using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

using WPFDark.Properties;

namespace WPFDark;
public class ThemeManager
{
    private static ThemeManager? _themeManagerInstance;

    private readonly Application? application;

    //private Window? mainWindow;

    private ResourceDictionary? resources;

    internal static string LibraryNamespace => Assembly.GetExecutingAssembly().GetName().Name;

    public static string ThemesDictionary => $"pack://application:,,,/{LibraryNamespace};component/Themes/Generic.xaml";
    /// <summary>
    /// 获取或设置应用程序的资源。
    /// </summary>
    public object TryFindResource(object resourceKey) { return Resources[resourceKey]; }
    /// <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}", "WPFDark");
    }
    private static bool ApplicationHasResources(Application? application)
    {
        return application is not null && application
            .Resources.MergedDictionaries
            .Where(e => e.Source is not null)
            .Any(
                e => e.Source
                    .ToString()
                    .Contains(LibraryNamespace));
    }
    /// <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;
        }
    }
}