1 files changed, 27 insertions, 2 deletions
diff --git a/BackEnd/Timeline/Services/User/IUserService.cs b/BackEnd/Timeline/Services/User/IUserService.cs
index 745bd524..6ea9a4d2 100644
--- a/BackEnd/Timeline/Services/User/IUserService.cs
+++ b/BackEnd/Timeline/Services/User/IUserService.cs
@@ -5,8 +5,33 @@ using Timeline.Entities;
 
 namespace Timeline.Services.User
 {
-    public interface IUserService : IBasicUserService
-    {
+    public interface IUserService
+    {
+        /// <summary>
+        /// Check if a user exists.
+        /// </summary>
+        /// <param name="id">The id of the user.</param>
+        /// <returns>True if exists. Otherwise false.</returns>
+        Task<bool> CheckUserExistenceAsync(long id);
+
+        /// <summary>
+        /// Get the user id of given username.
+        /// </summary>
+        /// <param name="username">Username of the user.</param>
+        /// <returns>The id of the user.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="username"/> is null.</exception>
+        /// <exception cref="ArgumentException">Thrown when <paramref name="username"/> is of bad format.</exception>
+        /// <exception cref="EntityNotExistException">Thrown when the user with given username does not exist.</exception>
+        Task<long> GetUserIdByUsernameAsync(string username);
+
+        /// <summary>
+        /// Get the username modified time of a user.
+        /// </summary>
+        /// <param name="userId">User id.</param>
+        /// <returns>The time.</returns>
+        /// <exception cref="EntityNotExistException">Thrown when user does not exist.</exception>
+        Task<DateTime> GetUsernameLastModifiedTimeAsync(long userId);
+
         /// <summary>
         /// Try to get a user by id.
         /// </summary>