//go:build cgo

package filter

import (
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	"github.com/dh1tw/gosamplerate"
	"log"
)

const (
	QualityBest    ResampleQuality = gosamplerate.SRC_SINC_BEST_QUALITY
	QualityGood    ResampleQuality = gosamplerate.SRC_SINC_MEDIUM_QUALITY
	QualityFast    ResampleQuality = gosamplerate.SRC_SINC_FASTEST
	QualityFastest ResampleQuality = gosamplerate.SRC_LINEAR
)

func (f ResampleFilter) Process(source audio.Source) audio.Source {
	if source.GetSampleRate() == f.sampleRate { //no change
		return source
	}

	outSource := audio.NewSource[float32](source.GetBitDepth(), f.sampleRate, source.GetChannels())

	go func() {
		defer outSource.Close()

		blockSize := f.blockSize * source.GetChannels()
		samplerateConverter, err := gosamplerate.New(int(f.quality), source.GetChannels(), blockSize)

		if err != nil {
			log.Panic(err)
		}
		defer gosamplerate.Delete(samplerateConverter)

		ratio := float64(f.sampleRate) / float64(source.GetSampleRate())

		for block := range source.ToFloat32().GetBlocks() {
			for len(block) >= blockSize {
				b, err := samplerateConverter.Process(block[0:blockSize], ratio, false)
				if err != nil {
					log.Panic(err)
				}
				if len(b) > 0 {
					outSource.IngestFloat32(b)
				}
				block = block[blockSize:]
			}
			if len(block) > 0 {
				b, err := samplerateConverter.Process(block, ratio, false)
				if err != nil {
					log.Panic(err)
				}
				if len(b) > 0 {
					outSource.IngestFloat32(b)
				}
			}
		}
		b, err := samplerateConverter.Process([]float32{}, ratio, true)
		if err != nil {
			log.Panic(err)
		}
		if len(b) > 0 {
			outSource.IngestFloat32(b)
		}
	}()

	return outSource
}