add GitHub update check support (#336)

src/StardewModdingAPI.Web/Controllers/ModsController.cs

@@ -44,6 +44,7 @@ namespace StardewModdingAPI.Web.Controllers
             this.Repositories =
                 new IModRepository[]
                 {
+                    new GitHubRepository(config.GitHubKey, config.GitHubBaseUrl, config.GitHubReleaseUrlFormat, config.GitHubUserAgent, config.GitHubAcceptHeader),
                     new NexusRepository(config.NexusKey, config.NexusUserAgent, config.NexusBaseUrl, config.NexusModUrlFormat)
                 }
                 .ToDictionary(p => p.VendorKey, StringComparer.CurrentCultureIgnoreCase);

src/StardewModdingAPI.Web/Framework/ConfigModels/ModUpdateCheckConfig.cs

@@ -3,9 +3,36 @@ namespace StardewModdingAPI.Web.Framework.ConfigModels
     /// <summary>The config settings for mod update checks.</summary>
     public class ModUpdateCheckConfig
     {
+        /*********
+        ** Accessors
+        *********/
+        /****
+        ** General
+        ****/
         /// <summary>The number of minutes update checks should be cached before refetching them.</summary>
         public int CacheMinutes { get; set; }
 
+        /****
+        ** GitHub
+        ****/
+        /// <summary>The repository key for Nexus Mods.</summary>
+        public string GitHubKey { get; set; }
+
+        /// <summary>The user agent for the GitHub API client.</summary>
+        public string GitHubUserAgent { get; set; }
+
+        /// <summary>The base URL for the GitHub API.</summary>
+        public string GitHubBaseUrl { get; set; }
+
+        /// <summary>The URL for a GitHub API latest-release query excluding the <see cref="GitHubBaseUrl"/>, where {0} is the organisation and project name.</summary>
+        public string GitHubReleaseUrlFormat { get; set; }
+
+        /// <summary>The Accept header value expected by the GitHub API.</summary>
+        public string GitHubAcceptHeader { get; set; }
+
+        /****
+        ** Nexus Mods
+        ****/
         /// <summary>The repository key for Nexus Mods.</summary>
         public string NexusKey { get; set; }
 

src/StardewModdingAPI.Web/Framework/ModRepositories/GitHubRepository.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Threading.Tasks;
+using Newtonsoft.Json;
+using Pathoschild.Http.Client;
+using StardewModdingAPI.Web.Models;
+
+namespace StardewModdingAPI.Web.Framework.ModRepositories
+{
+    /// <summary>An HTTP client for fetching mod metadata from GitHub project releases.</summary>
+    internal class GitHubRepository : IModRepository
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The underlying HTTP client.</summary>
+        private readonly IClient Client;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The unique key for this vendor.</summary>
+        public string VendorKey { get; }
+
+        /// <summary>The URL for a Nexus Mods API query excluding the base URL, where {0} is the mod ID.</summary>
+        public string ReleaseUrlFormat { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="vendorKey">The unique key for this vendor.</param>
+        /// <param name="baseUrl">The base URL for the Nexus Mods API.</param>
+        /// <param name="releaseUrlFormat">The URL for a Nexus Mods API query excluding the <paramref name="baseUrl"/>, where {0} is the mod ID.</param>
+        /// <param name="userAgent">The user agent for the GitHub API client.</param>
+        /// <param name="acceptHeader">The Accept header value expected by the GitHub API.</param>
+        public GitHubRepository(string vendorKey, string baseUrl, string releaseUrlFormat, string userAgent, string acceptHeader)
+        {
+            this.VendorKey = vendorKey;
+            this.ReleaseUrlFormat = releaseUrlFormat;
+
+            this.Client = new FluentClient(baseUrl)
+                .SetUserAgent(string.Format(userAgent, this.GetType().Assembly.GetName().Version))
+                .AddDefault(req => req.WithHeader("Accept", acceptHeader));
+        }
+
+        /// <summary>Get metadata about a mod in the repository.</summary>
+        /// <param name="id">The mod ID in this repository.</param>
+        public async Task<ModInfoModel> GetModInfoAsync(string id)
+        {
+            try
+            {
+                GitRelease release = await this.Client
+                    .GetAsync(string.Format(this.ReleaseUrlFormat, id))
+                    .As<GitRelease>();
+
+                return new ModInfoModel(id, release.Tag, $"https://github.com/{id}/releases");
+            }
+            catch (Exception ex)
+            {
+                return new ModInfoModel(ex.ToString());
+            }
+        }
+
+        /// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
+        public void Dispose()
+        {
+            this.Client.Dispose();
+        }
+
+
+        /*********
+        ** Private models
+        *********/
+        /// <summary>Metadata about a GitHub release tag.</summary>
+        private class GitRelease
+        {
+            /*********
+            ** Accessors
+            *********/
+            /// <summary>The display name.</summary>
+            [JsonProperty("name")]
+            public string Name { get; set; }
+
+            /// <summary>The semantic version string.</summary>
+            [JsonProperty("tag_name")]
+            public string Tag { get; set; }
+        }
+    }
+}

src/StardewModdingAPI.Web/appsettings.json

@@ -7,6 +7,13 @@
   },
   "ModUpdateCheck": {
     "CacheMinutes": 60,
+
+    "GitHubKey": "GitHub",
+    "GitHubUserAgent": "SMAPI/{0} (+https://github.com/Pathoschild/SMAPI)",
+    "GitHubBaseUrl": "https://api.github.com",
+    "GitHubReleaseUrlFormat": "repos/{0}/releases/latest",
+    "GitHubAcceptHeader": "application/vnd.github.v3+json",
+
     "NexusKey": "Nexus",
     "NexusUserAgent": "Nexus Client v0.63.15",
     "NexusBaseUrl": "http://www.nexusmods.com/stardewvalley",