Authenticate with OAuth

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
// Copyright 2021 Esri.
//
// 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: http://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.

using Esri.ArcGISRuntime.Security;
using System;
using System.Threading.Tasks;
using Xamarin.Forms;

#if __ANDROID__ || __IOS__
using Xamarin.Essentials;
using System.Collections.Generic;
#endif

#if __ANDROID__
using Android.App;
using Application = Xamarin.Forms.Application;
using Android.Content;
using Android.Content.PM;
#endif

namespace Forms.Helpers
{
    internal static class ArcGISLoginPrompt
    {
        private const string ArcGISOnlineUrl = "https://www.arcgis.com/sharing/rest";

        // - The Client ID for an app registered with the server (the ID below is for a public app created by the ArcGIS Runtime team).
        public const string AppClientId = @"6wMAmbUEX1rvsOb4";

        // - An optional client secret for the app (only needed for the OAuthClientCredentials authorization type).
        private const string ClientSecret = "";

        // - A URL for redirecting after a successful authorization (this must be a URL configured with the app).
        private const string OAuthRedirectUrl = @"forms-samples-app://auth";

        public static async Task<bool> EnsureAGOLCredentialAsync()
        {
            bool loggedIn = false;

            try
            {
                // Create a challenge request for portal credentials (OAuth credential request for arcgis.com)
                CredentialRequestInfo challengeRequest = new CredentialRequestInfo
                {
                    // Use the OAuth authorization code workflow.
                    GenerateTokenOptions = new GenerateTokenOptions
                    {
                        TokenAuthenticationType = TokenAuthenticationType.OAuthAuthorizationCode
                    },

                    // Indicate the url (portal) to authenticate with (ArcGIS Online)
                    ServiceUri = new Uri(ArcGISOnlineUrl)
                };

                // Call GetCredentialAsync on the AuthenticationManager to invoke the challenge handler
                Credential cred = await AuthenticationManager.Current.GetCredentialAsync(challengeRequest, false);
                loggedIn = cred != null;
            }
            catch (OperationCanceledException)
            {
                // OAuth login was canceled, no need to display error to user.
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Login failed", ex.Message, "OK");
            }

            return loggedIn;
        }

        public static void SetChallengeHandler()
        {
            // Define the server information for ArcGIS Online
            ServerInfo portalServerInfo = new ServerInfo(new Uri(ArcGISOnlineUrl))
            {
                TokenAuthenticationType = TokenAuthenticationType.OAuthAuthorizationCode,
                OAuthClientInfo = new OAuthClientInfo(AppClientId, new Uri(OAuthRedirectUrl))
            };

            // If a client secret has been configured, set the authentication type to OAuth client credentials.
            if (!string.IsNullOrEmpty(ClientSecret))
            {
                // If a client secret is specified then use the TokenAuthenticationType.OAuthClientCredentials type.
                portalServerInfo.TokenAuthenticationType = TokenAuthenticationType.OAuthClientCredentials;
                portalServerInfo.OAuthClientInfo.ClientSecret = ClientSecret;
            }

            // Register this server with AuthenticationManager.
            AuthenticationManager.Current.RegisterServer(portalServerInfo);

            // Use a function in this class to challenge for credentials.
            AuthenticationManager.Current.ChallengeHandler = new ChallengeHandler(PromptCredentialAsync);

            // Set the OAuthAuthorizeHandler component (this class) for Android or iOS platforms.
#if __ANDROID__ || __IOS__
            AuthenticationManager.Current.OAuthAuthorizeHandler = new OAuthAuthorize();
#endif
        }

        // ChallengeHandler function that will be called whenever access to a secured resource is attempted.
        public static async Task<Credential> PromptCredentialAsync(CredentialRequestInfo info)
        {
            Credential credential = null;

            try
            {
                // IOAuthAuthorizeHandler will challenge the user for OAuth credentials.
                credential = await AuthenticationManager.Current.GenerateCredentialAsync(info.ServiceUri);
            }
            // OAuth login was canceled, no need to display error to user.
            catch (TaskCanceledException) { }
            catch (OperationCanceledException) { }

            return credential;
        }
    }

    #region IOAuthAuthorizationHandler implementation

#if __ANDROID__ || __IOS__
    public class OAuthAuthorize : IOAuthAuthorizeHandler
    {
        // Use a TaskCompletionSource to track the completion of the authorization.
        private TaskCompletionSource<IDictionary<string, string>> _taskCompletionSource;

        // IOAuthAuthorizeHandler.AuthorizeAsync implementation.
        public async Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
        {
            try
            {
                _taskCompletionSource = new TaskCompletionSource<IDictionary<string, string>>();

#if __IOS__
                Device.BeginInvokeOnMainThread(async () =>
                {
#endif
                try
                {
                    var result = await WebAuthenticator.AuthenticateAsync(authorizeUri, callbackUri);
                    _taskCompletionSource.SetResult(result.Properties);
                }
                catch (Exception ex)
                {
                    _taskCompletionSource.TrySetException(ex);
                }
#if __IOS__
                });
#endif
                return await _taskCompletionSource.Task;
            }
            catch (Exception) { }
            return null;
        }
    }
#endif

#if __ANDROID__

    [Activity(NoHistory = true, LaunchMode = LaunchMode.SingleTop)]
    [IntentFilter(new[] { Intent.ActionView },
       Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
       DataScheme = "forms-samples-app", DataHost = "auth")]
    public class WebAuthenticationCallbackActivity : WebAuthenticatorCallbackActivity
    {
    }
#endif

    #endregion IOAuthAuthorizationHandler implementation
}