hanzo.ai/components/auth/opened.tsx

'use client'
// The sign-in link from the email, opened (lib/auth/link). It lands on the
// callback with its address and code in the fragment, and:
//
//   a tab here waits on it   the tab takes the code and finishes the sign-in it
//                            began; this one follows it in once it has
//   this browser asked       no tab waits, so the sign-in finishes here
//   anywhere else            the code, to type where the sign-in began, and a
//                            press to sign in here instead
//
// Nothing is spent on arrival anywhere but the browser that asked, so a mail
// scanner that opens the link signs nobody in.

import { useEffect, useRef, useState } from 'react'
import { SignupRequired } from '@hanzo/iam'
import { useI18n } from '@hanzo/i18n/react'
import { Text } from '@hanzo/ui'
import { Action } from '@hanzo/ui/marketing'
import { Focus, LARGE, Wait } from '@/components/shell/focus'
import { markMethod } from '@hanzo/app/lib/intent'
import { authorize } from '@hanzo/app/lib/tags'
import { useClient } from '@hanzo/app/lib/signout'
import { Sheet, said, Wrong } from '@/components/auth/steps'
import { CHANNEL, type Handed, marked, unmark, WAIT } from '@/lib/auth/link'
import { AUP_VERSION, TERMS_VERSION } from '@hanzo/app/lib/terms'

const POLICY = { terms: TERMS_VERSION, aup: AUP_VERSION }

/** Where the access token is kept: written by whichever tab signs in. */
const TOKEN = 'hanzo_iam_access_token'

type State = 'asking' | 'taken' | 'shown'

export function Opened({ handed }: { handed: Handed }) {
  const { t } = useI18n()
  const iam = useClient()
  const [state, setState] = useState<State>('asking')
  const [busy, setBusy] = useState(false)
  const [wrong, setWrong] = useState<string | null>(null)
  const asked = useRef(false)

  /** The sign-in, finished in this tab. */
  async function here() {
    setBusy(true)
    setWrong(null)
    try {
      const to = await iam.loginWithCode(handed.email, handed.code)
      unmark()
      markMethod('code')
      window.location.assign(authorize(to))
    } catch (err) {
      if (err instanceof SignupRequired) {
        try {
          const to = await iam.createAccountWithCode(handed.email, handed.code, POLICY)
          unmark()
          markMethod('code')
          window.location.assign(authorize(to))
          return
        } catch (createErr) {
          setWrong(said(createErr, t))
        }
      } else {
        setWrong(said(err, t))
      }
      setBusy(false)
      setState('shown')
    }
  }

  useEffect(() => {
    if (asked.current) return
    asked.current = true
    // The code leaves the address bar and the history.
    window.history.replaceState(null, '', window.location.pathname + window.location.search)
    const channel = typeof BroadcastChannel === 'undefined' ? null : new BroadcastChannel(CHANNEL)
    const timer = setTimeout(() => {
      channel?.close()
      if (marked(handed.email)) void here()
      else setState('shown')
    }, WAIT)
    if (channel) {
      channel.onmessage = (e: MessageEvent) => {
        if ((e.data as { taken?: string } | null)?.taken !== handed.code) return
        clearTimeout(timer)
        channel.close()
        setState('taken')
      }
      channel.postMessage(handed)
    }
    // Once, on arrival.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [])

  // The tab that took the code signs in; this one follows it into the app.
  useEffect(() => {
    if (state !== 'taken') return
    const on = (e: StorageEvent) => {
      if (e.key === TOKEN && e.newValue) window.location.replace('/')
    }
    window.addEventListener('storage', on)
    return () => window.removeEventListener('storage', on)
  }, [state])

  // The focused page (components/shell/focus), as every step of the way in.
  if (state !== 'shown') return <Wait title={t('Signing you in')} line={state === 'taken' ? t('On the tab where you started.') : undefined} />
  // The code reads left to right in any language (`data-i18n-ltr`).
  return (
    <Focus id="code-title" title={t('Your sign-in code')} line={t('Enter this code in the tab where you started signing in.')}>
      <Sheet label={t('Your code')}>
        <Text render="p" m={0} fontFamily="$mono" fontSize="$9" fontWeight="600" letterSpacing={6} color="$ink" text="center" aria-label={t('Verification code')} data-i18n-ltr>
          {handed.code}
        </Text>
        <Wrong text={wrong} />
        <Action render="button" type="button" fill disabled={busy} onClick={() => void here()} {...LARGE}>
          {t(busy ? 'One moment…' : 'Sign in on this device instead')}
        </Action>
      </Sheet>
    </Focus>
  )
}