An Client To Call G2Rail Mobile Client

g2rail_mobile_client.dart

import 'dart:async';
import 'dart:convert';
import 'dart:io';


import 'package:crypto/crypto.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:meta/meta.dart';

class SearchCriteria {
  String from;
  String to;
  String date;
  String time;
  int adult;
  int child;

  SearchCriteria(from, to, date, time, adult, child) {
    this.from = from;
    this.to = to;
    this.date = date;
    this.time = time;
    this.adult = adult;
    this.child = child;
  }

  String toQuery() {
    return "from=$from&to=$to&date=$date&time=$time&adult=$adult&child=$child";
  }

  Map<String, dynamic> toMap() {
    return {
      "from": from,
      "to": to,
      "date": date,
      "time": time,
      "adult": adult,
      "child": child
    };
  }
}

class GrailApiClient {
  final baseUrl;
  final apiKey;
  final secret;
  final http.Client httpClient;

  GrailApiClient({@required this.httpClient,
    @required this.baseUrl,
    @required this.apiKey,
    @required this.secret})
      : assert(httpClient != null);


  Map<String, String> getAuthorizationHeaders(Map<String, dynamic> params) {
    var timestamp = DateTime.now();
    params['t'] = (timestamp.millisecondsSinceEpoch ~/ 1000).toString();
    params['api_key'] = apiKey;

    var sortedKeys = params.keys.toList()
      ..sort((a, b) => a.compareTo(b));
    StringBuffer buffer = StringBuffer("");
    sortedKeys.forEach((key) {
      if (params[key] is List || params[key] is Map) return;
      buffer.write('$key=${params[key].toString()}');
    });
    buffer.write(secret);

    String hashString = buffer.toString();
    String authorization = md5.convert(utf8.encode(hashString)).toString();

    return {
      "From": apiKey,
      "Content-Type": 'application/json',
      "Authorization": authorization,
      "Date": HttpDate.format(timestamp),
      "Api-Locale": "zh-TW"
    };
  }

  Future<dynamic> getSolutions(from, to, date, time, adult, child) async {
    final criteria = SearchCriteria(from, to, date, time, adult, child);
    final solutionUrl =
        '$baseUrl/api/v2/online_solutions/?${criteria.toQuery()}';

    final solutionResponse = await this
        .httpClient
        .get(Uri.parse(solutionUrl), headers: getAuthorizationHeaders(criteria.toMap()));

    if (solutionResponse.statusCode != 200) {
      throw Exception('error getting solutions');
    }

    final solutionsJson = jsonDecode(solutionResponse.body);

    return solutionsJson;
  }

  Future<dynamic> getAsyncResult(String asyncKey) async {
    final asyncResultURl = '$baseUrl/api/v2/async_results/$asyncKey';
    final asyncResult = await this.httpClient.get(Uri.parse(asyncResultURl),
        headers: getAuthorizationHeaders({"async_key": asyncKey}));
    return {"data": jsonDecode(utf8.decode(asyncResult.bodyBytes))};
  }
}

main.dart

main() {
  var client  =  GrailApiClient(httpClient: http.Client(), baseUrl: "----", apiKey: "---", secret: "---");
  var asyncKey = client.getSolutions("BERLIN", "FRANKFURT", "2022-10-28", "10:00", 1, 0);
}