using System.Security;
using System.Security.Claims;
using System.Security.Policy;
using System.Security.Principal;
using System.Text;
using System.Text.Unicode;
using System.Threading.Tasks.Sources;

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Primitives;

using UAParser;

namespace AuthStudy.Authentication.Browser
{
    /// <summary>
    /// 浏览器认证 处理器
    /// 可实现子接口 IAuthenticationRequestHandler, 以控制后续中间件是否执行.
    /// </summary>
    public class BrowserAuthenticationHandler<TOptions> :
        IAuthenticationHandler, IAuthenticationRequestHandler, IAuthenticationSignInHandler, IAuthenticationSignOutHandler
        where TOptions : AuthenticationSchemeOptions, new()
    {
        public const string DefaultAuthenticationScheme = BrowserAuthenticationDefault.AuthenticationSchemeName;

        public HttpContext? CurrentHttpContext;

        public List<string> supportedBrowsers = new() { "Chrome", "Edge" };

        /// <summary>
        /// 认证
        /// </summary>
        public Task<AuthenticateResult> AuthenticateAsync()
        {
            var properties = new AuthenticationProperties();
            properties.Items.Add("x-test", "测试");

            //获取浏览器信息
            CurrentHttpContext?.Request.Headers.TryGetValue("User-Agentx", out StringValues browserInfo);

            ClientInfo clientInfo = Parser.GetDefault().Parse(CurrentHttpContext?.Request.Headers["User-Agent"]);
            if (!supportedBrowsers.Contains(clientInfo.UA.Family))
            {
                var success = AuthenticateResult.Fail($"不支持的浏览器：{clientInfo.UA.Family}", properties);

                return Task.FromResult(success);
            }

            //声明(身份项)
            var role = new Claim(ClaimTypes.Role, "Admin");
            var email = new Claim(ClaimTypes.Email, "bicijinlian@168.com");

            //声明集合
            var Claims = new List<Claim>();
            Claims.Add(role);
            Claims.Add(email);

            //身份：包含声明集合，是声明集合的包装类，一个身份对应多个声明
            var claimsIdentity = new ClaimsIdentity(Claims, DefaultAuthenticationScheme);

            //当事人/主角：是身份Identity的包装，对应多个身份
            var claimsPrincipal = new ClaimsPrincipal(claimsIdentity);

            //票据：对Principal的包装，一对一
            var ticket = new AuthenticationTicket(claimsPrincipal, DefaultAuthenticationScheme);

            //认证结果：认证信息会写入 当前请求的 User属性中，供下一个授权中间件使用
            var result = AuthenticateResult.Success(ticket);

            //调用登陆
            //CurrentHttpContext?.SignInAsync(BrowserAuthentication.DefaultAuthenticationScheme, claimsPrincipal, properties);

            return Task.FromResult(result);
        }

        /// <summary>
        /// 无认证：服务端向客户端(浏览器)发质询(要求提供一个新票据),质询体现为 htpp请求的响应。
        /// </summary>
        public Task ChallengeAsync(AuthenticationProperties? properties)
        {
            properties?.Parameters.Add("x-itme", "无效的认证");

            CurrentHttpContext!.Response.StatusCode = 401;
            if (CurrentHttpContext?.Response.Body.CanWrite ?? false)
            {
                var msg = UTF8Encoding.UTF8.GetBytes("认证无效");
                CurrentHttpContext!.Response.Body.WriteAsync(msg);
            }
            CurrentHttpContext?.Items.Add("认证结束时间", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
            return Task.CompletedTask;
        }

        /// <summary>
        /// 无权限：服务端向客户端(浏览器)发质询(要求提供一个新票据),质询体现为 htpp请求的响应。
        /// </summary>
        public Task ForbidAsync(AuthenticationProperties? properties)
        {
            CurrentHttpContext!.Response.StatusCode = 403;
            if (CurrentHttpContext?.Response.Body.CanWrite ?? false)
            {
                var msg = UTF8Encoding.UTF8.GetBytes("无权访问");
                CurrentHttpContext!.Response.Body.WriteAsync(msg);
            }
            return Task.CompletedTask;
        }

        /// <summary>
        /// IAuthenticationRequestHandler
        /// 返回true,立即反回，不执行后续中间件
        /// </summary>
        /// <returns></returns>
        public Task<bool> HandleRequestAsync()
        {
            return Task.FromResult(false);
        }

        /// <summary>
        /// 初始化
        /// </summary>
        public async Task InitializeAsync(AuthenticationScheme scheme, Microsoft.AspNetCore.Http.HttpContext context)
        {
            //初始化工作，传递给认证方法和授权中间件
            CurrentHttpContext = context;

            context.Items.Add("认证初始时间", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));

            await Task.CompletedTask;
        }

        /// <summary>
        /// 登陆方法
        /// 写入Cookie和Session，认证信息持久化等
        /// </summary>
        public Task SignInAsync(ClaimsPrincipal user, AuthenticationProperties? properties)
        {
            //导航到登陆页
            CurrentHttpContext?.Response.Redirect("https://www.baidu.com");

            return Task.CompletedTask;
        }

        /// <summary>
        /// 退出方法: 反操作登陆方法
        /// 清除Cookie和Session，删除认证信息的持久化，作废票据等
        /// </summary>
        public Task SignOutAsync(AuthenticationProperties? properties)
        {
            //导航到登陆页
            CurrentHttpContext?.Response.Redirect("/api/auth/login");
            return Task.CompletedTask;
        }
    }
}