"""检索 API：POST /api/v1/search"""

from hashlib import sha256
from typing import Any

import structlog
from fastapi import APIRouter, Depends

from app.api.response import ApiError, ok
from app.core.auth import AuthUser, get_current_user
from app.core.retriever import Retriever
from app.models.search import SearchRequest
from app.services.redis import get_cache

logger = structlog.get_logger()

router = APIRouter(prefix="/api/v1", tags=["search"])

# 模块级懒加载单例，避免每请求重建 Qdrant/Embedding client
_retriever: Retriever | None = None


def _get_retriever() -> Retriever:
    global _retriever
    if _retriever is None:
        _retriever = Retriever()
    return _retriever


def _cache_key(request: SearchRequest) -> str:
    """检索缓存键：query + top_k + summarize 的短哈希（三者均影响结果集，需参与键计算）"""
    digest = sha256((request.query + "|" + str(request.top_k) + "|" + str(request.summarize)).encode()).hexdigest()[:16]
    return f"search:{digest}"


@router.post("/search")
async def search(request: SearchRequest, user: AuthUser = Depends(get_current_user)) -> dict[str, Any]:
    """分层检索入口，返回统一包装的 SearchResponse

    先查 Redis 缓存：命中直接返回缓存的响应；未命中走检索流程并回写缓存。
    缓存读写失败均降级为无缓存行为，不影响检索。
    """
    cache_key = _cache_key(request)
    cached = await get_cache().get_json(cache_key)
    if cached is not None:
        logger.info("检索缓存命中", query=request.query, cache_key=cache_key)
        return cached

    try:
        response = await _get_retriever().search(request)
    except ApiError:
        raise
    except Exception as exc:
        logger.exception("检索失败", query=request.query)
        raise ApiError(2000, f"检索失败: {exc}") from exc

    result = ok(response.model_dump())
    await get_cache().set_json(cache_key, result)
    return result