app.py

from fastapi import FastAPI, Header, HTTPException
from pydantic import BaseModel
import requests
import os
import re

app = FastAPI()

# ============================================
# API KEYS
# ============================================

MY_API_KEY = os.getenv("MY_API_KEY")
NVIDIA_API_KEY = os.getenv("NVIDIA_API_KEY")

# ============================================
# NVIDIA CONFIG
# ============================================

NVIDIA_URL = "https://integrate.api.nvidia.com/v1/chat/completions"

MODEL_NAME = "moonshotai/kimi-k2.6"

# ============================================
# REQUEST MODELS
# ============================================

class Message(BaseModel):
    role: str
    content: str

class ChatRequest(BaseModel):
    model: str = MODEL_NAME
    messages: list[Message]

# ============================================
# HOME ROUTE
# ============================================

@app.get("/")
def home():
    return {
        "status": "online",
        "provider": "NVIDIA",
        "model": MODEL_NAME,
        "message": "Advanced AI API is running"
    }

# ============================================
# CLEAN RESPONSE
# ============================================

def clean_response(text):

    if not text:
        return "I'm here. How can I help you?"

    # Remove thinking tags
    text = re.sub(r"<think>.*?</think>", "", text, flags=re.DOTALL)

    # Remove extra spaces
    text = re.sub(r"\s+", " ", text)

    return text.strip()

# ============================================
# CHAT ENDPOINT
# ============================================

@app.post("/v1/chat/completions")
async def chat(
    request: ChatRequest,
    authorization: str = Header(None)
):

    # Check auth
    if not authorization:
        raise HTTPException(
            status_code=401,
            detail="Missing Authorization header"
        )

    token = authorization.replace("Bearer ", "").strip()

    if token != MY_API_KEY:
        raise HTTPException(
            status_code=403,
            detail="Invalid API key"
        )

    # Strong system prompt
    system_prompt = """
You are a highly accurate conversational AI assistant.

Rules:
- Reply naturally like a real human.
- Keep responses concise and clean.
- Use excellent grammar.
- Never hallucinate facts.
- Never invent information.
- If unsure, say you are unsure.
- Stay relevant to the user's message.
- Never generate random languages.
- Reply in English unless the user speaks Bangla.
- If the user speaks Bangla, reply naturally in Bangla.
- Avoid robotic wording.
- Do not generate code unless requested.
"""

    # Build messages
    messages = [
        {
            "role": "system",
            "content": system_prompt
        }
    ]

    for m in request.messages:
        messages.append({
            "role": m.role,
            "content": m.content.strip()
        })

    # NVIDIA request headers
    headers = {
        "Authorization": f"Bearer {NVIDIA_API_KEY}",
        "Content-Type": "application/json"
    }

    # NVIDIA request body
    payload = {
        "model": MODEL_NAME,
        "messages": messages,
        "max_tokens": 512,
        "temperature": 0.2,
        "top_p": 0.7,
        "stream": False
    }

    try:

        response = requests.post(
            NVIDIA_URL,
            headers=headers,
            json=payload,
            timeout=120
        )

        data = response.json()

        output = data["choices"][0]["message"]["content"]

        output = clean_response(output)

        if len(output.strip()) == 0:
            output = "I'm here. How can I help you?"

        return {
            "object": "chat.completion",
            "model": MODEL_NAME,
            "choices": [
                {
                    "index": 0,
                    "message": {
                        "role": "assistant",
                        "content": output
                    },
                    "finish_reason": "stop"
                }
            ]
        }

    except Exception as e:

        raise HTTPException(
            status_code=500,
            detail=str(e)
        )