/** Nickname rules, docs/05-accounts-auth.md §2. Shared by server validation and client form. */
export const NICK_MIN = 2;
export const NICK_MAX = 12;

const ALLOWED = /^[0-9A-Za-z가-힣ㄱ-ㅎㅏ-ㅣ _.\-]+$/;

// Minimal built-in list; the server may extend it. Matching ignores spaces and punctuation.
const BANNED = ['시발', '씨발', '병신', '좆', '개새끼', '느금', '니애미', 'fuck', 'shit', 'bitch'];

export function normalizeNickname(raw: string): string {
  return raw.normalize('NFC').trim().replace(/\s+/g, ' ');
}

export function containsProfanity(text: string): boolean {
  const squashed = text.normalize('NFC').toLowerCase().replace(/[\s_.\-*0-9]/g, '');
  return BANNED.some((w) => squashed.includes(w));
}

export function maskProfanity(text: string): string {
  let out = text;
  for (const w of BANNED) {
    out = out.replace(new RegExp(w.split('').map(escapeRe).join('[\\s_.\\-*]*'), 'gi'), (m) => '*'.repeat(m.length));
  }
  return out;
}

function escapeRe(s: string): string {
  return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

/** Returns a Korean error message, or null when valid. Input must already be normalized. */
export function nicknameError(nick: string): string | null {
  const len = [...nick].length;
  if (len < NICK_MIN) return `닉네임은 ${NICK_MIN}글자 이상이어야 해요.`;
  if (len > NICK_MAX) return `닉네임은 ${NICK_MAX}글자까지 쓸 수 있어요.`;
  if (!ALLOWED.test(nick)) return '한글, 영어, 숫자와 _ - . 만 쓸 수 있어요.';
  if (containsProfanity(nick)) return '다른 닉네임을 써 주세요.';
  return null;
}

const ADJ = ['용감한', '느긋한', '반짝이는', '씩씩한', '졸린', '신나는', '똑똑한', '배고픈', '귀여운', '날쌘', '든든한', '행복한'];
const NOUN = ['호랑이', '고양이', '거북이', '다람쥐', '부엉이', '펭귄', '판다', '토끼', '여우', '돌고래', '곰돌이', '참새'];

export function suggestNickname(rand: () => number = Math.random): string {
  const a = ADJ[Math.floor(rand() * ADJ.length)]!;
  const n = NOUN[Math.floor(rand() * NOUN.length)]!;
  return `${a} ${n}`;
}