/**
 * spec-template-sync: verify /spec templates ↔ generated docs stay in sync.
 *
 * Per codex T8 / eng plan: regen and assert no drift. Catches commits that
 * edit a template but forget to run `bun run gen:skill-docs`, or vice versa.
 *
 * /spec is carved (skeleton + sections/gate-and-file.md), so BOTH generated
 * artifacts are checked: a stale section is the same drift bug as a stale
 * skeleton — the on-demand file is what the agent executes at Phase 4.5.
 */
import { describe, test, expect } from 'bun:test';
import * as fs from 'fs';
import * as path from 'path';
import { spawnSync } from 'child_process';

const ROOT = path.resolve(import.meta.dir, '..');

const GENERATED_PATHS = [
  path.join(ROOT, 'spec', 'SKILL.md'),
  path.join(ROOT, 'spec', 'sections', 'gate-and-file.md'),
];

describe('/spec template/generated sync', () => {
  test('regenerating spec/SKILL.md + sections produces byte-identical output', () => {
    const before = GENERATED_PATHS.map((p) => fs.readFileSync(p));

    const res = spawnSync('bun', ['run', 'gen:skill-docs'], {
      cwd: ROOT,
      encoding: 'utf-8',
      timeout: 120_000,
      // Scrubbed env: bun test runs a shard's files serially in ONE process,
      // so an earlier test's env mutations (GSTACK_*/GBRAIN_* detection vars)
      // leak into inherited process.env and change generator output — this
      // test failed in-suite while passing solo on an identical tree. The
      // generator's output must be a function of the templates, not of
      // whichever test ran before this one.
      env: {
        PATH: process.env.PATH ?? '',
        HOME: process.env.HOME ?? '',
        TMPDIR: process.env.TMPDIR ?? '',
      },
    });
    expect(res.status).toBe(0);

    for (let i = 0; i < GENERATED_PATHS.length; i++) {
      const after = fs.readFileSync(GENERATED_PATHS[i]);
      expect({ file: path.relative(ROOT, GENERATED_PATHS[i]), identical: after.equals(before[i]) })
        .toEqual({ file: path.relative(ROOT, GENERATED_PATHS[i]), identical: true });
    }
  }, 130_000);

  test('generated /spec docs carry the auto-generated header', () => {
    for (const p of GENERATED_PATHS) {
      const generated = fs.readFileSync(p, 'utf-8');
      expect(generated).toMatch(/AUTO-GENERATED|do not edit directly/i);
    }
  });
});