app/services/presence.py

from __future__ import annotations

from datetime import timedelta

from app.web import local_now


HEARTBEAT_INTERVAL_SECONDS = 5
ONLINE_WINDOW_SECONDS = 15
PRESENCE_WRITE_INTERVAL_SECONDS = HEARTBEAT_INTERVAL_SECONDS
PRESENCE_OVERVIEW_PULL_SECONDS = 5


def online_cutoff(reference_time=None):
    now = reference_time or local_now()
    return now - timedelta(seconds=ONLINE_WINDOW_SECONDS)


def is_online(last_seen_at, reference_time=None) -> bool:
    if not last_seen_at:
        return False
    return last_seen_at >= online_cutoff(reference_time)


def unix_seconds(value) -> int | None:
    if not value:
        return None
    return int(value.timestamp())


def should_write_presence(session: dict, reference_time=None, force: bool = False) -> bool:
    now = reference_time or local_now()
    now_seconds = int(now.timestamp())
    if force:
        session["presence_last_written_at"] = now_seconds
        return True

    last_written = int(session.get("presence_last_written_at", 0) or 0)
    if now_seconds - last_written < PRESENCE_WRITE_INTERVAL_SECONDS:
        return False

    session["presence_last_written_at"] = now_seconds
    return True