/**
 * Hermetic HOME for snapshot / byte-stability tests.
 *
 * The COL collision-scanner and the CLAUDE.md cascade resolve ~/.claude from
 * process.env.HOME (see scanners/lib/active-config-reader.mjs — enumeratePlugins,
 * enumerateSkills, walkClaudeMdCascade). A CLI spawned with the developer's real
 * HOME picks up their installed plugins/skills and user CLAUDE.md, which makes
 * byte-snapshots machine- and time-dependent: the snapshots seeded on one machine
 * drift the moment another machine (or the same machine, later) has a different
 * ~/.claude. Pointing HOME at an empty temp dir isolates every snapshot/byte test
 * from user state, exactly as tests/scanners/collision.test.mjs already does for
 * the COL unit test.
 *
 * Writes any CLI may make under HOME (sessions, baselines) land in the temp dir,
 * never in the repo.
 */
import { mkdtempSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';

export const HERMETIC_HOME = mkdtempSync(join(tmpdir(), 'config-audit-hermetic-home-'));

/** Subprocess env with HOME/USERPROFILE redirected to the empty hermetic dir. */
export function hermeticEnv(extra = {}) {
  return { ...process.env, HOME: HERMETIC_HOME, USERPROFILE: HERMETIC_HOME, ...extra };
}

/** Run an in-process callback with process.env.HOME pointed at the hermetic dir. */
export async function withHermeticHome(fn) {
  const originalHome = process.env.HOME;
  const originalProfile = process.env.USERPROFILE;
  process.env.HOME = HERMETIC_HOME;
  process.env.USERPROFILE = HERMETIC_HOME;
  try {
    return await fn();
  } finally {
    if (originalHome === undefined) delete process.env.HOME; else process.env.HOME = originalHome;
    if (originalProfile === undefined) delete process.env.USERPROFILE; else process.env.USERPROFILE = originalProfile;
  }
}