import os

from .base import LLMError, LLMProvider
from .openai_provider import OpenAIProvider
from .deepseek_provider import DeepSeekProvider


class LLMFactory:
    """LLM Provider工厂 - 统一创建和管理Provider实例"""

    _providers: dict[str, type[LLMProvider]] = {}

    @classmethod
    def register(cls, name: str, provider_cls: type[LLMProvider]) -> None:
        """
        注册Provider类

        Args:
            name: Provider名称（如 "openai", "deepseek"）
            provider_cls: LLMProvider子类
        """
        cls._providers[name.lower()] = provider_cls

    @classmethod
    def create(cls, provider: str | None = None, model: str | None = None) -> LLMProvider:
        """
        创建LLM Provider实例

        Args:
            provider: 提供商名称，如 "openai" | "deepseek"
                      为None时从环境变量 DEFAULT_LLM_PROVIDER 读取，默认 "openai"
            model: 覆盖默认模型名

        Returns:
            LLMProvider实例

        Raises:
            LLMError: provider未注册时
        """
        provider_name = (provider or os.getenv("DEFAULT_LLM_PROVIDER", "openai")).lower()

        if provider_name not in cls._providers:
            available = ", ".join(cls._providers.keys()) or "(无)"
            raise LLMError(
                f"未注册的Provider: {provider_name}，可用: {available}",
                provider="factory",
            )

        provider_cls = cls._providers[provider_name]
        return provider_cls(model=model) if model else provider_cls()

    @classmethod
    def get_default(cls) -> LLMProvider:
        """获取默认provider（等价于 create()）"""
        return cls.create()

    @classmethod
    def list_providers(cls) -> list[str]:
        """列出所有已注册的Provider名称"""
        return list(cls._providers.keys())


# ---- 自动注册内置Provider ----
LLMFactory.register("openai", OpenAIProvider)
LLMFactory.register("deepseek", DeepSeekProvider)