const { Values } = require("./import-estx.cjs");

// Preserve every unedited property byte and the surrounding memory-table records.
function updateOptions(buffer, changes, encode) {
  const pieces = [];
  let cursor = 0,
    offset = 0;
  const remaining = new Map(Object.entries(changes));
  while ((offset = buffer.indexOf("TPF0", offset)) >= 0) {
    const length = offset >= 4 ? buffer.readUInt32LE(offset - 4) : 0;
    if (length < 6 || offset + length > buffer.length) {
      offset += 4;
      continue;
    }
    const reader = new Values(buffer.subarray(offset, offset + length));
    const className = reader.short();
    reader.short();
    const changesForClass = remaining.get(className);
    if (!changesForClass) {
      offset += length;
      continue;
    }
    const edits = [];
    while (reader.buffer[reader.position] !== 0) {
      const name = reader.short(),
        start = reader.position;
      reader.value();
      if (Object.hasOwn(changesForClass, name)) {
        edits.push([start, reader.position, encode(changesForClass[name])]);
        delete changesForClass[name];
      }
    }
    const end = reader.position;
    for (const [name, value] of Object.entries(changesForClass)) {
      const key = Buffer.from(name, "ascii");
      edits.push([end, end, Buffer.concat([Buffer.from([key.length]), key, encode(value)])]);
    }
    const parts = [];
    let position = 0;
    for (const [start, stop, data] of edits) {
      parts.push(reader.buffer.subarray(position, start), data);
      position = stop;
    }
    parts.push(reader.buffer.subarray(position));
    const object = Buffer.concat(parts),
      size = Buffer.alloc(4);
    size.writeUInt32LE(object.length);
    pieces.push(buffer.subarray(cursor, offset - 4), size, object);
    cursor = offset + length;
    offset = cursor;
    remaining.delete(className);
  }
  if (remaining.size) throw Error(`ESTX 옵션 객체 없음: ${[...remaining.keys()].join(", ")}`);
  pieces.push(buffer.subarray(cursor));
  return Buffer.concat(pieces);
}
module.exports = { updateOptions };