package main

import (
	"embed"
	"flag"
	"log"
	"os"
	"path/filepath"
	"runtime"

	"github.com/wailsapp/wails/v2"
	"github.com/wailsapp/wails/v2/pkg/options"
	"github.com/wailsapp/wails/v2/pkg/options/assetserver"
)

//go:embed frontend/dist
var assets embed.FS

func main() {
	apiURL := flag.String("api", "https://vpn.em-sysadmin.xyz", "API server URL")
	dataDir := flag.String("data", defaultDataDir(), "data directory")
	flag.Parse()

	// Ensure data dir exists
	os.MkdirAll(*dataDir, 0o755)

	// Setup file logging so we always have diagnostics
	logPath := filepath.Join(*dataDir, "vpnem.log")
	logFile, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o644)
	if err == nil {
		log.SetOutput(logFile)
		defer logFile.Close()
	}

	log.Printf("vpnem starting, data=%s, api=%s, os=%s", *dataDir, *apiURL, runtime.GOOS)

	// Kill previous instances of vpnem and sing-box
	killPrevious()

	// Check wintun.dll on Windows
	if runtime.GOOS == "windows" {
		exe, _ := os.Executable()
		exeDir := filepath.Dir(exe)
		wintunPaths := []string{
			filepath.Join(exeDir, "wintun.dll"),
			filepath.Join(*dataDir, "wintun.dll"),
			"wintun.dll",
		}
		found := false
		for _, p := range wintunPaths {
			if _, err := os.Stat(p); err == nil {
				log.Printf("wintun.dll found: %s", p)
				found = true
				break
			}
		}
		if !found {
			log.Printf("WARNING: wintun.dll not found! TUN will fail. Searched: %v", wintunPaths)
		}
	}

	app := NewApp(*dataDir, *apiURL)

	log.Println("starting Wails UI")
	if err := wails.Run(&options.App{
		Title:     "vpnem",
		Width:     480,
		Height:    600,
		MinWidth:  400,
		MinHeight: 500,
		AssetServer: &assetserver.Options{
			Assets: assets,
		},
		OnStartup:  app.startup,
		OnShutdown: app.shutdown,
		Bind: []interface{}{
			app,
		},
	}); err != nil {
		log.Printf("FATAL wails error: %v", err)
		// On Windows, also write to a visible error file
		if runtime.GOOS == "windows" {
			errPath := filepath.Join(*dataDir, "ERROR.txt")
			os.WriteFile(errPath, []byte("vpnem failed to start:\n"+err.Error()+"\n\nCheck vpnem.log for details.\n"), 0o644)
		}
		os.Exit(1)
	}
}

func defaultDataDir() string {
	if runtime.GOOS == "windows" {
		return `C:\ProgramData\vpnem`
	}
	home, _ := os.UserHomeDir()
	return filepath.Join(home, ".local", "share", "vpnem")
}