ical_offset/main.py

"""
Take existing calendar and update it slightly
"""

import logging
from datetime import date, datetime, time, timedelta

import requests
from flask import Flask, Response, make_response, request
from icalendar import Calendar, Event
from werkzeug.middleware.proxy_fix import ProxyFix

app = Flask(__name__)
app.wsgi_app = ProxyFix(app.wsgi_app, x_proto=1)  # type: ignore[assignment]


@app.route("/", methods=["get"])
def process() -> Response:
    """
    Fetch ICS url and convert from Events to Todos

    Returns:
        Response: ical response
    """

    # Fetch existing calendar
    orig = requests.get(request.args["url"], timeout=30)
    days = int(request.args.get("days", "0"))
    hours = int(request.args.get("hours", "0"))
    mins = int(request.args.get("mins", "0"))

    if orig.status_code != 200:
        logging.warning("%s returned a %d", orig.request.url, orig.status_code)
        return make_response(orig.text, orig.status_code)

    orig_cal = Calendar.from_ical(orig.text)
    cal = Calendar()

    cal.add("version", "2.0")
    cal.add(
        "prodid",
        "-//Scott Wallace//event2task//EN",
    )

    for component in orig_cal.subcomponents:
        if isinstance(component, Event):
            entry = Event()

            entry.add("description", component["description"])
            entry.add("dtstamp", component["dtstamp"])
            if days or hours or mins:
                start = component.decoded("dtstart")
                end = component.decoded("dtend")
                if isinstance(start, date):
                    entry.add(
                        "dtstart",
                        datetime.combine(start, time(0))
                        + timedelta(days=days, hours=hours, minutes=mins),
                    )
                if isinstance(end, date):
                    entry.add(
                        "dtend",
                        datetime.combine(end, time(0))
                        + timedelta(days=days, hours=hours, minutes=mins),
                    )

            if not entry.get("dtstart"):
                entry.add("dtstart", component["dtstart"])
            if not entry.get("dtend"):
                entry.add("dtend", component["dtend"])

            entry.add("summary", component["summary"])
            entry.add("uid", component["uid"])

            cal.add_component(entry)

    return Response(
        cal.to_ical().decode().replace("\\r\\n", "\n").strip(),
        headers={"content-type": "text/calendar; charset=UTF-8"},
    )