"""LLM Provider 工厂：按配置创建 provider，并执行数据零出域红线校验。"""

from __future__ import annotations

from app.config import EGRESS_PROVIDERS, LLMProviderName, Settings, get_settings
from app.llm.base import LLMProvider
from app.llm.providers import DashScopeProvider, MockProvider, VllmProvider


class EgressPolicyError(RuntimeError):
    """数据零出域红线违规。"""


def get_llm_provider(settings: Settings | None = None) -> LLMProvider:
    settings = settings or get_settings()

    # 红线：prod 环境禁止公网 provider
    if settings.is_prod and settings.llm_provider in EGRESS_PROVIDERS:
        raise EgressPolicyError(
            f"数据零出域红线违规：prod 环境禁止使用公网 LLM Provider "
            f"'{settings.llm_provider.value}'。"
        )

    if settings.llm_provider == LLMProviderName.dashscope:
        return DashScopeProvider(
            api_key=settings.dashscope_api_key, model=settings.dashscope_model
        )
    if settings.llm_provider == LLMProviderName.vllm:
        return VllmProvider(base_url=settings.vllm_base_url, model=settings.vllm_model)
    if settings.llm_provider == LLMProviderName.mock:
        return MockProvider()

    raise ValueError(f"未知的 LLM Provider: {settings.llm_provider}")