from passlib.context import CryptContext
from sqlmodel import Session, select
from typing import Optional

from models.user import User, UserCreate
from models.db import get_session_context # Using context manager for direct use
from services.logger import app_logger

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)

def get_user(db: Session, username: str) -> Optional[User]:
    statement = select(User).where(User.username == username)
    user = db.exec(statement).first()
    return user

def create_user_in_db(user_data: UserCreate) -> Optional[User]:
    hashed_password = get_password_hash(user_data.password)
    db_user = User(
        username=user_data.username,
        hashed_password=hashed_password,
        email=user_data.email,
        full_name=user_data.full_name
    )
    try:
        with get_session_context() as db:
            # Check if user already exists
            existing_user = get_user(db, user_data.username)
            if existing_user:
                app_logger.warning(f"User {user_data.username} already exists.")
                return None # Or raise an exception
            
            db.add(db_user)
            db.commit() # Commit is handled by context manager, but explicit commit for return
            db.refresh(db_user)
        return db_user
    except Exception as e:
        app_logger.error(f"Error creating user {user_data.username}: {e}")
        return None

def authenticate_user(username: str, password: str) -> Optional[User]:
    with get_session_context() as db:
        user = get_user(db, username)
        if not user:
            return None
        if not verify_password(password, user.hashed_password):
            return None
        return user