"""Registry that auto-discovers mutation rules from the rules directory."""

import importlib
import inspect
from pathlib import Path
from typing import Dict, List, Type

from app.dataset.rules.base import MutationRule


class RuleRegistry:
    def __init__(self, rules_dir: Path):
        self.rules_dir = rules_dir
        self._rules: Dict[str, List[MutationRule]] = {}

    def discover(self) -> None:
        """Scan rules directory and register all MutationRule subclasses."""
        self._rules.clear()
        for lang_dir in self.rules_dir.iterdir():
            if not lang_dir.is_dir():
                continue
            for py_file in lang_dir.glob("*.py"):
                if py_file.name.startswith("_"):
                    continue
                module_name = f"app.dataset.rules.{lang_dir.name}.{py_file.stem}"
                try:
                    module = importlib.import_module(module_name)
                except Exception:
                    continue
                for _, obj in inspect.getmembers(module, inspect.isclass):
                    if (
                        issubclass(obj, MutationRule)
                        and obj is not MutationRule
                        and not getattr(obj, "__abstractmethods__", False)
                    ):
                        rule = obj()
                        self._rules.setdefault(rule.language, []).append(rule)

    def rules_for(self, language: str) -> List[MutationRule]:
        return self._rules.get(language, [])

    def all_rules(self) -> Dict[str, List[MutationRule]]:
        return self._rules.copy()


def get_registry() -> RuleRegistry:
    registry = RuleRegistry(Path(__file__).parent)
    registry.discover()
    return registry