'use client';

import { useState } from 'react';
import { signIn } from 'next-auth/react';
import { useRouter, useSearchParams } from 'next/navigation';
import Link from 'next/link';
import { useTranslations } from 'next-intl';

interface Props {
  hasOidc: boolean;
  oidcLabel: string;
  hasGoogle: boolean;
  hasGitHub: boolean;
}

export default function LoginClient({ hasOidc, oidcLabel, hasGoogle, hasGitHub }: Props) {
  const t = useTranslations('auth.login');
  const router = useRouter();
  const params = useSearchParams();
  const callbackUrl = params.get('callbackUrl') ?? '/';
  const resetSuccess = params.get('reset') === '1';
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [error, setError] = useState<string | null>(null);
  const [loading, setLoading] = useState(false);

  const handleCredentials = async (e: React.FormEvent) => {
    e.preventDefault();
    setLoading(true);
    setError(null);
    const res = await signIn('credentials', {
      email,
      password,
      redirect: false,
    });
    setLoading(false);
    if (res?.error) {
      setError(t('error'));
    } else {
      await migrateThenRedirect(callbackUrl, router);
    }
  };

  return (
    <main style={styles.page}>
      <h1 style={styles.heading}>{t('title')}</h1>
      {resetSuccess && (
        <p role="status" style={styles.success}>{t('resetSuccess')}</p>
      )}
      <form onSubmit={handleCredentials} style={styles.form} noValidate>
        <label style={styles.label} htmlFor="email">{t('email')}</label>
        <input
          id="email"
          type="email"
          value={email}
          onChange={(e) => setEmail(e.target.value)}
          required
          autoComplete="email"
          style={styles.input}
        />
        <label style={styles.label} htmlFor="password">{t('password')}</label>
        <input
          id="password"
          type="password"
          value={password}
          onChange={(e) => setPassword(e.target.value)}
          required
          autoComplete="current-password"
          style={styles.input}
        />
        {error && <p role="alert" style={styles.error}>{error}</p>}
        <button type="submit" disabled={loading} style={styles.btn}>
          {loading ? t('submitting') : t('submit')}
        </button>
        <Link href="/auth/forgot-password" style={styles.forgotLink}>{t('forgotPassword')}</Link>
      </form>

      {(hasGoogle || hasGitHub || hasOidc) && <div style={styles.divider}><span>{t('or')}</span></div>}

      <div style={styles.oauthGroup}>
        {hasGoogle && (
          <button type="button" onClick={() => signIn('google', { callbackUrl })} style={styles.oauthBtn}>
            {t('continueWithGoogle')}
          </button>
        )}
        {hasGitHub && (
          <button type="button" onClick={() => signIn('github', { callbackUrl })} style={styles.oauthBtn}>
            {t('continueWithGitHub')}
          </button>
        )}
        {hasOidc && (
          <button type="button" onClick={() => signIn('authentik', { callbackUrl })} style={styles.oauthBtn}>
            {t('continueWith', { provider: oidcLabel })}
          </button>
        )}
      </div>

      <p style={styles.footer}>
        {t('noAccount')}{' '}
        <Link href="/auth/register" style={styles.link}>{t('register')}</Link>
      </p>
    </main>
  );
}

async function migrateThenRedirect(callbackUrl: string, router: ReturnType<typeof useRouter>) {
  const anonId = sessionStorage.getItem('curio_uid');
  if (anonId) {
    try {
      await fetch('/api/auth/migrate-session', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ anonUserId: anonId }),
      });
      sessionStorage.removeItem('curio_uid');
    } catch {
      // non-blocking
    }
  }
  // Sync saved locale preference to cookie so UI reflects user's language
  try {
    const localeRes = await fetch('/api/user/locale');
    if (localeRes.ok) {
      const { locale } = (await localeRes.json()) as { locale: string };
      document.cookie = `NEXT_LOCALE=${locale};path=/;max-age=${60 * 60 * 24 * 365};samesite=lax`;
    }
  } catch {
    // non-blocking
  }
  router.refresh();
  router.push(callbackUrl);
}

const styles = {
  page: {
    display: 'flex',
    flexDirection: 'column' as const,
    alignItems: 'center',
    minHeight: '100svh',
    padding: 'var(--space-8)',
    paddingTop: 'var(--space-16)',
    gap: 'var(--space-4)',
  },
  heading: {
    fontFamily: 'var(--font-display)',
    fontSize: '1.5rem',
    fontWeight: 500,
    color: 'var(--color-ink)',
    marginBottom: 'var(--space-4)',
  },
  form: {
    width: '100%',
    maxWidth: '26rem',
    display: 'flex',
    flexDirection: 'column' as const,
    gap: 'var(--space-2)',
  },
  label: {
    fontFamily: 'var(--font-display)',
    fontSize: '0.875rem',
    fontWeight: 500,
    color: 'var(--color-ink)',
    marginTop: 'var(--space-3)',
  },
  input: {
    width: '100%',
    padding: 'var(--space-3) var(--space-4)',
    background: 'var(--color-surface)',
    border: '1px solid var(--color-border)',
    borderRadius: '4px',
    fontFamily: 'var(--font-body)',
    fontSize: '1rem',
    color: 'var(--color-ink)',
    outline: 'none',
  },
  error: {
    color: 'var(--color-misconception)',
    fontSize: '0.875rem',
    margin: 0,
  },
  btn: {
    marginTop: 'var(--space-4)',
    padding: 'var(--space-3) var(--space-6)',
    background: 'var(--color-accent)',
    color: 'var(--color-on-accent)',
    border: 'none',
    borderRadius: '4px',
    fontFamily: 'var(--font-display)',
    fontSize: '0.9375rem',
    fontWeight: 500,
    cursor: 'pointer',
  },
  divider: {
    width: '100%',
    maxWidth: '26rem',
    display: 'flex',
    alignItems: 'center',
    gap: 'var(--space-3)',
    color: 'var(--color-ink-faint)',
    fontSize: '0.875rem',
    marginTop: 'var(--space-2)',
  },
  oauthGroup: {
    width: '100%',
    maxWidth: '26rem',
    display: 'flex',
    flexDirection: 'column' as const,
    gap: 'var(--space-2)',
  },
  oauthBtn: {
    width: '100%',
    padding: 'var(--space-3) var(--space-4)',
    background: 'var(--color-surface)',
    border: '1px solid var(--color-border)',
    borderRadius: '4px',
    fontFamily: 'var(--font-display)',
    fontSize: '0.9375rem',
    color: 'var(--color-ink)',
    cursor: 'pointer',
  },
  footer: {
    fontSize: '0.875rem',
    color: 'var(--color-ink-muted)',
    marginTop: 'var(--space-4)',
  },
  link: {
    color: 'var(--color-accent)',
    textDecoration: 'none',
  },
  forgotLink: {
    color: 'var(--color-ink-muted)',
    fontSize: '0.8125rem',
    textDecoration: 'none',
    textAlign: 'right' as const,
    marginTop: 'var(--space-1)',
  },
  success: {
    width: '100%',
    maxWidth: '26rem',
    padding: 'var(--space-3) var(--space-4)',
    background: 'var(--color-mastered-subtle)',
    color: 'var(--color-mastered)',
    borderRadius: '4px',
    fontSize: '0.875rem',
    margin: 0,
  },
} as const;