async function startSession()

in challenge4/frontend/components/voice-mode.tsx [22:91]
55 lines of code
7 McCabe index (conditional complexity)

  async function startSession() {
    try {
      if (!isSessionStarted) {
        setIsSessionStarted(true)
        // Get an ephemeral session token
        const session = await fetch('/api/session').then(response =>
          response.json()
        )
        const sessionToken = session.client_secret.value
        const sessionId = session.id

        console.log('Session id:', sessionId)

        // Create a peer connection
        const pc = new RTCPeerConnection()

        // Set up to play remote audio from the model
        if (!audioElement.current) {
          audioElement.current = document.createElement('audio')
        }
        audioElement.current.autoplay = true
        pc.ontrack = e => {
          if (audioElement.current) {
            audioElement.current.srcObject = e.streams[0]
          }
        }

        const stream = await navigator.mediaDevices.getUserMedia({
          audio: true
        })

        stream.getTracks().forEach(track => {
          const sender = pc.addTrack(track, stream)
          if (sender) {
            tracks.current = [...(tracks.current || []), sender]
          }
        })

        // Set up data channel for sending and receiving events
        const dc = pc.createDataChannel('oai-events')
        setDataChannel(dc)

        // Start the session using the Session Description Protocol (SDP)
        const offer = await pc.createOffer()
        await pc.setLocalDescription(offer)

        const sdpResponse = await fetch(
          `${REALTIME_BASE_URL}?model=${REALTIME_MODEL}`,
          {
            method: 'POST',
            body: offer.sdp,
            headers: {
              Authorization: `Bearer ${sessionToken}`,
              'Content-Type': 'application/sdp'
            }
          }
        )

        const answer: RTCSessionDescriptionInit = {
          type: 'answer',
          sdp: await sdpResponse.text()
        }
        await pc.setRemoteDescription(answer)

        peerConnection.current = pc
      }
    } catch (error) {
      console.error('Error starting session:', error)
    }
  }