init commit,

99_references/supabase-examples/realtime/nextjs-auth-presence/pages/_app.tsx

@@ -0,0 +1,43 @@
+import { createBrowserSupabaseClient, Session } from '@supabase/auth-helpers-nextjs'
+import { SessionContextProvider } from '@supabase/auth-helpers-react'
+import type { AppProps } from 'next/app'
+import { useRouter } from 'next/router'
+import { useEffect, useState } from 'react'
+import '../styles/globals.css'
+
+function MyApp({
+  Component,
+  pageProps,
+}: AppProps<{
+  initialSession: Session
+}>) {
+  const router = useRouter()
+  const [supabaseClient] = useState(() => createBrowserSupabaseClient())
+
+  useEffect(() => {
+    const {
+      data: { subscription },
+    } = supabaseClient.auth.onAuthStateChange((event, session) => {
+      switch (event) {
+        case 'SIGNED_IN':
+          router.push('/')
+          return
+        case 'SIGNED_OUT':
+          router.push('/login')
+          return
+      }
+    })
+    return subscription.unsubscribe
+  }, [])
+
+  return (
+    <SessionContextProvider
+      supabaseClient={supabaseClient}
+      initialSession={pageProps.initialSession}
+    >
+      <Component {...pageProps} />
+    </SessionContextProvider>
+  )
+}
+
+export default MyApp