package opus

import (
	"bytes"
	"git.gammaspectra.live/S.O.N.G/Kirika/audio"
	libopus "git.gammaspectra.live/S.O.N.G/go-pus"
	"io"
)

const OPUS_SAMPLE_RATE int = 48000

type Format struct {
}

func NewFormat() Format {
	return Format{}
}

func (f Format) Open(r io.ReadSeekCloser, blockSize int) (*audio.Stream, error) {
	stream, err := libopus.NewStream(r)
	if err != nil {
		return nil, err
	}

	newChannel := make(chan []float32)

	go func() {
		defer stream.Close()
		defer close(newChannel)

		for {

			buf := make([]float32, blockSize*2)

			n, err := stream.ReadStereoFloat32(buf)
			if err != nil {
				return
			}

			if n > 0 {
				newChannel <- buf[:n*2]
			}
		}
	}()

	//We always get two channels via stereo api
	return audio.NewStream(newChannel, 2, float64(OPUS_SAMPLE_RATE), blockSize), nil
}

func (f Format) Identify(peek []byte, extension string) bool {
	return bytes.Compare(peek[:4], []byte{'O', 'g', 'g', 'S'}) == 0 || extension == "opus"
}