pico.chat/apps/webrtc.js

const getOrCreateRpc = (username) => {
    if(State.username === username) {
        return
    }
    if(!State.rpcs[username]) {

        rpc.onicecandidate = ({candidate}) => {
            if(candidate) {
                wire({kind: 'peerInfo', value: {type: 'candidate', candidate}})
            }
        }
        rpc.ontrack = (e) => {
            State.streams[username] = e.streams[0]
            m.redraw()
        }
        rpc.onclose = (e) => {
            console.log(username, e)
        }
        rpc.oniceconnectionstatechange = (e) => {
            m.redraw()
        }
        State.rpcs[username] = rpc
    }
    return State.rpcs[username]
}
const onPeerInfo = async ({detail: message}) => {
    const localStream = State.streams[State.username]
    const rpc = localStream && getOrCreateRpc(message.source)
    const resetStreams = () => {
        rpc.getSenders().forEach(sender => rpc.removeTrack(sender))
        localStream.getTracks().forEach(track => rpc.addTrack(track, localStream))
    }
    if(rpc && message.value.type === 'request') {
        resetStreams()
        const localOffer = await rpc.createOffer()
        await rpc.setLocalDescription(localOffer)
        wire({kind: 'peerInfo', value: localOffer, target: message.source})
    }
    else if(rpc && message.value.type === 'offer') {
        resetStreams()
        const remoteOffer = new RTCSessionDescription(message.value)
        await rpc.setRemoteDescription(remoteOffer)
        const localAnswer = await rpc.createAnswer()
        await rpc.setLocalDescription(localAnswer)
        wire({kind: 'peerInfo', value: localAnswer, target: message.source})
    }
    else if(rpc && message.value.type === 'answer') {
        const remoteAnswer = new RTCSessionDescription(message.value)
        await rpc.setRemoteDescription(remoteAnswer)
    }
    else if(rpc && message.value.type === 'candidate') {
        const candidate = new RTCIceCandidate(message.value.candidate)
        rpc.addIceCandidate(candidate)
    }
    else if(message.value.type === 'stop') {
        if(State.streams[message.source]) {
            State.streams[message.source].getTracks().map(track => track.stop())
            delete State.streams[message.source]
        }
        if(State.rpcs[message.source]) {
            State.rpcs[message.source].close()
            delete State.rpcs[message.source]
        }
    }
    else if(rpc) {
        console.log('uncaught', message)
    }
}