import 'package:flame_lua_runtime/runtime/diagnostics/runtime_diagnostics.dart';
import 'package:flame_lua_runtime/runtime/events/runtime_event_dispatcher.dart';
import 'package:flame_lua_runtime/runtime/lifecycle/runtime_session.dart';
import 'package:flame_lua_runtime/runtime/models/game_diff.dart';
import 'package:flame_lua_runtime/runtime/models/runtime_event.dart';
import 'package:flame_lua_runtime/runtime/packages/game_package.dart';
import 'package:flame_lua_runtime/runtime/scripting/runtime_script_services.dart';
import 'package:flame_lua_runtime/runtime/scripting/script_engine.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  group('RuntimeEventDispatcher', () {
    test('dispatches queued events serially', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine();
      final applied = <GameDiff>[];
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => true,
        applyDiff: applied.add,
      );

      dispatcher
        ..enqueue(const RuntimeEvent(type: 'tap', target: 'a'))
        ..enqueue(const RuntimeEvent(type: 'tap', target: 'b'));

      await Future<void>.delayed(Duration.zero);

      expect(script.events.map((event) => event.target), ['a', 'b']);
      expect(applied, hasLength(2));
    });

    test('drops events for removed scope', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine();
      var alive = true;
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => alive,
        applyDiff: (_) {},
      );

      dispatcher.enqueue(const RuntimeEvent(type: 'tap', scope: 'dialog'));
      alive = false;

      await Future<void>.delayed(Duration.zero);

      expect(script.events, isEmpty);
    });

    test('drops events with stale target epoch', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine();
      var currentEpoch = 2;
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => true,
        isNodeEpochAlive: (_, epoch) => epoch == currentEpoch,
        applyDiff: (_) {},
      );

      dispatcher.enqueue(
        const RuntimeEvent(type: 'tap', target: 'button', targetEpoch: 1),
      );
      currentEpoch = 3;

      await Future<void>.delayed(Duration.zero);

      expect(script.events, isEmpty);
    });

    test('drops queued events after dispose', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine();
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => true,
        applyDiff: (_) {},
      );

      dispatcher.enqueue(const RuntimeEvent(type: 'tap'));
      dispatcher.dispose();

      await Future<void>.delayed(Duration.zero);

      expect(script.events, isEmpty);
    });

    test('drops queued events after session dispose', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine();
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => true,
        applyDiff: (_) {},
      );

      dispatcher.enqueue(const RuntimeEvent(type: 'tap'));
      session.dispose();

      await Future<void>.delayed(Duration.zero);

      expect(script.events, isEmpty);
    });

    test('continues draining after a script error', () async {
      final session = _activeSession();
      final script = _FakeScriptEngine()..failNext = true;
      final errors = <Object>[];
      final diagnostics = RuntimeDiagnostics();
      final dispatcher = RuntimeEventDispatcher(
        session: session,
        scriptEngine: script,
        isScopeAlive: (_) => true,
        applyDiff: (_) {},
        diagnostics: diagnostics,
        onError: errors.add,
      );

      dispatcher
        ..enqueue(const RuntimeEvent(type: 'tap', target: 'bad'))
        ..enqueue(const RuntimeEvent(type: 'tap', target: 'good'));

      await Future<void>.delayed(Duration.zero);

      expect(errors, hasLength(1));
      expect(diagnostics.entries, hasLength(1));
      expect(
        diagnostics.entries.single.type,
        RuntimeDiagnosticType.luaEventError,
      );
      expect(diagnostics.entries.single.context['target'], 'bad');
      expect(script.events.map((event) => event.target), ['bad', 'good']);
    });
  });
}

RuntimeSession _activeSession() {
  final session = RuntimeSession(gameId: 'test')..beginLoading();
  session.activate();
  return session;
}

class _FakeScriptEngine implements ScriptEngine {
  final events = <RuntimeEvent>[];
  bool failNext = false;

  @override
  Future<void> loadPackage(
    GamePackage package, {
    RuntimeScriptServices services = const RuntimeScriptServices(),
  }) async {}

  @override
  bool smokeTest(Map<String, Object?> context) => true;

  @override
  GameDiff init(Map<String, Object?> context) => GameDiff.empty;

  @override
  GameDiff dispatchEvent(RuntimeEvent event) {
    events.add(event);
    if (failNext) {
      failNext = false;
      throw StateError('boom');
    }
    return GameDiff.empty;
  }
}