Add GithubUpdateManager class to replace the static factory

src/Squirrel/GithubUpdateManager.cs

@@ -0,0 +1,196 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
+using System.Reflection;
+using System.Runtime.Serialization;
+using System.Text;
+using System.Threading.Tasks;
+using Squirrel.Json;
+
+namespace Squirrel
+{
+    /// <summary>
+    /// An implementation of UpdateManager which supports checking updates and 
+    /// downloading releases directly from GitHub releases
+    /// </summary>
+#if NET5_0_OR_GREATER
+    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
+#endif
+    public class GithubUpdateManager : UpdateManager
+    {
+        private readonly string repoUrl;
+        private readonly string accessToken;
+        private readonly bool prerelease;
+
+        /// <inheritdoc cref="UpdateManager(string, string)"/>
+        /// <param name="repoUrl">
+        /// The URL of the GitHub repository to download releases from 
+        /// (e.g. https://github.com/myuser/myrepo)
+        /// </param>
+        /// <param name="applicationName">
+        /// The name of your application should correspond with the 
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
+        /// <param name="prerelease">
+        /// If true, the latest pre-release will be downloaded. If false, the latest 
+        /// stable release will be downloaded.
+        /// </param>
+        /// <param name="accessToken">
+        /// The GitHub access token to use with the request to download releases. 
+        /// If left empty, the GitHub rate limit for unauthenticated requests allows 
+        /// for up to 60 requests per hour, limited by IP address.
+        /// </param>
+        public GithubUpdateManager(string repoUrl, string applicationName, bool prerelease = false, string accessToken = null)
+            : this(repoUrl, applicationName, null, null, prerelease, accessToken)
+        {
+        }
+
+        /// <inheritdoc cref="UpdateManager(string, string)"/>
+        /// <param name="repoUrl">
+        /// The URL of the GitHub repository to download releases from 
+        /// (e.g. https://github.com/myuser/myrepo)
+        /// </param>
+        /// <param name="applicationName">
+        /// The name of your application should correspond with the 
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
+        /// <param name="urlDownloader">
+        /// A custom file downloader, for using non-standard package sources or adding 
+        /// proxy configurations. 
+        /// </param>
+        /// <param name="prerelease">
+        /// If true, the latest pre-release will be downloaded. If false, the latest 
+        /// stable release will be downloaded.
+        /// </param>
+        /// <param name="accessToken">
+        /// The GitHub access token to use with the request to download releases. 
+        /// If left empty, the GitHub rate limit for unauthenticated requests allows 
+        /// for up to 60 requests per hour, limited by IP address.
+        /// </param>
+        public GithubUpdateManager(string repoUrl, string applicationName, bool prerelease = false, string accessToken = null, IFileDownloader urlDownloader = null)
+            : this(repoUrl, applicationName, null, urlDownloader, prerelease, accessToken)
+        {
+        }
+
+        /// <inheritdoc cref="UpdateManager(string, string)"/>
+        /// <param name="repoUrl">
+        /// The URL of the GitHub repository to download releases from 
+        /// (e.g. https://github.com/myuser/myrepo)
+        /// </param>
+        /// <param name="applicationName">
+        /// The name of your application should correspond with the 
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
+        /// <param name="urlDownloader">
+        /// A custom file downloader, for using non-standard package sources or adding 
+        /// proxy configurations. 
+        /// </param>
+        /// <param name="localAppDataDirectoryOverride">
+        /// Provide a custom location for the system LocalAppData, it will be used 
+        /// instead of <see cref="Environment.SpecialFolder.LocalApplicationData"/>.
+        /// </param>
+        /// <param name="prerelease">
+        /// If true, the latest pre-release will be downloaded. If false, the latest 
+        /// stable release will be downloaded.
+        /// </param>
+        /// <param name="accessToken">
+        /// The GitHub access token to use with the request to download releases. 
+        /// If left empty, the GitHub rate limit for unauthenticated requests allows 
+        /// for up to 60 requests per hour, limited by IP address.
+        /// </param>
+        public GithubUpdateManager(string repoUrl,
+            string applicationName,
+            string localAppDataDirectoryOverride,
+            IFileDownloader urlDownloader,
+            bool prerelease,
+            string accessToken)
+            : base(null, applicationName, localAppDataDirectoryOverride, urlDownloader)
+        {
+            this.repoUrl = repoUrl;
+            this.accessToken = accessToken;
+            this.prerelease = prerelease;
+        }
+
+        /// <inheritdoc />
+        public override async Task<UpdateInfo> CheckForUpdate(bool ignoreDeltaUpdates = false, Action<int> progress = null, UpdaterIntention intention = UpdaterIntention.Update)
+        {
+            await EnsureReleaseUrl().ConfigureAwait(false);
+            return await base.CheckForUpdate(ignoreDeltaUpdates, progress, intention).ConfigureAwait(false);
+        }
+
+        /// <inheritdoc />
+        public override async Task DownloadReleases(IEnumerable<ReleaseEntry> releasesToDownload, Action<int> progress = null)
+        {
+            await EnsureReleaseUrl().ConfigureAwait(false);
+            await base.DownloadReleases(releasesToDownload, progress).ConfigureAwait(false);
+        }
+
+        private async Task EnsureReleaseUrl()
+        {
+            if (this.updateUrlOrPath == null) {
+                this.updateUrlOrPath = await GetLatestGithubRelease().ConfigureAwait(false);
+            }
+        }
+
+        private async Task<string> GetLatestGithubRelease()
+        {
+            var repoUri = new Uri(repoUrl);
+            var userAgent = new ProductInfoHeaderValue("Squirrel", AssemblyRuntimeInfo.ExecutingAssemblyName.Version.ToString());
+
+            if (repoUri.Segments.Length != 3) {
+                throw new Exception("Repo URL must be to the root URL of the repo e.g. https://github.com/myuser/myrepo");
+            }
+
+            var releasesApiBuilder = new StringBuilder("repos")
+                .Append(repoUri.AbsolutePath)
+                .Append("/releases");
+
+            if (!string.IsNullOrWhiteSpace(accessToken))
+                releasesApiBuilder.Append("?access_token=").Append(accessToken);
+
+            Uri baseAddress;
+
+            if (repoUri.Host.EndsWith("github.com", StringComparison.OrdinalIgnoreCase)) {
+                baseAddress = new Uri("https://api.github.com/");
+            } else {
+                // if it's not github.com, it's probably an Enterprise server
+                // now the problem with Enterprise is that the API doesn't come prefixed
+                // it comes suffixed
+                // so the API path of http://internal.github.server.local API location is
+                // http://interal.github.server.local/api/v3. 
+                baseAddress = new Uri(string.Format("{0}{1}{2}/api/v3/", repoUri.Scheme, Uri.SchemeDelimiter, repoUri.Host));
+            }
+
+            // above ^^ notice the end slashes for the baseAddress, explained here: http://stackoverflow.com/a/23438417/162694
+
+            using var client = new HttpClient() { BaseAddress = baseAddress };
+            client.DefaultRequestHeaders.UserAgent.Add(userAgent);
+            var response = await client.GetAsync(releasesApiBuilder.ToString()).ConfigureAwait(false);
+            response.EnsureSuccessStatusCode();
+
+            var releases = SimpleJson.DeserializeObject<List<Release>>(await response.Content.ReadAsStringAsync().ConfigureAwait(false));
+            var latestRelease = releases
+                .Where(x => prerelease || !x.Prerelease)
+                .OrderByDescending(x => x.PublishedAt)
+                .First();
+
+            var latestReleaseUrl = latestRelease.HtmlUrl.Replace("/tag/", "/download/");
+            return latestReleaseUrl;
+        }
+
+        [DataContract]
+        private class Release
+        {
+            [DataMember(Name = "prerelease")]
+            public bool Prerelease { get; set; }
+
+            [DataMember(Name = "published_at")]
+            public DateTime PublishedAt { get; set; }
+
+            [DataMember(Name = "html_url")]
+            public string HtmlUrl { get; set; }
+        }
+    }
+}

src/Squirrel/UpdateManager.ApplyReleases.cs

@@ -16,7 +16,7 @@
 
 namespace Squirrel
 {
-    public sealed partial class UpdateManager
+    public partial class UpdateManager
     {
         internal class ApplyReleasesImpl : IEnableLogger
         {

src/Squirrel/UpdateManager.CheckForUpdates.cs

@@ -9,7 +9,7 @@
 
 namespace Squirrel
 {
-    public sealed partial class UpdateManager
+    public partial class UpdateManager
     {
         internal class CheckForUpdateImpl : IEnableLogger
         {

src/Squirrel/UpdateManager.DownloadReleases.cs

@@ -8,7 +8,7 @@
 
 namespace Squirrel
 {
-    public sealed partial class UpdateManager
+    public partial class UpdateManager
     {
         internal class DownloadReleasesImpl : IEnableLogger
         {

src/Squirrel/UpdateManager.Factory.cs

@@ -11,7 +11,7 @@
 
 namespace Squirrel
 {
-    public sealed partial class UpdateManager
+    public partial class UpdateManager
     {
         [DataContract]
         private class Release
@@ -26,6 +26,12 @@ private class Release
             public string HtmlUrl { get; set; }
         }
 
+        /// <summary>
+        /// This function is obsolete and will be removed in a future version,
+        /// see the <see cref="GithubUpdateManager" /> class for a replacement.
+        /// </summary>
+        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
+        [Obsolete("Use 'new GithubUpdateManager(...)' instead")]
         public static async Task<UpdateManager> GitHubUpdateManager(
             string repoUrl,
             string applicationName = null,

src/Squirrel/UpdateManager.InstallHelpers.cs

@@ -14,7 +14,7 @@
 
 namespace Squirrel
 {
-    public sealed partial class UpdateManager
+    public partial class UpdateManager
     {
         internal class InstallHelperImpl : IEnableLogger
         {

src/Squirrel/UpdateManager.cs

@@ -24,7 +24,7 @@ namespace Squirrel
 #if NET5_0_OR_GREATER
     [System.Runtime.Versioning.SupportedOSPlatform("windows")]
 #endif
-    public sealed partial class UpdateManager : IUpdateManager, IEnableLogger
+    public partial class UpdateManager : IUpdateManager, IEnableLogger
     {
         /// <summary>The name of the application.</summary>
         public string ApplicationName => applicationName;
@@ -38,7 +38,9 @@ public sealed partial class UpdateManager : IUpdateManager, IEnableLogger
         private readonly string rootAppDirectory;
         private readonly string applicationName;
         private readonly IFileDownloader urlDownloader;
-        private readonly string updateUrlOrPath;
+
+        /// <summary>The url to use when checking for or downloading updates</summary>
+        protected string updateUrlOrPath;
 
         private readonly object lockobj = new object();
         private IDisposable updateLock;
@@ -53,7 +55,8 @@ public sealed partial class UpdateManager : IUpdateManager, IEnableLogger
         /// </param>
         /// <param name="applicationName">
         /// The name of your application should correspond with the 
-        /// appdata directory name, and the name used with Squirrel releasify/pack.</param>
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
         public UpdateManager(string urlOrPath, string applicationName)
             : this(urlOrPath, applicationName, null, null)
         {
@@ -65,7 +68,8 @@ public UpdateManager(string urlOrPath, string applicationName)
         /// </param>
         /// <param name="applicationName">
         /// The name of your application should correspond with the 
-        /// appdata directory name, and the name used with Squirrel releasify/pack.</param>
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
         /// <param name="urlDownloader">
         /// A custom file downloader, for using non-standard package sources or adding proxy configurations. 
         /// </param>
@@ -80,15 +84,17 @@ public UpdateManager(string urlOrPath, string applicationName, IFileDownloader u
         /// </param>
         /// <param name="applicationName">
         /// The name of your application should correspond with the 
-        /// appdata directory name, and the name used with Squirrel releasify/pack.</param>
+        /// appdata directory name, and the name used with Squirrel releasify/pack.
+        /// </param>
         /// <param name="urlDownloader">
         /// A custom file downloader, for using non-standard package sources or adding proxy configurations. 
         /// </param>
         /// <param name="localAppDataDirectoryOverride">
         /// Provide a custom location for the system LocalAppData, it will be used 
         /// instead of <see cref="Environment.SpecialFolder.LocalApplicationData"/>.
         /// </param>
-        public UpdateManager(string urlOrPath,
+        public UpdateManager(
+            string urlOrPath,
             string applicationName,
             string localAppDataDirectoryOverride,
             IFileDownloader urlDownloader)
@@ -109,7 +115,7 @@ public UpdateManager(string urlOrPath,
         }
 
         /// <inheritdoc/>
-        public async Task<UpdateInfo> CheckForUpdate(bool ignoreDeltaUpdates = false, Action<int> progress = null, UpdaterIntention intention = UpdaterIntention.Update)
+        public virtual async Task<UpdateInfo> CheckForUpdate(bool ignoreDeltaUpdates = false, Action<int> progress = null, UpdaterIntention intention = UpdaterIntention.Update)
         {
             var checkForUpdate = new CheckForUpdateImpl(rootAppDirectory);
 
@@ -118,7 +124,7 @@ public async Task<UpdateInfo> CheckForUpdate(bool ignoreDeltaUpdates = false, Ac
         }
 
         /// <inheritdoc/>
-        public async Task DownloadReleases(IEnumerable<ReleaseEntry> releasesToDownload, Action<int> progress = null)
+        public virtual async Task DownloadReleases(IEnumerable<ReleaseEntry> releasesToDownload, Action<int> progress = null)
         {
             var downloadReleases = new DownloadReleasesImpl(rootAppDirectory);
             await acquireUpdateLock().ConfigureAwait(false);