createLogin = ({ firebaseApp, // Firebase project app that owns the users prepareBackendURL = "https://webcode.run/observablehq.com/@endpointservices/login-with-comment;prepare", verifyBackendURL = "https://webcode.run/observablehq.com/@endpointservices/login-with-comment;verify" } = {}) => { const auth = getAuth(firebaseApp); // When no-one is logged in we want don't want the cell to resolve, so we return a promise // We want that promise to be resolved next time we get a value let firstResolve; const updateResult = () => { const newValue = auth.currentUser; if (firstResolve) { firstResolve(newValue); } if (!newValue) { if (!firstResolve) userUi.value = new Promise((resolve) => (firstResolve = resolve)); else userUi.value = undefined; } else { userUi.value = newValue; } userUi.dispatchEvent( new CustomEvent("input", { bubbles: true, detail: { user: userUi.value || null } }) ); }; const userUi = html`${viewroutine(async function* () { let response; let err = ""; const actionWas = (action) => response && response.actions.includes(action); // On a new page refresh the currentUser is unknown and we have to listen to the auth state change to discover // the initial state. This article explains it well // https://medium.com/firebase-developers/why-is-my-currentuser-null-in-firebase-auth-4701791f74f0 if (!mutable authStateKnown) { let ready = null; const isReady = new Promise((resolve) => (ready = resolve)); onAuthStateChanged(auth, ready); await isReady; mutable authStateKnown = true; } await new Promise((r) => r()); // micro tick so userUi initializes while (true) { try { // update overall view state updateResult(); if (!auth.currentUser) { const loginUi = screen({ auth, actions: ["login"] }); // We need to see if someone logs in via a side channel const unsubscribe = onAuthStateChanged(auth, (user) => { if (user) loginUi.dispatchEvent(new Event("input", { bubbles: true })); }); response = yield* ask(loginUi); unsubscribe(); } else { const logoutUi = screen({ auth, actions: ["logout"] }); // We need to see if someone logout ivia a side channel const unsubscribe = onAuthStateChanged(auth, (user) => { if (!user) logoutUi.dispatchEvent(new Event("input", { bubbles: true })); }); response = yield* ask(logoutUi); unsubscribe(); } if (actionWas("logout")) { console.log("Logging out"); yield screen({ auth, info: md`Logging out...` }); await signOut(auth); } if (actionWas("login")) { console.log("login"); const privateCode = randomId(64); const publicCode = await hash(privateCode); yield screen({ auth, info: md`Preparing...` }); await prepare(publicCode, prepareBackendURL); let relmeauth = false; while (!auth.currentUser) { while (!actionWas("verify")) { console.log("prompt verify"); response = yield* ask( screen({ auth, info: md`1. ${err}Add a comment containing **${publicCode}** to this notebook using the cell burger menu to the left. 2. Click login to complete login.

\n⚠️ Logging in discloses your [Observable](https://observablehq.com/) username to the notebook author. ${actionWas("copy") ? "\ncopied to clipboard" : ""}`, actions: ["copy", "verify"], toggles: [ { code: "profile_relmeauth", label: html`[optional] scan for teams?`, value: relmeauth, caption: html`

how does scanning work?

${md`From your Observablehq profile URL we look for weblinks to team profile URLs, and if those profile URLs also weblink to your profile URL we consider you to have admin access for that team (see [relmeauth](https://observablehq.com/@endpointservices/auth#observable_features))`}

` } ] }) ); if (actionWas("copy")) { navigator.clipboard.writeText( "public auth code: " + publicCode ); } relmeauth = response.profile_relmeauth === true; } console.log("Relmeauth scan?", relmeauth); response = undefined; console.log("verify"); yield screen({ auth, info: md`Checking...` }); try { const verification = await verify({ verifyBackendURL, notebookURL: html``.href.split("?")[0], privateCode, relmeauth }); if (verification.access_token) { await signInWithCustomToken(auth, verification.access_token); } else { debugger; throw new Error("no token returned"); } } catch (error) { debugger; err = `⚠️ ${error.message}\n\n`; } } } } catch (err) { yield* ask( screen({ auth, info: md`Uexpected error: ${err.message}`, actions: ["ok"] }) ); } } })}`; return userUi; }