Add basic support for prerelease versions

GitHubRelease.cs

@@ -1,30 +1,84 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
 using System.Globalization;
+using System.Net.Http.Headers;
+using System.Text.RegularExpressions;
 
 namespace ChrisKaczor.ApplicationUpdate
 {
     public partial class GitHubRelease
     {
-        [JsonProperty("tag_name")]
-        public string? TagName { get; set; }
+        private const string LatestSegment = "/latest";
 
-        [JsonProperty("assets")]
-        public List<Asset>? Assets { get; set; }
+        private static readonly HttpClient HttpClient = new()
+        {
+            DefaultRequestHeaders =
+                { UserAgent = { ProductInfoHeaderValue.Parse(UpdateCheck.ApplicationName.Replace(" ", "")) } }
+        };
+
+        private static GitHubRelease? FromJson(string json) =>
+            JsonConvert.DeserializeObject<GitHubRelease>(json, Converter.Settings);
+
+        private static List<GitHubRelease>? FromJsonArray(string json) =>
+            JsonConvert.DeserializeObject<List<GitHubRelease>>(json, Converter.Settings);
+
+        [JsonProperty("tag_name")] public string? TagName { get; set; }
+
+        [JsonProperty("assets")] public List<Asset>? Assets { get; set; }
+
+        [JsonProperty("prerelease")] public bool Prerelease { get; set; }
+
+        public static async Task<VersionInfo?> GetLatestAsync(string baseUrl)
+        {
+            try
+            {
+                var url = baseUrl.EndsWith(LatestSegment) ? baseUrl : baseUrl + LatestSegment;
+
+                var json = await HttpClient.GetStringAsync(url);
+
+                var release = FromJson(json);
+
+                var versionInfo = VersionInfo.CreateFromGitHubRelease(release);
+
+                return versionInfo;
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
+
+        public static async Task<VersionInfo?> GetLatestPrereleaseAsync(string baseUrl)
+        {
+            try
+            {
+                var url = baseUrl.EndsWith(LatestSegment) ? baseUrl[..^LatestSegment.Length] : baseUrl;
+
+                var json = await HttpClient.GetStringAsync(url);
+
+                var releases = FromJsonArray(json);
+
+                var release = releases?.FirstOrDefault();
+
+                if (release == null)
+                    return null;
+
+                var versionInfo = VersionInfo.CreateFromGitHubRelease(release);
+
+                return versionInfo;
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
     }
 
     public class Asset
     {
-        [JsonProperty("created_at")]
-        public DateTimeOffset? CreatedAt { get; set; }
+        [JsonProperty("created_at")] public DateTimeOffset? CreatedAt { get; set; }
 
-        [JsonProperty("browser_download_url")]
-        public string? BrowserDownloadUrl { get; set; }
-    }
-
-    public partial class GitHubRelease
-    {
-        public static GitHubRelease? FromJson(string json) => JsonConvert.DeserializeObject<GitHubRelease>(json, Converter.Settings);
+        [JsonProperty("browser_download_url")] public string? BrowserDownloadUrl { get; set; }
     }
 
     internal class Converter