tagger/Tagger/Service/CustomAuthStateProvider.cs

using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.AspNetCore.Components.Server.ProtectedBrowserStorage;
using System.Security.Claims;

namespace Tagger.Service;

public class CustomAuthStateProvider : AuthenticationStateProvider
{
    private readonly ProtectedSessionStorage SessionStorage;
    private ClaimsPrincipal Anonymous = new(new ClaimsIdentity());

    public CustomAuthStateProvider(ProtectedSessionStorage sessionStorage)
    {
        SessionStorage = sessionStorage;
    }

    public override async Task<AuthenticationState> GetAuthenticationStateAsync()
    {
        var userSessionStorageResult = await SessionStorage.GetAsync<User>(nameof(User));
        
        if(!userSessionStorageResult.Success || userSessionStorageResult.Value is null)
            return new AuthenticationState(Anonymous);

        var claimPrincipal = new ClaimsPrincipal(new ClaimsIdentity(new List<Claim>
        {
            new Claim(ClaimTypes.Name, userSessionStorageResult.Value.Name)
        }));
        return new(claimPrincipal);
    }

    public async Task SetSession(User? user)
    {
        if(user is null)
            await SessionStorage.DeleteAsync(nameof(User));
        else
            await SessionStorage.SetAsync(nameof(User), user);
    }
}