using System.Reflection;
using System.Windows.Controls;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using WPFluent.Controls;
using WPFluent.Extensions;
using WPFluent.Markup;

namespace WPFluent.Appearance;

/// <summary>
/// 允许通过交换包含动态资源的资源字典来管理应用程序主题。
/// </summary>
/// <example>
/// <code lang="csharp"> ThemeManager.ChangeAppTheme( ThemeType.Light );</code> <code lang="csharp"> if
/// (ThemeManager.GetAppTheme() == ThemeType.Dark) { ThemeManager.ChangeAppTheme(
/// ThemeType.Light ); }</code> <code> ThemeManager.Changed += (theme, accent) => {
/// Debug.WriteLine($"Application theme changed to {theme.ToString()}"); };</code>
/// </example>
public class ThemeManager
{
    internal static string LibraryNamespace => Assembly.GetExecutingAssembly().GetName().Name;

    public static string ThemesDictionaryPath => $"pack://application:,,,/{LibraryNamespace};component/Themes/";

    private static ThemeType _activeApplicationTheme = ThemeType.Unknow;
    public static event Action<ThemeType, Color>? Changed;

    #region Animation


    private static Task AnimateBrushColorAsync(SolidColorBrush brush, Color toColor, int durationMs = 500)
    {
        if (brush.IsFrozen)
            return Task.CompletedTask; // 冻结的Brush无法动画，直接返回完成的Task

        var tcs = new TaskCompletionSource<bool>();
        var anim = new ColorAnimation
        {
            To = toColor,
            Duration = TimeSpan.FromMilliseconds(durationMs),
            EasingFunction = new CubicEase { EasingMode = EasingMode.EaseInOut },
            FillBehavior = FillBehavior.HoldEnd
        };

        // 在动画完成时标记任务完成
        anim.Completed += (s, e) => tcs.SetResult(true);
        brush.BeginAnimation(SolidColorBrush.ColorProperty, anim);

        return tcs.Task;
    }

    /// <summary>
    /// 带淡入淡出过渡动画的主题切换
    /// </summary>
    private static async void ApplyThemeWithAnimation(ThemeType theme)
    {
        try
        {
            var window = Application.Current.MainWindow;
            if (window == null) return;
            // 确保内容容器支持 Children
            if (!(window.Content is Panel panel))
                throw new InvalidOperationException("ThemeManager requires Window.Content to be a Panel.");

            // 创建遮罩
            var overlay = new Rectangle
            {
                Fill = new SolidColorBrush(Colors.Black),
                Opacity = 0,
                IsHitTestVisible = false,
            };
            Panel.SetZIndex(overlay, int.MaxValue);
            panel.Children.Add(overlay);

            // 淡入
            await AnimateOpacity(overlay, 0, 1, TimeSpan.FromMilliseconds(300));

            // 切换资源字典
            //ApplyThemeInternal(theme);
            ChangeAppTheme(theme);

            // 淡出
            await AnimateOpacity(overlay, 1, 0, TimeSpan.FromMilliseconds(300));
            panel.Children.Remove(overlay);

            Changed?.Invoke(theme, AccentColorManager.SystemAccent);
        }
        catch (Exception ex)
        {

        }
    }

    private static Task AnimateOpacity(UIElement element, double from, double to, TimeSpan duration)
    {
        var tcs = new TaskCompletionSource<bool>();
        var anim = new DoubleAnimation(from, to, new Duration(duration));
        anim.Completed += (s, e) => tcs.SetResult(true);
        element.BeginAnimation(UIElement.OpacityProperty, anim);
        return tcs.Task;
    }

    #endregion

    /// <summary>
    /// 将资源应用于 <paramref name="frameworkElement"/>.
    /// </summary>
    public static void ApplyResourcesToElement(FrameworkElement frameworkElement)
    {
        if (frameworkElement.Resources.MergedDictionaries.Count <
            ThemeManager.Current.Resources.MergedDictionaries.Count)
        {
            foreach (var dictionary in ThemeManager.Current.Resources.MergedDictionaries)
            {
                frameworkElement.Resources.MergedDictionaries.Add(dictionary);
            }
        }
    }

    /// <summary>
    /// 更改当前应用程序主题。
    /// </summary>
    /// <param name="applicationTheme">要设置的主题</param>
    /// <param name="backgroundEffect">是否应用自定义背景效果。</param>
    /// <param name="updateAccent">是否应更改颜色强调。</param>
    public static void ChangeAppTheme(ThemeType applicationTheme, WindowBackdropType backgroundEffect = WindowBackdropType.Mica,
        bool updateAccent = true)
    {
        if (updateAccent)
        {
            //TODO
            AccentColorManager.Apply(
                Color.FromRgb(194, 115, 37),
                applicationTheme,
                false);
        }

        if (applicationTheme == ThemeType.Unknow)
        {
            return;
        }

        ResourceDictionaryManager appDictionaries = new();

        var themeDictionaryName = applicationTheme switch
        {
            ThemeType.Light => "Light",
            ThemeType.Dark => "Dark",
            ThemeType.HcWhite => "HCWhite",
            ThemeType.HcBlack => "HCBlack",
            _ => "Light"
        };
        //ApplyThemeWithAnimation(applicationTheme);
        if (!appDictionaries.UpdateDictionary(
                "themes",
                new Uri($"{ThemesDictionaryPath}{themeDictionaryName}.xaml", UriKind.Absolute)))
        {
            return;
        }

        _activeApplicationTheme = applicationTheme;

        Changed?.Invoke(applicationTheme, AccentColorManager.SystemAccent);

        if (Current.MainWindow is Window mainWindow)
        {
            WindowBackgroundManager.UpdateBackground(mainWindow, applicationTheme, backgroundEffect);
        }
    }

    /// <summary>
    /// 获取当前设置的应用程序主题。
    /// </summary>
    /// <returns><see cref="ThemeType.Unknow"/> if something goes wrong.</returns>
    public static ThemeType GetAppTheme()
    {
        if (_activeApplicationTheme == ThemeType.Unknow)
        {
            ResourceDictionaryManager appDictionaries = new();
            var themeDictionary = appDictionaries.LookupDictionary("themes");

            if (themeDictionary == null)
            {
                return ThemeType.Unknow;
            }

            var themeUri = themeDictionary.Source.ToString();

            if (themeUri.Contains("light", StringComparison.OrdinalIgnoreCase))
            {
                _activeApplicationTheme = ThemeType.Light;
            }

            if (themeUri.Contains("dark", StringComparison.OrdinalIgnoreCase))
            {
                _activeApplicationTheme = ThemeType.Dark;
            }
            if (themeUri.Contains("hcwhite", StringComparison.OrdinalIgnoreCase))
            {
                _activeApplicationTheme = ThemeType.HcWhite;
            }

            if (themeUri.Contains("hcblack", StringComparison.OrdinalIgnoreCase))
            {
                _activeApplicationTheme = ThemeType.HcBlack;
            }
        }

        return _activeApplicationTheme;
    }
    #region UiApplication

    private static ThemeManager? _themeManagerInstance;

    private readonly Application? application;

    private Window? mainWindow;

    private ResourceDictionary? resources;

    /// <summary>
    /// 初始化 <see cref="ThemeManager"/> 实例.
    /// </summary>
    private ThemeManager(Application? application)
    {
        if (application is null)
        {
            return;
        }

        if (!ApplicationHasResources(application))
        {
            return;
        }

        this.application = application;

        System.Diagnostics.Debug
            .WriteLine($"INFO | {typeof(ThemeManager)} application is {this.application}", "WPFluent");
    }

    private static bool ApplicationHasResources(Application? application)
    {
        return application
            .Resources.MergedDictionaries
            .Where(e => e.Source is not null)
            .Any(
                e => e.Source
                    .ToString()
                    .Contains(ThemeManager.LibraryNamespace, StringComparison.OrdinalIgnoreCase));
    }

    /// <summary>
    /// 将应用程序的 变为 shutdown 模式。
    /// </summary>
    public void Shutdown() { application?.Shutdown(); }

    /// <summary>
    /// 获取或设置应用程序的资源。
    /// </summary>
    public object TryFindResource(object resourceKey) { return Resources[resourceKey]; }

    /// <summary>
    /// 获取当前UI应用程序。
    /// </summary>
    public static ThemeManager Current
    {
        get
        {
            _themeManagerInstance ??= new ThemeManager(Application.Current);

            return _themeManagerInstance;
        }
    }


    /// <summary>
    /// 获取或设置应用程序的主窗口。
    /// </summary>
    public Window? MainWindow
    {
        get => application?.MainWindow ?? mainWindow;
        set
        {
            if (application != null)
            {
                application.MainWindow = value;
            }

            mainWindow = value;
        }
    }

    /// <summary>
    /// 获取或设置应用程序的资源。
    /// </summary>
    public ResourceDictionary Resources
    {
        get
        {
            if (resources is null)
            {
                resources = [];

                try
                {
                    var themesDictionary = new ThemesDictionary();
                    var controlsDictionary = new ControlsDictionary();
                    resources.MergedDictionaries.Add(themesDictionary);
                    resources.MergedDictionaries.Add(controlsDictionary);
                }
                catch
                {
                }
            }

            return application?.Resources ?? resources;
        }
        set
        {
            if (application is not null)
            {
                application.Resources = value;
            }

            resources = value;
        }
    }
    #endregion
}