stack/apps/web/src/spa/pages/login.tsx

import { useEffect, useState, type FormEvent, type ReactElement } from 'react';
import { Link, useNavigate } from 'react-router-dom';
import { SsoProviderButtons } from '@/components/auth/sso-provider-buttons';
import { api } from '@/lib/api';
import { authClient, signIn } from '@/lib/auth-client';
import type { SsoProviderDiscovery } from '@/lib/sso';

export function LoginPage(): ReactElement {
  const navigate = useNavigate();
  const [error, setError] = useState<string | null>(null);
  const [loading, setLoading] = useState(false);
  const [ssoProviders, setSsoProviders] = useState<SsoProviderDiscovery[]>([]);
  const [ssoLoadingProviderId, setSsoLoadingProviderId] = useState<
    SsoProviderDiscovery['id'] | null
  >(null);

  useEffect(() => {
    let active = true;

    void api<SsoProviderDiscovery[]>('/api/sso/providers').then(
      (providers) => {
        if (active) setSsoProviders(providers.filter((provider) => provider.configured));
      },
      () => {
        if (active) setSsoProviders([]);
      },
    );

    return () => {
      active = false;
    };
  }, []);

  async function handleSubmit(event: FormEvent<HTMLFormElement>): Promise<void> {
    event.preventDefault();
    setError(null);
    setLoading(true);

    const form = new FormData(event.currentTarget);
    const email = String(form.get('email') ?? '');
    const password = String(form.get('password') ?? '');

    try {
      const result = await signIn.email({ email, password });

      if (result.error) {
        setError(result.error.message ?? 'Sign in failed');
        return;
      }

      navigate('/chat', { replace: true });
    } catch (caught: unknown) {
      setError(caught instanceof Error ? caught.message : 'Sign in failed');
    } finally {
      setLoading(false);
    }
  }

  async function handleSsoSignIn(providerId: SsoProviderDiscovery['id']): Promise<void> {
    setError(null);
    setSsoLoadingProviderId(providerId);

    try {
      const result = await authClient.signIn.oauth2({
        providerId,
        callbackURL: '/chat',
        newUserCallbackURL: '/chat',
      });

      if (result.error) {
        setError(result.error.message ?? `Sign in with ${providerId} failed`);
        setSsoLoadingProviderId(null);
      }
    } catch (caught: unknown) {
      setError(caught instanceof Error ? caught.message : `Sign in with ${providerId} failed`);
      setSsoLoadingProviderId(null);
    }
  }

  return (
    <div>
      <h1 className="text-2xl font-semibold">Sign in</h1>
      <p className="mt-1 text-sm text-text-secondary">Sign in to your Mosaic account</p>

      {error ? (
        <div
          role="alert"
          className="mt-4 rounded-lg border border-error/30 bg-error/10 px-4 py-3 text-sm text-error"
        >
          {error}
        </div>
      ) : null}

      <form className="mt-6 space-y-4" onSubmit={handleSubmit}>
        <div>
          <label htmlFor="email" className="block text-sm font-medium text-text-secondary">
            Email
          </label>
          <input
            id="email"
            name="email"
            type="email"
            autoComplete="email"
            required
            disabled={loading}
            className="mt-1 block w-full rounded-lg border border-surface-border bg-surface-elevated px-3 py-2 text-sm text-text-primary placeholder:text-text-muted focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:opacity-50"
            placeholder="[email protected]"
          />
        </div>

        <div>
          <label htmlFor="password" className="block text-sm font-medium text-text-secondary">
            Password
          </label>
          <input
            id="password"
            name="password"
            type="password"
            autoComplete="current-password"
            required
            disabled={loading}
            className="mt-1 block w-full rounded-lg border border-surface-border bg-surface-elevated px-3 py-2 text-sm text-text-primary placeholder:text-text-muted focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:opacity-50"
            placeholder="••••••••"
          />
        </div>

        <button
          type="submit"
          disabled={loading}
          className="w-full rounded-lg bg-blue-600 px-4 py-2.5 text-sm font-medium text-white transition-colors hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 focus:ring-offset-surface-card disabled:opacity-50"
        >
          {loading ? 'Signing in...' : 'Sign in'}
        </button>
      </form>

      <SsoProviderButtons
        providers={ssoProviders}
        loadingProviderId={ssoLoadingProviderId}
        onOidcSignIn={(providerId) => {
          void handleSsoSignIn(providerId);
        }}
      />

      <p className="mt-4 text-center text-sm text-text-muted">
        Don&apos;t have an account?{' '}
        <Link to="/register" className="text-blue-400 hover:text-blue-300">
          Sign up
        </Link>
      </p>
    </div>
  );
}