import { readdirSync, readFileSync } from "node:fs";

import { describe, expect, it } from "vitest";

// E28 S3d4 (B4, UX-15). One `h1` per page: the shell's hidden page name, or a view's own visible
// title through `PageHeading`, which makes the shell's step aside. A hand-written `<h1>` inside the
// shell would be a second one, beside the page name the shell already put there.
function sources(): Array<[string, string]> {
  const walk = (u: URL, prefix: string): Array<[string, string]> =>
    readdirSync(u, { withFileTypes: true }).flatMap((e) => {
      if (e.isDirectory()) return walk(new URL(`${e.name}/`, u), `${prefix}${e.name}/`);
      if (!/\.tsx$/.test(e.name) || e.name.includes(".test.")) return [];
      return [
        [`${prefix}${e.name}`, readFileSync(new URL(e.name, u), "utf-8")] as [string, string],
      ];
    });
  return walk(new URL("../", import.meta.url), "");
}

// Pages that render OUTSIDE the app shell own their h1 (no shell, no hidden page name).
const STANDALONE = new Set([
  "components/Welcome.tsx",
  "components/WatchPage.tsx",
  "components/legal/LegalLayout.tsx",
  "design-lab/DesignLab.tsx",
  // The shell's hidden h1 and the primitive itself.
  "components/ui/PageShell.tsx",
  "components/ui/Headings.tsx",
]);

describe("the page heading", () => {
  it("is written as PageHeading inside the shell, never as a hand <h1>", () => {
    const own = sources()
      .filter(([name]) => !STANDALONE.has(name))
      .filter(([, src]) => /<h1[\s>]/.test(src))
      .map(([name]) => name);
    expect(own).toEqual([]);
  });
});