Make launcher a Windows GUI app

cmd/vrc_osc_launcher/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"vrc_osc_go/internal/buildinfo"
+	"vrc_osc_go/internal/common"
+	"vrc_osc_go/internal/update"
+)
+
+func main() {
+	var baseURL string
+	var ownerRepo string
+	var assetName string
+	flag.StringVar(&baseURL, "base-url", "https://git.vrcworldtour.com", "Gitea base URL")
+	flag.StringVar(&ownerRepo, "repo", "every_holiday/VRCWT-OSC", "owner/repo")
+	flag.StringVar(&assetName, "asset", "vrc_osc-windows.zip", "release asset name")
+	flag.Parse()
+
+	client := &update.Client{BaseURL: baseURL}
+	mgr := &update.Manager{
+		Client:       client,
+		OwnerRepo:    ownerRepo,
+		AssetName:    assetName,
+		CurrentLabel: buildinfo.Version,
+	}
+	if _, err := mgr.CheckAndUpdate(); err != nil {
+		log.Printf("auto update skipped: %v", err)
+	}
+	exe := filepath.Join(common.RootDir(), "vrc_osc.exe")
+	if _, err := os.Stat(exe); err != nil {
+		showError("vrc_osc_launcher", "missing exe: "+err.Error())
+		log.Fatalf("missing exe: %v", err)
+	}
+	if err := update.Launch(exe, os.Args[1:]); err != nil {
+		showError("vrc_osc_launcher", "launch failed: "+err.Error())
+		log.Fatalf("launch failed: %v", err)
+	}
+}
+
+func showError(title, message string) {
+	user32 := syscall.NewLazyDLL("user32.dll")
+	msgBox := user32.NewProc("MessageBoxW")
+	const mbOK = 0x00000000
+	const mbIconError = 0x00000010
+	_, _, _ = msgBox.Call(
+		0,
+		uintptr(syscall.StringToUTF16Ptr(message)),
+		uintptr(syscall.StringToUTF16Ptr(title)),
+		uintptr(mbOK|mbIconError),
+	)
+}