using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.SignalR;
using Volo.Abp.Security.Claims;

namespace Sozsoft.Platform.Notifications;

/// <summary>
/// Bildirimlerin aninda duyuruldugu baglanti. Istemci yalnizca dinler; okundu/gosterildi
/// isaretleri REST ucundan gider, boylece yetki ve dogrulama tek yoldan gecer.
/// <para>
/// Kullanici ve kiraci bilgisi baglantinin claim'lerinden okunur: hub cagrilari HTTP ardisik
/// duzeni disinda calistigi icin AsyncLocal tabanli <c>ICurrentUser</c> her zaman dolu olmaz.
/// </para>
/// </summary>
[Authorize]
public class NotificationHub : Hub
{
    /// <summary>Istemcinin dinledigi olay adi; yeni bildirim uretildiginde tetiklenir.</summary>
    public const string NotificationReceived = "NotificationReceived";

    public override async Task OnConnectedAsync()
    {
        var (tenantId, userId) = GetConnectionIdentity();
        if (userId.HasValue)
        {
            await Groups.AddToGroupAsync(Context.ConnectionId, UserGroupName(tenantId, userId.Value));
        }

        await base.OnConnectedAsync();
    }

    private (Guid? TenantId, Guid? UserId) GetConnectionIdentity()
    {
        var user = Context.User;
        return (ParseGuid(user?.FindFirst(AbpClaimTypes.TenantId)?.Value),
            ParseGuid(user?.FindFirst(AbpClaimTypes.UserId)?.Value));
    }

    private static Guid? ParseGuid(string? value) =>
        Guid.TryParse(value, out var parsed) ? parsed : null;

    /// <summary>Bildirimler kullanici bazlidir; grup adi kiraci ile birlikte anahtarlanir.</summary>
    public static string UserGroupName(Guid? tenantId, Guid userId) =>
        $"notification:user:{tenantId?.ToString("N") ?? "host"}:{userId:N}";
}