"""厂商解析：按 provider id / modelPrefix / 默认厂商定位。"""
from __future__ import annotations

import logging
from typing import Optional

from ..models.config import AppConfig, Provider
from ..errors import HttpError

logger = logging.getLogger(__name__)


def resolve_provider(
    config: AppConfig,
    *,
    provider_id: Optional[str] = None,
    model: Optional[str] = None,
) -> Provider:
    """按优先级解析厂商：显式 id > modelPrefix 匹配 > 默认厂商。"""
    # 1. 显式 provider_id
    if provider_id:
        p = config.find_provider(provider_id)
        if not p:
            logger.warning("[resolver] provider not found or disabled: %s", provider_id)
            raise HttpError(
                f"Provider not found or disabled: {provider_id}",
                status=404,
                code="not_found",
            )
        return p

    # 2. modelPrefix 匹配
    if model:
        for p in config.providers:
            if not p.enabled or not p.model_prefix:
                continue
            if model.startswith(p.model_prefix):
                return p

    # 3. 默认厂商
    default = config.find_default_provider()
    if not default:
        logger.warning("[resolver] no enabled provider configured")
        raise HttpError(
            "No enabled provider configured. Add one in /admin.",
            status=503,
            code="service_unavailable",
        )
    return default


def normalize_model(provider: Provider, model: Optional[str], *, fallback: Optional[str] = None) -> str:
    """剥离 provider 前缀，回退到默认模型。"""
    if model:
        if provider.model_prefix and model.startswith(provider.model_prefix):
            return model[len(provider.model_prefix):]
        return model
    if fallback:
        return fallback
    if provider.type == "gemini":
        from ..config import GEMINI_DEFAULT_MODEL
        return GEMINI_DEFAULT_MODEL
    return "gpt-4o-mini"