import { useEffect, useState, type FormEvent } from 'react';
import { CheckCircle2, Eye, EyeOff } from 'lucide-react';
import ReactMarkdown from 'react-markdown';
import remarkGfm from 'remark-gfm';
import { BrandMark } from '../../components/BrandMark';
import { loginInstructor } from '../../lib/auth';
import type { AuthSession } from '../../types/auth';

type LoginPageProps = {
  onLogin: (session: AuthSession) => void;
};

const REMEMBERED_EMAIL_STORAGE_KEY = 'atnmy.lms.admin.login.rememberedEmail';
const DEFAULT_EMAIL = '';
const DEFAULT_PASSWORD = '';
const AUTH_BASE_URL = (import.meta.env.VITE_ATNMY_AUTH_URL ?? import.meta.env.VITE_ADS_IDE_AUTH_URL ?? 'https://auth.autonomystudio.net').replace(/\/+$/, '');
const LAUNCHER_API_BASE_URL = (import.meta.env.VITE_LAUNCHER_API_BASE_URL ?? 'https://portal-api.autonomystudio.net/api').replace(/\/+$/, '');
const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

export function LoginPage({ onLogin }: LoginPageProps) {
  const rememberedEmail = window.localStorage.getItem(REMEMBERED_EMAIL_STORAGE_KEY);
  const [email, setEmail] = useState(rememberedEmail ?? DEFAULT_EMAIL);
  const [password, setPassword] = useState(DEFAULT_PASSWORD);
  const [rememberEmail, setRememberEmail] = useState(Boolean(rememberedEmail));
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState('');
  const [showSignup, setShowSignup] = useState(false);
  const [signupNotice, setSignupNotice] = useState('');

  const handleSubmit = async (event: FormEvent<HTMLFormElement>) => {
    event.preventDefault();
    setLoading(true);
    setError('');

    try {
      const session = await loginInstructor(email, password);
      if (rememberEmail) {
        window.localStorage.setItem(REMEMBERED_EMAIL_STORAGE_KEY, email);
      } else {
        window.localStorage.removeItem(REMEMBERED_EMAIL_STORAGE_KEY);
      }
      onLogin(session);
    } catch (loginError) {
      setError(loginError instanceof Error ? loginError.message : '로그인에 실패했습니다.');
    } finally {
      setLoading(false);
    }
  };

  return (
    <main className="grid min-h-screen bg-white text-[#111827] lg:grid-cols-[minmax(420px,58%)_minmax(360px,42%)]">
      <section className="relative flex min-h-[42vh] overflow-hidden bg-[linear-gradient(145deg,#3b82f6_0%,#7048e8_54%,#4f46e5_100%)] px-7 py-8 text-white sm:px-12 lg:min-h-screen lg:px-[60px]">
        <div className="absolute inset-0 opacity-25">
          <div className="absolute left-[14%] top-[18%] h-40 w-40 rounded-full bg-white blur-3xl" />
          <div className="absolute bottom-[18%] right-[12%] h-56 w-56 rounded-full bg-[#93c5fd] blur-3xl" />
        </div>

        <div className="relative z-10 flex w-full max-w-[580px] flex-col">
          <BrandMark />

          <div className="my-auto py-12 lg:py-0">
            <p className="mb-4 text-[11px] font-extrabold uppercase tracking-[0.16em] text-white/70">Learning Management System</p>
            <h1 className="max-w-[520px] text-[34px] font-black leading-[1.12] tracking-[0] sm:text-[44px]">
              <span className="text-[#67e8f9]">자율주행</span> 교육 플랫폼
            </h1>
            <p className="mt-5 max-w-[410px] text-[14px] font-bold leading-6 text-white/82">
              실제 하드웨어와 시뮬레이션을 활용한 차세대 학습 관리 시스템
            </p>

            <div className="mt-8 grid max-w-[410px] gap-2.5 rounded-xl bg-white/12 p-4 ring-1 ring-white/18 backdrop-blur">
              {['실시간 모니터링 및 통합 관리', '하드웨어 플랫폼 상태 추적', 'AI 가이드 에스컬레이션'].map((item) => (
                <div className="flex items-center gap-3 text-[12px] font-bold text-white/88" key={item}>
                  <CheckCircle2 size={16} aria-hidden="true" />
                  {item}
                </div>
              ))}
            </div>
          </div>

          <p className="text-[12px] font-bold text-white/55">© 2026. All rights reserved.</p>
        </div>
      </section>

      <section className="flex min-h-[58vh] items-center justify-center px-7 py-10 sm:px-12 lg:min-h-screen">
        <div className="w-full max-w-[420px]">
          {showSignup ? (
            <InstructorSignupForm
              onCancel={() => setShowSignup(false)}
              onComplete={(registeredEmail) => {
                setEmail(registeredEmail);
                setShowSignup(false);
                setSignupNotice('회원가입이 완료되었습니다. 강사 계정으로 로그인할 수 있습니다.');
              }}
            />
          ) : <>
            <div className="mb-8">
              <h2 className="text-[26px] font-black tracking-[0] text-[#4f46e5]">강사 로그인</h2>
              <p className="mt-2.5 text-[13px] font-bold text-[#6b7280]">이메일과 비밀번호를 입력해주세요.</p>
            </div>

            <form className="grid gap-4" onSubmit={handleSubmit}>
            <label className="grid gap-2 text-[13px] font-extrabold text-[#303747]">
              이메일
              <input
                className="h-11 rounded-lg border border-[#d8dde8] bg-white px-4 text-[14px] font-bold text-[#111827] outline-none transition placeholder:text-[#a0a7b7] focus:border-[#4f46e5] focus:ring-4 focus:ring-[#4f46e5]/12"
                name="email"
                placeholder="이메일을 입력하세요"
                type="email"
                value={email}
                onChange={(event) => setEmail(event.target.value)}
                required
              />
            </label>

            <label className="grid gap-2 text-[13px] font-extrabold text-[#303747]">
              비밀번호
              <input
                className="h-11 rounded-lg border border-[#d8dde8] bg-white px-4 text-[14px] font-bold text-[#111827] outline-none transition placeholder:text-[#a0a7b7] focus:border-[#4f46e5] focus:ring-4 focus:ring-[#4f46e5]/12"
                name="password"
                placeholder="비밀번호를 입력하세요"
                type="password"
                value={password}
                onChange={(event) => setPassword(event.target.value)}
                required
              />
            </label>

            <div className="flex items-center justify-between gap-3">
              <label className="flex items-center gap-2 text-[12px] font-bold text-[#64748b]">
                <input
                  className="h-4 w-4 rounded border-[#d8dde8] accent-[#4f46e5]"
                  type="checkbox"
                  checked={rememberEmail}
                  onChange={(event) => setRememberEmail(event.target.checked)}
                />
                아이디 기억
              </label>
              <button className="text-[12px] font-extrabold text-[#4f46e5]" type="button">
                비밀번호를 잊으셨나요?
              </button>
            </div>

            <button
              className="h-12 rounded-lg bg-[#4f46e5] text-[14px] font-extrabold text-white shadow-[0_10px_24px_rgba(79,70,229,0.22)] transition hover:bg-[#4338ca] focus:outline-none focus:ring-4 focus:ring-[#4f46e5]/20 disabled:cursor-not-allowed disabled:opacity-70"
              type="submit"
              disabled={loading}
            >
              {loading ? '로그인 중...' : '로그인'}
            </button>

              {error ? <p className="text-center text-[12px] font-bold text-[#dc2626]">{error}</p> : null}
              {signupNotice ? <p className="text-center text-[12px] font-bold text-[#047857]">{signupNotice}</p> : null}
            </form>

            <div className="my-7 h-px bg-[#e3e7ef]" />
            <p className="text-center text-[12px] font-bold text-[#64748b]">
              강사 계정이 없으신가요?{' '}
              <button
                className="font-extrabold text-[#4f46e5] hover:text-[#4338ca] hover:underline"
                type="button"
                onClick={() => {
                  setError('');
                  setSignupNotice('');
                  setShowSignup(true);
                }}
              >
                회원가입
              </button>
            </p>
            <p className="mt-5 text-center text-[11px] font-bold leading-5 text-[#8b93a3]">접근 권한이 없는 계정은 관리자에게 문의하세요.</p>
          </>}
        </div>
      </section>
    </main>
  );
}

type InstructorSignupFormProps = {
  onCancel: () => void;
  onComplete: (email: string) => void;
};

function InstructorSignupForm({ onCancel, onComplete }: InstructorSignupFormProps) {
  const [name, setName] = useState('');
  const [email, setEmail] = useState('');
  const [password, setPassword] = useState('');
  const [passwordConfirm, setPasswordConfirm] = useState('');
  const [instructorInviteCode, setInstructorInviteCode] = useState('');
  const [verificationCode, setVerificationCode] = useState('');
  const [verificationEmail, setVerificationEmail] = useState('');
  const [codeSent, setCodeSent] = useState(false);
  const [codeTimer, setCodeTimer] = useState(0);
  const [sendingCode, setSendingCode] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const [showPassword, setShowPassword] = useState(false);
  const [showPasswordConfirm, setShowPasswordConfirm] = useState(false);
  const [agreeTerms, setAgreeTerms] = useState(false);
  const [agreePrivacy, setAgreePrivacy] = useState(false);
  const [error, setError] = useState('');
  const [termModal, setTermModal] = useState<{ title: string; body: string; loading: boolean } | null>(null);
  const normalizedEmail = email.trim().toLowerCase();
  const emailError = email.length > 0 && !EMAIL_PATTERN.test(email) ? '올바른 이메일 형식으로 입력해주세요.' : '';

  useEffect(() => {
    if (codeTimer <= 0) return;
    const timer = window.setTimeout(() => setCodeTimer((value) => value - 1), 1000);
    return () => window.clearTimeout(timer);
  }, [codeTimer]);

  const handleEmailChange = (value: string) => {
    setEmail(value);
    if (verificationEmail && value.trim().toLowerCase() !== verificationEmail) {
      setCodeSent(false);
      setVerificationCode('');
      setCodeTimer(0);
    }
  };

  const sendVerificationCode = async () => {
    if (!normalizedEmail || emailError) return;
    setSendingCode(true);
    setError('');
    try {
      const response = await fetch(`${AUTH_BASE_URL}/auth/email-verification/send`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        credentials: 'include',
        body: JSON.stringify({ email: normalizedEmail }),
      });
      if (response.status === 409) throw new Error('이미 가입된 이메일입니다.');
      if (!response.ok) throw new Error('인증코드 발송에 실패했습니다.');

      setCodeSent(true);
      setVerificationEmail(normalizedEmail);
      setVerificationCode('');
      setCodeTimer(60);
    } catch (sendError) {
      setCodeSent(false);
      setError(sendError instanceof Error ? sendError.message : '인증코드 발송에 실패했습니다.');
    } finally {
      setSendingCode(false);
    }
  };

  const handleSubmit = async (event: FormEvent<HTMLFormElement>) => {
    event.preventDefault();
    setError('');
    if (!name.trim()) return setError('이름을 입력해주세요.');
    if (emailError) return setError(emailError);
    if (password.length < 8) return setError('비밀번호는 8자 이상이어야 합니다.');
    if (password !== passwordConfirm) return setError('비밀번호가 일치하지 않습니다.');
    if (!agreeTerms || !agreePrivacy) return setError('필수 약관에 동의해주세요.');
    if (!/^[A-Za-z0-9]{6}$/.test(instructorInviteCode.trim())) return setError('강사 가입 코드 6자리를 입력해주세요.');
    if (!/^\d{6}$/.test(verificationCode)) return setError('이메일 인증코드 6자리를 입력해주세요.');
    if (!codeSent || verificationEmail !== normalizedEmail) return setError('현재 이메일로 인증코드를 다시 발송해주세요.');

    setSubmitting(true);
    try {
      const response = await fetch(`${AUTH_BASE_URL}/auth/instructor-signup`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        credentials: 'include',
        body: JSON.stringify({ name: name.trim(), email: normalizedEmail, password, verificationCode, instructorInviteCode: instructorInviteCode.trim().toUpperCase() }),
      });
      if (response.status === 409) throw new Error('이미 가입된 이메일입니다.');
      if (response.status === 400) throw new Error('인증코드 또는 강사 가입 코드가 올바르지 않습니다.');
      if (!response.ok) throw new Error('회원가입에 실패했습니다.');
      onComplete(normalizedEmail);
    } catch (signupError) {
      setError(signupError instanceof Error ? signupError.message : '회원가입에 실패했습니다.');
    } finally {
      setSubmitting(false);
    }
  };

  const openTermModal = async (key: 'terms' | 'privacy') => {
    const title = key === 'terms' ? '이용약관' : '개인정보 처리방침';
    setTermModal({ title, body: '', loading: true });
    try {
      const response = await fetch(`${LAUNCHER_API_BASE_URL}/terms/${key}`);
      if (!response.ok) throw new Error('약관을 불러오지 못했습니다.');
      const payload = await response.json() as { term?: { body?: string } };
      setTermModal({ title, body: payload.term?.body || '등록된 약관 내용이 없습니다.', loading: false });
    } catch (termError) {
      setTermModal({
        title,
        body: termError instanceof Error ? termError.message : '약관을 불러오지 못했습니다.',
        loading: false,
      });
    }
  };

  return (
    <>
      <div className="mb-6">
        <div className="flex items-center gap-3">
          <button className="text-[12px] font-extrabold text-[#64748b] hover:text-[#4f46e5]" type="button" onClick={onCancel}>로그인</button>
          <span className="h-3 w-px bg-[#d8dde8]" />
          <h2 className="text-[26px] font-black tracking-[0] text-[#4f46e5]">강사 회원가입</h2>
        </div>
        <p className="mt-2.5 text-[13px] font-bold text-[#6b7280]">강사 가입 코드를 입력해주세요.</p>
      </div>
      <form className="grid gap-3" onSubmit={handleSubmit}>
        <SignupInput label="이름" value={name} onChange={setName} placeholder="이름을 입력하세요" />
        <div className="grid gap-2 text-[13px] font-extrabold text-[#303747]">
          이메일
          <div className="flex gap-2">
            <input className="h-11 min-w-0 flex-1 rounded-lg border border-[#d8dde8] bg-white px-4 text-[14px] font-bold text-[#111827] outline-none transition placeholder:text-[#a0a7b7] focus:border-[#4f46e5] focus:ring-4 focus:ring-[#4f46e5]/12" type="email" value={email} onChange={(event) => handleEmailChange(event.target.value)} placeholder="이메일을 입력하세요" required />
            <button className="shrink-0 rounded-lg border border-[#c7d2fe] px-3 text-[12px] font-extrabold text-[#4f46e5] hover:bg-[#eef2ff] disabled:cursor-not-allowed disabled:opacity-60" type="button" onClick={() => void sendVerificationCode()} disabled={sendingCode || codeTimer > 0 || !normalizedEmail || Boolean(emailError)}>
              {sendingCode ? '발송 중' : codeTimer > 0 ? `${codeTimer}초` : codeSent ? '재발송' : '인증 발송'}
            </button>
          </div>
          {emailError ? <p className="text-[11px] text-[#dc2626]">{emailError}</p> : null}
        </div>
        <SignupInput label="인증코드" value={verificationCode} onChange={(value) => setVerificationCode(value.replace(/\D/g, '').slice(0, 6))} placeholder="이메일 인증코드 6자리를 입력하세요" inputMode="numeric" />
        {codeSent ? <p className="-mt-1 text-[11px] font-bold text-[#047857]">인증코드가 이메일로 발송되었습니다.</p> : null}
        <SignupInput label="강사 가입 코드" value={instructorInviteCode} onChange={(value) => setInstructorInviteCode(value.replace(/[^a-z0-9]/gi, '').toUpperCase().slice(0, 6))} placeholder="조직에서 받은 6자리 코드를 입력하세요" />
        <PasswordInput label="비밀번호" value={password} onChange={setPassword} placeholder="8자 이상 입력하세요" visible={showPassword} onToggle={() => setShowPassword((value) => !value)} />
        <PasswordInput label="비밀번호 확인" value={passwordConfirm} onChange={setPasswordConfirm} placeholder="비밀번호를 다시 입력하세요" visible={showPasswordConfirm} onToggle={() => setShowPasswordConfirm((value) => !value)} />
        <div className="mt-1 grid gap-2 text-[12px] font-bold text-[#64748b]">
          <label className="flex items-center gap-2"><input className="h-4 w-4 rounded border-[#d8dde8] accent-[#4f46e5]" type="checkbox" checked={agreeTerms} onChange={(event) => setAgreeTerms(event.target.checked)} /><button className="font-extrabold text-[#4f46e5] hover:underline" type="button" onClick={() => void openTermModal('terms')}>이용약관</button> 동의 (필수)</label>
          <label className="flex items-center gap-2"><input className="h-4 w-4 rounded border-[#d8dde8] accent-[#4f46e5]" type="checkbox" checked={agreePrivacy} onChange={(event) => setAgreePrivacy(event.target.checked)} /><button className="font-extrabold text-[#4f46e5] hover:underline" type="button" onClick={() => void openTermModal('privacy')}>개인정보 처리방침</button> 동의 (필수)</label>
        </div>
        {error ? <p className="text-center text-[12px] font-bold text-[#dc2626]">{error}</p> : null}
        <button className="mt-1 h-12 rounded-lg bg-[#4f46e5] text-[14px] font-extrabold text-white shadow-[0_10px_24px_rgba(79,70,229,0.22)] transition hover:bg-[#4338ca] disabled:cursor-not-allowed disabled:opacity-70" type="submit" disabled={submitting}>{submitting ? '가입 중...' : '회원가입'}</button>
      </form>
      {termModal ? <div className="fixed inset-0 z-50 flex items-center justify-center bg-[#111827]/45 px-4 backdrop-blur-sm" role="dialog" aria-modal="true" aria-label={termModal.title}>
        <div className="flex max-h-[78vh] w-full max-w-2xl flex-col overflow-hidden rounded-lg border border-[#d8dde8] bg-white shadow-2xl">
          <div className="flex items-center justify-between border-b border-[#e3e7ef] px-5 py-4"><h3 className="text-[15px] font-extrabold text-[#303747]">{termModal.title}</h3><button className="text-[20px] leading-none text-[#64748b] hover:text-[#111827]" type="button" onClick={() => setTermModal(null)} aria-label="닫기">×</button></div>
          <div className="min-h-0 overflow-y-auto px-5 py-4 text-[13px] leading-6 text-[#4b5563]">
            {termModal.loading ? '불러오는 중...' : (
              <div className="break-words [overflow-wrap:anywhere] [&_h1]:mb-4 [&_h1]:text-xl [&_h1]:font-bold [&_h2]:mb-3 [&_h2]:mt-6 [&_h2]:text-lg [&_h2]:font-bold [&_h3]:mb-2 [&_h3]:mt-4 [&_h3]:text-base [&_h3]:font-bold [&_p]:my-3 [&_ul]:my-3 [&_ul]:list-disc [&_ul]:pl-5 [&_ol]:my-3 [&_ol]:list-decimal [&_ol]:pl-5 [&_li]:my-1 [&_blockquote]:border-l-4 [&_blockquote]:border-[#d8dde8] [&_blockquote]:pl-4 [&_hr]:my-5 [&_hr]:border-[#d8dde8] [&_a]:text-[#2563eb] [&_a]:underline [&_pre]:overflow-x-auto [&_pre]:rounded [&_pre]:bg-[#f1f5f9] [&_pre]:p-3 [&_th]:border [&_th]:border-[#d8dde8] [&_th]:bg-[#f1f5f9] [&_th]:px-3 [&_th]:py-2 [&_td]:border [&_td]:border-[#d8dde8] [&_td]:px-3 [&_td]:py-2">
                <ReactMarkdown remarkPlugins={[remarkGfm]} skipHtml components={{
                  a: ({ node: _node, ...props }) => <a {...props} target="_blank" rel="noopener noreferrer" />,
                  table: ({ node: _node, ...props }) => <div className="my-3 overflow-x-auto"><table {...props} className="w-full border-collapse text-left" /></div>,
                }}>{termModal.body}</ReactMarkdown>
              </div>
            )}
          </div>
        </div>
      </div> : null}
    </>
  );
}

type SignupInputProps = {
  label: string;
  value: string;
  onChange: (value: string) => void;
  placeholder: string;
  inputMode?: 'numeric';
};

function SignupInput({ label, value, onChange, placeholder, inputMode }: SignupInputProps) {
  return <label className="grid gap-2 text-[13px] font-extrabold text-[#303747]">{label}<input className="h-11 rounded-lg border border-[#d8dde8] bg-white px-4 text-[14px] font-bold text-[#111827] outline-none transition placeholder:text-[#a0a7b7] focus:border-[#4f46e5] focus:ring-4 focus:ring-[#4f46e5]/12" value={value} onChange={(event) => onChange(event.target.value)} placeholder={placeholder} inputMode={inputMode} required /></label>;
}

type PasswordInputProps = Omit<SignupInputProps, 'inputMode'> & { visible: boolean; onToggle: () => void };

function PasswordInput({ label, value, onChange, placeholder, visible, onToggle }: PasswordInputProps) {
  return <label className="grid gap-2 text-[13px] font-extrabold text-[#303747]">{label}<span className="relative"><input className="h-11 w-full rounded-lg border border-[#d8dde8] bg-white px-4 pr-11 text-[14px] font-bold text-[#111827] outline-none transition placeholder:text-[#a0a7b7] focus:border-[#4f46e5] focus:ring-4 focus:ring-[#4f46e5]/12" type={visible ? 'text' : 'password'} value={value} onChange={(event) => onChange(event.target.value)} placeholder={placeholder} required /><button className="absolute right-3 top-1/2 -translate-y-1/2 text-[#8b93a3] hover:text-[#4f46e5]" type="button" onClick={onToggle} aria-label={visible ? '비밀번호 숨기기' : '비밀번호 보기'}>{visible ? <EyeOff size={17} /> : <Eye size={17} />}</button></span></label>;
}