package main

import (
	"fmt"

	"github.com/aler9/gortsplib"
	"github.com/aler9/gortsplib/pkg/base"
	"github.com/aler9/gortsplib/pkg/rtph264"
	"github.com/pion/rtp"
)

// This example shows how to
// 1. connect to a RTSP server and read all tracks on a path
// 2. check whether there's an H264 track
// 3. get H264 NALUs of that track

func main() {
	var h264Track int
	dec := rtph264.NewDecoder()

	c := gortsplib.Client{
		// called when a RTP packet arrives
		OnPacketRTP: func(c *gortsplib.Client, trackID int, payload []byte) {
			if trackID != h264Track {
				return
			}

			// parse RTP packet
			var pkt rtp.Packet
			err := pkt.Unmarshal(payload)
			if err != nil {
				return
			}

			// decode H264 NALUs from RTP packets
			nalus, _, err := dec.Decode(&pkt)
			if err != nil {
				return
			}

			// print NALUs
			for _, nalu := range nalus {
				fmt.Printf("received H264 NALU of size %d\n", len(nalu))
			}
		},
	}

	// parse URL
	u, err := base.ParseURL("rtsp://localhost:8554/mystream")
	if err != nil {
		panic(err)
	}

	// connect to the server
	err = c.Start(u.Scheme, u.Host)
	if err != nil {
		panic(err)
	}

	// get available methods
	_, err = c.Options(u)
	if err != nil {
		panic(err)
	}

	// find published tracks
	tracks, baseURL, _, err := c.Describe(u)
	if err != nil {
		panic(err)
	}

	// find the H264 track
	h264Track = func() int {
		for i, track := range tracks {
			if track.IsH264() {
				return i
			}
		}
		return -1
	}()
	if h264Track < 0 {
		panic("H264 track not found")
	}

	// setup all tracks
	for _, t := range tracks {
		_, err := c.Setup(true, baseURL, t, 0, 0)
		if err != nil {
			panic(err)
		}
	}

	// start reading tracks
	_, err = c.Play(nil)
	if err != nil {
		panic(err)
	}

	// wait until a fatal error
	panic(c.Wait())
}