ical_offset/main.py

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

from datetime import datetime, time, timedelta

import requests
from flask import Flask, Response, request
from icalendar import Calendar, Event  # type: ignore[import]
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'])
    days = request.args.get('days', '0')
    hours = request.args.get('hours', '0')
    mins = request.args.get('mins', '0')

    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'])
            entry.add(
                'dtstart',
                datetime.combine(component.decoded('dtstart'), time(0))
                + timedelta(days=int(days), hours=int(hours), minutes=int(mins)),
            )
            entry.add(
                'dtend',
                datetime.combine(component.decoded('dtend'), time(0))
                + timedelta(days=int(days), hours=int(hours), minutes=int(mins)),
            )
            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'},
    )