feat: ✨ webrtc answer

client/src/webrtc.rs

@@ -8,7 +8,10 @@ use web_sys::{
     wasm_bindgen::{JsCast, JsValue, prelude::Closure},
 };
 
-use crate::signal::{receive_answer, receive_ice_candidate, send_ice_candidate, send_offer};
+use crate::signal::{
+    receive_answer, receive_ice_candidate, receive_offer, send_answer, send_ice_candidate,
+    send_offer,
+};
 
 pub struct WebRTC {
     audio_stream: Option<MediaStream>,
@@ -160,4 +163,58 @@ impl WebRTC {
         }
         return Err(Error::WebRTCOffer);
     }
+
+    async fn answer(&mut self) -> Result<(), Error> {
+        if let Ok(received_offer) = receive_offer() {
+            let offer = RtcSessionDescriptionInit::new(RtcSdpType::Offer);
+            offer.set_sdp(&received_offer.get_data());
+
+            let set_remote_description_promise =
+                self.peer_connection.set_remote_description(&offer);
+            JsFuture::from(set_remote_description_promise)
+                .await
+                .map_err(|_| Error::WebRTCSetRemoteDescription)?;
+
+            let answer_promise = self.peer_connection.create_answer();
+            match JsFuture::from(answer_promise)
+                .await
+                .map_err(|_| Error::WebRTCAnswer)
+            {
+                Ok(answer) => {
+                    let answer_session_description_protocol =
+                        Reflect::get(&answer, &JsValue::from_str("sdp"))
+                            .map_err(|_| Error::WebRTCSessionDescriptionProtocol)?;
+                    match answer_session_description_protocol
+                        .as_string()
+                        .ok_or_else(|| Error::WebRTCAnswer)
+                    {
+                        Ok(answer_session_description_protocol) => {
+                            let answer = RtcSessionDescriptionInit::new(RtcSdpType::Answer);
+                            answer.set_sdp(&answer_session_description_protocol);
+
+                            let set_local_description_promise =
+                                self.peer_connection.set_local_description(&answer);
+                            JsFuture::from(set_local_description_promise)
+                                .await
+                                .map_err(|_| Error::WebRTCSetLocalDescription)?;
+
+                            send_answer(&answer_session_description_protocol)?;
+
+                            return Ok(());
+                        }
+                        Err(err_val) => {
+                            log!(
+                                "Error: WebRTC Answer | Session Description Protocol String Transformation | {}",
+                                err_val
+                            );
+                        }
+                    }
+                }
+                Err(err_val) => {
+                    log!("Error: WebRTC Answer | Promise | {}", err_val);
+                }
+            }
+        }
+        Err(Error::WebRTCAnswer)
+    }
 }