main.py

import os
from fastapi import FastAPI
from fastapi.staticfiles import StaticFiles
from fastapi.responses import FileResponse, StreamingResponse
from pydantic import BaseModel
from openai import OpenAI
from dotenv import load_dotenv

load_dotenv()

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key=os.getenv("OPENROUTER_API_KEY"),
)

app = FastAPI(title="Simple Chatbot")


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


class ChatRequest(BaseModel):
    messages: list[Message]


@app.post("/api/chat")
async def chat(request: ChatRequest):
    """Stream a chat completion from OpenRouter."""

    def generate():
        stream = client.chat.completions.create(
            model="openrouter/free",
            messages=[m.model_dump() for m in request.messages],
            stream=True,
        )
        for chunk in stream:
            if chunk.choices and chunk.choices[0].delta.content:
                yield chunk.choices[0].delta.content

    return StreamingResponse(generate(), media_type="text/plain")


# Serve the frontend
app.mount("/static", StaticFiles(directory="static"), name="static")


@app.get("/")
async def root():
    return FileResponse("static/index.html")