// 원본 인쇄양식 파일(.pfot — mnuPrintFormatSave 0x10ed000 · Load 0x10ed318): 인쇄정보표(DatPrintOption) MIDAS 이진 한 벌.
// 읽기는 import-print.cjs 와 같은 꼴. 쓰기는 같은 꼴의 바탕 파일(필드 설명자)을 받아 행 부분만 새로 만든다.
// .gfot(화면 격자 열 배치)는 웹 격자와 호환되지 않아 다루지 않는다.
const { readPrintOptions } = require("./import-print.cjs");

function layout(buffer) {
  if (buffer.length < 24 || buffer.readUInt32LE(0) !== 0xbde01996)
    throw Error("인쇄양식 파일 헤더 오류");
  const count = buffer.readUInt16LE(12),
    start = buffer.readUInt16LE(22);
  let at = 24;
  const fields = [];
  for (let i = 0; i < count; i++) {
    const length = buffer[at];
    const name = buffer.subarray(at + 1, at + 1 + length).toString("ascii");
    at += 1 + length;
    const width = buffer.readUInt16LE(at),
      kind = buffer.readUInt16LE(at + 2),
      attributes = buffer.readUInt16LE(at + 6);
    at += 8;
    for (let j = 0; j < attributes; j++) {
      at += 1 + buffer[at];
      const size = buffer.readUInt16LE(at),
        type = buffer.readUInt16LE(at + 2);
      at += 4;
      at += type === 73 ? 2 + buffer.readUInt16LE(at) : size;
    }
    fields.push({ name, width, kind });
  }
  return { count, start, fields, flag: buffer[start] };
}

// rows: 인쇄정보표 행들(읽은 값). BLOB(75) 칸은 비워 씀.
function write(template, rows) {
  const { count, start, fields, flag } = layout(template);
  const encoder = (s) => {
    const bytes = [];
    for (const ch of String(s)) {
      const code = ch.codePointAt(0);
      if (code < 0x80) bytes.push(code);
      else {
        const found = cp949Table().get(ch);
        if (found == null) throw Error(`인쇄양식 글자를 cp949 로 바꿀 수 없습니다: ${ch}`);
        bytes.push(found >> 8, found & 0xff);
      }
    }
    return Buffer.from(bytes);
  };
  const parts = [Buffer.from(template.subarray(0, start))];
  parts[0].writeUInt16LE(rows.length, 14);
  for (const row of rows) {
    const status = Buffer.alloc(Math.ceil(count / 4)),
      values = [];
    fields.forEach(({ name, width, kind }, i) => {
      const v = row[name];
      if (kind === 75 && v?.binary != null) {
        const data = Buffer.from(v.binary, "base64"),
          length = Buffer.alloc(4);
        length.writeUInt32LE(data.length);
        values.push(length, data);
        return;
      }
      if (v == null || kind === 75) {
        status[i >> 2] |= (row.__nulls?.[name] || 1) << ((i % 4) * 2);
        return;
      }
      if (kind === 1 && width === 4) {
        const b = Buffer.alloc(4);
        b.writeInt32LE(Number(v) | 0);
        values.push(b);
      } else if (kind === 3 && width === 2) {
        const b = Buffer.alloc(2);
        b.writeInt16LE(Number(v) | 0);
        values.push(b);
      } else if (kind === 4 && width === 8) {
        const b = Buffer.alloc(8);
        b.writeDoubleLE(Number(v));
        values.push(b);
      } else if (kind === 73 && width === 1) {
        const text = encoder(v);
        if (text.length > 255) throw Error(`인쇄양식 글이 너무 깁니다: ${name}`);
        values.push(Buffer.from([text.length]), text);
      } else throw Error(`인쇄양식 필드형 오류: ${name}/${kind}/${width}`);
    });
    parts.push(Buffer.from([flag]), status, ...values);
  }
  return Buffer.concat(parts);
}

let table = null;
function cp949Table() {
  if (table) return table;
  table = new Map();
  const decoder = new TextDecoder("euc-kr");
  for (let hi = 0x81; hi <= 0xfe; hi++)
    for (let lo = 0x41; lo <= 0xfe; lo++) {
      const ch = decoder.decode(Buffer.from([hi, lo]));
      if (ch.length === 1 && ch !== "�" && !table.has(ch)) table.set(ch, (hi << 8) | lo);
    }
  return table;
}

// BLOB(설명 등)까지 담아 읽기 — 그대로 다시 쓰면 원본과 같은 바이트
function readFull(buffer) {
  const { count, start, fields } = layout(buffer),
    rows = buffer.readUInt16LE(14),
    decoder = new TextDecoder("euc-kr");
  let at = start;
  const out = [];
  for (let r = 0; r < rows; r++) {
    at += 1;
    const status = buffer.subarray(at, at + Math.ceil(count / 4));
    at += status.length;
    const row = {};
    fields.forEach(({ name, width, kind }, i) => {
      const state = (status[i >> 2] >> ((i % 4) * 2)) & 3;
      if (state) {
        if (state !== 1) (row.__nulls ||= {})[name] = state; // 빈 칸 표지(1·2)도 그대로 되살리게
        return;
      }
      if (kind === 1 && width === 4) ((row[name] = buffer.readInt32LE(at)), (at += 4));
      else if (kind === 3 && width === 2) ((row[name] = buffer.readInt16LE(at)), (at += 2));
      else if (kind === 4 && width === 8) ((row[name] = buffer.readDoubleLE(at)), (at += 8));
      else if (kind === 73 && width === 1) {
        const n = buffer[at];
        row[name] = decoder.decode(buffer.subarray(at + 1, at + 1 + n));
        at += 1 + n;
      } else if (kind === 75) {
        const n = buffer.readUInt32LE(at);
        row[name] = { binary: buffer.subarray(at + 4, at + 4 + n).toString("base64") };
        at += 4 + n;
      } else throw Error(`인쇄양식 필드형 오류: ${name}/${kind}/${width}`);
    });
    out.push(row);
  }
  return out;
}

module.exports = { read: (buffer) => readPrintOptions(buffer), readFull, write, layout };