DPREAFA9

1using System;
2using System.Collections.Generic;
3using System.Linq;
4using System.Text;
5using System.Threading.Tasks;
6using Windows.Security.Authentication.Web;
7using Windows.Web.Http;
8using Windows.Data.Json;
9using System.IO;
10
11namespace ProjekatOoad.Services
12{
13    class FourSquareConnector
14    {
15        //OauthToken glavni potreban za Rest pozive, cuva autorizaciju da se moze obaviti poziv
16        private string oAuthToken;
17        //id i secret su potrebni da se dobije oauth
18        private string clientId;
19        private string clientSecret;
20        //na koju stranicu da se ide nakon zavrsene autorizacije
21        private string redirectUri;
22
23        // konstruktor prima objekat sa postavkama 
24        public FourSquareConnector(JsonObject fourSquareSettings)
25        {
26            clientId = fourSquareSettings.GetNamedString("clientId");
27            clientSecret = fourSquareSettings.GetNamedString("clientSecret");
28            redirectUri = fourSquareSettings.GetNamedString("redirectUri");
29        }
30
31        public string OAuthToken
32        {
33            get
34            {
35                return oAuthToken;
36            }
37            set
38            {
39                oAuthToken = value;
40            }
41        }
42        //Cilj metode je da pronadje i postavi OAuthToken
43        public async Task authenticate()
44        {
45            try
46            {
47                //Sastavi url poziva
48                String foursqareApiUrl = "https://foursquare.com/oauth2/authenticate?client_id=" + clientId + "&response_type=code&redirect_uri=" + redirectUri;
49                Uri StartUri = new Uri(foursqareApiUrl);
50                //poziv authentifikacije, ovo ce otvorit forsquare web stranicu koja trazi od korisnika da se loguje
51                WebAuthenticationResult WebAuthenticationResult = await WebAuthenticationBroker.AuthenticateAsync(WebAuthenticationOptions.None, StartUri, new Uri("https://www.google.ba/"));
52                //Ako je sve ok izvuci ce oauthtoken iz response
53                if (WebAuthenticationResult.ResponseStatus == WebAuthenticationStatus.Success)
54                {
55                    await getOuathToken(WebAuthenticationResult.ResponseData.ToString());
56                }
57                //ako nije ok treba baciti exception
58                else if (WebAuthenticationResult.ResponseStatus == WebAuthenticationStatus.ErrorHttp)
59                {
60                    throw new FourSquareAuthenticationException("HTTP Error returned by AuthenticateAsync() : " + WebAuthenticationResult.ResponseErrorDetail.ToString());
61                }
62                else
63                {
64                    throw new FourSquareAuthenticationException("Error returned by AuthenticiateAsync()" + WebAuthenticationResult.ResponseStatus.ToString());
65                }
66            }
67            catch (Exception Error)
68            {
69                throw Error;
70            }
71        }
72
73        private async Task getOuathToken(string webAuthResultResponseData)
74        {
75            //auth poziv dobije code parametar koji se zatim iskoristiti da se dobije oauth
76            //izdvajanje code parametra iz dobivenog stringa
77            string responseData = webAuthResultResponseData.Substring(webAuthResultResponseData.IndexOf("code"));
78            String[] keyValPairs = responseData.Split('&');
79            string code = null;
80            for (int i = 0; i < keyValPairs.Length; i++)
81            {
82                String[] splits = keyValPairs[i].Split('=');
83                if (splits[0].Equals("code"))
84                {
85                    code = splits[1];
86                }
87            }
88            // Koristenje code za dobivanje access tokena pozivom
89            HttpClient httpClient = new HttpClient();
90            string response = await httpClient.GetStringAsync(new Uri("https://foursquare.com/oauth2/access_token?client_id=" + clientId + "&client_secret=" + clientSecret + "&grant_type=authorization_code&redirect_uri=" + redirectUri + "&code=" + code));
91            JsonObject value = JsonValue.Parse(response).GetObject();
92            OAuthToken = value.GetNamedString("access_token");
93        }
94    }
95}