// skill-registry-atomic.test.mjs — #51 (v7.8.3): saveRegistry must write
// atomically (temp file + rename). A torn write would parse-fail in
// loadRegistry and silently reset to an empty registry (permanent data loss).
// Zero external dependencies: node:test + node:assert only.

import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import { mkdtempSync, chmodSync, readFileSync, readdirSync, rmSync } from 'node:fs';
import { join } from 'node:path';
import { tmpdir } from 'node:os';
import { loadRegistry, saveRegistry, registryPath } from '../../scanners/lib/skill-registry.mjs';

describe('skill-registry — atomic saveRegistry (v7.8.3 #51)', () => {
  it('replaces the registry file via temp+rename (write survives a read-only target)', () => {
    const root = mkdtempSync(join(tmpdir(), 'llmsec-registry-atomic-'));
    try {
      const registry = loadRegistry(root);
      registry.entries['f'.repeat(64)] = { name: 'first', last_scanned: new Date().toISOString() };
      const filePath = saveRegistry(registry, root);
      assert.equal(filePath, registryPath(root));

      // A direct writeFileSync to a read-only file throws EACCES. An atomic
      // temp+rename replaces the file because only directory write permission
      // is required.
      chmodSync(filePath, 0o444);
      registry.entries['a'.repeat(64)] = { name: 'second', last_scanned: new Date().toISOString() };
      saveRegistry(registry, root);

      const raw = JSON.parse(readFileSync(filePath, 'utf8'));
      assert.equal(raw.entry_count, 2, 'expected atomic rename to replace the read-only file');
      assert.ok(raw.entries['a'.repeat(64)], 'second entry persisted');

      const leftovers = readdirSync(join(root, 'reports')).filter((f) => f !== 'skill-registry.json');
      assert.deepEqual(leftovers, [], 'no temp files left behind');
    } finally {
      try { rmSync(root, { recursive: true, force: true }); } catch { /* ignore */ }
    }
  });
});