import { useState, useEffect } from 'react';
import { useNavigate } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import { Shield, Eye, EyeOff, Lock, User, Fingerprint, KeyRound, AlertCircle } from 'lucide-react';
import { useAuth, type UserRole } from '@/app/auth/AuthContext';

/*
 * SFR-01: 시스템 로그인 및 권한 관리
 * - 해양경찰 SSO·공무원증·GPKI 등 기존 인증체계 로그인 연동
 * - 역할 기반 권한 관리(RBAC)
 * - 비밀번호 정책, 계정 잠금 정책
 * - 감사 로그 기록
 * - 5회 연속 실패 시 계정 잠금(30분)
 */

type AuthMethod = 'password' | 'gpki' | 'sso';

// SFR-01: 시뮬레이션 계정 (역할별)
const DEMO_ACCOUNTS: Record<string, { pw: string; name: string; rank: string; org: string; role: UserRole }> = {
  admin:    { pw: 'admin1234!', name: '김영수', rank: '사무관', org: '본청 정보통신과', role: 'ADMIN' },
  operator: { pw: 'oper12345!', name: '이상호', rank: '경위', org: '서해지방해경청', role: 'OPERATOR' },
  analyst:  { pw: 'anal12345!', name: '정해진', rank: '주무관', org: '남해지방해경청', role: 'ANALYST' },
  field:    { pw: 'field1234!', name: '박민수', rank: '경사', org: '5001함 삼봉', role: 'FIELD' },
  viewer:   { pw: 'view12345!', name: '최원석', rank: '6급', org: '해수부 어업관리과', role: 'VIEWER' },
};

const MAX_LOGIN_ATTEMPTS = 5;
const LOCKOUT_DURATION = 30 * 60 * 1000; // 30분

export function LoginPage() {
  const { t } = useTranslation('auth');
  const navigate = useNavigate();
  const { user, login } = useAuth();
  const [authMethod, setAuthMethod] = useState<AuthMethod>('password');
  const [userId, setUserId] = useState('');
  const [password, setPassword] = useState('');
  const [showPw, setShowPw] = useState(false);
  const [error, setError] = useState('');
  const [loading, setLoading] = useState(false);
  const [failCount, setFailCount] = useState(0);
  const [lockedUntil, setLockedUntil] = useState<number | null>(null);

  // user 상태가 확정된 후 대시보드로 이동
  useEffect(() => {
    if (user) navigate('/dashboard', { replace: true });
  }, [user, navigate]);

  const doLogin = (method: AuthMethod, account?: typeof DEMO_ACCOUNTS[string]) => {
    const u = account || DEMO_ACCOUNTS['operator'];
    login({
      id: userId || u.role,
      name: u.name,
      rank: u.rank,
      org: u.org,
      role: u.role,
      authMethod: method,
      loginAt: new Date().toISOString().replace('T', ' ').slice(0, 19),
    });
  };

  const handleLogin = (e: React.FormEvent) => {
    e.preventDefault();
    setError('');

    // SFR-01: 계정 잠금 확인
    if (lockedUntil && Date.now() < lockedUntil) {
      const remainMin = Math.ceil((lockedUntil - Date.now()) / 60000);
      setError(t('error.locked', { minutes: remainMin }));
      return;
    }

    if (authMethod === 'password') {
      if (!userId.trim()) { setError(t('error.emptyId')); return; }
      if (!password.trim()) { setError(t('error.emptyPassword')); return; }
      if (password.length < 9) { setError(t('error.invalidPassword')); return; }
    }

    setLoading(true);
    setTimeout(() => {
      setLoading(false);

      // SFR-01: ID/PW 인증 시 계정 검증
      const account = DEMO_ACCOUNTS[userId.toLowerCase()];
      if (authMethod === 'password' && (!account || account.pw !== password)) {
        const newCount = failCount + 1;
        setFailCount(newCount);
        if (newCount >= MAX_LOGIN_ATTEMPTS) {
          setLockedUntil(Date.now() + LOCKOUT_DURATION);
          setError(t('error.maxFailed', { max: MAX_LOGIN_ATTEMPTS }));
        } else {
          setError(t('error.wrongCredentials', { count: newCount, max: MAX_LOGIN_ATTEMPTS }));
        }
        return;
      }

      setFailCount(0);
      setLockedUntil(null);
      doLogin(authMethod, account);
    }, 1200);
  };

  const DEMO_ROLE_LABELS: Record<UserRole, string> = {
    ADMIN: t('demo.admin'),
    OPERATOR: t('demo.operator'),
    ANALYST: t('demo.analyst'),
    FIELD: t('demo.field'),
    VIEWER: t('demo.viewer'),
  };

  const authMethods: { key: AuthMethod; icon: React.ElementType; label: string; desc: string }[] = [
    { key: 'password', icon: Lock, label: t('authMethod.password'), desc: t('authMethod.passwordDesc') },
    { key: 'gpki', icon: Fingerprint, label: t('authMethod.gpki'), desc: t('authMethod.gpkiDesc') },
    { key: 'sso', icon: KeyRound, label: t('authMethod.sso'), desc: t('authMethod.ssoDesc') },
  ];

  return (
    <div className="min-h-screen bg-background flex items-center justify-center relative overflow-hidden">
      {/* 배경 그리드 */}
      <div className="absolute inset-0 opacity-[0.03]" style={{
        backgroundImage: 'linear-gradient(#3b82f6 1px, transparent 1px), linear-gradient(90deg, #3b82f6 1px, transparent 1px)',
        backgroundSize: '60px 60px',
      }} />

      {/* 로그인 카드 */}
      <div className="relative z-10 w-full max-w-md mx-4">
        {/* 로고 영역 */}
        <div className="text-center mb-8">
          <div className="inline-flex items-center justify-center w-16 h-16 rounded-2xl bg-blue-600/20 border border-blue-500/30 mb-4">
            <Shield className="w-8 h-8 text-blue-400" />
          </div>
          <h1 className="text-xl font-bold text-heading">{t('title')}</h1>
          <p className="text-[11px] text-hint mt-1">{t('subtitle')}</p>
        </div>

        <div className="bg-card border border-border rounded-2xl shadow-2xl shadow-black/40 overflow-hidden">
          {/* 인증 방식 선택 탭 */}
          <div className="flex border-b border-border">
            {authMethods.map((m) => (
              <button
                key={m.key}
                onClick={() => { setAuthMethod(m.key); setError(''); }}
                className={`flex-1 flex flex-col items-center gap-1 py-3 transition-colors ${
                  authMethod === m.key
                    ? 'bg-blue-600/10 border-b-2 border-blue-500 text-blue-400'
                    : 'text-hint hover:bg-surface-overlay hover:text-label'
                }`}
              >
                <m.icon className="w-4 h-4" />
                <span className="text-[9px] font-medium whitespace-nowrap">{m.label}</span>
              </button>
            ))}
          </div>

          <div className="p-6">
            {/* ID/PW 로그인 */}
            {authMethod === 'password' && (
              <form onSubmit={handleLogin} className="space-y-4">
                <div>
                  <label className="text-[10px] text-muted-foreground font-medium mb-1 block whitespace-nowrap">{t('form.userId')}</label>
                  <div className="relative">
                    <User className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-hint" />
                    <input
                      type="text"
                      value={userId}
                      onChange={(e) => setUserId(e.target.value)}
                      placeholder={t('form.userIdPlaceholder')}
                      className="w-full bg-surface-overlay border border-slate-700/50 rounded-lg pl-10 pr-4 py-2.5 text-sm text-heading placeholder:text-hint focus:outline-none focus:border-blue-500/60 focus:ring-1 focus:ring-blue-500/20"
                      autoComplete="username"
                    />
                  </div>
                </div>

                <div>
                  <label className="text-[10px] text-muted-foreground font-medium mb-1 block whitespace-nowrap">{t('form.password')}</label>
                  <div className="relative">
                    <Lock className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-hint" />
                    <input
                      type={showPw ? 'text' : 'password'}
                      value={password}
                      onChange={(e) => setPassword(e.target.value)}
                      placeholder={t('form.passwordPlaceholder')}
                      className="w-full bg-surface-overlay border border-slate-700/50 rounded-lg pl-10 pr-10 py-2.5 text-sm text-heading placeholder:text-hint focus:outline-none focus:border-blue-500/60 focus:ring-1 focus:ring-blue-500/20"
                      autoComplete="current-password"
                    />
                    <button
                      type="button"
                      onClick={() => setShowPw(!showPw)}
                      className="absolute right-3 top-1/2 -translate-y-1/2 text-hint hover:text-muted-foreground"
                    >
                      {showPw ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
                    </button>
                  </div>
                </div>

                {/* 비밀번호 정책 안내 */}
                <div className="bg-surface-overlay rounded-lg p-3 space-y-1">
                  <div className="text-[9px] text-hint font-medium">{t('passwordPolicy.title')}</div>
                  <ul className="text-[9px] text-hint space-y-0.5">
                    <li>{t('passwordPolicy.minLength')}</li>
                    <li>{t('passwordPolicy.changeInterval')}</li>
                    <li>{t('passwordPolicy.lockout')}</li>
                    <li>{t('passwordPolicy.reuse')}</li>
                  </ul>
                </div>

                {error && (
                  <div className="flex items-center gap-2 text-red-400 text-[11px] bg-red-500/10 border border-red-500/20 rounded-lg px-3 py-2">
                    <AlertCircle className="w-3.5 h-3.5 shrink-0" />
                    {error}
                  </div>
                )}

                <button
                  type="submit"
                  disabled={loading}
                  className="w-full py-2.5 bg-blue-600 hover:bg-blue-500 disabled:bg-blue-600/50 text-heading text-sm font-bold rounded-lg transition-colors flex items-center justify-center gap-2 whitespace-nowrap"
                >
                  {loading ? (
                    <>
                      <div className="w-4 h-4 border-2 border-white/30 border-t-white rounded-full animate-spin" />
                      {t('button.authenticating')}
                    </>
                  ) : t('button.login')}
                </button>

                {/* 데모 퀵로그인 */}
                <div className="pt-2 border-t border-border">
                  <div className="text-[9px] text-hint text-center mb-2">{t('demo.title')}</div>
                  <div className="grid grid-cols-5 gap-1.5">
                    {Object.entries(DEMO_ACCOUNTS).map(([key, acct]) => (
                      <button
                        key={key}
                        type="button"
                        onClick={() => doLogin('password', acct)}
                        className="py-1.5 rounded-md text-[9px] font-medium bg-surface-overlay border border-border text-muted-foreground hover:text-heading hover:bg-switch-background/60 transition-colors whitespace-nowrap"
                      >
                        {DEMO_ROLE_LABELS[acct.role]}
                      </button>
                    ))}
                  </div>
                </div>
              </form>
            )}

            {/* GPKI 인증 */}
            {authMethod === 'gpki' && (
              <div className="space-y-4">
                <div className="text-center py-6">
                  <Fingerprint className="w-12 h-12 text-blue-400 mx-auto mb-3" />
                  <p className="text-sm text-heading font-medium">{t('gpki.title')}</p>
                  <p className="text-[10px] text-hint mt-1">{t('gpki.desc')}</p>
                </div>

                <div className="bg-surface-overlay rounded-lg p-4 border border-dashed border-slate-700/50">
                  <div className="text-center">
                    <div className="text-[10px] text-hint mb-2">{t('gpki.certStatus')}</div>
                    <div className="flex items-center justify-center gap-2">
                      <div className="w-2 h-2 rounded-full bg-yellow-500 animate-pulse" />
                      <span className="text-[11px] text-yellow-400">{t('gpki.certWaiting')}</span>
                    </div>
                  </div>
                </div>

                <button
                  onClick={() => { setLoading(true); setTimeout(() => { setLoading(false); doLogin('gpki', DEMO_ACCOUNTS['operator']); }, 1500); }}
                  disabled={loading}
                  className="w-full py-2.5 bg-blue-600 hover:bg-blue-500 disabled:bg-blue-600/50 text-heading text-sm font-bold rounded-lg transition-colors flex items-center justify-center gap-2 whitespace-nowrap"
                >
                  {loading ? (
                    <><div className="w-4 h-4 border-2 border-white/30 border-t-white rounded-full animate-spin" />{t('gpki.authenticating')}</>
                  ) : t('gpki.start')}
                </button>

                <p className="text-[9px] text-hint text-center">
                  {t('gpki.internalOnly')}
                </p>
              </div>
            )}

            {/* SSO 연동 */}
            {authMethod === 'sso' && (
              <div className="space-y-4">
                <div className="text-center py-6">
                  <KeyRound className="w-12 h-12 text-green-400 mx-auto mb-3" />
                  <p className="text-sm text-heading font-medium">{t('sso.title')}</p>
                  <p className="text-[10px] text-hint mt-1">{t('sso.desc')}</p>
                </div>

                <div className="bg-green-900/20 border border-green-700/30 rounded-lg p-3">
                  <div className="flex items-center gap-2 text-[10px] text-green-400">
                    <Shield className="w-3.5 h-3.5" />
                    {t('sso.tokenDetected')}
                  </div>
                </div>

                <button
                  onClick={() => { setLoading(true); setTimeout(() => { setLoading(false); doLogin('sso', DEMO_ACCOUNTS['operator']); }, 800); }}
                  disabled={loading}
                  className="w-full py-2.5 bg-green-600 hover:bg-green-500 disabled:bg-green-600/50 text-heading text-sm font-bold rounded-lg transition-colors flex items-center justify-center gap-2 whitespace-nowrap"
                >
                  {loading ? (
                    <><div className="w-4 h-4 border-2 border-white/30 border-t-white rounded-full animate-spin" />{t('sso.authenticating')}</>
                  ) : t('sso.autoLogin')}
                </button>

                <p className="text-[9px] text-hint text-center">
                  {t('sso.sessionNote')}
                </p>
              </div>
            )}
          </div>

          {/* 하단 정보 */}
          <div className="px-6 py-3 bg-background border-t border-border">
            <div className="flex items-center justify-between text-[8px] text-hint">
              <span>{t('footer.version')}</span>
              <span>{t('footer.org')}</span>
            </div>
          </div>
        </div>

        {/* 접근 권한 안내 */}
        <div className="mt-4 text-center">
          <p className="text-[9px] text-hint">
            {t('accessNotice')}
          </p>
        </div>
      </div>
    </div>
  );
}