Add protected admin scope with login

RazorPagesMovie/Pages/Login.cshtml.cs

@@ -0,0 +1,53 @@
+using System.Security.Claims;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.EntityFrameworkCore;
+using RazorPagesMovie.Data;
+using RazorPagesMovie.Models;
+
+namespace RazorPagesMovie.Pages;
+
+public class LoginModel : PageModel
+{
+    private readonly RazorPagesMovieContext _context;
+
+    public LoginModel(RazorPagesMovieContext context)
+    {
+        _context = context;
+    }
+
+    [BindProperty]
+    public string Username { get; set; } = string.Empty;
+
+    [BindProperty]
+    public string Password { get; set; } = string.Empty;
+
+    public string? ErrorMessage { get; set; }
+
+    public void OnGet()
+    {
+    }
+
+    public async Task<IActionResult> OnPostAsync(string? returnUrl)
+    {
+        var user = await _context.AdminUser.SingleOrDefaultAsync(u => u.Username == Username);
+        var hasher = new PasswordHasher<AdminUser>();
+
+        if (user is null || hasher.VerifyHashedPassword(user, user.PasswordHash, Password) == PasswordVerificationResult.Failed)
+        {
+            ErrorMessage = "Benutzername oder Passwort ist falsch.";
+            return Page();
+        }
+
+        var identity = new ClaimsIdentity(
+            new[] { new Claim(ClaimTypes.Name, user.Username) },
+            CookieAuthenticationDefaults.AuthenticationScheme);
+
+        await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, new ClaimsPrincipal(identity));
+
+        return LocalRedirect(returnUrl ?? "/Admin");
+    }
+}