"""Algorithm interface and registry for password hashing."""

from __future__ import annotations

from typing import Protocol


class Algorithm(Protocol):
    """Protocol defining the interface for password hashing algorithms."""

    identifier: str

    def hash(self, password: str, **kwargs) -> tuple[str, str]:
        """Hash a password and return (salt_b64, hash_b64)."""
        ...

    def verify(self, password: str, salt_b64: str, hash_b64: str, **kwargs) -> bool:
        """Verify a password against stored salt and hash."""
        ...


# Algorithm registry
_ALGORITHMS: dict[str, Algorithm] = {}


def register_algorithm(algo: Algorithm) -> None:
    """Register an algorithm in the global registry."""
    _ALGORITHMS[algo.identifier] = algo


def get_algorithm(name: str) -> Algorithm:
    """Get an algorithm by name from the registry."""
    if name not in _ALGORITHMS:
        raise ValueError(f"Unknown algorithm: {name}")
    return _ALGORITHMS[name]


def list_algorithms() -> list[str]:
    """Return list of registered algorithm identifiers."""
    return sorted(_ALGORITHMS.keys())


# Import to auto-register algorithms
import pbkdf2_algorithm  # noqa: E402, F401