import { existsSync } from 'fs';
import { basename, join, resolve } from 'path';

let cachedDir: string | null = null;

export function getDataDir(): string {
  const fromEnv = (process.env.DATA_DIR || '').trim();
  if (fromEnv) return fromEnv;

  if (cachedDir) return cachedDir;

  const cwd = process.cwd();
  const cwdBase = basename(cwd);
  const parentDir = join(cwd, '..');
  const parentLooksLikeRoot = [
    join(parentDir, 'docker-compose.yml'),
    join(parentDir, 'Dockerfile'),
    join(parentDir, '.env'),
  ].some((marker) => existsSync(marker));
  const candidates = cwdBase === 'orchestrator' && parentLooksLikeRoot
    ? [join(parentDir, 'data'), join(cwd, 'data')]
    : [join(cwd, 'data'), join(parentDir, 'data')];

  for (const candidate of candidates) {
    if (existsSync(candidate)) {
      cachedDir = resolve(candidate);
      return cachedDir;
    }
  }

  cachedDir = resolve(join(cwd, 'data'));
  return cachedDir;
}