from typing import Any, Dict, List, Optional, Union

from sqlalchemy.orm import Session

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


def get_by_id(db: Session, user_id: str) -> Optional[User]:
    """
    Get a user by ID.
    
    Args:
        db: Database session
        user_id: User ID
        
    Returns:
        Optional[User]: User if found, None otherwise
    """
    return db.query(User).filter(User.id == user_id).first()


def get_by_email(db: Session, email: str) -> Optional[User]:
    """
    Get a user by email.
    
    Args:
        db: Database session
        email: User email
        
    Returns:
        Optional[User]: User if found, None otherwise
    """
    return db.query(User).filter(User.email == email).first()


def get_by_username(db: Session, username: str) -> Optional[User]:
    """
    Get a user by username.
    
    Args:
        db: Database session
        username: Username
        
    Returns:
        Optional[User]: User if found, None otherwise
    """
    return db.query(User).filter(User.username == username).first()


def get_all(db: Session, skip: int = 0, limit: int = 100) -> List[User]:
    """
    Get all users.
    
    Args:
        db: Database session
        skip: Number of users to skip
        limit: Maximum number of users to return
        
    Returns:
        List[User]: List of users
    """
    return db.query(User).offset(skip).limit(limit).all()


def create(db: Session, *, obj_in: UserCreate) -> User:
    """
    Create a new user.
    
    Args:
        db: Database session
        obj_in: User creation data
        
    Returns:
        User: Created user
    """
    db_obj = User(
        email=obj_in.email,
        username=obj_in.username,
        hashed_password=get_password_hash(obj_in.password),
        full_name=obj_in.full_name,
        role=obj_in.role,
        is_active=True,
    )
    db.add(db_obj)
    db.commit()
    db.refresh(db_obj)
    return db_obj


def update(
    db: Session, *, db_obj: User, obj_in: Union[UserUpdate, Dict[str, Any]]
) -> User:
    """
    Update a user.
    
    Args:
        db: Database session
        db_obj: User to update
        obj_in: User update data
        
    Returns:
        User: Updated user
    """
    if isinstance(obj_in, dict):
        update_data = obj_in
    else:
        update_data = obj_in.model_dump(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 in update_data:
        if hasattr(db_obj, field):
            setattr(db_obj, field, update_data[field])
            
    db.add(db_obj)
    db.commit()
    db.refresh(db_obj)
    return db_obj


def delete(db: Session, *, user_id: str) -> User:
    """
    Delete a user.
    
    Args:
        db: Database session
        user_id: User ID
        
    Returns:
        User: Deleted user
    """
    user = db.query(User).filter(User.id == user_id).first()
    db.delete(user)
    db.commit()
    return user


def authenticate(db: Session, *, email: str, password: str) -> Optional[User]:
    """
    Authenticate a user.
    
    Args:
        db: Database session
        email: User email
        password: User password
        
    Returns:
        Optional[User]: User if authentication successful, None otherwise
    """
    user = get_by_email(db, email=email)
    if not user:
        return None
    if not verify_password(password, user.hashed_password):
        return None
    return user


def is_active(user: User) -> bool:
    """
    Check if a user is active.
    
    Args:
        user: User to check
        
    Returns:
        bool: True if the user is active
    """
    return user.is_active


def is_admin(user: User) -> bool:
    """
    Check if a user is an admin.
    
    Args:
        user: User to check
        
    Returns:
        bool: True if the user is an admin
    """
    return user.role == UserRole.ADMIN