Re-implemented functionality from original sample

Author: jasonjoh

.vscode/launch.json

@@ -13,14 +13,7 @@
       "args": [],
       "cwd": "${workspaceFolder}",
       "stopAtEntry": false,
-      "console": "internalConsole"
-    },
-    {
-      "name": "PowerShell: Launch Current File",
-      "type": "PowerShell",
-      "request": "launch",
-      "script": "${file}",
-      "cwd": "${file}"
+      "console": "externalTerminal"
     }
   ]
 }

DeltaQuery/Authentication/DeviceCodeAuthProvider.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+using Microsoft.Graph;
+using Microsoft.Identity.Client;
+using System;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Threading.Tasks;
+
+namespace DeltaQuery.Authentication
+{
+    public class DeviceCodeAuthProvider : IAuthenticationProvider
+    {
+        private IPublicClientApplication _msalClient;
+        private string[] _scopes;
+        private IAccount _userAccount;
+
+        public DeviceCodeAuthProvider(string appId, string[] scopes)
+        {
+            _scopes = scopes;
+
+            _msalClient = PublicClientApplicationBuilder
+                .Create(appId)
+                .WithAuthority(AadAuthorityAudience.AzureAdAndPersonalMicrosoftAccount, true)
+                .Build();
+        }
+
+        public async Task<string> GetAccessToken()
+        {
+            // If there is no saved user account, the user must sign-in
+            if (_userAccount == null)
+            {
+                try
+                {
+                    // Invoke device code flow so user can sign-in with a browser
+                    var result = await _msalClient.AcquireTokenWithDeviceCode(_scopes, callback => {
+                        Console.WriteLine(callback.Message);
+                        return Task.FromResult(0);
+                    }).ExecuteAsync();
+
+                    _userAccount = result.Account;
+                    return result.AccessToken;
+                }
+                catch (Exception exception)
+                {
+                    Console.WriteLine($"Error getting access token: {exception.Message}");
+                    return null;
+                }
+            }
+            else
+            {
+                // If there is an account, call AcquireTokenSilent
+                // By doing this, MSAL will refresh the token automatically if
+                // it is expired. Otherwise it returns the cached token.
+
+                    var result = await _msalClient
+                        .AcquireTokenSilent(_scopes, _userAccount)
+                        .ExecuteAsync();
+
+                   return result.AccessToken;
+            }
+        }
+
+        // This is the required method to implement IAuthenticationProvider
+        // The Graph SDK will call this method each time it makes a Graph
+        // call.
+        public async Task AuthenticateRequestAsync(HttpRequestMessage requestMessage)
+        {
+            requestMessage.Headers.Authorization =
+                new AuthenticationHeaderValue("bearer", await GetAccessToken());
+        }
+    }
+}

DeltaQuery/DeltaQuery.csproj

@@ -1,14 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
-
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp3.1</TargetFramework>
+    <UserSecretsId>8f7bbee5-dcc4-411f-a100-5a7c1ccef5b6</UserSecretsId>
   </PropertyGroup>
-
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="3.1.1" />
     <PackageReference Include="Microsoft.Graph" Version="1.21.0" />
     <PackageReference Include="Microsoft.Identity.Client" Version="4.8.0" />
   </ItemGroup>
-
-</Project>
+</Project>

DeltaQuery/Program.cs

@@ -1,12 +1,101 @@
-using System;
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+using DeltaQuery.Authentication;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Graph;
+using System;
+using System.Threading.Tasks;
 
 namespace DeltaQuery
 {
     class Program
     {
-        static void Main(string[] args)
+        // The Microsoft Graph permission scopes used by the app
+        static string[] _scopes = { "User.Read", "Mail.Read" };
+
+        // The number of seconds to wait between delta queries
+        static int _pollIntervalInSecs = 30;
+        static GraphServiceClient _graphClient;
+
+        static async Task Main(string[] args)
+        {
+            var appConfig = LoadAppSettings();
+
+            var authProvider = new DeviceCodeAuthProvider(
+                appConfig["AzureAppId"], _scopes);
+
+            _graphClient = new GraphServiceClient(authProvider);
+
+            await WatchMailFolders(_pollIntervalInSecs);
+        }
+
+        static async Task WatchMailFolders(int pollInterval)
+        {
+            // Get first page of mail folders
+            IMailFolderDeltaCollectionPage deltaCollection;
+            deltaCollection = await _graphClient.Me.MailFolders
+                .Delta()
+                .Request()
+                .GetAsync();
+
+            // TODO: Keep an in-memory dictionary of folder names and ids, use this to give more info
+            // Example: "Folder test renamed to test2" or "Folder test2 deleted" or "Folder foo moved to deleted items"
+            while(true)
+            {
+                if (deltaCollection.CurrentPage.Count <= 0)
+                {
+                    Console.WriteLine("No changes...");
+                }
+                else
+                {
+                    bool morePagesAvailable = false;
+                    do
+                    {
+                        morePagesAvailable = deltaCollection.NextPageRequest != null;
+                        foreach(var mailFolder in deltaCollection.CurrentPage)
+                        {
+                            bool isDeleted = mailFolder.AdditionalData != null ?
+                                mailFolder.AdditionalData.ContainsKey("@removed") :
+                                false;
+
+                            Console.WriteLine($"Folder {mailFolder.DisplayName} {(isDeleted ? "deleted" : "created/updated")}");
+                        }
+
+                        if (morePagesAvailable)
+                        {
+                            deltaCollection = await deltaCollection.NextPageRequest.GetAsync();
+                        }
+                    }
+                    while (morePagesAvailable);
+                }
+
+                var deltaLink = deltaCollection.AdditionalData["@odata.deltaLink"];
+                if (!string.IsNullOrEmpty(deltaLink.ToString()))
+                {
+                    Console.WriteLine($"Processed current delta. Will check back in {pollInterval} seconds.");
+                    await Task.Delay(pollInterval * 1000);
+
+                    deltaCollection.InitializeNextPageRequest(_graphClient, deltaLink.ToString());
+                    deltaCollection = await deltaCollection.NextPageRequest.GetAsync();
+                }
+            }
+        }
+
+        static IConfigurationRoot LoadAppSettings()
         {
-            Console.WriteLine("Hello World!");
+            // Load the values stored in the secret
+            // manager
+            var appConfig = new ConfigurationBuilder()
+                .AddUserSecrets<Program>()
+                .Build();
+
+            // Check for required settings
+            if (string.IsNullOrEmpty(appConfig["AzureAppId"]))
+            {
+                return null;
+            }
+
+            return appConfig;
         }
     }
 }

README.md

@@ -12,7 +12,7 @@ extensions:
 ---
 # Microsoft Graph delta query sample
 
-This console application demonstrates how to make [delta queries](https://docs.microsoft.com/graph/delta-query-overview) to Microsoft Graph, allowing applications to request only changed entities within a target resource. This sample monitors changes of messages in the user's inbox.
+This console application demonstrates how to make [delta queries](https://docs.microsoft.com/graph/delta-query-overview) to Microsoft Graph, allowing applications to request only changed entities within a target resource. This sample monitors changes to the mail folders in a user's mailbox.
 
 ## How To Run This Sample
 
@@ -87,8 +87,44 @@ The [RegisterApp.ps1](RegisterApp.ps1) script uses the [Azure AD PowerShell for
 
 ### Step 2: Configure the sample
 
+1. Open your command-line interface (CLI) in the directory that contains **DeltaQuery.csproj**.
+
+1. Run the following command.
+
+    ```Shell
+    dotnet user-secrets init
+    ```
+
+1. Run the following command to store your application ID (obtained in the previous step) to the secret manager Be sure to replace `YOUR_APP_ID` with your application ID.
+
+    ```Shell
+    dotnet user-secrets set AzureAppId YOUR_APP_ID
+    ```
+
 ### Step 3: Run the sample
 
+#### Option 1: Using Visual Studio Code
+
+1. Open the root folder of this sample using Visual Studio Code.
+
+1. On the **Debug** menu, choose **Start Debugging**.
+
+#### Option 2: From the command line
+
+1. Open your command-line interface (CLI) in the directory that contains **DeltaQuery.csproj**.
+
+1. Run the following command to build the sample.
+
+    ```Shell
+    dotnet build
+    ```
+
+1. Run the following command to run the sample.
+
+    ```Shell
+    dotnet run
+    ```
+
 ## Contributing
 
 If you'd like to contribute to this sample, see [CONTRIBUTING.MD](/CONTRIBUTING.md).