/**
 * 회의록 Markdown에서 업무 체크리스트 툴팁용 짧은 요약 추출 (저장 시 summary_text 보조용)
 */

function stripMd(s) {
  if (!s) return "";
  return s
    .replace(/\r\n/g, "\n")
    .replace(/\*\*([^*]+)\*\*/g, "$1")
    .replace(/__([^_]+)__/g, "$1")
    .replace(/^[-*•]\s+/gm, "")
    .replace(/^\d+\.\s+/gm, "")
    .replace(/\s+/g, " ")
    .trim();
}

function truncate(s, maxLen) {
  const t = (s || "").trim();
  if (t.length <= maxLen) return t;
  return t.slice(0, maxLen - 1).trim() + "…";
}

/** 체크리스트/액션 등 툴팁에 부적합한 섹션 제목 */
const SKIP_SECTION = /체크리스트|액션|후속\s*확인|참석|결정\s*사항|action\s*items/i;

/** 요약으로 쓰기 좋은 섹션 제목 */
const PREFERRED = /요약|개요|핵심|summary|논의\s*안건|회의\s*내용|discussion/i;

/**
 * @param {string} markdown
 * @param {number} [maxLen]
 * @returns {string}
 */
function extractMeetingSummary(markdown, maxLen = 800) {
  const md = (markdown || "").trim();
  if (!md) return "";

  const lines = md.split(/\r?\n/);
  /** @type {{ h: string, body: string }[]} */
  const sections = [];
  for (let i = 0; i < lines.length; ) {
    const line = lines[i];
    const hm = line.match(/^#{1,6}\s+(.+)$/);
    if (!hm) {
      i++;
      continue;
    }
    const heading = hm[1].replace(/\*\*/g, "").trim();
    const body = [];
    let j = i + 1;
    while (j < lines.length) {
      const tj = lines[j].trim();
      if (/^#{1,6}\s+/.test(tj)) break;
      body.push(lines[j]);
      j++;
    }
    const joined = body.join("\n").trim();
    if (joined.length >= 4) sections.push({ h: heading, body: joined });
    i = j;
  }

  const preferred = sections.find((s) => PREFERRED.test(s.h) && !SKIP_SECTION.test(s.h));
  if (preferred) return truncate(stripMd(preferred.body), maxLen);

  const firstOk = sections.find((s) => !SKIP_SECTION.test(s.h) && s.body.length >= 12);
  if (firstOk) return truncate(stripMd(firstOk.body), maxLen);

  let plain = md.replace(/^#{1,6}\s+.*$/gm, "").trim();
  plain = plain.replace(/^[-*•]\s+.*$/gm, "").trim();
  if (plain.length < 30) plain = stripMd(md);
  return truncate(stripMd(plain), maxLen);
}

module.exports = {
  extractMeetingSummary,
  stripMd,
  truncate,
};