From 40d79e69b007147353127f157bfb8d30f62386f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miroslav=20=C5=A0ediv=C3=BD?= <sedivy.miro@gmail.com>
Date: Wed, 24 Nov 2021 23:56:36 +0100
Subject: [PATCH] WebRTC: add onnegotiationneeded handler.

---
 src/component/internal/messages.ts | 38 +++++++++++++++++++-----------
 src/component/internal/webrtc.ts   | 31 +++++++++++++++---------
 2 files changed, 44 insertions(+), 25 deletions(-)

diff --git a/src/component/internal/messages.ts b/src/component/internal/messages.ts
index f4d108b6..6b46909c 100644
--- a/src/component/internal/messages.ts
+++ b/src/component/internal/messages.ts
@@ -73,6 +73,25 @@ export class NekoMessages extends EventEmitter<NekoEvents> {
       this._connection.websocket.send(EVENT.SIGNAL_CANDIDATE, candidate)
       this.emit('connection.webrtc.sdp.candidate', 'local', candidate)
     })
+
+    this._connection.webrtc.on('negotiation', ({ sdp, type }: RTCSessionDescriptionInit) => {
+      if (!sdp) {
+        this._remoteLog.warn(`sdp empty while negotiation event`)
+        return
+      }
+
+      if (type == 'answer') {
+        this._connection.websocket.send(EVENT.SIGNAL_ANSWER, { sdp })
+      //} else if (type == 'offer') {
+      //  // Todo: Implement
+      //  this._connection.websocket.send(EVENT.SIGNAL_OFFER, { sdp })
+      } else {
+        this._remoteLog.warn(`unsupported negotiation type`, { type })
+      }
+
+      // TODO: Pass type as well.
+      this.emit('connection.webrtc.sdp', 'local', sdp)
+    })
   }
 
   /////////////////////////////
@@ -121,29 +140,20 @@ export class NekoMessages extends EventEmitter<NekoEvents> {
   // Signal Events
   /////////////////////////////
 
-  protected async [EVENT.SIGNAL_PROVIDE]({ sdp: remoteSdp, video, iceservers }: message.SignalProvide) {
+  protected async [EVENT.SIGNAL_PROVIDE]({ sdp, video, iceservers }: message.SignalProvide) {
     this._localLog.debug(`EVENT.SIGNAL_PROVIDE`)
-    this.emit('connection.webrtc.sdp', 'remote', remoteSdp)
+    this.emit('connection.webrtc.sdp', 'remote', sdp)
 
-    const localSdp = await this._connection.webrtc.connect(remoteSdp, iceservers)
-    this._connection.websocket.send(EVENT.SIGNAL_ANSWER, {
-      sdp: localSdp,
-    })
-
-    this.emit('connection.webrtc.sdp', 'local', localSdp)
+    await this._connection.webrtc.connect(sdp, iceservers)
     Vue.set(this._state.connection.webrtc, 'video', video)
   }
 
+  // Todo: Use on-offer event intead.
   protected async [EVENT.SIGNAL_RESTART]({ sdp }: message.SignalAnswer) {
     this._localLog.debug(`EVENT.SIGNAL_RESTART`)
     this.emit('connection.webrtc.sdp', 'remote', sdp)
 
-    const localSdp = await this._connection.webrtc.offer(sdp)
-    this._connection.websocket.send(EVENT.SIGNAL_ANSWER, {
-      sdp: localSdp,
-    })
-
-    this.emit('connection.webrtc.sdp', 'local', localSdp)
+    await this._connection.webrtc.setOffer(sdp)
   }
 
   protected [EVENT.SIGNAL_CANDIDATE](candidate: message.SignalCandidate) {
diff --git a/src/component/internal/webrtc.ts b/src/component/internal/webrtc.ts
index f125a146..d354be03 100644
--- a/src/component/internal/webrtc.ts
+++ b/src/component/internal/webrtc.ts
@@ -22,6 +22,7 @@ export interface NekoWebRTCEvents {
   disconnected: (error?: Error) => void
   track: (event: RTCTrackEvent) => void
   candidate: (candidate: RTCIceCandidateInit) => void
+  negotiation: (description: RTCSessionDescriptionInit) => void
   stats: (stats: WebRTCStats) => void
   ['cursor-position']: (data: CursorPosition) => void
   ['cursor-image']: (data: CursorImage) => void
@@ -66,7 +67,7 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
     this._log.debug(`adding remote ICE candidate`, { candidate })
   }
 
-  public async connect(sdp: string, iceServers: ICEServer[]): Promise<string> {
+  public async connect(sdp: string, iceServers: ICEServer[]) {
     if (!this.supported) {
       throw new Error('browser does not support webrtc')
     }
@@ -143,19 +144,27 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
       }
     }
 
-    this._peer.onnegotiationneeded = () => {
-      this._log.warn(`negotiation is needed`)
+    this._peer.onnegotiationneeded = async () => {
+      const state = this._peer!.iceConnectionState
+      this._log.warn(`negotiation is needed`, { state })
+
+      const offer = await this._peer?.createOffer()
+      this._peer!.setLocalDescription(offer)
+
+      if (offer) {
+        this.emit('negotiation', offer)
+      } else {
+        this._log.warn(`megotiatoion offer is empty`)
+      }
     }
 
     this._peer.ontrack = this.onTrack.bind(this)
     this._peer.ondatachannel = this.onDataChannel.bind(this)
-    this._peer.addTransceiver('audio', { direction: 'recvonly' })
-    this._peer.addTransceiver('video', { direction: 'recvonly' })
 
-    return await this.offer(sdp)
+    await this.setOffer(sdp)
   }
 
-  public async offer(sdp: string) {
+  public async setOffer(sdp: string) {
     if (!this._peer) {
       throw new Error('attempting to set offer for nonexistent peer')
     }
@@ -174,11 +183,11 @@ export class NekoWebRTC extends EventEmitter<NekoWebRTCEvents> {
     const answer = await this._peer.createAnswer()
     this._peer!.setLocalDescription(answer)
 
-    if (!answer.sdp) {
-      throw new Error('sdp answer is empty')
+    if (answer) {
+      this.emit('negotiation', answer)
+    } else {
+      this._log.warn(`negiotation answer is empty`)
     }
-
-    return answer.sdp
   }
 
   public disconnect() {