chat2.py

# openai basic chatbot with rolling 5-chat history

from openai import OpenAI

from rich.console import Console
from rich.markdown import Markdown

import os

import file_helper as fh

# initialize OpenRouter client
client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key=os.environ.get("OPENROUTER_API_KEY"),
    default_headers={
        "HTTP-Referer": "http://localhost",
        "X-Title": "Basic OpenRouter ChatBot",
    }
)

# initialize rich Console
console = Console()

# system message (always at index 0)
system_msg = {"role": "system", "content": "You are a Harvard CS50 teaching assistant for David Malan the Instructor. You are able to help me with any Computer Science related questions."}

# initialize messages list with system message
messages = [system_msg]

# maximum number of user-assistant pairs to keep
MAX_PAIRS = 5

print("Chat with rolling 5-chat history. Type 'quit' or 'exit' to end.")

while True:
    # get user input
    user_input = input("\nYou: ")

    # check for exit condition
    if user_input.lower() in ('quit', 'exit'):
        print("Goodbye!")
        break

    # append user message to messages
    messages.append({"role": "user", "content": user_input})

    # make the API call with current messages
    response = client.chat.completions.create(
        model="qwen/qwen3-coder",
        messages=messages
    )

    # extract the raw markdown text
    raw_text = response.choices[0].message.content

    # append assistant response to messages
    messages.append({"role": "assistant", "content": raw_text})

    # enforce rolling history: keep only MAX_PAIRS user-assistant pairs
    # total messages = system (1) + pairs * 2
    current_pairs = (len(messages) - 1) // 2
    print(f"[Debug] pairs: {current_pairs}, total messages: {len(messages)}")
    if current_pairs > MAX_PAIRS:
        # remove oldest pair (messages[1] = first user, messages[2] = first assistant)
        # delete both at once using slice assignment
        messages[1:3] = []
        print(f"[Debug] removed oldest pair, new pairs: {current_pairs-1}")

    # render with Rich
    md = Markdown(raw_text)
    console.print(md)

    # log response
    fh.log_response(raw_text)