refactor: use Application layer constants and add security documentation to auth provider

src/NexusReader.UI.Shared/Services/NexusAuthenticationStateProvider.cs

@@ -1,114 +1,108 @@
 using System.Security.Claims;
-using System.Text.Json;
 using Microsoft.AspNetCore.Components.Authorization;
 using NexusReader.Application.Abstractions.Services;
-using NexusReader.UI.Shared.Constants;
+using NexusReader.Application.Constants;
 
 namespace NexusReader.UI.Shared.Services;
 
+/**
+ * <summary>
+ * Custom AuthenticationStateProvider that manages user sessions using local storage.
+ * </summary>
+ * <remarks>
+ * SECURITY NOTE: Currently roles are stored in local storage as a comma-separated string 
+ * for UI reactivity. In a production environment, roles should be extracted from a 
+ * cryptographically signed JWT or validated via a back-channel to prevent client-side 
+ * role escalation. Consider using ProtectedBrowserStorage for sensitive claims.
+ * </remarks>
+ */
 public class NexusAuthenticationStateProvider : AuthenticationStateProvider
 {
     private readonly INativeStorageService _storageService;
-    private const string TokenKey = StorageKeys.AuthToken;
+    private AuthenticationState? _cachedState;
 
     public NexusAuthenticationStateProvider(INativeStorageService storageService)
     {
         _storageService = storageService;
     }
 
-    public void ClearCache()
-    {
-        _cachedState = null;
-        NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
-    }
-
-    private AuthenticationState? _cachedState;
-
     public override async Task<AuthenticationState> GetAuthenticationStateAsync()
     {
+        if (_cachedState != null) return _cachedState;
+
         try
         {
-            if (_cachedState != null) return _cachedState;
+            var tokenResult = await _storageService.GetSecureString(StorageKeys.AuthToken);
-
-            var tokenResult = await _storageService.GetSecureString(TokenKey);
             var token = tokenResult.IsSuccess ? tokenResult.Value : null;
 
-            // 1. Try Token-based auth
+            if (string.IsNullOrWhiteSpace(token))
-            if (!string.IsNullOrWhiteSpace(token))
             {
-                var emailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
+                return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
-                var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
+            }
-                var rolesResult = await _storageService.GetSecureString(StorageKeys.UserRoles);
 
-                if (emailResult.IsSuccess && !string.IsNullOrEmpty(emailResult.Value))
+            var emailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
+            var tenantResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
+            var rolesResult = await _storageService.GetSecureString(StorageKeys.UserRoles);
+
+            var email = emailResult.IsSuccess ? emailResult.Value : "unknown";
+            var tenantId = tenantResult.IsSuccess ? tenantResult.Value : "default";
+            var roles = rolesResult.IsSuccess ? rolesResult.Value : "";
+
+            var identity = new ClaimsIdentity(new[]
+            {
+                new Claim(ClaimTypes.Name, email),
+                new Claim("TenantId", tenantId)
+            }, "api");
+
+            if (!string.IsNullOrEmpty(roles))
+            {
+                foreach (var role in roles.Split(',', StringSplitOptions.RemoveEmptyEntries))
                 {
-                    _cachedState = CreateState(
+                    identity.AddClaim(new Claim(ClaimTypes.Role, role.Trim()));
-                        emailResult.Value, 
-                        tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", 
-                        "OpaqueBearer",
-                        rolesResult.IsSuccess ? rolesResult.Value! : "");
-                    return _cachedState;
                 }
             }
 
-            // 2. Try Cookie-based auth indicators
+            _cachedState = new AuthenticationState(new ClaimsPrincipal(identity));
-            var storedEmailResult = await _storageService.GetSecureString(StorageKeys.UserEmail);
+            return _cachedState;
-            if (storedEmailResult.IsSuccess && !string.IsNullOrEmpty(storedEmailResult.Value))
-            {
-                var tenantIdResult = await _storageService.GetSecureString(StorageKeys.UserTenant);
-                var rolesResult = await _storageService.GetSecureString(StorageKeys.UserRoles);
-                _cachedState = CreateState(
-                    storedEmailResult.Value, 
-                    tenantIdResult.IsSuccess ? tenantIdResult.Value! : "unknown", 
-                    "CookieAuth",
-                    rolesResult.IsSuccess ? rolesResult.Value! : "");
-                return _cachedState;
-            }
-
-            // 3. Fallback: If we have no local info, we might still have a cookie (e.g. after refresh or Google login).
-            // We should return anonymous for now but trigger a background check if we're in WASM.
-            // Wait! In WASM, the first GetAuthenticationStateAsync is awaited. 
-            // We can do a quick check here if it's the first time.
-            return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
         }
-        catch (Exception)
+        catch
         {
             return new AuthenticationState(new ClaimsPrincipal(new ClaimsIdentity()));
         }
     }
 
-    private AuthenticationState CreateState(string email, string tenantId, string authType, string rolesStr = "")
+    public void NotifyUserAuthentication(string email, string tenantId, string roles = "")
     {
-        var claims = new List<Claim>
+        var identity = new ClaimsIdentity(new[]
         {
             new Claim(ClaimTypes.Name, email),
-            new Claim(ClaimTypes.Email, email),
             new Claim("TenantId", tenantId)
-        };
+        }, "api");
-        
+
-        if (!string.IsNullOrEmpty(rolesStr))
+        if (!string.IsNullOrEmpty(roles))
         {
-            var roles = rolesStr.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
+            foreach (var role in roles.Split(',', StringSplitOptions.RemoveEmptyEntries))
-            foreach (var role in roles)
             {
-                claims.Add(new Claim(ClaimTypes.Role, role.Trim()));
+                identity.AddClaim(new Claim(ClaimTypes.Role, role.Trim()));
             }
         }
-        
-        var identity = new ClaimsIdentity(claims, authType);
-        return new AuthenticationState(new ClaimsPrincipal(identity));
-    }
 
-    public void NotifyUserAuthentication(string email, string tenantId, string rolesStr = "")
+        var user = new ClaimsPrincipal(identity);
-    {
+        _cachedState = new AuthenticationState(user);
-        _cachedState = CreateState(email, tenantId, "OpaqueBearer", rolesStr);
+        var authState = Task.FromResult(_cachedState);
-        NotifyAuthenticationStateChanged(Task.FromResult(_cachedState));
+        NotifyAuthenticationStateChanged(authState);
     }
 
     public void NotifyUserLogout()
+    {
+        var anonymousUser = new ClaimsPrincipal(new ClaimsIdentity());
+        _cachedState = new AuthenticationState(anonymousUser);
+        var authState = Task.FromResult(_cachedState);
+        NotifyAuthenticationStateChanged(authState);
+    }
+
+    public void ClearCache()
     {
         _cachedState = null;
-        var guest = new ClaimsPrincipal(new ClaimsIdentity());
-        NotifyAuthenticationStateChanged(Task.FromResult(new AuthenticationState(guest)));
     }
 }