이벤트 전날, 디스코드에 구글 캘린더 토대로 D-1 메세지 띄워주기

const raw = $json.body || $json.data || $json || '';
const ics = typeof raw === 'string' ? raw : JSON.stringify(raw);

// 1) 줄 접힘 해제
const unfolded = ics
  .split(/\r?\n/)
  .reduce((acc, line) => {
    if (line.startsWith(' ') || line.startsWith('\t')) acc[acc.length - 1] += line.slice(1);
    else acc.push(line);
    return acc;
  }, [])
  .join('\n');

// 2) VEVENT 블록 추출
const events = [];
let cur = null;
for (const line of unfolded.split('\n')) {
  if (line === 'BEGIN:VEVENT') cur = [];
  else if (line === 'END:VEVENT') { if (cur) events.push(cur.join('\n')); cur = null; }
  else if (cur) cur.push(line);
}

// 유틸
function parseKV(line) {
  const [left, valueRaw] = line.split(':');
  const value = (valueRaw || '').trim();
  const [prop, ...params] = left.split(';');
  const key = prop.toUpperCase();
  const pmap = {};
  for (const p of params) { const [k,v] = p.split('='); if (k && v) pmap[k.toUpperCase()] = v; }
  return { key, params: pmap, value };
}
function toKSTDateStr(d) {
  return new Intl.DateTimeFormat('en-CA', { timeZone: 'Asia/Seoul', year: 'numeric', month: '2-digit', day: '2-digit' }).format(d);
}
function toKSTDateTimeStr(d) {
  const ymd = toKSTDateStr(d);
  const hm = new Intl.DateTimeFormat('en-GB', { timeZone: 'Asia/Seoul', hour: '2-digit', minute: '2-digit', hour12: false }).format(d);
  return `${ymd} ${hm}`;
}
function parseDate({ value, tzid }) {
  // 종일: YYYYMMDD
  if (/^\d{8}$/.test(value)) {
    const y = +value.slice(0,4), m = +value.slice(4,6)-1, d = +value.slice(6,8);
    // KST 00:00 을 UTC로 저장 (KST -9h)
    return new Date(Date.UTC(y, m, d, -9, 0, 0));
  }
  // UTC: ...Z
  if (value.endsWith('Z')) {
    const iso = value.replace(/^(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})Z$/, '$1-$2-$3T$4:$5:$6Z');
    return new Date(iso);
  }
  // 로컬시간 (+TZID)
  const y = +value.slice(0,4), m = +value.slice(4,6)-1, d = +value.slice(6,8);
  const hh = +value.slice(9,11), mm = +value.slice(11,13), ss = +value.slice(13,15);
  const isKST = tzid && tzid.toLowerCase() === 'asia/seoul';
  return new Date(Date.UTC(y, m, d, (isKST ? hh-9 : hh-9), mm, ss));
}

// 3) 필드 추출
const out = [];
for (const block of events) {
  let title='', description='', location='', url='', organizer='';
  let start=null, end=null;
  for (const ln of block.split('\n')) {
    if (!ln.includes(':')) continue;
    const { key, params, value } = parseKV(ln);
    if (key==='SUMMARY') title = value;
    else if (key==='DESCRIPTION') description = value;
    else if (key==='LOCATION') location = value;
    else if (key==='URL') url = value;
    else if (key==='ORGANIZER') organizer = value;
    else if (key==='DTSTART') start = parseDate({ value, tzid: params.TZID });
    else if (key==='DTEND') end = parseDate({ value, tzid: params.TZID });
  }
  if (!start) continue;
  out.push({
    json: {
      title: title || '(제목 없음)',
      description, location, url, organizer,
      start_utc: start.toISOString(),
      end_utc: end ? end.toISOString() : null,
      start_kst_text: toKSTDateTimeStr(start),
      end_kst_text: end ? toKSTDateTimeStr(end) : null,
      start_kst_date: toKSTDateStr(start), // YYYY-MM-DD (내일 비교용)
    }
  });
}
return out;

function kstYYYYMMDD(date) {
  return new Intl.DateTimeFormat('en-CA', {
    timeZone: 'Asia/Seoul', year: 'numeric', month: '2-digit', day: '2-digit'
  }).format(date);
}
// 오늘(KST)
const now = new Date();
const todayKst = kstYYYYMMDD(now);

// 내일(KST) 구하기: 오늘 00:00 KST를 기준으로 +1일
const [y,m,d] = todayKst.split('-').map(Number);
const base = new Date(Date.UTC(y, m-1, d, 15, 0, 0)); // KST 00:00 == 전날 15:00 UTC
base.setUTCDate(base.getUTCDate() + 1);
const tomorrowKst = kstYYYYMMDD(base);

// 필터
return items.filter(it => it.json.start_kst_date === tomorrowKst);

if (items.length === 0) return [];

return items.map((it) => {
  const { title, start_kst_text, end_kst_text, location, url } = it.json;
  const lines = [
    '📅 **내일 일정 리마인드**',
    `제목: ${title}`,
    `시간: ${start_kst_text}${end_kst_text ? ' ~ ' + end_kst_text : ''}`,
  ];
  if (location) lines.push(`장소: ${location}`);
  if (url) lines.push(`링크: ${url}`);
  return { json: { content: lines.join('\n') } };
});