package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	//"sync"

	"github.com/pion/webrtc/v3"
)

func main() {
	// Статический HTML фронтенд
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		http.ServeFile(w, r, "index.html")
	})

	// Сигналлинг: прием Offer и возврат Answer
	http.HandleFunc("/sdp", handleSignaling)

	fmt.Println("Server starting on :8080 at auth.shaiheprjct.ru")
	http.ListenAndServe(":8080", nil)
}

func handleSignaling(w http.ResponseWriter, r *http.Request) {
	var offer webrtc.SessionDescription
	if err := json.NewDecoder(r.Body).Decode(&offer); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	config := webrtc.Configuration{
		ICEServers: []webrtc.ICEServer{
			{
				URLs: []string{"stun:88.210.53.29:3478"},
			},
			{
				URLs:           []string{"turn:88.210.53.29:3478"},
				Username:       "shaihe",
				Credential:     "zaq1xsw2",
				CredentialType: webrtc.ICECredentialTypePassword,
			},
		},
	}

	peerConnection, err := webrtc.NewPeerConnection(config)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Обработка входящего DataChannel
	peerConnection.OnDataChannel(func(d *webrtc.DataChannel) {
		fmt.Printf("New DataChannel %s %d\n", d.Label(), d.ID())

		d.OnOpen(func() {
			fmt.Printf("Data channel '%s' open\n", d.Label())
		})

		d.OnMessage(func(msg webrtc.DataChannelMessage) {
			fmt.Printf("Message from DataChannel '%s': %s\n", d.Label(), string(msg.Data))
			// Эхо-ответ (имитация UDP ответа)
			d.SendText("Echo: " + string(msg.Data))
		})
	})

	// Установка удаленного описания (Offer)
	err = peerConnection.SetRemoteDescription(offer)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Создание Answer
	answer, err := peerConnection.CreateAnswer(nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// Сбор ICE кандидатов (упрощенно: ждем завершения сбора перед отправкой Answer)
	gatherComplete := webrtc.GatheringCompletePromise(peerConnection)
	peerConnection.SetLocalDescription(answer)
	<-gatherComplete

	json.NewEncoder(w).Encode(peerConnection.LocalDescription())
}