app.py

"""
Usman's Agent — portfolio chat endpoint powered by Gemini API.

Deploy on a Hugging Face Space (SDK: Docker).
Set GEMINI_API_KEY as a Space secret.
The portfolio frontend POSTs to /chat with { messages: [...], system: "..." }
and expects { reply: "..." }.
"""
import os
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from google import genai
from google.genai import types

GEMINI_API_KEY = os.environ.get("GEMINI_API_KEY", "")
MODEL_ID = os.environ.get("MODEL_ID", "gemini-2.5-flash")
MAX_NEW_TOKENS = int(os.environ.get("MAX_NEW_TOKENS", "1024"))
HISTORY_TURNS = int(os.environ.get("HISTORY_TURNS", "8"))

client = genai.Client(api_key=GEMINI_API_KEY)

app = FastAPI(title="Usman's Agent")

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


class ChatRequest(BaseModel):
    messages: list
    system: str | None = None


@app.get("/")
def health():
    return {"status": "ok", "model": MODEL_ID}


@app.post("/chat")
def chat(req: ChatRequest):
    system = req.system or ""
    turns = [m for m in req.messages if m.get("role") in ("user", "assistant")][-HISTORY_TURNS:]

    history = []
    for m in turns[:-1]:
        role = "model" if m["role"] == "assistant" else "user"
        history.append(types.Content(role=role, parts=[types.Part(text=m["content"])]))

    last = turns[-1]["content"] if turns else ""

    chat_session = client.chats.create(
        model=MODEL_ID,
        config=types.GenerateContentConfig(
            system_instruction=system,
            max_output_tokens=MAX_NEW_TOKENS,
            temperature=0.7,
        ),
        history=history,
    )
    response = chat_session.send_message(last)
    reply = response.text.strip()
    return {"reply": reply}