game-ideas/src/GameIdeas/Client/GameIdeas.BlazorApp/Services/JwtAuthenticationStateProvider.cs

using Blazored.LocalStorage;
using GameIdeas.Shared.Constants;
using GameIdeas.Shared.Dto;
using Microsoft.AspNetCore.Components.Authorization;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;

namespace GameIdeas.BlazorApp.Services;

public class JwtAuthenticationStateProvider(ILocalStorageService localStorage) : AuthenticationStateProvider
{
    public override async Task<AuthenticationState> GetAuthenticationStateAsync()
    {
        var savedToken = await localStorage.GetItemAsStringAsync(GlobalConstants.LS_AUTH_STORAGE_KEY);

        if (!string.IsNullOrWhiteSpace(savedToken))
        {
            try
            {
                var token = new JwtSecurityTokenHandler().ReadJwtToken(savedToken);

                return new AuthenticationState(
                    new ClaimsPrincipal(new ClaimsIdentity(token.Claims, "jwt"))
                );
            }
            catch
            {
                await localStorage.RemoveItemAsync(GlobalConstants.LS_AUTH_STORAGE_KEY);
            }
        }

        return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
    }

    public async Task NotifyUserAuthenticationAsync(TokenDto token)
    {
        if (token?.Token != null)
        {
            await localStorage.SetItemAsStringAsync(GlobalConstants.LS_AUTH_STORAGE_KEY, token.Token);
        }

        if (token?.Expiration != null)
        {
            await localStorage.SetItemAsStringAsync(GlobalConstants.LS_EXPIRED_STORAGE_KEY, token.Expiration.Value.ToString());
        }

        NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
    }

    public async Task NotifyUserLogoutAsync()
    {
        await localStorage.RemoveItemAsync(GlobalConstants.LS_AUTH_STORAGE_KEY);

        var nobody = new ClaimsPrincipal(new ClaimsIdentity());
        NotifyAuthenticationStateChanged(Task.FromResult(new AuthenticationState(nobody)));
    }
}