import { test as base } from '@playwright/test';
import { mkdirSync, writeFileSync } from 'fs';
import { randomUUID } from 'crypto';
import path from 'path';

// Re-exported so specs can import everything from here — expect, Page,
// APIRequestContext — and get the coverage-collecting `test` at the same time.
// The explicit `test` below wins over the star export.
export * from '@playwright/test';

const NYC_OUTPUT = path.resolve(__dirname, '..', '..', '.nyc_output');
const collectingCoverage = process.env.COVERAGE === 'true';

// Set once any page reports instrumentation. Checked by the collection script so
// an empty run fails loudly instead of publishing 0% — see the note below.
const MARKER = path.join(NYC_OUTPUT, '.collected');

/**
 * Flushes istanbul's per-page counters after each test.
 *
 * Coverage lives in `window.__coverage__` on the page and dies with it, so it
 * has to be read before the page closes — one file per test, because the suite
 * runs fullyParallel and workers would otherwise overwrite each other.
 */
export const test = base.extend<{ collectCoverage: void }>({
  collectCoverage: [
    async ({ page }, use) => {
      await use();

      if (!collectingCoverage) return;

      // The page may already be closed by a test that navigated away or crashed;
      // a missing sample is not worth failing a passing test over. The run-level
      // check catches the case that actually matters — no samples at all.
      const coverage = await page
        .evaluate(() => (window as unknown as { __coverage__?: unknown }).__coverage__)
        .catch(() => undefined);

      if (!coverage) return;

      mkdirSync(NYC_OUTPUT, { recursive: true });
      writeFileSync(path.join(NYC_OUTPUT, `${randomUUID()}.json`), JSON.stringify(coverage));
      writeFileSync(MARKER, 'ok');
    },
    { auto: true }
  ]
});