using Dpz.Core.Service.Mediator.Features.Account.Queries;

namespace Dpz.Core.Web.Library.Middleware;

/// <summary>
/// 用户资料刷新中间件
/// 每次请求时检查当前登录用户的资料是否被标记为已变更（通过 FusionCache 存储的变更时间戳），
/// 若资料已过期则重新查询用户信息并刷新登录态
/// </summary>
public class UserProfileRefreshMiddleware(
    RequestDelegate next,
    IFusionCache fusionCache,
    ILogger<UserProfileRefreshMiddleware> logger
)
{
    public async Task InvokeAsync(
        HttpContext context,
        IMediator mediator,
        IApplicationSignInManager signInManager
    )
    {
        if (context.User.Authenticated)
        {
            await RefreshProfileIfNeededAsync(context, mediator, signInManager);
        }

        await next(context);
    }

    /// <summary>
    /// 检查用户资料是否需要刷新并执行刷新
    /// 比较缓存中的资料变更时间与登录态中记录的最后刷新时间，
    /// 若变更时间晚于刷新时间则重新查询用户信息并更新登录态
    /// </summary>
    private async Task RefreshProfileIfNeededAsync(
        HttpContext context,
        IMediator mediator,
        IApplicationSignInManager signInManager
    )
    {
        var account = context.User.NameIdentifier;
        var sessionId = context.User.SessionId;
        if (string.IsNullOrWhiteSpace(account) || string.IsNullOrWhiteSpace(sessionId))
        {
            return;
        }

        // 从 FusionCache 读取用户资料变更时间戳
        var changedAt = await fusionCache.GetOrDefaultAsync<DateTime>(
            UserSessionKeys.ChangedAtKey(account),
            token: context.RequestAborted
        );
        if (changedAt == default)
        {
            return;
        }

        // 当前登录态中的最后刷新时间已不早于变更时间，无需刷新
        var refreshedAt = ReadProfileRefreshedAt(context);
        if (refreshedAt >= changedAt)
        {
            return;
        }

        // 重新查询用户最新信息
        var userInfo = await mediator.Send(
            new GetUserInfoRequest { Account = account },
            context.RequestAborted
        );
        if (userInfo == null)
        {
            logger.LogWarning(
                "User profile refresh skipped because account was not found: {Account}",
                account
            );
            return;
        }

        // 更新登录态中的用户信息
        userInfo.SessionId = sessionId;
        await signInManager.RefreshSignInAsync(userInfo);
    }

    /// <summary>
    /// 从当前用户 Claims 中读取最近一次资料刷新的时间
    /// </summary>
    private static DateTime ReadProfileRefreshedAt(HttpContext context)
    {
        var raw = context.User.FindFirst(UserSessionKeys.ProfileRefreshedAtClaim)?.Value;
        if (
            DateTime.TryParse(
                raw,
                CultureInfo.InvariantCulture,
                DateTimeStyles.RoundtripKind,
                out var refreshedAt
            )
        )
        {
            return refreshedAt;
        }

        return default;
    }
}

/// <summary>
/// 用户资料刷新中间件的注册扩展
/// </summary>
public static class UserProfileRefreshMiddlewareExtensions
{
    public static IApplicationBuilder UseUserProfileRefresh(this IApplicationBuilder app)
    {
        return app.UseMiddleware<UserProfileRefreshMiddleware>();
    }
}