import ssl
import socket
import datetime
import argparse
import urllib.request
import urllib.parse
import pprint

def get_ssl_expiry_date(hostname, port=443):
    """Gets the SSL certificate expiry date for a given hostname."""
    try:
        context = ssl.create_default_context()
        with socket.create_connection((hostname, port)) as sock:
            with context.wrap_socket(sock, server_hostname=hostname) as ssock:
                cert = ssock.getpeercert()
                expiry_date = datetime.datetime.strptime(cert['notAfter'], '%b %d %H:%M:%S %Y %Z')
                return expiry_date, cert
    except Exception as e:
        print(f"Error: Could not retrieve SSL certificate for {hostname}: {e}")
        return None, None

def check_expiry_and_notify(hostname, ntfy_topic, ntfy_server="https://ntfy.sh"):
    """Checks SSL expiry and sends a notification if it expires within a week."""
    expiry_date, cert = get_ssl_expiry_date(hostname)
    if expiry_date:
        print(f"Certificate details for {hostname}:")
        pprint.pprint(cert) #print the cert in a readable way.
        now = datetime.datetime.now()
        one_week_from_now = now + datetime.timedelta(weeks=1)

        if expiry_date < one_week_from_now:
            message = f"SSL certificate for {hostname} expires on {expiry_date.strftime('%Y-%m-%d %H:%M:%S')}"
            send_ntfy_notification(ntfy_server, ntfy_topic, message)
            print(f"Notification sent: {message}")
        else:
            print(f"SSL certificate for {hostname} expires after one week.")

def send_ntfy_notification(server, topic, message):
    """Sends a notification to ntfy.sh using urllib."""
    url = f"{server}/{topic}"
    data = message.encode('utf-8')
    try:
        req = urllib.request.Request(url, data=data, method='POST')
        with urllib.request.urlopen(req) as response:
            if response.getcode() >= 400:
                print(f"ntfy request failed with status: {response.getcode()}")
    except urllib.error.URLError as e:
        print(f"Error sending ntfy notification: {e}")

def main():
    parser = argparse.ArgumentParser(description="Check SSL certificate expiry and send ntfy notification.")
    parser.add_argument("hostname", help="The hostname to check.")
    parser.add_argument("ntfy_topic", help="The ntfy.sh topic to send notifications to.")
    parser.add_argument("--ntfy_server", default="https://ntfy.sh", help="The ntfy.sh server URL (default: https://ntfy.sh).")

    args = parser.parse_args()

    check_expiry_and_notify(args.hostname, args.ntfy_topic, args.ntfy_server)

if __name__ == "__main__":
    main()