import 'dart:async' as async;

import 'package:flame_lua_runtime/runtime/resources/resource_load_limiter.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  group('ResourceLoadLimiter', () {
    test('limits concurrent tasks', () async {
      final limiter = ResourceLoadLimiter(2);
      var active = 0;
      var maxActive = 0;

      Future<int> task(int value) async {
        active++;
        if (active > maxActive) {
          maxActive = active;
        }
        await Future<void>.delayed(const Duration(milliseconds: 5));
        active--;
        return value;
      }

      final results = await Future.wait([
        limiter.run(() => task(1)),
        limiter.run(() => task(2)),
        limiter.run(() => task(3)),
        limiter.run(() => task(4)),
      ]);

      expect(results, [1, 2, 3, 4]);
      expect(maxActive, 2);
      expect(limiter.activeCount, 0);
      expect(limiter.pendingCount, 0);
    });

    test('clearPending cancels queued tasks', () async {
      final limiter = ResourceLoadLimiter(1);
      final hold = async.Completer<void>();

      final first = limiter.run(() => hold.future);
      final second = limiter.run(() async => 2);

      expect(limiter.activeCount, 1);
      expect(limiter.pendingCount, 1);

      final secondExpectation = expectLater(
        second,
        throwsA(isA<ResourceLoadCancelledException>()),
      );

      limiter.clearPending();
      hold.complete();

      await first;
      await secondExpectation;
    });

    test('rejects invalid concurrency', () {
      expect(() => ResourceLoadLimiter(0), throwsArgumentError);
    });
  });
}