import fs from 'node:fs';
import path from 'node:path';

export const GENERATED_ROOT = 'test/qkforce';
export const GENERATED_MANIFEST = `${GENERATED_ROOT}/manifest.json`;
const fail = message => { throw new Error(`Invalid QKForce generated workspace: ${message}`); };

function localFile(root, relative) {
  if (typeof relative !== 'string' || !relative.startsWith(`${GENERATED_ROOT}/`)
      || relative.includes('\\') || relative.split('/').some(part => !part || part === '.' || part === '..')) {
    fail('unsafe generated file path');
  }
  let current = path.resolve(root);
  for (const segment of relative.split('/')) {
    current = path.join(current, segment);
    let stat;
    try { stat = fs.lstatSync(current); } catch { fail('declared generated file is missing'); }
    if (stat.isSymbolicLink()) fail('generated paths must not contain symlinks');
  }
  if (!fs.statSync(current).isFile()) fail('declared generated input must be a file');
  return current;
}

export function loadGeneratedWorkspace(root = process.cwd()) {
  const manifestPath = path.join(root, GENERATED_MANIFEST);
  if (!fs.existsSync(manifestPath)) {
    // A local template checkout may run the example. An API package never may.
    if (fs.existsSync(path.join(root, 'qkforce-package-manifest.json'))) fail('regenerate the project before execution');
    return null;
  }
  let manifest;
  try { manifest = JSON.parse(fs.readFileSync(localFile(root, GENERATED_MANIFEST), 'utf8')); }
  catch { fail('generated manifest is not readable JSON'); }
  if (manifest?.schemaVersion !== 1 || !Array.isArray(manifest.features)
      || manifest.features.length === 0) fail('select at least one project test case');
  if (new Set(manifest.features).size !== manifest.features.length) fail('duplicate feature paths');
  for (const file of manifest.features) {
    if (typeof file !== 'string' || !file.startsWith(`${GENERATED_ROOT}/features/`) || !file.endsWith('.feature')) fail('invalid feature path');
    localFile(root, file);
  }
  if (manifest.steps !== `${GENERATED_ROOT}/steps.mjs` || manifest.selectors !== `${GENERATED_ROOT}/selectors.json`) fail('unsupported generated module paths');
  localFile(root, manifest.steps);
  localFile(root, manifest.selectors);
  return Object.freeze({ specs: manifest.features.map(file => `./${file}`), imports: [`./${manifest.steps}`] });
}

export function loadGeneratedSelectors(root = process.cwd()) {
  const value = JSON.parse(fs.readFileSync(localFile(root, `${GENERATED_ROOT}/selectors.json`), 'utf8'));
  if (!value || typeof value !== 'object' || Array.isArray(value)) fail('selectors must be an object');
  return value;
}