Add username availability check and fix cursor initialization in user.py; update token validation in api_security.py

auth/user.py

@@ -3,7 +3,7 @@ import db
 from dotenv import load_dotenv
 import logging
 import os
-
+import mariadb
 #Logging
 
 logging.basicConfig(
@@ -29,7 +29,7 @@ if db_host == None:
     os._exit(1)
 
 db.connect(db_user, db_psswd, db_host, int(db_port), db_name)
-
+cursor = db.connection.cursor()
 
 def create_user(username, password):
     user = username
@@ -67,3 +67,14 @@ def delete_user(username, password):
             logging.info(f"User {username} was successfully deleted")
         except Exception as e:
             logging.error(e)
+
+def check_username(username):
+    try:
+        cursor.execute("SELECT 1 FROM user WHERE username = ?", (username,))
+        exists = cursor.fetchone() is not None
+        return exists  # True if taken, False if available
+    except db.IntegrityError as e:
+        if e.errno == 1062:
+            logging.error("Username taken")
+            return True #If the username is not available it returns True
+