import { describe, it, expect } from 'vitest';
import { readdirSync, readFileSync } from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';

// Belt-and-braces detector for the birpc teardown race named in ADR-012 / #553.
// ESLint catches the pattern at save time, CI grep catches it before the test
// suite launches, and this in-suite test catches it at every vitest invocation —
// the layer hardest to disable or scope around.
//
// We scan source text rather than parsing AST: fast, no parser dependency,
// good enough for the named anti-pattern. The pattern matches
// `vi.mock(<arg>, async ... { ... await import(...) ... })`.

const ASYNC_MOCK_WITH_DYNAMIC_IMPORT = /vi\.mock\([^)]*,\s*async[^{]*\{[\s\S]*?await\s+import\s*\(/;

export function hasAsyncMockFactoryWithDynamicImport(source: string): boolean {
	return ASYNC_MOCK_WITH_DYNAMIC_IMPORT.test(source);
}

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const SRC_ROOT = path.resolve(__dirname, '..');

function findBrowserSpecs(): string[] {
	const entries = readdirSync(SRC_ROOT, { recursive: true, withFileTypes: true });
	return entries
		.filter(
			(e) =>
				e.isFile() && (e.name.endsWith('.svelte.test.ts') || e.name.endsWith('.svelte.spec.ts'))
		)
		.map((e) => path.join(e.parentPath ?? (e as { path: string }).path, e.name));
}

describe('scan: hasAsyncMockFactoryWithDynamicImport', () => {
	it('flags async vi.mock factory with await import in body', () => {
		const fixture = `vi.mock('$app/stores', async () => {
			const mod = await import('./__mocks__/navigatingStore');
			return { navigating: mod.navigatingStore };
		});`;
		expect(hasAsyncMockFactoryWithDynamicImport(fixture)).toBe(true);
	});

	it('does not flag sync vi.mock factory', () => {
		const fixture = `vi.mock('$app/state', () => ({ navigating: { type: null } }));`;
		expect(hasAsyncMockFactoryWithDynamicImport(fixture)).toBe(false);
	});

	it('does not flag async vi.mock factory without dynamic import', () => {
		const fixture = `vi.mock('foo', async () => {
			const x = await Promise.resolve(42);
			return { bar: x };
		});`;
		expect(hasAsyncMockFactoryWithDynamicImport(fixture)).toBe(false);
	});

	it('does not flag dynamic import outside any vi.mock', () => {
		const fixture = `async function load() {
			const mod = await import('./something');
			return mod.default;
		}`;
		expect(hasAsyncMockFactoryWithDynamicImport(fixture)).toBe(false);
	});

	it('flags async factory written as async function expression', () => {
		const fixture = `vi.mock('foo', async function () {
			const mod = await import('./bar');
			return mod;
		});`;
		expect(hasAsyncMockFactoryWithDynamicImport(fixture)).toBe(true);
	});
});

describe('browser specs: no async vi.mock factory contains await import', () => {
	it('every src/**/*.svelte.{test,spec}.ts file is clean', () => {
		const specFiles = findBrowserSpecs();
		expect(specFiles.length).toBeGreaterThan(0);
		const offenders = specFiles.filter((file) =>
			hasAsyncMockFactoryWithDynamicImport(readFileSync(file, 'utf-8'))
		);
		expect(offenders).toEqual([]);
	});
});