update: DB manipulation interfaces

app/database/user.py

@@ -106,3 +106,57 @@ def create_user(self, username, password):
         except Exception as e:
             print(f"[ERROR] {FILE_NAME}: create_user: {e}")
             return False
+
+    def remove_user(self, username):
+        """
+        Removes a user record from the database by username.
+        Args:
+            username (str): The username of the user to remove.
+        Returns:
+            bool: True if the user was removed successfully, False otherwise.
+        Raises:
+            Exception: If there is an error executing the database query.
+        """
+        query = f"DELETE FROM {self.table_user} WHERE userid = ?;"
+
+        if DEBUG_MODE:
+            print(f"[DEBUG] {FILE_NAME}: remove_user: {query} with username: {username}")
+
+        try:
+            self.cursor.execute(query, (username,))
+            self.connection.commit()
+            return True
+
+        except Exception as e:
+            print(f"[ERROR] {FILE_NAME}: remove_user: {e}")
+            return False
+
+    def remove_invalid_user(self):
+        """
+        Removes invalid user records from the database.
+        This method is a placeholder for future implementation.
+        """
+        query = f"DELETE FROM {self.table_user} WHERE userid IS NULL OR trim(userid) = '';"
+
+        try:
+            self.cursor.execute(query)
+            self.connection.commit()
+            return True
+        except Exception as e:
+            print(f"[ERROR] {FILE_NAME}: remove_invalid_user: {e}")
+            return False
+
+    def remove_all(self):
+        """
+        Removes all user records from the database.
+        This method is a placeholder for future implementation.
+        """
+        query = f"DELETE FROM {self.table_user};"
+
+        try:
+            self.cursor.execute(query)
+            self.connection.commit()
+            return True
+        except Exception as e:
+            print(f"[ERROR] {FILE_NAME}: remove_all: {e}")
+            return False