, window);
        }
        windowScaleFactor = 1.0f / window[int(windowSize)];
    }

    // Prepare frequency space vector. The resulting FFT vector is only half as long.
    auto *freqData = new kiss_fft_cpx[size_t(windowSize) / 2];
    auto *data = new float[size_t(windowSize)];

    // Copy the first channel's audio into a vector for the FFT display;
    // Fill the data vector indices that cannot be covered with sample data with 0
    if (numSamples < windowSize) {
        std::fill(&data[numSamples], &data[windowSize - 1], 0);
    }
    // Normalize signals to [0,1] to get correct dB values later on
    for (uint i = 0; i < numSamples && i < windowSize; ++i) {
        // Performance note: Benchmarking has shown that using the if/else inside the loop
        // does not do noticeable worse than keeping it outside (perhaps the branch predictor
        // is good enough), so it remains in there for better readability.
        if (windowType != FFTTools::Window_Rect) {
            data[i] = float(audioFrame.data()[i * numChannels + channel]) / 32767.0f * window[int(i)];
        } else {
            data[i] = float(audioFrame.data()[i * numChannels + channel]) / 32767.0f;
        }
    }

    // Calculate the Fast Fourier Transform for the input data
    kiss_fftr(myCfg, data, freqData);

    // Logarithmic scale: 20 * log ( 2 * magnitude / N ) with magnitude = sqrt(r² + i²)
    // with N = FFT size (after FFT, 1/2 window size)
    for (uint i = 0; i < windowSize / 2; ++i) {
        // Logarithmic scale: 20 * log ( 2 * magnitude / N ) with magnitude = sqrt(r² + i²)
        // with N = FFT size (after FFT, 1/2 window size)
        freqSpectrum[i] =
            20 *
            logf(powf(powf(fabs(freqData[i].r * windowScaleFactor), 2) + powf(fabs(freqData[i].i * windowScaleFactor), 2), .5) / (float(windowSize) / 2.0f)) /
            logf(10);
        ;
    }

#ifdef DEBUG_FFTTOOLS
    std::ofstream mFile;
    mFile.open("/tmp/freq.m");
    if (!mFile) {
        qCDebug(KDENLIVE_LOG) << "Opening file failed.";
    } else {
        mFile << "val = [ ";

        for (int sample = 0; sample < 256; ++sample) {
            mFile << data[sample] << ' ';
        }
        mFile << " ];\n";

        mFile << "freq = [ ";
        for (int sample = 0; sample < 256; ++sample) {
            mFile << freqData[sample].r << '+' << freqData[sample].i << "*i ";
        }
        mFile << " ];\n";

        mFile.close();
        qCDebug(KDENLIVE_LOG) << "File written.";
    }
#endif

#ifdef DEBUG_FFTTOOLS
    qCDebug(KDENLIVE_LOG) << "Calculated FFT in " << start.elapsed() << " ms.";
#endif
    delete[] freqData;
    delete[] data;
}

const QVector<float> FFTTools::interpolatePeakPreserving(const QVector<float> &in, const uint targetSize, uint left, uint right, float fill)
{
#ifdef DEBUG_FFTTOOLS
    QTime start = QTime::currentTime();
#endif

    if (right == 0) {
        Q_ASSERT(in.size() > 0);
        right = uint(in.size()) - 1;
    }
    Q_ASSERT(targetSize > 0);
    Q_ASSERT(left < right);

    QVector<float> out(static_cast<int>(targetSize));

    float x;
    int xi;
    int i;
    if ((float(right - left)) / targetSize < 2.f) {
        float x_prev = 0;
        for (i = 0; i < int(targetSize); ++i) {

            // i:  Target index
            // x:  Interpolated source index (float!)
            // xi: floor(x)

            // Transform [0,targetSize-1] to [left,right]
            x = float(i) / (targetSize - 1) * (right - left) + left;
            xi = int(floor(x));

            if (x > float(in.size() - 1)) {
                // This may happen if right > in.size()-1; Fill the rest of the vector
                // with the default value now.
                break;
            }

            // Use linear interpolation in order to get smoother display
            if (xi == 0 || xi == in.size() - 1) {
                // ... except if we are at the left or right border of the input signal.
                // Special case here since we consider previous and future values as well for
                // the actual interpolation (not possible here).
                out[i] = in[xi];
            } else {
                if (in[xi] > in[xi + 1] && x_prev < float(xi)) {
                    // This is a hack to preserve peaks.
                    // Consider f = {0, 100, 0}
                    //          x = {0.5,  1.5}
                    // Then x is 50 both times, and the 100 peak is lost.
                    // Get it back here for the first x after the peak (which is at xi).
                    // (x is the first after the peak if the previous x was smaller than floor(x).)
                    out[i] = in[xi];
                } else {
                    out[i] = (xi + 1.f - x) * in[xi] + (x - xi) * in[xi + 1];
                }
            }
            x_prev = x;
        }
    } else {
        // If there are more than 2 samples per pixel in average, then use the maximum of them
        // since by only looking at the left sample we might miss some maxima.
        int src = int(left);
        for (i = 0; i < int(targetSize); ++i) {

            // x:  right bound
            // xi: floor(x)
            x = float(i + 1) / (targetSize - 1) * (right - left) + left;
            xi = int(floor(x));
            out[i] = fill;

            for (; src < xi && src < in.size(); ++src) {
                if (out[i] < in[src]) {
                    out[i] = in[src];
                }
            }

            //             xi_prev = xi;
        }
    }
    // Fill the rest of the vector if the right border exceeds the input vector.
    for (; i < int(targetSize); ++i) {
        out[i] = fill;
    }

#ifdef DEBUG_FFTTOOLS
    qCDebug(KDENLIVE_LOG) << "Interpolated " << targetSize << " nodes from " << in.size() << " input points in " << start.elapsed() << " ms";
#endif

    return out;
}

#ifdef DEBUG_FFTTOOLS
#undef DEBUG_FFTTOOLS
#endif
