eShopOnWeb/src/Web/Areas/Identity/Pages/Account/Logout.cshtml.cs

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.eShopWeb.Infrastructure.Identity;
using Microsoft.eShopWeb.Web.Configuration;
using Microsoft.Extensions.Caching.Memory;
using Microsoft.Extensions.Logging;
using System;
using System.Linq;
using System.Security.Claims;
using System.Threading.Tasks;

namespace Microsoft.eShopWeb.Web.Areas.Identity.Pages.Account
{
    //TODO : replace IMemoryCache by distributed cache if you are in multi-host scenario
    public class LogoutModel : PageModel
    {
        private readonly SignInManager<ApplicationUser> _signInManager;
        private readonly ILogger<LogoutModel> _logger;
        private readonly IMemoryCache _cache;

        public LogoutModel(SignInManager<ApplicationUser> signInManager, ILogger<LogoutModel> logger, IMemoryCache cache)
        {
            _signInManager = signInManager;
            _logger = logger;
            _cache = cache;
        }

        public void OnGet()
        {
        }

        public async Task<IActionResult> OnPost(string returnUrl = null)
        {
            await _signInManager.SignOutAsync();
            await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);
            var userId = _signInManager.Context.User.Claims.First(c => c.Type == ClaimTypes.Name);
            var identityKey = _signInManager.Context.Request.Cookies[ConfigureCookieSettings.IdentifierCookieName];
            _cache.Set($"{userId.Value}:{identityKey}", identityKey, new MemoryCacheEntryOptions
            {
                AbsoluteExpiration = DateTime.Now.AddMinutes(ConfigureCookieSettings.ValidityMinutesPeriod)
            });

            _logger.LogInformation("User logged out.");
            if (returnUrl != null)
            {
                return LocalRedirect(returnUrl);
            }
            else
            {
                return RedirectToPage("/Index");
            }
        }
    }
}