agenda/update_gwr_advance_ticket_date.py

#!/usr/bin/python3
"""Update GWR advance ticket date cache."""

import os.path
import smtplib
import sys
from email.message import EmailMessage
from email.utils import formatdate, make_msgid

import requests

from agenda import gwr

config = __import__("config.default", fromlist=[""])


def send_mail(subject: str, body: str) -> None:
    """Send an e-mail."""
    msg = EmailMessage()

    msg["Subject"] = subject
    msg["To"] = f"{config.NAME} <{config.MAIL_TO}>"
    msg["From"] = f"{config.NAME} <{config.MAIL_FROM}>"
    msg["Date"] = formatdate()
    msg["Message-ID"] = make_msgid()

    msg.set_content(body)

    s = smtplib.SMTP(config.SMTP_HOST)
    s.sendmail(config.MAIL_TO, [config.MAIL_TO], msg.as_string())
    s.quit()


def main() -> None:
    """Get date from web page and compare with existing."""
    filename = os.path.join(config.DATA_DIR, "advance-tickets.html")
    existing_html = open(filename).read()
    existing_date = gwr.extract_weekday_date(existing_html)

    new_html = requests.get(gwr.url).text
    open(filename, "w").write(new_html)

    new_date = gwr.extract_weekday_date(new_html)

    if existing_date == new_date:
        if sys.stdin.isatty():
            print("date has't changed:", existing_date)
        return

    subject = f"New GWR advance ticket booking date: {new_date}"
    body = f"""Old date: {existing_date}
New date: {new_date}

{gwr.url}

Agenda: https://edwardbetts.com/agenda/
"""
    send_mail(subject, body)


if __name__ == "__main__":
    main()