main.dart

// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import 'dart:async' show Future;
import 'dart:io';

import 'package:args/args.dart';
import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart' as shelf_io;
import 'package:shelf_router/shelf_router.dart';

class Service {
  // The [Router] can be used to create a handler, which can be used with
  // [shelf_io.serve].
  Handler get handler {
    final router = Router();

    // Handlers can be added with `router.<verb>('<route>', handler)`, the
    // '<route>' may embed URL-parameters, and these may be taken as parameters
    // by the handler (but either all URL parameters or no URL parameters, must
    // be taken parameters by the handler).
    router.get('/say-hi/<name>', (Request request, String name) {
      return Response.ok('hi $name');
    });

    // Embedded URL parameters may also be associated with a regular-expression
    // that the pattern must match.
    router.get('/user/<userId|[0-9]+>', (Request request, String userId) {
      return Response.ok('User has the user-number: $userId');
    });

    // Handlers can be asynchronous (returning `FutureOr` is also allowed).
    router.get('/wave', (Request request) async {
      await Future<void>.delayed(const Duration(milliseconds: 100));
      return Response.ok('_o/');
    });

    // Other routers can be mounted...
    router.mount('/api/', Api().router.call);

    // You can catch all verbs and use a URL-parameter with a regular expression
    // that matches everything to catch app.
    router.all('/<ignored|.*>', (Request request) {
      return Response.notFound('Page not found');
    });

    return router.call;
  }
}

class Api {
  Future<Response> _messages(Request request) async {
    return Response.ok('[]');
  }

  // By exposing a [Router] for an object, it can be mounted in other routers.
  Router get router {
    final router = Router();

    // A handler can have more that one route.
    router.get('/messages', _messages);
    router.get('/messages/', _messages);

    // This nested catch-all, will only catch /api/.* when mounted above.
    // Notice that ordering if annotated handlers and mounts is significant.
    router.all('/<ignored|.*>', (Request request) => Response.notFound('null'));

    return router;
  }
}

// Run shelf server and host a [Service] instance on port 8080.
void main(List<String> args) async {
  final parser = _getParser();

  String address;
  int port;
  try {
    final result = parser.parse(args);
    address = result['address'] as String;
    port = int.parse(result['port'] as String);
  } on FormatException catch (e) {
    stderr
      ..writeln(e.message)
      ..writeln(parser.usage);
    // http://linux.die.net/include/sysexits.h
    // #define EX_USAGE	64	/* command line usage error */
    exit(64);
  }

  final service = Service();
  final server = await shelf_io.serve(service.handler, address, port);
  print('Server running on localhost:${server.port}');
}

ArgParser _getParser() => ArgParser()
  ..addOption('port', abbr: 'p', defaultsTo: '8080', help: 'Port to listen on')
  ..addOption('address',
      abbr: 'a', defaultsTo: 'localhost', help: 'Address to listen on');