// 원본 문서 레코드(.opt = MIDAS TClientDataSet 이진 묶음, 머리 96 19 E0 BD) 일반 읽기 — 갑지·표지·공사설명서·시방서.
// 필드형: 1/4 정수 · 3/2 짧은 정수 · 4/8 실수 · 73/1 문자열(cp949) · 75/4 BLOB(바이트 그대로).
// WPTools BLOB 은 wptText 로 글자만 꺼낸다(서식 버림).
const zlib = require("node:zlib");
const decoder = new TextDecoder("euc-kr");

function readRecords(buffer) {
  if (!buffer || buffer.length < 24 || buffer.readUInt32LE(0) !== 0xbde01996)
    throw Error("문서 레코드 머리 오류");
  const count = buffer.readUInt16LE(12),
    rows = buffer.readUInt16LE(14),
    start = buffer.readUInt16LE(22);
  if (count > 1024 || rows > 10000 || start > buffer.length) throw Error("문서 레코드 크기 오류");
  let at = 24;
  const take = (n) => {
    if (n < 0 || at + n > buffer.length) throw Error("문서 레코드 범위 오류");
    const out = buffer.subarray(at, at + n);
    at += n;
    return out;
  };
  const fields = [];
  for (let i = 0; i < count; i++) {
    const name = take(take(1)[0]).toString("ascii"),
      width = take(2).readUInt16LE(),
      kind = take(2).readUInt16LE();
    take(2);
    const attributes = take(2).readUInt16LE();
    for (let j = 0; j < attributes; j++) {
      take(take(1)[0]);
      const size = take(2).readUInt16LE(),
        type = take(2).readUInt16LE();
      if (type === 73) take(take(2).readUInt16LE());
      else take(size);
    }
    fields.push({ name, width, kind });
  }
  at = start;
  const out = [];
  for (let r = 0; r < rows; r++) {
    take(1);
    const status = take(Math.ceil(count / 4)),
      row = {};
    fields.forEach(({ name, width, kind }, i) => {
      const state = (status[i >> 2] >> ((i % 4) * 2)) & 3;
      if (state === 1 || state === 2) return (row[name] = null);
      if (kind === 1 && width === 4) row[name] = take(4).readInt32LE();
      else if (kind === 3 && width === 2) row[name] = take(2).readInt16LE();
      else if (kind === 4 && width === 8) row[name] = take(8).readDoubleLE();
      else if (kind === 73 && width === 1)
        row[name] = decoder.decode(take(take(1)[0])).replace(/\0+$/, "");
      else if (kind === 75 && width === 4) row[name] = Buffer.from(take(take(4).readUInt32LE()));
      else throw Error(`문서 레코드 필드형 오류: ${name}/${kind}/${width}`);
    });
    out.push(row);
  }
  return out;
}

function wptText(blob) {
  if (!blob?.length) return "";
  let bytes = blob;
  if (bytes[0] === 0x78) bytes = zlib.inflateSync(bytes);
  const source = decoder.decode(bytes);
  if (!source.startsWith("<!WPTools")) return source.trim();
  return source
    .replace(/<(numberstyles|stylesheet)[\s\S]*?<\/\1>/gi, "")
    .replace(/<\/(div|p)>|<br\s*\/?>/gi, "\n")
    .replace(/<[^>]*>/g, "")
    .replace(/&lt;/g, "<")
    .replace(/&gt;/g, ">")
    .replace(/&quot;/g, '"')
    .replace(/&#(\d+);/g, (_, n) => String.fromCharCode(Number(n)))
    .replace(/&amp;/g, "&")
    .replace(/[ \t]+\n/g, "\n")
    .replace(/\n{3,}/g, "\n\n")
    .trim();
}

// 갑지·표지·공사설명서·시방서 → project.docs (글자 필드만; 서식·여백은 원본에 그대로 둔다)
function readDocuments(files) {
  const docs = {};
  const one = (name) => {
    const key = [...files.keys()].find((k) => k.toLowerCase() === name.toLowerCase());
    return key ? readRecords(files.get(key))[0] || null : null;
  };
  const gabgi = one("DatGabgi.opt");
  if (gabgi)
    docs.gabgi = {
      Name: gabgi.Name ?? "",
      Position: gabgi.Position ?? "",
      CompanyName: gabgi.CompanyName ?? "",
      Explan: wptText(gabgi.EXPLEAN),
      Cost: wptText(gabgi.Cost),
      Gulga: gabgi.Gulga
        ? decoder
            .decode(gabgi.Gulga)
            .split(/\r?\n/)
            .map((line) => line.trim())
            .filter(Boolean)
        : [],
      Date: gabgi.Date ?? "",
      YearShow: Boolean(gabgi.YearShow),
      DayShow: Boolean(gabgi.DayShow),
      CompanyPos: gabgi.CompanyPos ?? 1,
    };
  const cover = one("DatCover.opt");
  if (cover)
    docs.cover = {
      Name: cover.Name ?? "",
      Name2: cover.Name2 ?? "",
      CompanyName: cover.CompanyName ?? "",
      Date: cover.Date ?? "",
      YearShow: Boolean(cover.YearShow),
      CompanyPos: cover.CompanyPos ?? 1,
    };
  for (const [key, file] of [
    ["explan", "DatExplean.opt"],
    ["sibang", "DatSiBang.opt"],
  ]) {
    const row = one(file);
    if (row) docs[key] = { text: wptText(row.Editor) };
  }
  return docs;
}

module.exports = { readRecords, wptText, readDocuments };