import { strict as assert } from 'node:assert';
import { test } from 'node:test';
import { readdirSync } from 'node:fs';
import { join } from 'node:path';

/**
 * Guard against same-directory filenames that differ only by case (e.g.
 * `threadSummary.ts` vs `ThreadSummary.tsx`). On case-insensitive filesystems
 * (the Windows release runner) an extensionless import of one can resolve to
 * the OTHER file — rolldown tries `.ts` before `.tsx` — producing
 * MISSING_EXPORT failures that never reproduce on the Linux/macOS machines the
 * project is developed and web-deployed on. This broke the desktop release
 * build twice before being diagnosed; this test makes the collision a local,
 * immediate failure instead.
 */
const findCaseCollisions = (dir: string, collisions: string[]): void => {
  const entries = readdirSync(dir, { withFileTypes: true });
  const seen = new Map<string, string>();
  entries.forEach((entry) => {
    // Compare basenames without extension: `Foo.tsx` collides with `foo.ts`
    // because module resolution is extensionless.
    const stem = entry.isDirectory() ? entry.name : entry.name.replace(/\.[^.]+$/, '');
    const key = stem.toLowerCase();
    const existing = seen.get(key);
    if (existing !== undefined && existing !== stem) {
      collisions.push(`${dir}: "${existing}" vs "${stem}"`);
    }
    if (existing === undefined) seen.set(key, stem);
    if (entry.isDirectory()) {
      findCaseCollisions(join(dir, entry.name), collisions);
    }
  });
};

test('no same-directory filenames differing only by case under src/', () => {
  const collisions: string[] = [];
  findCaseCollisions('src', collisions);
  assert.deepEqual(
    collisions,
    [],
    `Case-colliding names break Windows builds:\n${collisions.join('\n')}`,
  );
});