// Package stream contains the Stream object.
package stream

import (
	"sync"
	"sync/atomic"
	"time"

	"github.com/bluenviron/gortsplib/v5"
	"github.com/bluenviron/gortsplib/v5/pkg/description"
	"github.com/bluenviron/gortsplib/v5/pkg/format"
	"github.com/pion/rtp"

	"github.com/bluenviron/mediamtx/internal/errordumper"
	"github.com/bluenviron/mediamtx/internal/logger"
	"github.com/bluenviron/mediamtx/internal/unit"
)

// Stream is a media stream.
// It stores tracks, readers and allows to write data to readers, remuxing it when needed.
type Stream struct {
	Desc              *description.Session
	UseRTPPackets     bool
	WriteQueueSize    int
	RTPMaxPayloadSize int
	ReplaceNTP        bool
	Parent            logger.Writer

	bytesReceived    *uint64
	bytesSent        *uint64
	medias           map[*description.Media]*streamMedia
	mutex            sync.RWMutex
	rtspStream       *gortsplib.ServerStream
	rtspsStream      *gortsplib.ServerStream
	readers          map[*Reader]struct{}
	processingErrors *errordumper.Dumper

	hasReaders chan struct{}
}

// Initialize initializes a Stream.
func (s *Stream) Initialize() error {
	s.bytesReceived = new(uint64)
	s.bytesSent = new(uint64)
	s.medias = make(map[*description.Media]*streamMedia)
	s.readers = make(map[*Reader]struct{})
	s.hasReaders = make(chan struct{})

	s.processingErrors = &errordumper.Dumper{
		OnReport: func(val uint64, last error) {
			if val == 1 {
				s.Parent.Log(logger.Warn, "processing error: %v", last)
			} else {
				s.Parent.Log(logger.Warn, "%d processing errors, last was: %v", val, last)
			}
		},
	}
	s.processingErrors.Start()

	for _, media := range s.Desc.Medias {
		s.medias[media] = &streamMedia{
			media:             media,
			useRTPPackets:     s.UseRTPPackets,
			rtpMaxPayloadSize: s.RTPMaxPayloadSize,
			replaceNTP:        s.ReplaceNTP,
			onBytesReceived:   s.onBytesReceived,
			onBytesSent:       s.onBytesSent,
			writeRTSP:         s.writeRTSP,
			processingErrors:  s.processingErrors,
			parent:            s.Parent,
		}
		err := s.medias[media].initialize()
		if err != nil {
			return err
		}
	}

	return nil
}

// Close closes all resources of the stream.
func (s *Stream) Close() {
	s.processingErrors.Stop()

	if s.rtspStream != nil {
		s.rtspStream.Close()
	}
	if s.rtspsStream != nil {
		s.rtspsStream.Close()
	}
}

// BytesReceived returns received bytes.
func (s *Stream) BytesReceived() uint64 {
	return atomic.LoadUint64(s.bytesReceived)
}

// BytesSent returns sent bytes.
func (s *Stream) BytesSent() uint64 {
	bytesSent := atomic.LoadUint64(s.bytesSent)

	s.mutex.RLock()
	defer s.mutex.RUnlock()

	if s.rtspStream != nil {
		stats := s.rtspStream.Stats()
		bytesSent += stats.BytesSent
	}
	if s.rtspsStream != nil {
		stats := s.rtspsStream.Stats()
		bytesSent += stats.BytesSent
	}

	return bytesSent
}

// RTSPStream returns the RTSP stream.
func (s *Stream) RTSPStream(server *gortsplib.Server) *gortsplib.ServerStream {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	if s.rtspStream == nil {
		s.rtspStream = &gortsplib.ServerStream{
			Server: server,
			Desc:   s.Desc,
		}
		err := s.rtspStream.Initialize()
		if err != nil {
			panic(err)
		}
	}
	return s.rtspStream
}

// RTSPSStream returns the RTSPS stream.
func (s *Stream) RTSPSStream(server *gortsplib.Server) *gortsplib.ServerStream {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	if s.rtspsStream == nil {
		s.rtspsStream = &gortsplib.ServerStream{
			Server: server,
			Desc:   s.Desc,
		}
		err := s.rtspsStream.Initialize()
		if err != nil {
			panic(err)
		}
	}
	return s.rtspsStream
}

// AddReader adds a reader.
// Used by all protocols except RTSP.
func (s *Stream) AddReader(r *Reader) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	s.readers[r] = struct{}{}

	for medi, formats := range r.onDatas {
		sm := s.medias[medi]

		for forma, onData := range formats {
			sf := sm.formats[forma]
			sf.onDatas[r] = onData
		}
	}

	r.queueSize = s.WriteQueueSize
	r.start()

	select {
	case <-s.hasReaders:
	default:
		close(s.hasReaders)
	}
}

// RemoveReader removes a reader.
// Used by all protocols except RTSP.
func (s *Stream) RemoveReader(r *Reader) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	r.stop()

	for medi, formats := range r.onDatas {
		sm := s.medias[medi]

		for forma := range formats {
			sf := sm.formats[forma]
			delete(sf.onDatas, r)
		}
	}

	delete(s.readers, r)
}

// WaitForReaders waits for the stream to have at least one reader.
func (s *Stream) WaitForReaders() {
	<-s.hasReaders
}

// WriteUnit writes a Unit.
func (s *Stream) WriteUnit(medi *description.Media, forma format.Format, u *unit.Unit) {
	sm := s.medias[medi]
	sf := sm.formats[forma]

	s.mutex.RLock()
	defer s.mutex.RUnlock()

	sf.writeUnit(u)
}

func (s *Stream) onBytesReceived(v uint64) {
	atomic.AddUint64(s.bytesReceived, v)
}

func (s *Stream) onBytesSent(v uint64) {
	atomic.AddUint64(s.bytesSent, v)
}

func (s *Stream) writeRTSP(medi *description.Media, pkts []*rtp.Packet, ntp time.Time) {
	if s.rtspStream != nil {
		for _, pkt := range pkts {
			s.rtspStream.WritePacketRTPWithNTP(medi, pkt, ntp) //nolint:errcheck
		}
	}

	if s.rtspsStream != nil {
		for _, pkt := range pkts {
			s.rtspsStream.WritePacketRTPWithNTP(medi, pkt, ntp) //nolint:errcheck
		}
	}
}