import json
import aiohttp
import chainlit as cl
from typing import AsyncIterator
from configs import DEFAULT_MODEL, BACKEND_BASE_URL

def sync_session_model() -> tuple[str, list]:
    """Checks for chat profile changes and resets model and history if needed."""
    current_profile = cl.user_session.get("chat_profile") or DEFAULT_MODEL
    current_model = cl.user_session.get("model")
    if current_model != current_profile:
        cl.user_session.set("model", current_profile)
        cl.user_session.set("history", [])

    model = cl.user_session.get("model")
    history = cl.user_session.get("history")

    return model, history

async def post_agent_request(session: aiohttp.ClientSession, query: str, model: str, history: list) -> aiohttp.ClientResponse:
    """Makes a POST request, returns a response object."""
    return await session.post(
        BACKEND_BASE_URL,
        json={"query": query, "model": model, "history": history[:-1]})

async def parse_sse_stream(response: aiohttp.ClientResponse) -> AsyncIterator[dict]:
    """Iterates SSE response bytes, decodes and parses lines."""
    async for raw_line in response.content:
        line = raw_line.decode("utf-8").strip()
        if not line.startswith("data: "):
            continue    
        data = line[6:]
        if data == "[DONE]":
            break
        parsed = json.loads(data)
        yield parsed

async def finalize_message(msg: cl.Message, cancelled: bool, history: list) -> list:
    """Updates message and appends assistant response to history."""
    await msg.update()
    if msg.content and not cancelled:
        history.append({"role": "assistant", "content": msg.content})
    return history