FastAPI ve Gemini 3.7 API ile Gerçek Zamanlı Streaming ve Function Calling

import json
from typing import AsyncGenerator
from fastapi import FastAPI, HTTPException
from fastapi.responses import StreamingResponse
from google import genai
from google.genai import types

app = FastAPI(title="Gemini Streaming API")
ai_client = genai.Client()

async def generate_gemini_stream(prompt: str) -> AsyncGenerator[str, None]:
    try:
        response = ai_client.models.generate_content_stream(
            model="gemini-3.7-flash",
            contents=prompt,
            config=types.GenerateContentConfig(
                temperature=0.3,
                max_output_tokens=2048,
            )
        )
        for chunk in response:
            if chunk.text:
                # SSE standart veri biçimi: data: <payload>\n\n
                payload = json.dumps({"text": chunk.text})
                yield f"data: {payload}\n\n"
    except Exception as exc:
        err_payload = json.dumps({"error": str(exc)})
        yield f"data: {err_payload}\n\n"

@app.get("/api/chat/stream")
async def chat_stream_endpoint(q: str):
    if not q.strip():
        raise HTTPException(status_code=400, detail="Sorgu boş olamaz.")
    
    headers = {
        "Content-Type": "text/event-stream",
        "Cache-Control": "no-cache",
        "Connection": "keep-alive",
        "X-Accel-Buffering": "no", # Nginx önbelleğe almasını kapatır
    }
    return StreamingResponse(generate_gemini_stream(q), headers=headers)