run.py

import os
from datetime import datetime
from flask import Flask, redirect, render_template, request, session, url_for

app = Flask(__name__,)
app.secret_key = os.getenv("SECRET", "randomstring123")
messages = []

def add_message(username, message):
    """Add messages to the messages list"""
    now = datetime.now().strftime("%H:%M:%S")
    messages.append({"timestamp": now, "from": username, "message": message})

@app.route('/', methods = ["GET", "POST"])
def index():
    """Main page with instructions"""

    if request.method == "POST":
        session["username"] = request.form["username"]

    if "username" in session:
        return redirect(url_for("user", username=session["username"]))

    return render_template("index.html")

@app.route('/chat/<username>', methods = ["GET", "POST"])
def user(username):
    """Add & Display chat messages"""

    if request.method == "POST":
        username = session ["username"]
        message = request.form ["message"]
        add_message(username, message)
        return redirect(url_for("user", username=session["username"]))

    return render_template("chat.html", username = username, chat_messages = messages)

app.run(host=os.getenv("IP", "0.0.0.0"), port=int(os.getenv("PORT", "5000")), debug=False)