import os
import urllib.error
import urllib.request


def send_ntfy_notification(title, message, click_url=None):
    server = os.getenv('NTFY_SERVER', '').rstrip('/')
    topic = os.getenv('NTFY_TOPIC', '').strip()
    if not server or not topic:
        return False

    request = urllib.request.Request(
        f'{server}/{topic}',
        data=message.encode('utf-8'),
        method='POST',
    )
    request.add_header('Title', title)
    request.add_header('Tags', 'calendar,question')
    if click_url:
        request.add_header('Click', click_url)

    try:
        with urllib.request.urlopen(request, timeout=5):
            return True
    except (urllib.error.URLError, TimeoutError):
        return False