"""User-related business logic."""
from __future__ import annotations

from collections.abc import Sequence

from app.core.security import PasswordHasher
from app.models.user import User, UserCreate
from app.repositories.user_repo import UserRepository


class UserServiceError(Exception):
    """Base class for user service errors."""


class UserAlreadyExistsError(UserServiceError):
    """Raised when attempting to create a user with duplicate email."""


class UserNotFoundError(UserServiceError):
    """Raised when user record cannot be located."""


class UserService:
    """Encapsulates user-related workflows."""

    def __init__(self, user_repository: UserRepository, password_hasher: PasswordHasher) -> None:
        self._repository = user_repository
        self._password_hasher = password_hasher

    async def list_users(self) -> Sequence[User]:
        return await self._repository.list()

    async def get_user(self, user_id: int) -> User:
        user = await self._repository.get_by_id(user_id)
        if user is None:
            raise UserNotFoundError(f"User {user_id} not found")
        return user

    async def create_user(self, data: UserCreate) -> User:
        existing = await self._repository.get_by_email(data.email)
        if existing is not None:
            raise UserAlreadyExistsError(f"User {data.email} already exists")

        hashed_password = self._password_hasher.hash(data.password)
        user = await self._repository.create(data=data, hashed_password=hashed_password)
        await self._repository.session.commit()
        await self._repository.session.refresh(user)
        return user