"""Model registry for tkmlr.

New backends can be added without editing the factory by decorating a builder:

    @register_model("my_model")
    def build_my_model(**params):
        return MyRegressor(**params)
"""
from __future__ import annotations

from typing import Callable, Dict, Iterable

from .base import BaseRegressor

ModelBuilder = Callable[..., BaseRegressor]
_MODEL_REGISTRY: Dict[str, ModelBuilder] = {}


def register_model(name: str):
    def decorator(func: ModelBuilder) -> ModelBuilder:
        _MODEL_REGISTRY[name.lower()] = func
        return func

    return decorator


def create_model(name: str, **params) -> BaseRegressor:
    key = name.lower()
    if key not in _MODEL_REGISTRY:
        known = ", ".join(sorted(_MODEL_REGISTRY))
        raise ValueError(f"Unknown model '{name}'. Registered models: {known}")
    return _MODEL_REGISTRY[key](**params)


def registered_models() -> Iterable[str]:
    return sorted(_MODEL_REGISTRY)