#!/usr/bin/python

def main(url, timezone, future_weeks, filename):
    """parse ical calendar and insert values into html template.
    """
    html_list = ics2list(url, timezone, future_weeks)
    calendarlist2jinja(html_list, filename)

def ics2list(url, timezone, future_weeks):
    """parse ical calendar into a list
    """
    import requests
    import arrow
    from ics import Calendar

    now = arrow.now(timezone)
    period = (now.floor('day'), now.replace(weeks=+future_weeks))

    calendar = Calendar(requests.get(url).text)
    html_list = []
    for event in calendar.events:
        if event.end > period[0] and event.begin < period[1]:
        # only display events which have not ended yet
        # and start earlier than defined above
            duration = event.end - event.begin
            # short, full day and multi day events display datetime differently
            if duration.days < 1:
                event_date = (event.begin.format('DD.MM.YYYY, HH:mm')
                              + ' &ndash; '
                              + event.end.format('HH:mm'))
            elif duration.days == 1:
                event_date = event.begin.format('DD.MM.YYYY') + ', all day'
            elif duration.days > 1:
                # in ics file the end date is the day after end date at 00:00:00
                corrected_end_date = event.end.replace(days=- 1)
                event_date = (event.begin.format('DD.MM.YYYY')
                              + ' &ndash; '
                              + corrected_end_date.format('DD.MM.YYYY'))
            else:
                event_date = ''
            # create list of dictionaries for jinja2 template
            event = dict(date=event_date,
                         name=event.name,
                         location=event.location)
            html_list.append(event)
    return html_list

def calendarlist2jinja(html_list, filename):
    """write list of events to jinja html template
    """

    import os
    from jinja2 import Environment, FileSystemLoader

    # Capture our current directory
    this_dir = os.path.dirname(os.path.abspath(__file__))

    # Create the jinja2 environment.
    # Notice the use of trim_blocks, which greatly helps control whitespace.
    j2_env = Environment(loader=FileSystemLoader(this_dir),
                         trim_blocks=True)
    output = j2_env.get_template('template.html').render(html_list=html_list)
    out_file = open(this_dir + filename, "w")
    out_file.write(output.encode("utf-8"))
    out_file.close()


if __name__ == '__main__':
    main(url='https://portal.idiv.de/ssf/ical/basic.ics?bi=393&ui=1026&pd=171497477d81eb659bd832ffe26c8bfe39d65fc3&v=1',
         timezone='Europe/Berlin',
         future_weeks=4,
         filename="/website/events.html")