import '../diagnostics/runtime_diagnostics.dart';
import '../lifecycle/runtime_serial_queue.dart';
import '../lifecycle/runtime_session.dart';
import '../models/game_diff.dart';
import '../models/runtime_event.dart';
import '../scripting/script_engine.dart';
import 'runtime_event_gate.dart';

class RuntimeEventDispatcher {
  RuntimeEventDispatcher({
    required RuntimeSession session,
    required ScriptEngine scriptEngine,
    required bool Function(String id) isScopeAlive,
    bool Function(String id, int epoch)? isNodeEpochAlive,
    required void Function(GameDiff diff) applyDiff,
    RuntimeDiagnostics? diagnostics,
    void Function(Object error)? onError,
  }) : _scriptEngine = scriptEngine,
       _applyDiff = applyDiff,
       _diagnostics = diagnostics,
       _onError = onError,
       _gate = RuntimeEventGate(
         session: session,
         isScopeAlive: isScopeAlive,
         isNodeEpochAlive: isNodeEpochAlive,
       ) {
    _queue = RuntimeSerialQueue<RuntimeEvent>(
      shouldContinue: () => !_disposed && session.isActive,
      onItem: _dispatch,
    );
  }

  final ScriptEngine _scriptEngine;
  final void Function(GameDiff diff) _applyDiff;
  final RuntimeDiagnostics? _diagnostics;
  final void Function(Object error)? _onError;
  final RuntimeEventGate _gate;
  late final RuntimeSerialQueue<RuntimeEvent> _queue;
  bool _disposed = false;

  int get pendingEventCount => _queue.pendingCount;

  void enqueue(RuntimeEvent event) {
    if (_disposed || !_gate.session.isActive) {
      return;
    }
    _queue.enqueue(_gate.attachSession(event));
  }

  void dispose() {
    _disposed = true;
    _queue.dispose();
  }

  void _dispatch(RuntimeEvent event) {
    if (!_gate.accepts(event)) {
      return;
    }

    try {
      final diff = _scriptEngine.dispatchEvent(event);
      if (_disposed || !_gate.session.isActive || !_gate.accepts(event)) {
        return;
      }
      _applyDiff(diff);
    } catch (error) {
      _diagnostics?.record(
        type: RuntimeDiagnosticType.luaEventError,
        message: 'Lua event dispatch failed',
        error: error,
        context: {
          'eventType': event.type,
          if (event.target != null) 'target': event.target,
          if (event.handler != null) 'handler': event.handler,
        },
      );
      _onError?.call(error);
    }
  }
}