'use client';

import { useState, useEffect, useMemo, useCallback } from 'react';
import { useAuth } from '@/contexts/AuthContext';
import { useMarket } from '@/contexts/MarketContext';
import { useSearchParams } from 'next/navigation';
import { Mail, Lock, User, AlertCircle, Loader2 } from 'lucide-react';
import { isSupabaseEnabled } from '@/lib/supabase/client';
import { validatePassword, getStrengthColor, getStrengthLabel, getStrengthPercent } from '@/lib/password-validation';

export default function AuthForm() {
  const { market } = useMarket();
  const isUS = market === 'us';
  const [isLogin, setIsLogin] = useState(true);
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState('');
  const { signIn, signUp } = useAuth();
  const searchParams = useSearchParams();
  const passwordCheck = useMemo(() => validatePassword(password), [password]);
  const t = useCallback((tr: string, en: string) => isUS ? en : tr, [isUS]);
  const strengthLabel = isUS
    ? passwordCheck.strength === 'fair'
      ? 'Fair'
      : passwordCheck.strength === 'good'
        ? 'Good'
        : passwordCheck.strength === 'strong'
          ? 'Strong'
          : getStrengthLabel(passwordCheck.strength)
    : getStrengthLabel(passwordCheck.strength)

  // Banned user redirect handling
  useEffect(() => {
    if (searchParams.get('banned') === '1') {
      setError(t('Hesabınız engellenmiştir. Yönetici ile iletişime geçin.', 'Your account has been blocked. Contact the administrator.'));
    }
  }, [searchParams, t]);

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setError('');
    setLoading(true);

    // Validate password strength on signup
    if (!isLogin && !passwordCheck.valid) {
      setError(t('Şifre gereksinimleri: ', 'Password requirements: ') + passwordCheck.errors.join(', '));
      setLoading(false);
      return;
    }

    try {
      const { error } = isLogin
        ? await signIn(email, password)
        : await signUp(email, password);

      if (error) {
        setError(error.message);
      } else {
        if (!isLogin) {
          setError(t('Kayıt başarılı! Lütfen email adresinizi doğrulayın.', 'Registration successful! Please verify your email address.'));
        } else {
          // Wait a moment for @supabase/ssr to persist session cookies before navigating.
          // If cookies don't appear, navigating to a protected route will bounce back to /login.
          const hasSbCookie = () => typeof document !== 'undefined' && document.cookie.includes('sb-')

          let attempts = 0
          while (!hasSbCookie() && attempts < 20) {
            // 20 * 50ms = 1s max
            // eslint-disable-next-line no-await-in-loop
            await new Promise((r) => setTimeout(r, 50))
            attempts += 1
          }

          if (!hasSbCookie()) {
            setError(
              t(
                'Giriş başarılı görünüyor ama oturum cookie yazılamadı. Lütfen siteyi sadece http://localhost:3001 üzerinden açın (127.0.0.1 değil) ve tarayıcıda cookie engeli olmadığından emin olun.',
                'Sign-in appears successful but the session cookie could not be written. Open the site only via http://localhost:3001 (not 127.0.0.1) and make sure cookies are not blocked in the browser.'
              )
            )
            return
          }

          window.location.replace('/');
        }
      }
    } catch (err) {
      setError(t('Bir hata oluştu. Lütfen tekrar deneyin.', 'An error occurred. Please try again.'));
    } finally {
      setLoading(false);
    }
  };

  return (
    <div className="max-w-md mx-auto">
      <div className="bg-white rounded-lg shadow-lg p-8">
        <div className="text-center mb-8">
          <User className="w-12 h-12 text-primary-600 mx-auto mb-4" />
          <h2 className="text-2xl font-bold text-gray-900">
            {isLogin ? t('Giriş Yap', 'Sign In') : t('Kayıt Ol', 'Sign Up')}
          </h2>
          <p className="text-gray-600 mt-2">
            {isLogin
              ? t('Portföyünüze erişmek için giriş yapın', 'Sign in to access your portfolio')
              : t('Yeni bir hesap oluşturun', 'Create a new account')}
          </p>
        </div>

        <form onSubmit={handleSubmit} className="space-y-6">
          {!isSupabaseEnabled && (
            <div className="flex items-start gap-2 p-4 bg-amber-50 border border-amber-200 rounded-lg">
              <AlertCircle className="w-5 h-5 text-amber-700 flex-shrink-0 mt-0.5" />
              <p className="text-sm text-amber-800">
                {t('Giriş/Kayıt devre dışı: Supabase yapılandırılmamış. Netlify/yerel ortamda', 'Sign-in/Sign-up disabled: Supabase is not configured. In Netlify/local environments add')}
                <span className="font-mono"> NEXT_PUBLIC_SUPABASE_URL</span> ve
                <span className="font-mono"> NEXT_PUBLIC_SUPABASE_ANON_KEY</span> {t('değişkenlerini ekleyin.', 'environment variables.')}
              </p>
            </div>
          )}
          <div>
            <label htmlFor="auth-email" className="block text-sm font-medium text-gray-700 mb-2">
              Email
            </label>
            <div className="relative">
              <Mail className="absolute left-3 top-1/2 transform -translate-y-1/2 text-gray-400 w-5 h-5" aria-hidden="true" />
              <input
                id="auth-email"
                type="email"
                value={email}
                onChange={(e) => setEmail(e.target.value)}
                className="w-full pl-10 pr-4 py-3 border border-gray-300 rounded-lg focus:ring-2 focus:ring-primary-500 focus:border-primary-500"
                placeholder="ornek@email.com"
                required
                autoComplete="email"
              />
            </div>
          </div>

          <div>
            <label htmlFor="auth-password" className="block text-sm font-medium text-gray-700 mb-2">
              {t('Şifre', 'Password')}
            </label>
            <div className="relative">
              <Lock className="absolute left-3 top-1/2 transform -translate-y-1/2 text-gray-400 w-5 h-5" aria-hidden="true" />
              <input
                id="auth-password"
                type="password"
                value={password}
                onChange={(e) => setPassword(e.target.value)}
                className="w-full pl-10 pr-4 py-3 border border-gray-300 rounded-lg focus:ring-2 focus:ring-primary-500 focus:border-primary-500"
                placeholder="••••••••"
                required
                minLength={8}
                autoComplete={isLogin ? 'current-password' : 'new-password'}
              />
            </div>
            {!isLogin && password.length > 0 && (
              <div className="mt-2">
                <div className="flex items-center gap-2">
                  <div className="flex-1 h-1.5 bg-gray-200 rounded-full overflow-hidden">
                    <div
                      className={`h-full rounded-full transition-all duration-300 ${getStrengthColor(passwordCheck.strength)}`}
                      style={{ width: `${getStrengthPercent(passwordCheck.strength)}%` }}
                    />
                  </div>
                  <span className="text-xs font-medium text-gray-600">{strengthLabel}</span>
                </div>
                {passwordCheck.errors.length > 0 && (
                  <ul className="mt-1 space-y-0.5">
                    {passwordCheck.errors.map((err, i) => (
                      <li key={i} className="text-xs text-red-500">• {err}</li>
                    ))}
                  </ul>
                )}
              </div>
            )}
            {!isLogin && password.length === 0 && (
              <p className="text-xs text-gray-500 mt-1">{t('En az 8 karakter, büyük harf, küçük harf ve rakam', 'At least 8 characters, uppercase, lowercase, and a number')}</p>
            )}
          </div>

          {error && (
            <div className="flex items-start gap-2 p-4 bg-red-50 border border-red-200 rounded-lg">
              <AlertCircle className="w-5 h-5 text-red-600 flex-shrink-0 mt-0.5" />
              <p className="text-sm text-red-600">{error}</p>
            </div>
          )}

          <button
            type="submit"
            disabled={loading || !isSupabaseEnabled}
            className="w-full bg-primary-600 text-white py-3 rounded-lg hover:bg-primary-700 disabled:bg-gray-300 disabled:cursor-not-allowed flex items-center justify-center gap-2 font-medium"
          >
            {loading ? (
              <>
                <Loader2 className="w-5 h-5 animate-spin" />
                {t('İşlem yapılıyor...', 'Processing...')}
              </>
            ) : isLogin ? (
              t('Giriş Yap', 'Sign In')
            ) : (
              t('Kayıt Ol', 'Sign Up')
            )}
          </button>
        </form>

        <div className="mt-6 text-center">
          <button
            onClick={() => {
              setIsLogin(!isLogin);
              setError('');
            }}
            className="text-primary-600 hover:text-primary-800 font-medium"
          >
            {isLogin
              ? t('Hesabınız yok mu? Kayıt olun', 'Don\'t have an account? Sign up')
              : t('Zaten hesabınız var mı? Giriş yapın', 'Already have an account? Sign in')}
          </button>
        </div>
      </div>
    </div>
  );
}