import { createHash } from "node:crypto";
import { mkdir, readFile, readdir, stat, writeFile } from "node:fs/promises";
import path from "node:path";

/** @param {string} name @param {string} fallback */
function argumentValue(name, fallback) {
  const index = process.argv.indexOf(name);
  return index >= 0 && process.argv[index + 1]
    ? process.argv[index + 1]
    : fallback;
}

const policyPath = argumentValue(
  "--policy",
  "config/security/secret-scan-policy.json",
);
const artifactPath = argumentValue(
  "--artifact",
  "artifacts/security/scan.sarif",
);
const policy = JSON.parse(await readFile(policyPath, "utf8"));
const findings =
  /** @type {Array<{
   *   ruleId: string,
   *   file: string,
   *   line: number,
   *   fingerprint: string
   * }>} */ ([]);
const policyFailures = [];
const patterns = [
  {
    id: "private-key",
    expression: /-----BEGIN (?:RSA |EC )?PRIVATE KEY-----/g,
  },
  { id: "aws-access-key", expression: /\bAKIA[0-9A-Z]{16}\b/g },
  { id: "github-token", expression: /\bgh[pousr]_[A-Za-z0-9_]{30,}\b/g },
  {
    id: "assigned-secret",
    expression:
      /\b(?:client_secret|password|private_key)\s*[:=]\s*["'][^"'${}]{12,}["']/gi,
  },
];

/** @param {string} target @returns {Promise<string[]>} */
async function filesWithin(target) {
  try {
    const metadata = await stat(target);
    if (metadata.isFile()) return [target];
    const entries = await readdir(target, { withFileTypes: true });
    const nested = /** @type {string[][]} */ (await Promise.all(
      entries.map((entry) => {
        const child = path.join(target, entry.name);
        return entry.isDirectory() ? filesWithin(child) : [child];
      }),
    ));
    return nested.flat();
  } catch {
    return [];
  }
}

const excluded = new Set(
  /** @type {string[]} */ (policy.excludedPaths ?? []).map((entry) =>
    entry.replaceAll("\\", "/"),
  ),
);
const allowlist =
  /** @type {Array<{
   *   path: string,
   *   ruleId: string,
   *   owner: string,
   *   reason: string,
   *   expiresAt: string
   * }>} */ (policy.allowlist ?? []);
for (const entry of allowlist) {
  const expiry = Date.parse(entry.expiresAt);
  if (
    !entry.path.startsWith("tests/") ||
    !entry.owner?.trim() ||
    !entry.reason?.trim() ||
    !Number.isFinite(expiry) ||
    expiry <= Date.now()
  ) {
    policyFailures.push(
      `invalid or expired secret allowlist entry: ${entry.path}:${entry.ruleId}`,
    );
  }
}

const roots = [
  ...(/** @type {string[]} */ (policy.trackedRoots ?? [])),
  ...(/** @type {string[]} */ (policy.generatedRoots ?? [])),
];
const scanFiles = (
  await Promise.all(roots.map((root) => filesWithin(root)))
).flat();
for (const scanFile of [...new Set(scanFiles)].sort()) {
  const normalized = scanFile.replaceAll("\\", "/");
  if (
    [...excluded].some(
      (entry) => normalized === entry || normalized.startsWith(`${entry}/`),
    ) ||
    /\.(?:png|jpe?g|gif|webp|woff2?|zip|gz|sarif)$/i.test(normalized)
  ) {
    continue;
  }
  let content;
  try {
    content = await readFile(scanFile, "utf8");
  } catch {
    continue;
  }
  for (const pattern of patterns) {
    pattern.expression.lastIndex = 0;
    for (const match of content.matchAll(pattern.expression)) {
      const isAllowed = allowlist.some(
        (entry) =>
          entry.path === normalized &&
          entry.ruleId === pattern.id &&
          Date.parse(entry.expiresAt) > Date.now(),
      );
      if (isAllowed) continue;
      const prefix = content.slice(0, match.index);
      findings.push({
        ruleId: pattern.id,
        file: normalized,
        line: prefix.split(/\r?\n/).length,
        fingerprint: createHash("sha256")
          .update(`${pattern.id}:${normalized}:${String(match.index)}`)
          .digest("hex"),
      });
    }
  }
}

const sarif = {
  version: "2.1.0",
  $schema: "https://json.schemastore.org/sarif-2.1.0.json",
  runs: [
    {
      tool: {
        driver: {
          name: "ca-frontend-secret-scan",
          rules: patterns.map((pattern) => ({
            id: pattern.id,
            shortDescription: { text: "Potential credential material" },
          })),
        },
      },
      results: [
        ...findings.map((finding) => ({
          ruleId: finding.ruleId,
          message: {
            text: "Potential secret material must be removed.",
          },
          partialFingerprints: {
            primaryLocationLineHash: finding.fingerprint,
          },
          locations: [
            {
              physicalLocation: {
                artifactLocation: { uri: finding.file },
                region: { startLine: finding.line },
              },
            },
          ],
        })),
        ...policyFailures.map((failure) => ({
          ruleId: "invalid-allowlist",
          message: { text: failure },
        })),
      ],
    },
  ],
};

await mkdir(path.dirname(artifactPath), { recursive: true });
await writeFile(artifactPath, `${JSON.stringify(sarif, null, 2)}\n`);
if (findings.length > 0 || policyFailures.length > 0) {
  process.stderr.write(
    `Security scan found ${findings.length + policyFailures.length} blocking result(s).\n`,
  );
  process.exit(1);
}
process.stdout.write(
  `Tracked source, config, built asset and artifact secret scan: PASS (${scanFiles.length} files)\n`,
);