package main

import (
	"flag"
	"fmt"
	"math/rand"

	"github.com/pions/webrtc"

	gst "github.com/pions/webrtc/examples/internal/gstreamer-src"
	"github.com/pions/webrtc/examples/internal/signal"
)

func main() {
	audioSrc := flag.String("audio-src", "audiotestsrc", "GStreamer audio src")
	videoSrc := flag.String("video-src", "videotestsrc", "GStreamer video src")
	flag.Parse()

	// Everything below is the pion-WebRTC API! Thanks for using it ❤️.

	// Prepare the configuration
	config := webrtc.Configuration{
		ICEServers: []webrtc.ICEServer{
			{
				URLs: []string{"stun:stun.l.google.com:19302"},
			},
		},
	}

	// Create a new RTCPeerConnection
	peerConnection, err := webrtc.NewPeerConnection(config)
	if err != nil {
		panic(err)
	}

	// Set the handler for ICE connection state
	// This will notify you when the peer has connected/disconnected
	peerConnection.OnICEConnectionStateChange(func(connectionState webrtc.ICEConnectionState) {
		fmt.Printf("Connection State has changed %s \n", connectionState.String())
	})

	// Create a audio track
	opusTrack, err := peerConnection.NewTrack(webrtc.DefaultPayloadTypeOpus, rand.Uint32(), "audio", "pion1")
	if err != nil {
		panic(err)
	}
	_, err = peerConnection.AddTrack(opusTrack)
	if err != nil {
		panic(err)
	}

	// Create a video track
	vp8Track, err := peerConnection.NewTrack(webrtc.DefaultPayloadTypeVP8, rand.Uint32(), "video", "pion2")
	if err != nil {
		panic(err)
	}
	_, err = peerConnection.AddTrack(vp8Track)
	if err != nil {
		panic(err)
	}

	// Wait for the offer to be pasted
	offer := webrtc.SessionDescription{}
	signal.Decode(signal.MustReadStdin(), &offer)

	// Set the remote SessionDescription
	err = peerConnection.SetRemoteDescription(offer)
	if err != nil {
		panic(err)
	}

	// Create an answer
	answer, err := peerConnection.CreateAnswer(nil)
	if err != nil {
		panic(err)
	}

	// Sets the LocalDescription, and starts our UDP listeners
	err = peerConnection.SetLocalDescription(answer)
	if err != nil {
		panic(err)
	}

	// Output the answer in base64 so we can paste it in browser
	fmt.Println(signal.Encode(answer))

	// Start pushing buffers on these tracks
	gst.CreatePipeline(webrtc.Opus, []*webrtc.Track{opusTrack}, *audioSrc).Start()
	gst.CreatePipeline(webrtc.VP8, []*webrtc.Track{vp8Track}, *videoSrc).Start()

	// Block forever
	select {}
}