import 'dart:io';
import 'dart:convert';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as shelf_io;
import 'package:shelf_multipart/shelf_multipart.dart';
import 'package:shelf_router/shelf_router.dart';

void main() async {
  // Create a router
  final router = Router();

  // Define routes
  router.get('/greet', _handleGreet);
  router.post('/echo', _handleEcho);
  router.post('/upload', _handleFileUpload);

  // Create a middleware pipeline
  final handler = const Pipeline()
      .addMiddleware(logRequests())
      // .addMiddleware(_checkAuthorization())
      .addHandler(router);

  // Start the server
  final server = await shelf_io.serve(handler, 'localhost', 8080);
  print('Server listening on port ${server.port}');
}

// Handler for the /greet route with query parameters
Response _handleGreet(Request request) {
  final name = request.url.queryParameters['name'] ?? 'stranger';
  return Response.ok('Hello, $name!');
}

// Handler for the /echo route that handles POST JSON body
Future<Response> _handleEcho(Request request) async {
  final payload = await request.readAsString();
  final data = jsonDecode(payload) as Map;
  return Response.ok(jsonEncode(data),
      headers: {'Content-Type': 'application/json'});
}

// Handler for the /upload route that accepts file uploads
Future<Response> _handleFileUpload(Request request) async {
  final contentType = request.headers['content-type'];
  if (contentType == null || !contentType.contains('multipart/form-data')) {
    return Response(400, body: 'Unsupported content-type');
  }

  if (request.multipart() case var multipart?) {
    // Iterate over parts making up this request:
    List<String> uploadedFiles = [];
    await for (final part in multipart.parts) {
      // Headers are available through part.headers as a map:
      final contentDisposition = part.headers['content-disposition'];
      if (contentDisposition != null &&
          contentDisposition.contains('filename=')) {
        final name =
            RegExp(r'name="([^"]*)"').firstMatch(contentDisposition)?.group(1);
        final filename = RegExp(r'filename="([^"]*)"')
            .firstMatch(contentDisposition)
            ?.group(1);
        if (name != null && filename != null) {
          final file = File('uploads/$filename');
          await file.create(recursive: true);
          await part.pipe(file.openWrite());
          uploadedFiles.add(filename);
        }
      }
    }
    if (uploadedFiles.isNotEmpty) {
      return Response.ok('File(s) uploaded: $uploadedFiles');
    }
    {
      return Response(400, body: 'Unsupported content-type');
    }
  } else {
    return Response(401); // not a multipart request
  }
}

// Custom middleware for authorization
Middleware _checkAuthorization() {
  return (Handler handler) {
    return (Request request) async {
      // Protect routes with authorization
      if ((request.url.path.startsWith('greet') ||
              request.url.path.startsWith('echo') ||
              request.url.path.startsWith('upload')) &&
          request.headers['Authorization'] != 'Bearer mysecrettoken') {
        return Response.forbidden('Authorization header missing or invalid');
      }
      return handler(request);
    };
  };
}