Add authentication and authorization (#21)

Reviewed-on: #21

src/GameIdeas/Client/GameIdeas.BlazorApp/Services/JwtAuthenticationStateProvider.cs

@@ -0,0 +1,48 @@
+using Blazored.LocalStorage;
+using Microsoft.AspNetCore.Components.Authorization;
+using System.Security.Claims;
+using System.IdentityModel.Tokens.Jwt;
+using GameIdeas.Shared.Constants;
+
+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(string token)
+    {
+        await localStorage.SetItemAsStringAsync(GlobalConstants.LS_AUTH_STORAGE_KEY, token);
+
+        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)));
+    }
+}