fix: Don't allow user to create account with existing domain

accounts.py

@@ -53,6 +53,9 @@ def create_user(email, domain, password):
     # Check if user exists
     if db.search_users(email) != []:
         return {'success': False, 'message': 'User already exists'}
+    
+    if db.search_users_domain(domain) != []:
+        return {'success': False, 'message': 'Domain already exists'}
 
     db.add_user(email, domain, hashed_password, token)
     return {'success': True, 'message': 'User created', 'token': token}

db.py

@@ -64,6 +64,17 @@ def search_users(email):
     connection.close()
     return users
 
+def search_users_domain(domain):
+    connection = mysql.connector.connect(**dbargs)
+    cursor = connection.cursor()
+    cursor.execute("""
+        SELECT * FROM users WHERE domain = %s
+    """, (domain,))
+    users = cursor.fetchall()
+    cursor.close()
+    connection.close()
+    return users
+
 def search_users_token(token):
     connection = mysql.connector.connect(**dbargs)
     cursor = connection.cursor()