#!/usr/bin/env node
/**
 * Production dependency advisories, with an allowlist npm does not give you.
 *
 *   node scripts/audit-gate.mjs          # fail on unassessed high/critical
 *   node scripts/audit-gate.mjs --list   # print what is found, exit 0 regardless
 *
 *   0  no unassessed high/critical advisories in production dependencies
 *   1  unassessed advisories found — they are listed
 *   2  NOTHING WAS CHECKED — audit did not run, or its output was not the shape
 *      this understands. Not a pass, and CI must not treat it as one.
 *
 * ## Why this exists rather than `npm audit --audit-level=high`
 *
 * npm audit has no allowlist. So when an advisory lands that provably cannot
 * reach the application — a server-side CSRF in a router the app only uses
 * declaratively, say — there are exactly two options in plain npm, and both are
 * bad. Lower the threshold, which throws away a gate that has already caught
 * real issues. Or let CI sit red, which for an advisory with no fixed version
 * means indefinitely, and a permanently red gate is a gate everybody has
 * learned to ignore. That is `GUARDS.md` rule 6 arriving through the back door.
 *
 * The third option is to say **which** advisories have been assessed and why,
 * in a file somebody reviews. That is this.
 *
 * ## `--omit=dev` is the boundary, and it is a real one
 *
 * A build-time advisory in a test runner does not ship. The container holds
 * production dependencies, so those are what this asks about. Widening it to
 * dev pulls in advisories nothing can reach from outside and drowns the ones
 * that can.
 *
 * ## Rules for adding an entry — all four, or it is not an assessment
 *
 *   - **reason** — why it cannot reach THIS app, concretely, naming the file or
 *     the API that would have to be in use for it to matter. "Low risk" is not
 *     an assessment, it is an adjective.
 *   - **reachableIf** — what would make it reachable. This is the falsifiable
 *     half: without it, nobody can ever tell whether the waiver still holds.
 *   - **recheck** — the event that should retire the entry, not a date.
 *   - **Mirror it in the project's SECURITY document**, so an operator reading
 *     about the system's posture sees the same list a developer does. An
 *     exception that lives only in a script is one the security review misses.
 *
 * Delete an entry the moment a fix ships. An allowlist nobody prunes stops
 * being a record of decisions and becomes a list of things nobody looks at.
 *
 * ===========================================================================
 * TEMPLATE COPY — configure this before the first run
 * ===========================================================================
 *
 * Copy to `scripts/audit-gate.mjs`, add `"audit": "node scripts/audit-gate.mjs"`
 * to package.json, and — this is the step that matters — put it in whatever
 * command the gate actually runs. A guard wired to nothing is documentation.
 *
 * Set SECURITY_DOC below to where this project keeps its security document, so
 * the failure message names a path that exists. `docs/security/SECURITY.md` is
 * the template's location; a repository that keeps it elsewhere and does not
 * change this line prints a path a reader cannot open, which is exactly the
 * class of stale doc-claim `doc-claims.sh` exists to catch.
 *
 * ALLOWED starts empty, deliberately. An allowlist inherited from another
 * project waives advisories against an application that was never assessed —
 * and it waives them silently, which is the worst available outcome.
 */

// ===========================================================================
// CONFIGURATION
// ===========================================================================

/** Where this project's security document lives, for the failure message. */
const SECURITY_DOC = 'docs/security/SECURITY.md';

/**
 * Assessed advisories, keyed by the package name npm reports.
 *
 * Empty on purpose — see the header. A worked example of the shape, from the
 * project this came from:
 *
 *   'react-router': {
 *     reason:
 *       'Advisory is RSC Mode CSRF (action execution before a 400). This app ' +
 *       'is a Vite SPA using declarative <BrowserRouter> (client/main.tsx) — ' +
 *       'no RSC mode, no framework/data router, no createStaticHandler, no ' +
 *       '@react-router/* server package. No fixed version exists: the ' +
 *       'vulnerable range extends past the newest published release, and the ' +
 *       'only "fix" npm offers is a downgrade.',
 *     reachableIf: 'the app adopts RSC mode or a react-router server runtime',
 *     recheck: 'when react-router publishes a release above the vulnerable range',
 *   },
 *
 * Note what makes that one an assessment rather than a shrug: it names the
 * file, the four APIs that would have to be in use, and the release that
 * retires it.
 */
const ALLOWED = {};

// ===========================================================================

import { execFileSync } from 'node:child_process';

const listOnly = process.argv.includes('--list');

const die = (code, message) => {
  console.error(`[audit-gate] ${message}`);
  process.exit(code);
};

let raw;

try {
  raw = execFileSync('npm', ['audit', '--omit=dev', '--json'], {
    encoding: 'utf8',
    maxBuffer: 32 * 1024 * 1024,
  });
} catch (err) {
  // npm audit exits non-zero whenever it finds anything at all, so a throw here
  // is the normal path and the JSON is still on stdout. An empty stdout is the
  // abnormal one — npm itself failed, and nothing was measured.
  raw = err.stdout;

  if (!raw) {
    die(2, `npm audit produced no output (${err.message}) — nothing was checked`);
  }
}

let report;

try {
  report = JSON.parse(raw);
} catch {
  die(2, 'npm audit output was not JSON — nothing was checked');
}

// Distinguishing "no vulnerabilities" from "no vulnerabilities key" is the whole
// of GUARDS.md rule 5 applied to this script's own instrument. npm's audit JSON
// has changed shape between major versions before; a run against a shape this
// does not understand must not render as a clean bill of health.
if (typeof report.vulnerabilities !== 'object' || report.vulnerabilities === null) {
  die(2, 'npm audit output had no `vulnerabilities` object — nothing was checked');
}

const blocking = [];
const waived = [];

for (const [name, entry] of Object.entries(report.vulnerabilities)) {
  if (entry.severity !== 'high' && entry.severity !== 'critical') continue;

  (ALLOWED[name] ? waived : blocking).push({
    name,
    severity: entry.severity,
    range: entry.range,
  });
}

for (const { name, severity, range } of waived) {
  console.log(`[audit-gate] WAIVED  ${name} (${severity}, ${range}) — ${ALLOWED[name].reason}`);
}

if (blocking.length && !listOnly) {
  console.error(`\n[audit-gate] FAILED — ${blocking.length} unassessed high/critical advisory(ies):`);

  for (const { name, severity, range } of blocking) {
    console.error(`  ✗ ${name} (${severity}, ${range})`);
  }

  console.error(
    `\nFix it, or — only if it provably cannot reach this app — add an assessed entry\n` +
      `to this script and mirror it in ${SECURITY_DOC}. All four fields, or it is\n` +
      `not an assessment.`,
  );

  process.exit(1);
}

if (blocking.length) {
  console.log(`[audit-gate] --list: ${blocking.length} unassessed high/critical advisory(ies)`);

  for (const { name, severity, range } of blocking) {
    console.log(`  ✗ ${name} (${severity}, ${range})`);
  }
}

console.log(
  `[audit-gate] OK — 0 unassessed high/critical advisories in production dependencies` +
    (waived.length ? ` (${waived.length} assessed and waived)` : ''),
);