From 26991c9706bdddf12c44b5aa09d2e3dd5a1133a3 Mon Sep 17 00:00:00 2001
From: Kei-Luna <touhousetsuna@gmail.com>
Date: Wed, 13 May 2026 09:00:13 +0900
Subject: [PATCH] PatchDownload

---
 Common/Util/PatchDownloadService.cs | 47 +++++++++++++++++++++++++++++
 MikuSB.Loader/GameLaunchService.cs  |  1 +
 version.txt                         |  2 +-
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 Common/Util/PatchDownloadService.cs

diff --git a/Common/Util/PatchDownloadService.cs b/Common/Util/PatchDownloadService.cs
new file mode 100644
index 0000000..17e5623
--- /dev/null
+++ b/Common/Util/PatchDownloadService.cs
@@ -0,0 +1,47 @@
+using System.Net.Http.Headers;
+
+namespace MikuSB.Util;
+
+public static class PatchDownloadService
+{
+    private static readonly Logger Logger = new("PatchDownloader");
+    private const string PatchRelativePath = @"Patch\MikuSB-Patch.dll";
+    private const string PatchDownloadUrl =
+        "https://github.com/Kei-Luna/MikuSB-Patch/releases/download/MikuSB-Patch/MikuSB-Patch.dll";
+    private const int DownloadTimeoutSeconds = 60;
+
+    public static void EnsurePatchPresent()
+    {
+        var patchPath = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, PatchRelativePath));
+        if (File.Exists(patchPath))
+            return;
+
+        Directory.CreateDirectory(Path.GetDirectoryName(patchPath)!);
+        Logger.Warn($"Patch DLL not found. Downloading to {patchPath}.");
+
+        using var client = CreateHttpClient();
+        using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(DownloadTimeoutSeconds));
+        using var response = client.GetAsync(PatchDownloadUrl, HttpCompletionOption.ResponseHeadersRead, cts.Token)
+            .GetAwaiter().GetResult();
+        response.EnsureSuccessStatusCode();
+
+        using var source = response.Content.ReadAsStreamAsync(cts.Token).GetAwaiter().GetResult();
+        using var destination = File.Create(patchPath);
+        source.CopyTo(destination);
+
+        Logger.Info("Patch DLL download completed.");
+    }
+
+    private static HttpClient CreateHttpClient()
+    {
+        var client = new HttpClient
+        {
+            Timeout = Timeout.InfiniteTimeSpan
+        };
+
+        client.DefaultRequestHeaders.UserAgent.Add(
+            new ProductInfoHeaderValue("MikuSB-PatchDownloader", BuildVersion.Current));
+
+        return client;
+    }
+}
diff --git a/MikuSB.Loader/GameLaunchService.cs b/MikuSB.Loader/GameLaunchService.cs
index 2834210..23cf723 100644
--- a/MikuSB.Loader/GameLaunchService.cs
+++ b/MikuSB.Loader/GameLaunchService.cs
@@ -11,6 +11,7 @@ public static class GameLaunchService
     public static int Launch(params string[] extraGameArguments)
     {
         ConfigManager.LoadConfig();
+        PatchDownloadService.EnsurePatchPresent();
         var options = LaunchOptions.FromConfig(extraGameArguments);
         return Launch(options);
     }
diff --git a/version.txt b/version.txt
index 5bb3a00..c24093b 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-v=2.4
\ No newline at end of file
+v=2.5
\ No newline at end of file