refactor: move core files into separate dirs

server/core/auth.py

@@ -0,0 +1,48 @@
+from server.db.database import PostgresConnector
+from flask_bcrypt import Bcrypt
+
+class AuthManager:
+    def __init__(self, db: PostgresConnector, bcrypt: Bcrypt):
+        self.db = db
+        self.bcrypt = bcrypt
+
+    # private
+    def _save_user(self, username, email, password_hash):
+        query = """
+            INSERT INTO users (username, email, password_hash)
+            VALUES (%s, %s, %s)
+        """
+        self.db.execute(query, (username, email, password_hash))
+
+    # public
+    def register_user(self, username, email, password):
+        hashed_password = self.bcrypt.generate_password_hash(password).decode("utf-8")
+
+        if self.get_user_by_email(email):
+            raise ValueError("Email already registered")
+        
+        if self.get_user_by_username(username):
+            raise ValueError("Username already taken")
+
+        self._save_user(username, email, hashed_password)
+
+    def authenticate_user(self, username, password):
+        user = self.get_user_by_username(username)
+        if user and self.bcrypt.check_password_hash(user['password_hash'], password):
+            return user
+        return None
+    
+    def get_user_by_id(self, user_id):
+        query = "SELECT id, username, email FROM users WHERE id = %s"
+        result = self.db.execute(query, (user_id,), fetch=True)
+        return result[0] if result else None
+    
+    def get_user_by_username(self, username) -> dict:
+        query = "SELECT id, username, email, password_hash FROM users WHERE username = %s"
+        result = self.db.execute(query, (username,), fetch=True)
+        return result[0] if result else None
+    
+    def get_user_by_email(self, email) -> dict:
+        query = "SELECT id, username, email, password_hash FROM users WHERE email = %s"
+        result = self.db.execute(query, (email,), fetch=True)
+        return result[0] if result else None