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

from sqlalchemy import select
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

# For type hints
if TYPE_CHECKING:
    pass


async def get_by_id(db: Session, user_id: str) -> Optional[User]:
    """
    Get a user by ID.
    """
    # Check if db has execute method (AsyncSession)
    if hasattr(db, "execute"):
        result = await db.execute(select(User).filter(User.id == user_id))
        return result.scalars().first()
    # Synchronous operation
    return db.query(User).filter(User.id == user_id).first()


async def get_by_email(db: Session, email: str) -> Optional[User]:
    """
    Get a user by email.
    """
    # Check if db has execute method (AsyncSession)
    if hasattr(db, "execute"):
        result = await db.execute(select(User).filter(User.email == email))
        return result.scalars().first()
    # Synchronous operation
    return db.query(User).filter(User.email == email).first()


async def get_users(db: Session, skip: int = 0, limit: int = 100) -> List[User]:
    """
    Get a list of users with pagination.
    """
    # Check if db has execute method (AsyncSession)
    if hasattr(db, "execute"):
        result = await db.execute(select(User).offset(skip).limit(limit))
        return result.scalars().all()
    # Synchronous operation
    return db.query(User).offset(skip).limit(limit).all()


async def create(db: Session, *, obj_in: UserCreate) -> User:
    """
    Create a new user.
    """
    db_obj = User(
        email=obj_in.email,
        hashed_password=get_password_hash(obj_in.password),
        full_name=obj_in.full_name,
        is_active=True,
        is_superuser=False,
        email_verified=False,
    )
    db.add(db_obj)

    # Check if db has commit method that's a coroutine
    if (
        hasattr(db, "commit")
        and callable(db.commit)
        and hasattr(db.commit, "__await__")
    ):
        await db.commit()
        await db.refresh(db_obj)
    else:
        # Synchronous operation
        db.commit()
        db.refresh(db_obj)

    return db_obj


async def update(
    db: Session, *, db_obj: User, obj_in: Union[UserUpdate, Dict[str, Any]]
) -> User:
    """
    Update a user.
    """
    if isinstance(obj_in, dict):
        update_data = obj_in
    else:
        update_data = obj_in.model_dump(exclude_unset=True)

    if "password" in update_data and update_data["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)

    # Check if db has commit method that's a coroutine
    if (
        hasattr(db, "commit")
        and callable(db.commit)
        and hasattr(db.commit, "__await__")
    ):
        await db.commit()
        await db.refresh(db_obj)
    else:
        # Synchronous operation
        db.commit()
        db.refresh(db_obj)

    return db_obj


async def remove(db: Session, *, id: str) -> Optional[User]:
    """
    Delete a user.
    """
    user = await get_by_id(db, id)
    if user:
        if (
            hasattr(db, "delete")
            and callable(db.delete)
            and hasattr(db.delete, "__await__")
        ):
            await db.delete(user)
            await db.commit()
        else:
            # Synchronous operation
            db.delete(user)
            db.commit()
    return user


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


async def update_last_login(db: Session, *, user: User) -> User:
    """
    Update the last login timestamp for a user.
    """
    user.last_login = datetime.utcnow()
    db.add(user)

    # Check if db has commit method that's a coroutine
    if (
        hasattr(db, "commit")
        and callable(db.commit)
        and hasattr(db.commit, "__await__")
    ):
        await db.commit()
        await db.refresh(user)
    else:
        # Synchronous operation
        db.commit()
        db.refresh(user)

    return user