package hls

import (
	"bytes"
	"encoding/hex"
	"io"
	"strconv"
	"strings"

	"github.com/aler9/gortsplib"
)

type muxerPrimaryPlaylist struct {
	videoTrack *gortsplib.TrackH264
	audioTrack *gortsplib.TrackAAC

	cnt []byte
}

func newMuxerPrimaryPlaylist(
	videoTrack *gortsplib.TrackH264,
	audioTrack *gortsplib.TrackAAC,
) *muxerPrimaryPlaylist {
	p := &muxerPrimaryPlaylist{
		videoTrack: videoTrack,
		audioTrack: audioTrack,
	}

	var codecs []string

	if p.videoTrack != nil {
		sps := p.videoTrack.SPS()
		if len(sps) >= 4 {
			codecs = append(codecs, "avc1."+hex.EncodeToString(sps[1:4]))
		}
	}

	// https://developer.mozilla.org/en-US/docs/Web/Media/Formats/codecs_parameter
	if p.audioTrack != nil {
		codecs = append(codecs, "mp4a.40."+strconv.FormatInt(int64(p.audioTrack.Type()), 10))
	}

	p.cnt = []byte("#EXTM3U\n" +
		"#EXT-X-STREAM-INF:BANDWIDTH=200000,CODECS=\"" + strings.Join(codecs, ",") + "\"\n" +
		"stream.m3u8\n")

	return p
}

func (p *muxerPrimaryPlaylist) reader() io.Reader {
	return bytes.NewReader(p.cnt)
}