package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"syscall"
	"time"
	"unsafe"

	"github.com/getlantern/systray"
	"golang.org/x/sys/windows/registry"
)

// Set Windows dark/light mode via registry
func setMode(light bool) {
	key, _ := registry.OpenKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Themes\Personalize`, registry.SET_VALUE)
	defer key.Close()
	val := uint32(0)
	if light {
		val = 1
	}
	key.SetDWordValue("AppsUseLightTheme", val)
	key.SetDWordValue("SystemUsesLightTheme", val)
}

// Restart Explorer to fully apply theme
func restartExplorer() {
	exec.Command("taskkill", "/f", "/im", "explorer.exe").Run()
	time.Sleep(1 * time.Second)
	exec.Command("explorer.exe").Start()
}

// Get current theme mode from registry
func getCurrentMode() string {
	key, _ := registry.OpenKey(registry.CURRENT_USER, `Software\Microsoft\Windows\CurrentVersion\Themes\Personalize`, registry.QUERY_VALUE)
	defer key.Close()
	val, _, _ := key.GetIntegerValue("AppsUseLightTheme")
	if val == 1 {
		return "light"
	}
	return "dark"
}

// Find image in same dir with any supported extension
func findImageFile(name string) string {
	exePath, _ := os.Executable()
	dir := filepath.Dir(exePath)
	matches, _ := filepath.Glob(filepath.Join(dir, name+".*"))
	for _, f := range matches {
		ext := strings.ToLower(filepath.Ext(f))
		if ext == ".jpg" || ext == ".jpeg" || ext == ".png" || ext == ".bmp" || ext == ".webp" {
			return f
		}
	}
	return ""
}

// Get current wallpaper path from registry
func getCurrentWallpaper() string {
	key, _ := registry.OpenKey(registry.CURRENT_USER, `Control Panel\Desktop`, registry.QUERY_VALUE)
	defer key.Close()
	val, _, _ := key.GetStringValue("Wallpaper")
	return val
}

// Set desktop wallpaper via Windows API
func setWallpaper(path string) {
	user32 := syscall.NewLazyDLL("user32.dll")
	sysParam := user32.NewProc("SystemParametersInfoW")
	p, _ := syscall.UTF16PtrFromString(path)
	sysParam.Call(0x0014, 0, uintptr(unsafe.Pointer(p)), uintptr(0x01|0x02))
}

// Main background loop
func backgroundLoop() {
	lightImg := findImageFile("light")
	darkImg := findImageFile("dark")
	lastMode := getCurrentMode()

	for {
		hour := time.Now().Hour()
		newMode := "dark"
		var targetImg string

		if hour >= 6 && hour < 18 {
			newMode = "light"
			targetImg = lightImg
		} else {
			targetImg = darkImg
		}

		if newMode != lastMode {
			setMode(newMode == "light")
			restartExplorer()
			lastMode = newMode
		}

		if targetImg != "" && getCurrentWallpaper() != targetImg {
			setWallpaper(targetImg)
		}

		time.Sleep(60 * time.Second)
	}
}

// Load icon from local directory (icon.ico)
func getIconBytes() []byte {
	exePath, _ := os.Executable()
	iconPath := filepath.Join(filepath.Dir(exePath), "icon.ico")
	data, err := ioutil.ReadFile(iconPath)
	if err != nil {
		fmt.Println("icon.ico not found or unreadable.")
		return nil
	}
	return data
}

// Systray startup
func onReady() {
	icon := getIconBytes()
	if icon != nil {
		systray.SetIcon(icon)
	}
	systray.SetTitle("Auto Theme")
	systray.SetTooltip("Auto Theme + Wallpaper Switcher")

	mQuit := systray.AddMenuItem("Quit", "Exit the program")

	go func() {
		go backgroundLoop()
		<-mQuit.ClickedCh
		systray.Quit()
	}()
}

func onExit() {}

func main() {
	systray.Run(onReady, onExit)
}