using Microsoft.AspNetCore.Components;
using Microsoft.JSInterop;
using System.Globalization;

namespace Atomx.Admin.Client.Services
{
    /// <summary>
    /// 语言提供者服务
    /// </summary>
    public class LanguageProvider
    {
        private readonly IJSRuntime _jsRuntime;
        private readonly NavigationManager _navigationManager;
        private string _currentLanguage = "zh-Hans";

        public event Action? OnLanguageChanged;

        public LanguageProvider(IJSRuntime jsRuntime, NavigationManager navigationManager)
        {
            _jsRuntime = jsRuntime;
            _navigationManager = navigationManager;
        }

        public string CurrentLanguage
        {
            get => _currentLanguage;
            private set
            {
                if (_currentLanguage != value)
                {
                    _currentLanguage = value;

                    // 设置全局线程文化，确保 IStringLocalizer 等在随后的渲染中读取到新文化
                    try
                    {
                        var ci = new CultureInfo(value);
                        CultureInfo.DefaultThreadCurrentCulture = ci;
                        CultureInfo.DefaultThreadCurrentUICulture = ci;
                    }
                    catch
                    {
                        // 忽略无效 culture 字符串
                    }

                    OnLanguageChanged?.Invoke();
                }
            }
        }

        public List<string> SupportedLanguages { get; } = new()
    {
        "zh-Hans", // 简体中文
        "en-US"    // 英文（美国）
    };

        /// <summary>
        /// 初始化语言
        /// </summary>
        public async Task InitializeAsync()
        {
            // 尝试从本地存储获取保存的语言
            try
            {
                var savedLanguage = await _jsRuntime.InvokeAsync<string>("localStorage.getItem", "preferred-language");
                if (!string.IsNullOrEmpty(savedLanguage) && SupportedLanguages.Contains(savedLanguage))
                {
                    CurrentLanguage = savedLanguage;
                }
                else
                {
                    // 从浏览器获取语言
                    var browserLanguage = await _jsRuntime.InvokeAsync<string>("getBrowserLanguage");
                    CurrentLanguage = GetSupportedLanguage(browserLanguage);
                }
            }
            catch
            {
                // JS互操作可能不可用（在预渲染时）
                CurrentLanguage = "zh-Hans";
            }
        }

        /// <summary>
        /// 切换语言
        /// </summary>
        public async Task ChangeLanguageAsync(string languageCode)
        {
            if (SupportedLanguages.Contains(languageCode) && CurrentLanguage != languageCode)
            {
                CurrentLanguage = languageCode;

                // 保存到本地存储
                try
                {
                    await _jsRuntime.InvokeVoidAsync("localStorage.setItem", "preferred-language", languageCode);
                }
                catch
                {
                    // 忽略错误
                }

                // setter 已触发 OnLanguageChanged
            }
        }

        /// <summary>
        /// 获取支持的语言
        /// </summary>
        private string GetSupportedLanguage(string browserLanguage)
        {
            if (string.IsNullOrEmpty(browserLanguage))
                return "zh-Hans";

            // 检查完全匹配
            if (SupportedLanguages.Contains(browserLanguage))
                return browserLanguage;

            // 检查中性语言匹配
            var neutralLanguage = browserLanguage.Split('-')[0];
            foreach (var supported in SupportedLanguages)
            {
                if (supported.StartsWith(neutralLanguage))
                    return supported;
            }

            return "zh-Hans"; // 默认语言
        }
    }
}