// Package mpegts contains MPEG-ts utilities.
package mpegts

import (
	"errors"
	"time"

	"github.com/bluenviron/gortsplib/v4/pkg/description"
	"github.com/bluenviron/gortsplib/v4/pkg/format"
	"github.com/bluenviron/mediacommon/pkg/formats/mpegts"

	"github.com/bluenviron/mediamtx/internal/stream"
	"github.com/bluenviron/mediamtx/internal/unit"
)

// ErrNoTracks is returned when there are no supported tracks.
var ErrNoTracks = errors.New("no supported tracks found (supported are H265, H264," +
	" MPEG-4 Video, MPEG-1/2 Video, Opus, MPEG-4 Audio, MPEG-1 Audio, AC-3")

// ToStream converts a MPEG-TS stream to a server stream.
func ToStream(r *mpegts.Reader, stream **stream.Stream) ([]*description.Media, error) {
	var medias []*description.Media //nolint:prealloc

	var td *mpegts.TimeDecoder
	decodeTime := func(t int64) time.Duration {
		if td == nil {
			td = mpegts.NewTimeDecoder(t)
		}
		return td.Decode(t)
	}

	for _, track := range r.Tracks() { //nolint:dupl
		var medi *description.Media

		switch codec := track.Codec.(type) {
		case *mpegts.CodecH265:
			medi = &description.Media{
				Type: description.MediaTypeVideo,
				Formats: []format.Format{&format.H265{
					PayloadTyp: 96,
				}},
			}

			r.OnDataH26x(track, func(pts int64, _ int64, au [][]byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.H265{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					AU: au,
				})
				return nil
			})

		case *mpegts.CodecH264:
			medi = &description.Media{
				Type: description.MediaTypeVideo,
				Formats: []format.Format{&format.H264{
					PayloadTyp:        96,
					PacketizationMode: 1,
				}},
			}

			r.OnDataH26x(track, func(pts int64, _ int64, au [][]byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.H264{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					AU: au,
				})
				return nil
			})

		case *mpegts.CodecMPEG4Video:
			medi = &description.Media{
				Type: description.MediaTypeVideo,
				Formats: []format.Format{&format.MPEG4Video{
					PayloadTyp: 96,
				}},
			}

			r.OnDataMPEGxVideo(track, func(pts int64, frame []byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.MPEG4Video{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					Frame: frame,
				})
				return nil
			})

		case *mpegts.CodecMPEG1Video:
			medi = &description.Media{
				Type:    description.MediaTypeVideo,
				Formats: []format.Format{&format.MPEG1Video{}},
			}

			r.OnDataMPEGxVideo(track, func(pts int64, frame []byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.MPEG1Video{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					Frame: frame,
				})
				return nil
			})

		case *mpegts.CodecOpus:
			medi = &description.Media{
				Type: description.MediaTypeAudio,
				Formats: []format.Format{&format.Opus{
					PayloadTyp: 96,
					IsStereo:   (codec.ChannelCount >= 2),
				}},
			}

			r.OnDataOpus(track, func(pts int64, packets [][]byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.Opus{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					Packets: packets,
				})
				return nil
			})

		case *mpegts.CodecMPEG4Audio:
			medi = &description.Media{
				Type: description.MediaTypeAudio,
				Formats: []format.Format{&format.MPEG4Audio{
					PayloadTyp:       96,
					SizeLength:       13,
					IndexLength:      3,
					IndexDeltaLength: 3,
					Config:           &codec.Config,
				}},
			}

			r.OnDataMPEG4Audio(track, func(pts int64, aus [][]byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.MPEG4Audio{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					AUs: aus,
				})
				return nil
			})

		case *mpegts.CodecMPEG1Audio:
			medi = &description.Media{
				Type:    description.MediaTypeAudio,
				Formats: []format.Format{&format.MPEG1Audio{}},
			}

			r.OnDataMPEG1Audio(track, func(pts int64, frames [][]byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.MPEG1Audio{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					Frames: frames,
				})
				return nil
			})

		case *mpegts.CodecAC3:
			medi = &description.Media{
				Type: description.MediaTypeAudio,
				Formats: []format.Format{&format.AC3{
					PayloadTyp:   96,
					SampleRate:   codec.SampleRate,
					ChannelCount: codec.ChannelCount,
				}},
			}

			r.OnDataAC3(track, func(pts int64, frame []byte) error {
				(*stream).WriteUnit(medi, medi.Formats[0], &unit.AC3{
					Base: unit.Base{
						NTP: time.Now(),
						PTS: decodeTime(pts),
					},
					Frames: [][]byte{frame},
				})
				return nil
			})

		default:
			continue
		}

		medias = append(medias, medi)
	}

	if len(medias) == 0 {
		return nil, ErrNoTracks
	}

	return medias, nil
}