//go:build windows
// +build windows

package main

import (
	"log"

	"fyne.io/fyne/v2"
	"golang.org/x/sys/windows/registry"
)

// GetRegistryColorValue retrieves a DWORD value from the Windows registry.
func GetRegistryColorValue(keyPath, valueName string) (uint32, error) {
	key, err := registry.OpenKey(registry.CURRENT_USER, keyPath, registry.QUERY_VALUE)
	if err != nil {
		return 0, err
	}
	defer key.Close()

	value, _, err := key.GetIntegerValue(valueName)
	if err != nil {
		return 0, err
	}

	return uint32(value), nil
}

// ParseRegistryColorValue converts a DWORD value to RGB format.
func ParseRegistryColorValue(value uint32) (uint8, uint8, uint8) {
	return uint8(value & 0xFF), uint8((value >> 8) & 0xFF), uint8((value >> 16) & 0xFF)
}

// GetDarkMode checks if dark mode is enabled.
func GetDarkMode() (bool, error) {
	const keyPath = `Software\Microsoft\Windows\CurrentVersion\Themes\Personalize`
	const valueName = "AppsUseLightTheme"

	darkModeValue, err := GetRegistryColorValue(keyPath, valueName)
	if err != nil {
		return false, err
	}

	isDark := darkModeValue == 0
	return isDark, nil
}

// GetThemeWin retrieves the background and theme colors from the registry.
func GetThemeWin() (colBackground, colTheme [3]uint8, isDark bool, err error) {
	registryEntries := []struct {
		keyPath   string
		valueName string
	}{
		{`Software\Microsoft\Windows\CurrentVersion\Explorer\Accent`, "AccentColorMenu"},
		{`Software\Microsoft\Windows\DWM`, "AccentColor"},
	}

	isDark, err = GetDarkMode()
	if err != nil {
		return
	}

	blackRGB := [3]uint8{10, 10, 10}
	whiteRGB := [3]uint8{245, 245, 245}
	if isDark {
		colBackground = blackRGB
	} else {
		colBackground = whiteRGB
	}

	for _, entry := range registryEntries {
		registryValue, err := GetRegistryColorValue(entry.keyPath, entry.valueName)
		if err == nil {
			r, g, b := ParseRegistryColorValue(registryValue)
			if entry.valueName == "AccentColorMenu" || entry.valueName == "AccentColor" {
				colTheme = [3]uint8{r, g, b}
			}
		}
	}

	return
}

func ApplyTheme(a fyne.App) {
	colBackground, colTheme, isDark, err := GetThemeWin()
	if err != nil {
		log.Fatalf("Error: %v\n", err)
	}

	applyThemeToApp(a, colBackground, colTheme, isDark)
}