# uvicorn app:app --host 0.0.0.0 --port 7860 --reload 

from fastapi import FastAPI, Request, HTTPException, Depends, status
from fastapi.responses import Response # 导入Response
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials # 导入HTTPBearer和HTTPAuthorizationCredentials
import httpx # 使用httpx替代requests，因为requests是同步的，而FastAPI是异步的
import os, json
from dotenv import load_dotenv
from enum import Enum

# 加载环境变量
load_dotenv()

# 从环境变量获取代理自身的API密钥
proxy_api_key = os.getenv("PROXY_API_KEY")

# 定义HTTPBearer安全方案
security = HTTPBearer()

# 枚举校验协议类型
class ProtocolType(str, Enum):
    HTTP = "http"
    HTTPS = "https"

# 依赖函数：验证代理的API密钥
def verify_proxy_api_key(credentials: HTTPAuthorizationCredentials = Depends(security)):
    if not proxy_api_key or credentials.credentials != proxy_api_key:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid or missing proxy API key",
            headers={"WWW-Authenticate": "Bearer"},
        )
    return credentials.credentials

app = FastAPI(title="Gemini Proxy API")

@app.get("/")
def greet_json():
    return {"Hello": "World!"}

# 3. 健康检查接口（可选，用于验证服务是否正常）
@app.get("/health")
async def health_check():
    return {"status": "ok", "message": "Proxy service is running."}

gemini_api_keys_str = os.getenv("GEMINI_API_KEYS_STR")
try:
    gemini_api_keys_arr = json.loads(gemini_api_keys_str)
except json.JSONDecodeError as e:
    print(f"JSON 解析错误：{e}")
    gemini_api_keys_arr = []  # 解析失败时设置默认值
except Exception as e:
    print(f"其他错误：{e}")
    gemini_api_keys_arr = []

key_index = 0
keys_count = len(gemini_api_keys_arr)

@app.api_route("/v1/{protocol}/{host}/{path:path}", methods=["GET", "POST", "PUT", "DELETE"])
# @app.api_route("/v1/{protocol}/{host}/{path:path}", methods=["POST"])
async def proxy_gemini(request: Request, protocol: ProtocolType, host:str, path: str, proxy_api_key: str = Depends(verify_proxy_api_key)): # 添加代理认证依赖
    global key_index # 声明使用全局变量
    real_url = f"{protocol.value}://{host}/{path}"
    
    # 提取客户端请求的headers和body，透传给Gemini
    client_headers = dict(request.headers)
    
    # 移除FastAPI自带的Host头，避免Gemini校验报错
    client_headers.pop("host", None)
    
    # 将User-Agent改为curl/8.7.1，以模拟curl请求
    client_headers["User-Agent"] = "curl/8.7.1"
    
    # 添加Authorization头，用于Gemini的OpenAI兼容API
    if gemini_api_keys_arr: # 确保有可用的API密钥
        print(f"key_index: {key_index}")
        gemini_api_key = gemini_api_keys_arr[key_index]
        key_index = (key_index + 1) % keys_count
        print(f"next_key_index: {key_index}")
        client_headers["Authorization"] = f"Bearer {gemini_api_key}"
    elif gemini_api_key: # 如果没有API密钥列表，使用单个API密钥
        client_headers["Authorization"] = f"Bearer {gemini_api_key}"
    else:
        raise HTTPException(status_code=500, detail="No Gemini API keys configured.")
    
    try:
        # 读取客户端请求体
        client_body = await request.body()
        
        # 使用httpx异步客户端发起请求
        async with httpx.AsyncClient() as client:
            response = await client.request(
                method=request.method,
                url=real_url,
                headers=client_headers,
                content=client_body, # httpx使用content参数传递请求体
                timeout=30  # 超时时间，可调整
            )
        
        # 将Gemini的响应透传给客户端
        return Response(
            content=response.content,
            status_code=response.status_code,
            headers=dict(response.headers)
        )
    
    except httpx.RequestError as e:
        raise HTTPException(status_code=500, detail=f"转发请求失败：{str(e)}")
    except httpx.HTTPStatusError as e:
        raise HTTPException(status_code=e.response.status_code, detail=f"目标API返回错误：{e.response.text}")
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"转发失败：{str(e)}")