using System.Windows;

// 双开 WPF + WinForms 时,Application 在两个命名空间都有,固定走 WPF 的。
using Application = System.Windows.Application;

namespace WindowsGotify.Services;

public static class ThemeService
{
    public const string Light = "Light";
    public const string Dark = "Dark";
    public const string System = "System";

    public static event EventHandler? Changed;

    private static string _current = Light;

    public static string Current => _current;

    /// <summary>
    /// 切换到指定主题。currentTheme = "Light" / "Dark" / "System"(System 暂时等同 Light,V1 简化)。
    /// </summary>
    public static void Apply(string themeName)
    {
        if (string.IsNullOrWhiteSpace(themeName)) themeName = Light;
        // "System" 在 V1 简化:用 Light(后续可接 Windows 主题 API)
        if (themeName == System) themeName = Light;

        _current = themeName;
        var merged = Application.Current.Resources.MergedDictionaries;

        // 移除已有的 Themes/* 字典
        for (int i = merged.Count - 1; i >= 0; i--)
        {
            var src = merged[i].Source?.ToString();
            if (src != null && src.Contains("/Themes/", StringComparison.OrdinalIgnoreCase))
                merged.RemoveAt(i);
        }

        // 加载新主题
        var newDict = new ResourceDictionary
        {
            Source = new Uri($"/Themes/{themeName}.xaml", UriKind.Relative)
        };
        merged.Add(newDict);

        Changed?.Invoke(null, EventArgs.Empty);
    }

    public static void Toggle()
    {
        Apply(_current == Dark ? Light : Dark);
    }
}