/**
 * BACKLOG P0-13 / SEC-06 -- security-header REGRESSION GATE.
 *
 * Why this file exists: CHANGELOG.md asserted "security headers
 * (CSP/HSTS/X-Frame-Options/etc.)" while `main` contained zero such code for
 * weeks, and nothing in the repo could tell the difference. Adding the headers
 * without adding a gate would just reset that clock.
 *
 * WHAT THIS PROVES: that `next.config.mjs` -- the object Next.js actually
 * consumes -- still declares the required headers, with values that are still
 * strict. It reads the real config module; it does not re-import the header
 * list and compare it to itself. Every expectation below is written out here,
 * independently, so deleting or weakening a header in next.config.mjs fails
 * this test rather than silently changing both sides.
 *
 * WHAT IT DOES NOT PROVE: that a running instance serves them. Next freezes
 * `headers()` into .next/routes-manifest.json at build time, so the manifest
 * assertion at the bottom runs opportunistically when a build exists (locally,
 * or in any job that builds before testing). End-to-end, against a live
 * origin, is `node scripts/siax-doctor.mjs --live`.
 *
 * Runs inside `pnpm run test` -> the BLOCKING "CI (SIAX Cloud) / quality" job.
 */
import { describe, expect, it } from "vitest";
import { existsSync, readFileSync } from "node:fs";
import { fileURLToPath } from "node:url";
import path from "node:path";

const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..", "..");

type HeaderEntry = { key: string; value: string };
type HeaderRule = { source: string; headers: HeaderEntry[] };

/**
 * Required headers and how strict each must stay. Hardcoded on purpose --
 * this is the independent side of the comparison.
 */
const REQUIRED: { key: string; assert: (value: string) => void }[] = [
  {
    key: "Strict-Transport-Security",
    assert: (v) => {
      const maxAge = /max-age=(\d+)/.exec(v);
      expect(maxAge, `HSTS must carry a max-age, got: ${v}`).not.toBeNull();
      // >= 1 year: below that the header is decorative and ineligible for preload.
      expect(Number(maxAge![1])).toBeGreaterThanOrEqual(31536000);
      expect(v).toMatch(/includeSubDomains/i);
    },
  },
  {
    key: "X-Frame-Options",
    // SAMEORIGIN would be a weakening for this app: nothing here frames itself.
    assert: (v) => expect(v.trim().toUpperCase()).toBe("DENY"),
  },
  {
    key: "X-Content-Type-Options",
    assert: (v) => expect(v.trim().toLowerCase()).toBe("nosniff"),
  },
  {
    key: "Referrer-Policy",
    assert: (v) =>
      expect(["no-referrer", "same-origin", "strict-origin", "strict-origin-when-cross-origin"]).toContain(
        v.trim().toLowerCase(),
      ),
  },
  {
    key: "Permissions-Policy",
    assert: (v) => {
      for (const feature of ["camera", "microphone", "geolocation"]) {
        expect(v, `Permissions-Policy must disable ${feature}`).toMatch(
          new RegExp(`${feature}\\s*=\\s*\\(\\s*\\)`),
        );
      }
    },
  },
  {
    key: "Content-Security-Policy",
    assert: (v) => {
      const directives = new Map(
        v
          .split(";")
          .map((d) => d.trim())
          .filter(Boolean)
          .map((d) => {
            const [name, ...rest] = d.split(/\s+/);
            return [name.toLowerCase(), rest.join(" ")] as const;
          }),
      );
      expect(directives.get("default-src")).toBe("'self'");
      // Clickjacking defence that actually applies to modern browsers.
      expect(directives.get("frame-ancestors")).toBe("'none'");
      expect(directives.get("base-uri")).toBe("'self'");
      expect(directives.get("object-src")).toBe("'none'");
      expect(directives.get("form-action")).toBe("'self'");
      expect(directives.has("script-src")).toBe(true);
      expect(directives.has("connect-src")).toBe(true);
      expect(directives.has("frame-src")).toBe(true);

      // No wildcard sources anywhere: a bare `*` re-opens what this header exists to close.
      for (const [name, value] of directives) {
        expect(value.split(/\s+/), `CSP directive ${name} must not allow *`).not.toContain("*");
      }

      // 'unsafe-eval' is a dev-only relaxation (see next.config.mjs). Vitest runs
      // with NODE_ENV=test, so it must be absent here; if it ever appears outside
      // `next dev`, this fails.
      expect(process.env.NODE_ENV, "vitest is expected to run outside NODE_ENV=development").not.toBe(
        "development",
      );
      expect(v, "'unsafe-eval' must never ship outside next dev").not.toContain("unsafe-eval");
    },
  },
];

/** Rule sources that cover every path Next can serve. */
const CATCH_ALL_SOURCES = new Set(["/(.*)", "/:path*", "/(.*)?"]);

async function loadNextConfig(): Promise<{ poweredByHeader?: boolean; headers?: () => Promise<HeaderRule[]> }> {
  // Computed specifier on purpose: keeps `next.config.mjs` (a JS file outside
  // tsconfig.check.json's include) out of the blocking typecheck's graph.
  const url = new URL("../../next.config.mjs", import.meta.url).href;
  const mod = (await import(/* @vite-ignore */ url)) as { default: Awaited<ReturnType<typeof loadNextConfig>> };
  return mod.default;
}

describe("SEC-06: 0pt serves its own security headers (P0-13)", () => {
  it("next.config.mjs declares a headers() rule covering every path", async () => {
    const config = await loadNextConfig();
    expect(typeof config.headers, "next.config.mjs must export an async headers()").toBe("function");

    const rules = await config.headers!();
    expect(Array.isArray(rules)).toBe(true);

    const catchAll = rules.filter((r) => CATCH_ALL_SOURCES.has(r.source));
    expect(
      catchAll.length,
      `no catch-all header rule; sources were: ${rules.map((r) => r.source).join(", ")}`,
    ).toBeGreaterThan(0);
  });

  it("does not advertise the framework via X-Powered-By", async () => {
    const config = await loadNextConfig();
    expect(config.poweredByHeader).toBe(false);
  });

  for (const { key, assert } of REQUIRED) {
    it(`sets ${key} on every path, and keeps it strict`, async () => {
      const config = await loadNextConfig();
      const rules = await config.headers!();
      const applied = rules
        .filter((r) => CATCH_ALL_SOURCES.has(r.source))
        .flatMap((r) => r.headers)
        .filter((h) => h.key.toLowerCase() === key.toLowerCase());

      expect(
        applied.length,
        `${key} is not set for all paths -- CHANGELOG.md claims 0pt ships it. ` +
          `Either restore it in next.config.mjs or stop claiming it.`,
      ).toBe(1);

      assert(applied[0].value);
    });
  }

  it("the built routes-manifest carries the same headers (skipped when no build exists)", async () => {
    const manifestPath = path.join(REPO_ROOT, ".next", "routes-manifest.json");
    if (!existsSync(manifestPath)) {
      // `pnpm run test` runs before `pnpm run build` in .gitea/workflows/ci.yml,
      // so on a clean CI checkout there is nothing to read. Not a silent pass:
      // the config-level assertions above already ran and are blocking.
      return;
    }
    const manifest = JSON.parse(readFileSync(manifestPath, "utf8")) as {
      headers?: { source?: string; regex?: string; headers?: HeaderEntry[] }[];
    };
    const built = (manifest.headers ?? []).flatMap((r) => r.headers ?? []);
    expect(built.length, "a build exists but its routes-manifest has no headers").toBeGreaterThan(0);
    for (const { key } of REQUIRED) {
      expect(
        built.some((h) => h.key.toLowerCase() === key.toLowerCase()),
        `${key} missing from .next/routes-manifest.json -- it would not be served`,
      ).toBe(true);
    }
  });
});