import { readFileSync } from 'node:fs';
// Row 90 (#1584): the approved PRD's requirement ids as data, in ../requirements.json. The PRD
// (docs/prd/mosaic-stack.md) stays the reviewed source; tests/requirements.test.mjs fails unless
// the list holds its **REQ-...** ids in its order. A later PRD version is a new list in a reviewed
// commit. task.create refuses an id the list doesn't hold, and the broker's `requirements` verb
// returns the list to the sessions that create tasks. This module imports nothing from the bus,
// so the broker can load it. This function is the file's schema: it refuses any other shape.
export const REQUIREMENTS_FILE = new URL('../requirements.json', import.meta.url);
export const REQUIREMENT_ID = /^REQ-[A-Z]+-[1-9][0-9]*$/;
export class RequirementsError extends Error {}
const plain = (x) => x !== null && typeof x === 'object' && !Array.isArray(x);
const str = (x, max) => typeof x === 'string' && x.trim() !== '' && x.length <= max;
function exact(x, where, allowed) {
  if (!plain(x)) throw new RequirementsError(`${where}: not an object`);
  for (const k of Object.keys(x)) if (!allowed.includes(k)) throw new RequirementsError(`${where}: unknown key ${k}`);
  for (const k of allowed) if (!Object.hasOwn(x, k)) throw new RequirementsError(`${where}: missing ${k}`);
}
export function checkRequirements(list) {
  exact(list, 'list', ['prd', 'version', 'requirements']);
  if (!str(list.prd, 256) || !/^docs\/prd\/[a-z0-9-]+\.md$/.test(list.prd))
    throw new RequirementsError('prd: not a docs/prd/*.md path');
  if (typeof list.version !== 'string' || !/^[1-9][0-9]*\.[0-9]+$/.test(list.version))
    throw new RequirementsError('version: not a version such as 1.0');
  if (!Array.isArray(list.requirements) || !list.requirements.length)
    throw new RequirementsError('requirements: not a nonempty list');
  const seen = new Set();
  for (const [i, r] of list.requirements.entries()) {
    const at = `requirements[${i}]`;
    exact(r, at, ['id', 'title']);
    if (typeof r.id !== 'string' || !REQUIREMENT_ID.test(r.id)) throw new RequirementsError(`${at}.id: not a requirement id`);
    if (seen.has(r.id)) throw new RequirementsError(`${at}.id: ${r.id} twice`);
    seen.add(r.id);
    if (!str(r.title, 120) || r.title.includes('\n')) throw new RequirementsError(`${at}.title: not one line of 120 characters or fewer`);
  }
  return list;
}
function freeze(x) {
  if (x && typeof x === 'object') {
    for (const v of Object.values(x)) freeze(v);
    Object.freeze(x);
  }
  return x;
}
// The committed list, checked and frozen. A file that fails the check refuses to load.
export function loadRequirements(file = REQUIREMENTS_FILE) {
  let list;
  try {
    list = JSON.parse(readFileSync(file, 'utf8'));
  } catch (e) {
    throw new RequirementsError(e instanceof SyntaxError ? 'requirements.json: not JSON' : `requirements.json: ${e.code ?? 'unreadable'}`);
  }
  return freeze(checkRequirements(list));
}