from collections import OrderedDict
from threading import Thread

from flask import Flask

flask_app = Flask(__name__)


@flask_app.route("/", methods=["GET"])
def home() -> str:
    """
    Keepalive endpoint for hosting services.
    """
    return "I'm alive"


def keepalive_run() -> None:
    """
    Run keepalive Flask app in a daemon thread.
    """
    def flask_run():
        flask_app.run(host="0.0.0.0", port="7860")
    flask_thread = Thread(target=flask_run, daemon=True)
    flask_thread.start()


class LRUCache:
    """Least Recently Used (LRU) cache prototype implementation"""
    def __init__(self, max_size):
        self.max_size = max_size
        self.cache = OrderedDict()

    def __getitem__(self, key):
        try:
            val = self.cache[key]
            self.cache.move_to_end(key)
            return val
        except KeyError:
            return None

    def __setitem__(self, key, value):
        self.cache[key] = value
        self.cache.move_to_end(key)
        if len(self.cache) > self.max_size:
            self.cache.popitem(last=False)