main.py

from fastapi import FastAPI, Request, Header, HTTPException
from fastapi.responses import JSONResponse, Response
import httpx

app = FastAPI()

# Your internal real API key for TypeGPT (not exposed to users)
REAL_API_KEY = "sk-qO9N6kQEEULMWtF4YGVlTTSjIPllEm1h1wfEBzSmnSbxiXwe"
BASE_URL = "https://fast.typegpt.net"

# Public token users must send in their Authorization header
PUBLIC_AUTH_TOKEN = "TypeGPT-Free4ALL"

@app.api_route("/{path:path}", methods=["GET", "POST"])
async def proxy(request: Request, path: str, authorization: str = Header(None)):
    # Validate the Authorization header
    if not authorization or not authorization.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="Missing or malformed Authorization header.")
    
    token = authorization.replace("Bearer ", "").strip()

    if token != PUBLIC_AUTH_TOKEN:
        raise HTTPException(status_code=401, detail="Invalid Authorization token. Use 'TypeGPT-Free4ALL'.")

    # Construct URL to forward to the real backend
    target_url = f"{BASE_URL}/{path}"

    # Prepare headers with real API key
    headers = dict(request.headers)
    headers["Authorization"] = f"Bearer {REAL_API_KEY}"
    headers.pop("host", None)

    # Forward the request body
    body = await request.body()

    async with httpx.AsyncClient() as client:
        try:
            response = await client.request(
                method=request.method,
                url=target_url,
                content=body,
                headers=headers,
                timeout=60  # prevent hanging
            )
        except httpx.RequestError as e:
            raise HTTPException(status_code=502, detail=f"Request to backend failed: {e}")

    # Log response for debugging
    print("TypeGPT Response Status:", response.status_code)
    print("TypeGPT Response Headers:", response.headers)
    print("TypeGPT Response Content:", response.text[:200])  # limit output

    # Try to return JSON response, fallback to raw
    try:
        return JSONResponse(content=response.json(), status_code=response.status_code)
    except Exception:
        return Response(
            content=response.content,
            status_code=response.status_code,
            media_type=response.headers.get("content-type", "text/plain")
        )