package extractfreq

import (
	"log"
	"math/cmplx"

	"git.crumpington.com/public/jlaudio/lib/flac"
	"gonum.org/v1/gonum/fourier"
	"gonum.org/v1/plot"
	"gonum.org/v1/plot/plotter"
	"gonum.org/v1/plot/plotutil"
	"gonum.org/v1/plot/vg"
)

func PlotFFT(path string, nSamples int, targetFreq float64) {
	L, R, err := flac.Load(path)
	if err != nil {
		panic(err)
	}

	if nSamples < len(L) {
		nSamples = len(L)
	}

	data := make([]float64, nSamples)
	for i := range data {
		data[i] = float64(L[i]) + float64(R[i])
	}

	fft := fourier.NewFFT(nSamples)
	cCoeffs := fft.Coefficients(nil, data)
	amps := make([]float64, len(cCoeffs))
	freqs := make([]float64, len(cCoeffs))
	ampMax := float64(0)
	for i := range freqs {
		amps[i] = cmplx.Abs(cCoeffs[i])
		if amps[i] > ampMax {
			ampMax = amps[i]
		}
		freqs[i] = fft.Freq(i) * 48000
	}

	// Normalize coefficients.
	for i := range amps {
		amps[i] /= ampMax
	}

	/*
		// Use a moving window to search for local peaks.
		hws := []*HarmonicWindow{}

		// Bypass low-frequency samples.
		i := 0
		for i < len(freqs) && freqs[i] < 24 {
			i++
		}

		iCenter := i
		for iC{

		}
	*/
	// Find frequency window around midi note.

	p, err := plot.New()
	if err != nil {
		panic(err)
	}

	log.Printf("Making points...")
	pts := make(plotter.XYs, len(amps))
	for i := range amps {
		pts[i].X = freqs[i]
		pts[i].Y = amps[i]
	}

	log.Printf("Plotting...")
	if err = plotutil.AddLines(p, "fft", pts); err != nil {
		panic(err)
	}

	p.Y.Scale = plot.LogScale{}
	//p.X.Scale = plot.LogScale{}

	log.Printf("Saving...")
	if err := p.Save(8*vg.Inch, 8*vg.Inch, "plot.png"); err != nil {
		panic(err)
	}
}