// 규칙 기반 용어 검색 (AI 없음). 등록된 이름·동의어·검색 표현·설명 문자열만 찾는다.

const PUNCT = /[\s·\-–_/.,()（）'"’‘“”「」『』\[\]:;!?~]/g;
const CHO = "ㄱㄲㄴㄷㄸㄹㅁㅂㅃㅅㅆㅇㅈㅉㅊㅋㅌㅍㅎ";

export function normalize(s) {
  return String(s ?? "").normalize("NFC").toLowerCase().replace(PUNCT, "");
}

export function choseong(s) {
  let out = "";
  for (const ch of String(s ?? "")) {
    const c = ch.charCodeAt(0);
    if (c >= 0xac00 && c <= 0xd7a3) out += CHO[Math.floor((c - 0xac00) / 588)];
    else if (!PUNCT.test(ch)) out += ch.toLowerCase();
    PUNCT.lastIndex = 0;
  }
  return out;
}

export const isChoseongQuery = (q) => /^[ㄱ-ㅎ]{2,}$/.test(q.replace(/\s/g, ""));

function editDistance(a, b, max) {
  if (Math.abs(a.length - b.length) > max) return max + 1;
  let prev = Array.from({ length: b.length + 1 }, (_, i) => i);
  for (let i = 1; i <= a.length; i++) {
    const cur = [i];
    let rowMin = i;
    for (let j = 1; j <= b.length; j++) {
      cur[j] = Math.min(prev[j] + 1, cur[j - 1] + 1, prev[j - 1] + (a[i - 1] === b[j - 1] ? 0 : 1));
      rowMin = Math.min(rowMin, cur[j]);
    }
    if (rowMin > max) return max + 1;
    prev = cur;
  }
  return prev[b.length];
}

/** terms: [{i, n, a:[], q:[], x}] → 검색용 색인 */
export function buildIndex(terms) {
  return terms.map((t) => ({
    t,
    name: normalize(t.n),
    cho: choseong(t.n),
    aliases: (t.a || []).map((a) => [a, normalize(a)]),
    extra: (t.q || []).map((a) => [a, normalize(a)]),
    text: normalize(t.x || ""),
  }));
}

/**
 * 반환: [{t, score, reason}] 점수순.
 * reason: 사용자에게 보여줄 일치 이유 (예: "동의어 ‘HBM’ 일치")
 */
export function search(index, query, { limit = Infinity, fuzzy = true } = {}) {
  const raw = String(query ?? "").trim();
  if (!raw) return [];
  const q = normalize(raw);
  const words = raw.split(/[\s,]+/).map(normalize).filter(Boolean);
  const cho = isChoseongQuery(raw) ? raw.replace(/\s/g, "") : null;
  const hits = [];
  for (const e of index) {
    let score = 0;
    let reason = "";
    if (q) {
      if (e.name === q) { score = 100; reason = "용어 일치"; }
      else if (e.name.startsWith(q)) { score = 80; reason = "용어 앞부분 일치"; }
      else if (e.name.includes(q)) { score = 62; reason = "용어 일부 일치"; }
      if (score < 70) {
        for (const [orig, a] of e.aliases) {
          if (a === q) { score = 72; reason = `동의어 ‘${orig}’ 일치`; break; }
          if (a.includes(q) && score < 46) { score = 46; reason = `동의어 ‘${orig}’에 포함`; }
        }
      }
      if (score < 42) {
        for (const [orig, a] of e.extra) {
          if (a.includes(q) || (a.length >= 3 && q.includes(a))) { score = 42; reason = `검색 표현 ‘${orig}’`; break; }
        }
      }
      if (!score && e.text.includes(q)) { score = 16; reason = "설명 속 단어"; }
    }
    if (words.length > 1) {
      let matched = 0;
      let sub = 0;
      for (const w of words) {
        if (e.name.includes(w)) { sub += 8; matched++; }
        else if (e.aliases.some(([, a]) => a.includes(w)) || e.extra.some(([, a]) => a.includes(w))) { sub += 5; matched++; }
        else if (e.text.includes(w)) { sub += 2; matched++; }
      }
      if (matched) {
        const all = matched === words.length;
        const s = sub + (all ? 12 : 0);
        if (s > score) {
          score = s;
          reason = all ? "모든 단어 포함" : `${words.length}개 단어 중 ${matched}개 포함`;
        }
      }
    }
    if (cho && !score) {
      if (e.cho.startsWith(cho)) { score = 50; reason = "초성 일치"; }
      else if (e.cho.includes(cho)) { score = 34; reason = "초성 포함"; }
    }
    if (score) hits.push({ t: e.t, score: score - Math.min(e.name.length, 30) * 0.05, reason });
  }
  if (fuzzy && hits.length < 3 && q.length >= 2 && !cho) {
    const max = q.length <= 4 ? 1 : 2;
    const seen = new Set(hits.map((h) => h.t.i));
    for (const e of index) {
      if (seen.has(e.t.i)) continue;
      let d = editDistance(q, e.name, max);
      if (d > max && e.name.length > q.length) {
        // 긴 이름 앞부분과 비교 (예: '우선순이' → '우선순위 설정')
        d = editDistance(q, e.name.slice(0, q.length), max);
      }
      if (d <= max) hits.push({ t: e.t, score: 8 - d, reason: "비슷한 표기" });
    }
  }
  hits.sort((a, b) => b.score - a.score || a.t.n.localeCompare(b.t.n, "ko"));
  return hits.slice(0, limit);
}

/** 가나다 색인용 첫 글자 묶음 */
export function initialGroup(name) {
  const c = String(name).charCodeAt(0);
  if (c >= 0xac00 && c <= 0xd7a3) {
    const ch = CHO[Math.floor((c - 0xac00) / 588)];
    return { ㄲ: "ㄱ", ㄸ: "ㄷ", ㅃ: "ㅂ", ㅆ: "ㅅ", ㅉ: "ㅈ" }[ch] || ch;
  }
  if (/[a-z]/i.test(name[0])) return "A–Z";
  return "기타";
}