flutter_lua_runtime/lib/runtime/host/runtime_host_bridge.dart

import 'dart:async' as async;

import '../diagnostics/runtime_diagnostics.dart';
import '../models/runtime_event.dart';

typedef RuntimeHostCallHandler =
    async.FutureOr<Object?> Function(RuntimeHostCall call);
typedef RuntimeHostNotifyHandler =
    void Function(RuntimeHostNotification notification);

class RuntimeHostBridge {
  const RuntimeHostBridge({this.handlers = const {}, this.onNotify});

  final Map<String, RuntimeHostCallHandler> handlers;
  final RuntimeHostNotifyHandler? onNotify;
}

class RuntimeHostCall {
  const RuntimeHostCall({required this.id, required this.method, this.data});

  final String id;
  final String method;
  final Object? data;
}

class RuntimeHostNotification {
  const RuntimeHostNotification({required this.method, this.data});

  final String method;
  final Object? data;
}

class RuntimeHostBridgeManager {
  RuntimeHostBridgeManager({
    required RuntimeHostBridge bridge,
    required void Function(RuntimeEvent event) eventSink,
    RuntimeDiagnostics? diagnostics,
  }) : _bridge = bridge,
       _eventSink = eventSink,
       _diagnostics = diagnostics;

  final RuntimeHostBridge _bridge;
  final void Function(RuntimeEvent event) _eventSink;
  final RuntimeDiagnostics? _diagnostics;
  final Map<String, async.Completer<Object?>> _pendingLuaCalls = {};
  var _nextCallId = 0;
  bool _disposed = false;

  Future<void> callHost(RuntimeHostCall call) async {
    if (_disposed) {
      return;
    }
    final handler = _bridge.handlers[call.method];
    if (handler == null) {
      _emitHostCallResult(
        id: call.id,
        method: call.method,
        ok: false,
        error: 'No host handler registered for ${call.method}',
      );
      return;
    }

    try {
      final result = await handler(call);
      _emitHostCallResult(
        id: call.id,
        method: call.method,
        ok: true,
        result: result,
      );
    } catch (error) {
      _diagnostics?.record(
        type: RuntimeDiagnosticType.hostBridgeError,
        message: 'Runtime host call failed',
        error: error,
        context: {'id': call.id, 'method': call.method},
      );
      _emitHostCallResult(
        id: call.id,
        method: call.method,
        ok: false,
        error: error.toString(),
      );
    }
  }

  bool notifyHost(RuntimeHostNotification notification) {
    if (_disposed) {
      return false;
    }
    final handler = _bridge.onNotify;
    if (handler == null) {
      return false;
    }
    try {
      handler(notification);
      return true;
    } catch (error) {
      _diagnostics?.record(
        type: RuntimeDiagnosticType.hostBridgeError,
        message: 'Runtime host notification failed',
        error: error,
        context: {'method': notification.method},
      );
      return false;
    }
  }

  Future<Object?> callLua(
    String method, {
    Object? data,
    Duration timeout = const Duration(seconds: 15),
  }) {
    if (_disposed) {
      return Future<Object?>.error(StateError('Runtime host bridge disposed'));
    }
    final id = 'host:${++_nextCallId}';
    final completer = async.Completer<Object?>();
    _pendingLuaCalls[id] = completer;
    _emit(
      RuntimeEvent(
        type: RuntimeHostEventType.call,
        data: {
          'id': id,
          'method': method,
          if (data != null) 'data': _runtimeValue(data),
        },
      ),
    );
    return completer.future.timeout(
      timeout,
      onTimeout: () {
        _pendingLuaCalls.remove(id);
        throw async.TimeoutException(
          'Lua host call timed out: $method',
          timeout,
        );
      },
    );
  }

  bool notifyLua(String method, {Object? data}) {
    if (_disposed) {
      return false;
    }
    _emit(
      RuntimeEvent(
        type: RuntimeHostEventType.notify,
        data: {'method': method, if (data != null) 'data': _runtimeValue(data)},
      ),
    );
    return true;
  }

  bool completeLuaCall(String id, {Object? result, String? error}) {
    final completer = _pendingLuaCalls.remove(id);
    if (completer == null || completer.isCompleted) {
      return false;
    }
    if (error != null) {
      completer.completeError(StateError(error));
    } else {
      completer.complete(_runtimeValue(result));
    }
    return true;
  }

  void dispose() {
    _disposed = true;
    for (final completer in _pendingLuaCalls.values) {
      if (!completer.isCompleted) {
        completer.completeError(StateError('Runtime host bridge disposed'));
      }
    }
    _pendingLuaCalls.clear();
  }

  void _emitHostCallResult({
    required String id,
    required String method,
    required bool ok,
    Object? result,
    String? error,
  }) {
    _emit(
      RuntimeEvent(
        type: RuntimeHostEventType.callResult,
        data: {
          'id': id,
          'method': method,
          'ok': ok,
          if (ok) 'result': _runtimeValue(result),
          if (!ok && error != null) 'error': error,
        },
      ),
    );
  }

  void _emit(RuntimeEvent event) {
    if (_disposed) {
      return;
    }
    _eventSink(event);
  }

  Object? _runtimeValue(Object? value) {
    if (value == null || value is String || value is num || value is bool) {
      return value;
    }
    if (value is Iterable) {
      return value.map(_runtimeValue).toList(growable: false);
    }
    if (value is Map) {
      return {
        for (final entry in value.entries)
          entry.key.toString(): _runtimeValue(entry.value),
      };
    }
    return value.toString();
  }
}

abstract final class RuntimeHostEventType {
  static const notify = 'host_notify';
  static const call = 'host_call';
  static const callResult = 'host_call_result';
}