OAuth

'use server';

import { enhanceAction } from '@kit/next/actions';
import { getSupabaseServerClient } from '@kit/supabase/server-client';
import { z } from 'zod';

const OAuthProviderSchema = z.enum([
  'google',
  'github',
  'gitlab',
  'azure',
  'facebook',
]);

export const signInWithOAuthAction = enhanceAction(
  async (provider) => {
    const client = getSupabaseServerClient();
    const origin = process.env.NEXT_PUBLIC_SITE_URL!;

    const { data, error } = await client.auth.signInWithOAuth({
      provider,
      options: {
        redirectTo: `${origin}/auth/callback`,
      },
    });

    if (error) throw error;

    // Redirect to OAuth provider
    redirect(data.url);
  },
  {
    schema: OAuthProviderSchema,
  }
);

OAuth Callback Handler

// app/auth/callback/route.ts
import { createRouteHandlerClient } from '@supabase/auth-helpers-nextjs';
import { cookies } from 'next/headers';
import { NextResponse } from 'next/server';

export async function GET(request: Request) {
  const requestUrl = new URL(request.url);
  const code = requestUrl.searchParams.get('code');

  if (code) {
    const cookieStore = cookies();
    const supabase = createRouteHandlerClient({ cookies: () => cookieStore });

    await supabase.auth.exchangeCodeForSession(code);
  }

  // Redirect to home page
  return NextResponse.redirect(new URL('/home', request.url));
}

Customizing OAuth Flow

Scopes

Request specific permissions:

await client.auth.signInWithOAuth({
  provider: 'google',
  options: {
    scopes: 'email profile https://www.googleapis.com/auth/calendar',
  },
});

Query Parameters

Pass custom parameters:

await client.auth.signInWithOAuth({
  provider: 'azure',
  options: {
    queryParams: {
      prompt: 'consent',
      access_type: 'offline',
    },
  },
});

Skip Browser Redirect

For mobile apps or custom flows:

const { data } = await client.auth.signInWithOAuth({
  provider: 'google',
  options: {
    skipBrowserRedirect: true,
  },
});

// data.url contains the OAuth URL
// Handle redirect manually

Account Linking

Linking Additional Providers

Allow users to link multiple OAuth accounts:

export const linkOAuthProviderAction = enhanceAction(
  async (provider) => {
    const client = getSupabaseServerClient();
    const user = await requireAuth();

    const { data, error } = await client.auth.linkIdentity({
      provider,
    });

    if (error) throw error;

    redirect(data.url);
  },
  { schema: OAuthProviderSchema, auth: true }
);

Unlinking Providers

export const unlinkOAuthProviderAction = enhanceAction(
  async ({ provider, identityId }) => {
    const client = getSupabaseServerClient();

    const { error } = await client.auth.unlinkIdentity({
      identity_id: identityId,
    });

    if (error) throw error;

    revalidatePath('/settings/security');
  },
  {
    schema: z.object({
      provider: z.string(),
      identityId: z.string(),
    }),
    auth: true,
  }
);

Viewing Linked Identities

import { getSupabaseServerClient } from '@kit/supabase/server-client';

export async function getLinkedIdentities() {
  const client = getSupabaseServerClient();
  const { data: { user } } = await client.auth.getUser();

  return user?.identities || [];
}

User Data from OAuth

Accessing Provider Data

const { data: { user } } = await client.auth.getUser();

// User metadata from provider
const {
  full_name,
  avatar_url,
  email,
} = user.user_metadata;

// Provider-specific data
const identities = user.identities || [];
const googleIdentity = identities.find(i => i.provider === 'google');

console.log(googleIdentity?.identity_data);

Storing Additional Data

export const completeOAuthProfileAction = enhanceAction(
  async (data) => {
    const client = getSupabaseServerClient();
    const user = await requireAuth();

    // Update user metadata
    await client.auth.updateUser({
      data: {
        username: data.username,
        bio: data.bio,
      },
    });

    // Update profile in database
    await client.from('profiles').upsert({
      id: user.id,
      username: data.username,
      bio: data.bio,
      avatar_url: user.user_metadata.avatar_url,
    });

    redirect('/home');
  },
  { schema: ProfileSchema, auth: true }
);

Configuration

Enable OAuth in Config

// config/auth.config.ts
export const authConfig = {
  providers: {
    emailPassword: true,
    oAuth: ['google', 'github'],
  },
};

Conditional Rendering

import { authConfig } from '~/config/auth.config';

export function AuthProviders() {
  return (
    <>
      {authConfig.providers.emailPassword && <EmailPasswordForm />}

      {authConfig.providers.oAuth?.includes('google') && (
        <GoogleSignInButton />
      )}

      {authConfig.providers.oAuth?.includes('github') && (
        <GitHubSignInButton />
      )}
    </>
  );
}

Troubleshooting

Redirect URI Mismatch

Ensure redirect URIs match exactly:

• Check Supabase Dashboard → Authentication → URL Configuration
• Verify OAuth app settings in provider console
• Use exact URLs (including http/https)

Missing Email

Some providers don't share email by default:

const { data: { user } } = await client.auth.getUser();

if (!user.email) {
  // Request email separately or prompt user
  redirect('/auth/complete-profile');
}

Rate Limiting

OAuth providers may rate limit requests:

• Cache OAuth tokens appropriately
• Don't make excessive authorization requests
• Handle rate limit errors gracefully

Best Practices

1. Request minimum scopes - Only ask for what you need
2. Handle errors gracefully - OAuth can fail for many reasons
3. Verify email addresses - Some providers don't verify emails
4. Support account linking - Let users connect multiple providers
5. Provide fallback - Always offer email/password as backup
6. Log OAuth events - Track sign-ins and linking attempts
7. Test thoroughly - Test with real provider accounts