import json
from pathlib import Path


class AccountManager:
    """
    Класс для управления учётными записями пользователей.
    """

    def __init__(self, db_file: str | None):
        self.db_file = Path(db_file) if db_file else None
        if isinstance(self.db_file, Path) and not self.db_file.exists():
            self._save_db({})

    def set_db_file(self, db_file: str | None) -> None:
        self.db_file = Path(db_file) if db_file else None
        if isinstance(self.db_file, Path) and not self.db_file.exists():
            self._save_db({})

    def _load_db(self) -> dict:
        if not isinstance(self.db_file, Path):
            return {}
        if self.db_file.exists():
            return json.loads(self.db_file.read_text(encoding="utf-8"))
        return {}

    def _save_db(self, data: dict) -> None:
        if not isinstance(self.db_file, Path):
            raise RuntimeError("База данных не открыта")
        self.db_file.write_text(json.dumps(
            data, indent=2, ensure_ascii=False), encoding="utf-8")

    def add_user(self, username: str, password_hash: str, salt: str) -> None:
        data = self._load_db()
        data[username] = {"hash": password_hash, "salt": salt}
        self._save_db(data)

    def update_user(self, username: str, password_hash: str, salt: str) -> bool:
        data = self._load_db()
        if username not in data:
            return False
        data[username] = {"hash": password_hash, "salt": salt}
        self._save_db(data)
        return True

    def delete_user(self, username: str) -> bool:
        data = self._load_db()
        if username not in data:
            return False
        del data[username]
        self._save_db(data)
        return True

    def get_user(self, username: str) -> dict | None:
        data = self._load_db()
        return data.get(username)

    def list_users(self) -> list[str]:
        if not isinstance(self.db_file, Path):
            return []
        data = self._load_db()
        return list(data.keys())