import 'package:shelf/shelf.dart';
import 'dart:io';

/// 全局异常处理中间件
/// 捕获所有未处理的异常并返回适当的 HTTP 响应
Middleware exceptionHandler() {
  return (Handler innerHandler) {
    return (Request request) async {
      try {
        return await innerHandler(request);
      } on FormatException catch (e) {
        // 处理参数格式错误，如无效的 ID
        return Response.badRequest(
          body: 'Invalid parameter format: ${e.message}',
          headers: {'content-type': 'text/plain'},
        );
      } on PathNotFoundException catch (e) {
        // 处理路径未找到
        return Response.notFound('Resource not found: ${e.message}');
      } on FileSystemException catch (e) {
        // 处理文件系统错误
        return Response.internalServerError(
          body: 'File system error: ${e.message}',
          headers: {'content-type': 'text/plain'},
        );
      } on Exception catch (e) {
        // 处理其他已知异常
        return Response.internalServerError(
          body: 'Internal server error: ${e.toString()}',
          headers: {'content-type': 'text/plain'},
        );
      } catch (e, stackTrace) {
        // 处理未知异常
        print('Unhandled exception: $e');
        print('Stack trace: $stackTrace');
        return Response.internalServerError(
          body: 'An unexpected error occurred',
          headers: {'content-type': 'text/plain'},
        );
      }
    };
  };
}