from typing import List, Optional
from app.models.user import User
from app.schemas.user import UserCreate, UserUpdate

fake_users_db = [
    User(id=1, username="admin", email="admin@example.com", full_name="Admin User"),
    User(id=2, username="john", email="john@example.com", full_name="John Doe"),
    User(id=3, username="jane", email="jane@example.com", full_name="Jane Smith"),
]

class UserService:
    @staticmethod
    def get_all_users() -> List[User]:
        return fake_users_db

    @staticmethod
    def get_user_by_id(user_id: int) -> Optional[User]:
        for user in fake_users_db:
            if user.id == user_id:
                return user
        return None

    @staticmethod
    def create_user(user_data: UserCreate) -> User:
        new_id = max([u.id for u in fake_users_db]) + 1 if fake_users_db else 1
        new_user = User(
            id=new_id,
            username=user_data.username,
            email=user_data.email,
            full_name=user_data.full_name
        )
        fake_users_db.append(new_user)
        return new_user

    @staticmethod
    def update_user(user_id: int, user_data: UserUpdate) -> Optional[User]:
        for i, user in enumerate(fake_users_db):
            if user.id == user_id:
                update_data = user_data.model_dump(exclude_unset=True)
                for field, value in update_data.items():
                    setattr(user, field, value)
                return user
        return None

user_service = UserService()