from fastapi import FastAPI, Request, Response, HTTPException
from fastapi.middleware.cors import CORSMiddleware
import httpx
from contextlib import asynccontextmanager

# The target Azure VM backend URL
TARGET_URL = "https://snap-providers-mercy-protocol.trycloudflare.com"

# Use a global client to avoid creating a new one for every request (reduces RAM/CPU overhead)
client_state = {}

@asynccontextmanager
async def lifespan(app: FastAPI):
    # Initialize the client on startup
    client_state["client"] = httpx.AsyncClient(timeout=60.0)
    yield
    # Close the client on shutdown
    await client_state["client"].aclose()

app = FastAPI(lifespan=lifespan)

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

@app.api_route("/{path:path}", methods=["GET", "POST", "PUT", "DELETE", "OPTIONS"])
async def proxy(request: Request, path: str):
    """Forwards all requests to the target backend."""
    url = f"{TARGET_URL}/{path}"
    
    if request.method == "OPTIONS":
        return Response(status_code=200)

    client = client_state["client"]
    body = await request.body()
    headers = dict(request.headers)
    headers.pop("host", None)
    
    try:
        resp = await client.request(
            method=request.method,
            url=url,
            headers=headers,
            content=body
        )
        
        return Response(
            content=resp.content,
            status_code=resp.status_code,
            headers=dict(resp.headers)
        )
    except httpx.RequestError as e:
        raise HTTPException(status_code=502, detail=f"Proxy Error: {str(e)}")


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)