Implement password recovery feature with reset token and email notifications

FoodsharingSiegen.Server/Auth/AuthService.cs

@@ -50,6 +50,11 @@ namespace FoodsharingSiegen.Server.Auth
         /// </summary>
         private User? _user;
 
+        /// <summary>
+        /// The mail service
+        /// </summary>
+        private readonly IMailService _mailService;
+
         #endregion
 
         #region Setup/Teardown
@@ -60,14 +65,17 @@ namespace FoodsharingSiegen.Server.Auth
         /// <param name="context">The context</param>
         /// <param name="localStorageService">The local storage service</param>
         /// <param name="authenticationStateProvider">The authentication state provider</param>
+        /// <param name="mailService">The mail service</param>
         public AuthService(
             FsContext context,
             LocalStorageService localStorageService,
-            AuthenticationStateProvider authenticationStateProvider)
+            AuthenticationStateProvider authenticationStateProvider,
+            IMailService mailService)
         {
             Context = context;
             _localStorageService = localStorageService;
             _authenticationStateProvider = authenticationStateProvider;
+            _mailService = mailService;
         }
 
         #endregion
@@ -186,5 +194,52 @@ namespace FoodsharingSiegen.Server.Auth
         }
 
         #endregion
+
+        #region Password Recovery
+
+        public async Task InitiatePasswordReset(string email, string baseUri)
+        {
+            if (string.IsNullOrWhiteSpace(email)) return;
+
+            var user = await Context.Users!.FirstOrDefaultAsync(x => x.Mail.ToLower() == email.ToLower());
+            if (user == null) return; // Do not leak existence
+
+            var resetToken = Guid.NewGuid().ToString("N");
+            user.ResetToken = resetToken;
+            user.ResetTokenExpiry = DateTime.UtcNow.AddMinutes(30);
+
+            await Context.SaveChangesAsync();
+
+            var resetLink = $"{baseUri.TrimEnd('/')}/reset-password/{resetToken}";
+            var mailBody = $"Hallo {user.Name},<br><br>Um dein Passwort zurückzusetzen, klicke bitte auf den folgenden Link (dieser ist 30 Minuten gültig):<br><a href='{resetLink}'>{resetLink}</a><br><br>Viele Grüße<br>Dein Foodsharing Team";
+
+            await _mailService.SendEmailAsync(user.Mail, "Passwort zurücksetzen", mailBody);
+        }
+
+        public async Task<OperationResult> ResetPassword(string token, string newPassword)
+        {
+            if (string.IsNullOrWhiteSpace(token)) return new OperationResult(new Exception("Ungültiges Token."));
+            if (string.IsNullOrWhiteSpace(newPassword)) return new OperationResult(new Exception("Passwort darf nicht leer sein."));
+
+            var user = await Context.Users!.FirstOrDefaultAsync(x => x.ResetToken == token && x.ResetTokenExpiry > DateTime.UtcNow);
+            if (user == null) return new OperationResult(new Exception("Token ist ungültig oder abgelaufen."));
+
+            user.Password = newPassword;
+            user.ResetToken = null;
+            user.ResetTokenExpiry = null;
+
+            await Context.SaveChangesAsync();
+
+            return new OperationResult();
+        }
+
+        public async Task<bool> IsResetTokenValid(string token)
+        {
+            if (string.IsNullOrWhiteSpace(token)) return false;
+            var user = await Context.Users!.FirstOrDefaultAsync(x => x.ResetToken == token && x.ResetTokenExpiry > DateTime.UtcNow);
+            return user != null;
+        }
+
+        #endregion
     }
 }