"""Registries for filter pipeline stages and plugins."""

import importlib
import logging
from typing import Any, Dict, Iterable, Optional, Type

logger = logging.getLogger(__name__)

_STAGE_REGISTRY: Dict[str, Type[Any]] = {}
_PLUGIN_REGISTRY: Dict[str, Type[Any]] = {}
_DISCOVERED_MODULES = set()


def register_stage(name: str):
    """Register a pipeline stage class under a config name."""
    def decorator(stage_cls: Type[Any]):
        if name in _STAGE_REGISTRY and _STAGE_REGISTRY[name] is not stage_cls:
            logger.warning("Replacing registered filter stage '%s'", name)
        _STAGE_REGISTRY[name] = stage_cls
        return stage_cls

    return decorator


def register_plugin(name: str):
    """Register a filter plugin class under a config name."""
    def decorator(plugin_cls: Type[Any]):
        if name in _PLUGIN_REGISTRY and _PLUGIN_REGISTRY[name] is not plugin_cls:
            logger.warning("Replacing registered filter plugin '%s'", name)
        _PLUGIN_REGISTRY[name] = plugin_cls
        return plugin_cls

    return decorator


def get_stage_class(name: str) -> Optional[Type[Any]]:
    """Return a registered stage class by name."""
    return _STAGE_REGISTRY.get(name)


def get_plugin_class(name: str) -> Optional[Type[Any]]:
    """Return a registered plugin class by name."""
    return _PLUGIN_REGISTRY.get(name)


def get_registered_stages() -> Dict[str, Type[Any]]:
    """Return a copy of registered stage classes."""
    return dict(_STAGE_REGISTRY)


def get_registered_plugins() -> Dict[str, Type[Any]]:
    """Return a copy of registered plugin classes."""
    return dict(_PLUGIN_REGISTRY)


def discover_modules(module_names: Iterable[str]):
    """Import modules for registration side effects once."""
    for module_name in module_names:
        if not module_name or module_name in _DISCOVERED_MODULES:
            continue
        importlib.import_module(module_name)
        _DISCOVERED_MODULES.add(module_name)