Adds update notifications. Closes #24 (#25)

Author: waldekmastykarz

msgraph-developer-proxy/ProxyCommandHandler.cs

@@ -37,6 +37,16 @@ public async Task<int> InvokeAsync(InvocationContext context) {
             Configuration.AllowedErrors = allowedErrors;
             if (cloud is not null)
                 Configuration.Cloud = cloud;
+
+            var newReleaseInfo = await UpdateNotification.CheckForNewVersion();
+            if (newReleaseInfo != null) {
+                var originalColor = Console.ForegroundColor;
+                Console.ForegroundColor = ConsoleColor.Green;
+                Console.Error.WriteLine($"New version {newReleaseInfo.Version} of the Graph Developer Proxy is available.");
+                Console.Error.WriteLine($"See {newReleaseInfo.Url} for more information.");
+                Console.Error.WriteLine();
+                Console.ForegroundColor = originalColor;
+            }
 
             try {
                 await new ChaosEngine(Configuration).Run(cancellationToken);

msgraph-developer-proxy/UpdateNotification.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Net.Http.Headers;
+using System.Reflection;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading.Tasks;
+
+namespace Microsoft.Graph.DeveloperProxy {
+    internal class ReleaseInfo {
+        [JsonPropertyName("name")]
+        public string? Version { get; set; }
+        [JsonPropertyName("html_url")]
+        public string? Url { get; set; }
+
+        public ReleaseInfo() {
+        }
+    }
+
+    internal static class UpdateNotification {
+        private static readonly string releasesUrl = "https://api.github.com/repos/microsoftgraph/msgraph-developer-proxy/releases";
+
+        /// <summary>
+        /// Checks if a new version of the proxy is available.
+        /// </summary>
+        /// <returns>Instance of ReleaseInfo if a new version is available and null if the current version is the latest</returns>
+        public static async Task<ReleaseInfo?> CheckForNewVersion() {
+            try {
+                var latestRelease = await GetLatestRelease();
+                if (latestRelease == null || latestRelease.Version == null) {
+                    return null;
+                }
+
+                var latestReleaseVersion = new Version(latestRelease.Version.Substring(1)); // remove leading v
+                var currentVersion = GetCurrentVersion();
+
+                if (latestReleaseVersion > currentVersion) {
+                    return latestRelease;
+                }
+                else {
+                    return null;
+                }
+            }
+            catch {
+                return null;
+            }
+        }
+
+        private static Version GetCurrentVersion() {
+            var assembly = Assembly.GetExecutingAssembly();
+            var fvi = FileVersionInfo.GetVersionInfo(assembly.Location);
+            var currentVersion = new Version(fvi.ProductVersion);
+
+            return currentVersion;
+        }
+
+        private static async Task<ReleaseInfo?> GetLatestRelease() {
+            var http = new HttpClient();
+            // GitHub API requires user agent to be set
+            http.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("msgraph-developer-proxy", "1.0"));
+            var response = await http.GetStringAsync(releasesUrl);
+            var releases = JsonSerializer.Deserialize<ReleaseInfo[]>(response);
+
+            if (releases == null) {
+                return null;
+            }
+
+            // we assume releases are sorted descending by their creation date
+            foreach (var release in releases) {
+                // skip preview releases
+                if (release.Version == null ||
+                    release.Version.Contains("-")) {
+                    continue;
+                }
+
+                return release;
+            }
+
+            return null;
+        }
+    }
+}