import { constants } from 'node:fs';
import { open } from 'node:fs/promises';
import { isAbsolute } from 'node:path';

const MAX_REQUEST_BYTES = 64 * 1024;

/** Read a signed wallet request only from a bounded owner-only regular file. */
export async function loadPilotMoneroDepositRequestFile(path: string): Promise<unknown> {
  if (process.platform === 'win32') throw new Error('Pilot address command requires POSIX protected-file permission checks');
  if (!isAbsolute(path)) throw new Error('Pilot address request file path must be absolute');
  let file;
  try { file = await open(path, constants.O_RDONLY | constants.O_NOFOLLOW); }
  catch { throw new Error('Pilot address request file is inaccessible or is a symbolic link'); }
  try {
    const info = await file.stat();
    if (!info.isFile() || info.size < 1 || info.size > MAX_REQUEST_BYTES || (info.mode & 0o077) !== 0) {
      throw new Error('Pilot address request file must be bounded and owner-only');
    }
    const chunks: Buffer[] = [];
    let total = 0;
    for (;;) {
      const chunk = Buffer.allocUnsafe(Math.min(4096, MAX_REQUEST_BYTES + 1 - total));
      const { bytesRead } = await file.read(chunk);
      if (bytesRead === 0) break;
      total += bytesRead;
      if (total > MAX_REQUEST_BYTES) throw new Error('Pilot address request file exceeds size limit');
      chunks.push(chunk.subarray(0, bytesRead));
    }
    const text = new TextDecoder('utf-8', { fatal: true }).decode(Buffer.concat(chunks));
    try { return JSON.parse(text) as unknown; }
    catch { throw new Error('Pilot address request file does not contain valid JSON'); }
  } finally { await file.close(); }
}