from typing import Optional

from sqlalchemy.orm import Session

from app.core.security import get_password_hash, verify_password
from app.models.user import User
from app.schemas.user import UserCreate, UserUpdate


def get_user(db: Session, user_id: int) -> Optional[User]:
    """
    Get a user by ID
    """
    return db.query(User).filter(User.id == user_id).first()


def get_user_by_email(db: Session, email: str) -> Optional[User]:
    """
    Get a user by email
    """
    return db.query(User).filter(User.email == email).first()


def get_user_by_username(db: Session, username: str) -> Optional[User]:
    """
    Get a user by username
    """
    return db.query(User).filter(User.username == username).first()


def get_users(db: Session, skip: int = 0, limit: int = 100):
    """
    Get multiple users with pagination
    """
    return db.query(User).offset(skip).limit(limit).all()


def create_user(db: Session, user_in: UserCreate) -> User:
    """
    Create a new user
    """
    db_user = User(
        email=user_in.email,
        username=user_in.username,
        hashed_password=get_password_hash(user_in.password),
        is_active=True,
    )
    db.add(db_user)
    db.commit()
    db.refresh(db_user)
    return db_user


def update_user(db: Session, user_id: int, user_in: UserUpdate) -> Optional[User]:
    """
    Update a user
    """
    db_user = get_user(db, user_id)
    if not db_user:
        return None

    update_data = user_in.dict(exclude_unset=True)
    if update_data.get("password"):
        hashed_password = get_password_hash(update_data["password"])
        del update_data["password"]
        update_data["hashed_password"] = hashed_password

    for field, value in update_data.items():
        setattr(db_user, field, value)

    db.add(db_user)
    db.commit()
    db.refresh(db_user)
    return db_user


def delete_user(db: Session, user_id: int) -> Optional[User]:
    """
    Delete a user
    """
    db_user = get_user(db, user_id)
    if not db_user:
        return None

    db.delete(db_user)
    db.commit()
    return db_user


def authenticate_user(db: Session, email: str, password: str) -> Optional[User]:
    """
    Authenticate a user by email and password
    """
    user = get_user_by_email(db, email=email)
    if not user:
        return None
    if not verify_password(password, user.hashed_password):
        return None
    return user