import os
import requests
import google.generativeai as genai
import logging
from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import List

# --- 配置 ---
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# 从环境变量获取 API 密钥和后端 URL
GEMINI_API_KEY = os.getenv("GEMINI_API_KEY")
SEARCH_API_BASE_URL = os.getenv("SEARCH_API_BASE_URL")

# 配置 Google Gemini
genai.configure(api_key=GEMINI_API_KEY)
# 使用最新的 Flash 模型，性价比高
gemini_model = genai.GenerativeModel('gemini-2.5-flash')

# --- FastAPI 应用设置 ---
app = FastAPI(
    title="AI Search Agent",
    description="一个使用 Gemini-2.5-Flash 将自然语言转换为学术搜索查询的智能中间层。",
    version="1.0.0"
)

# 配置 CORS，允许您的前端 Space 访问
# TODO: 为了安全，您应该将 "*" 替换为您的前端 Space 的 URL
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # 允许所有来源
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# --- 数据模型 ---
class SearchRequest(BaseModel):
    platform: str
    query: str
    max_results: int = 10

# --- 核心 AI 功能 ---
async def get_ai_keywords(natural_language_query: str) -> str:
    """
    使用 Gemini 将自然语言查询转换为优化的布尔逻辑搜索关键词。
    """
    if not GEMINI_API_KEY:
        logger.warning("GEMINI_API_KEY 未设置，将使用原始查询。")
        return natural_language_query

    # 精心设计的 Prompt
    prompt = f"""
    You are an expert academic researcher. Your task is to convert a user's natural language query into a highly effective, concise, boolean-logic keyword string for searching academic databases like PubMed.
    - Use boolean operators like AND, OR.
    - Use parentheses for grouping.
    - Focus on core concepts.
    - Keep the string concise and in English.
    - Do not add any explanation, markdown, or quotation marks. Just return the pure keyword string.

    User Query: "{natural_language_query}"
    Keyword String:
    """

    try:
        logger.info(f"向 Gemini 发送请求，查询: '{natural_language_query}'")
        response = await gemini_model.generate_content_async(prompt)
        optimized_query = response.text.strip()
        
        logger.info(f"原始查询: '{natural_language_query}' -> Gemini 优化关键词: '{optimized_query}'")
        
        # 如果AI返回空，则回退到原始查询
        if not optimized_query:
            logger.warning("Gemini 返回空结果，回退到原始查询。")
            return natural_language_query
            
        return optimized_query
    except Exception as e:
        logger.error(f"调用 Gemini API 失败: {e}")
        # 如果AI调用失败，就回退到使用原始查询
        return natural_language_query

# --- API 端点 ---
@app.get("/")
def read_root():
    return {"status": "AI Search Agent is running"}

@app.post("/search")
async def intelligent_search(request: SearchRequest):
    """
    接收前端请求，进行 AI 优化，然后代理到搜索后端。
    """
    if not SEARCH_API_BASE_URL:
        raise HTTPException(status_code=500, detail="SEARCH_API_BASE_URL 未配置")

    # 1. 使用 Gemini 优化查询
    optimized_query = await get_ai_keywords(request.query)

    # 2. 准备发往 `paper-mcp-agent` 的请求体
    search_payload = {
        "platform": request.platform,
        "query": optimized_query, # 使用优化后的查询
        "max_results": request.max_results
    }

    # 3. 调用 `paper-mcp-agent` 搜索后端
    try:
        logger.info(f"向搜索后端发送请求: {search_payload}")
        search_url = f"{SEARCH_API_BASE_URL}/search"
        response = requests.post(search_url, json=search_payload, timeout=30)
        response.raise_for_status()  # 如果状态码不是 2xx，则抛出异常
        
        search_results = response.json()
        
        # 在最终结果中包含原始查询和优化后的查询，便于调试
        search_results['original_query'] = request.query
        search_results['optimized_query'] = optimized_query
        
        return search_results

    except requests.exceptions.RequestException as e:
        logger.error(f"调用搜索后端失败: {e}")
        raise HTTPException(status_code=503, detail=f"无法连接到搜索服务: {str(e)}")
    except Exception as e:
        logger.error(f"处理搜索时发生未知错误: {e}")
        raise HTTPException(status_code=500, detail=f"内部服务器错误: {str(e)}")