plugins-custom/events-ics/events.py

# -*- coding: utf-8 -*-
"""
events plugin for Pelican
=========================

This plugin looks for and parses an "events" directory and generates
blog posts with a user-defined event date. (typically in the future)
It also generates an ICalendar v2.0 calendar file.
https://en.wikipedia.org/wiki/ICalendar


Author: Federico Ceratto <federico.ceratto@gmail.com>
Released under AGPLv3+ license, see LICENSE

This is a custom Varia version of the event plugin.
Email: info@varia.zone
"""

from datetime import datetime, timedelta
from pelican import signals, utils
from collections import namedtuple, defaultdict
import icalendar
import logging
import os.path
import pytz

log = logging.getLogger(__name__)

TIME_MULTIPLIERS = {
    'w': 'weeks',
    'd': 'days',
    'h': 'hours',
    'm': 'minutes',
    's': 'seconds'
}

events = []
localized_events = defaultdict(list)
Event = namedtuple("Event", "dtstart dtend metadata rrule")


def parse_tstamp(ev, field_name):
    """Parse a timestamp string in format "YYYY-MM-DD HH:MM"

    :returns: datetime
    """
    try:
        return datetime.strptime(ev[field_name], '%Y-%m-%d %H:%M')
    except Exception as e:
        log.error("Unable to parse the '%s' field in the event named '%s': %s" \
            % (field_name, ev['title'], e))
        raise

def parse_timedelta(ev):
    """Parse a timedelta string in format [<num><multiplier> ]*
    e.g. 2h 30m

    :returns: timedelta
    """

    chunks = ev['event_duration'].split()
    tdargs = {}
    for c in chunks:
        try:
            m = TIME_MULTIPLIERS[c[-1]]
            val = int(c[:-1])
            tdargs[m] = val
        except KeyError:
            log.error("""Unknown time multiplier '%s' value in the \
'event_duration' field in the '%s' event. Supported multipliers \
are: '%s'.""" % (c, ev['title'], ' '.join(TIME_MULTIPLIERS)))
            raise RuntimeError("Unknown time multiplier '%s'" % c)
        except ValueError:
            log.error("""Unable to parse '%s' value in the 'event_duration' \
field in the '%s' event.""" % (c, ev['title']))
            raise ValueError("Unable to parse '%s'" % c)


    return timedelta(**tdargs)

def parse_recursion(ev, field_name):
    """
    Parse information about recurring events and return frequency of event and untill time.
    """
    chunks = ev[field_name].split()
    freq = chunks[0].upper()
    if 'until' in chunks:
        until = datetime.strptime(chunks[-1], '%Y-%m-%d')
        rrule = [freq, until] 
    else:
        rrule = [freq]
    return rrule

def parse_article(generator, metadata):
    """Collect articles metadata to be used for building the event calendar

    :returns: None
    """
    if 'event_start' not in metadata:
        return

    dtstart = parse_tstamp(metadata, 'event_start')
    rrule=[]
    if 'event_end' in metadata:
        dtend = parse_tstamp(metadata, 'event_end')

    elif 'event_duration' in metadata:
        dtdelta = parse_timedelta(metadata)
        dtend = dtstart + dtdelta

        if 'event_recurring' in metadata:
            rrule = parse_recursion(metadata, 'event_recurring')

    else:
        msg = "Either 'event_end' or 'event_duration' must be" + \
            " speciefied in the event named '%s'" % metadata['title']
        log.error(msg)
        raise ValueError(msg)

    events.append(Event(dtstart, dtend, metadata, rrule))


def generate_ical_file(generator):
    """Generate an iCalendar file
    """
    from icalendar import vDatetime as vd

    global events

    ics_calendars = generator.settings['PLUGIN_EVENTS']['ics_calendars']
    default_loc = generator.settings['PLUGIN_EVENTS']['default_location']
    category_calendar = generator.settings['PLUGIN_EVENTS']['calendar_per_category']

    if not ics_calendars:
        return

    if not category_calendar:
        ics_calendars = ics_calendars[:1]

    for calendar in ics_calendars:
        
        ics_fname = os.path.join(generator.settings['OUTPUT_PATH'], calendar)
        log.debug("Generating calendar at %s with %d events" % (ics_fname, len(events)))

        tz = generator.settings.get('TIMEZONE', 'UTC')
        tz = pytz.timezone(tz)

        ical = icalendar.Calendar()
        ical.add('prodid', '-//My calendar product//mxm.dk//')
        ical.add('version', '2.0')

        DEFAULT_LANG = generator.settings['DEFAULT_LANG']
        curr_events = events if not localized_events else localized_events[DEFAULT_LANG]
        for e in curr_events:

            if str(e.metadata['category']) in calendar or not category_calendar:
                #force convert to ical format here, because otherwise it doesn't happen?
                dtend = vd(e.dtend).to_ical()
                dtstart = vd(e.dtstart).to_ical()
                dtstamp = vd (e.metadata['date']).to_ical()

                # print('*'*10)
                # print(e.metadata['category'])

                ie = icalendar.Event(
                    summary=e.metadata['title'],
                    dtstart=dtstart, 
                    dtend=dtend,
                    dtstamp= dtstamp,
                    priority=5,
                    uid=e.metadata['title'],
                )
                if 'event_location' in e.metadata:
                    ie.add('location', e.metadata['event_location'])
                elif default_loc:
                    ie.add('location', default_loc)


                if 'event_recurring' in e.metadata:
                    if len(e.rrule)>=2:
                        ie.add('rrule', {'freq':e.rrule[0],'until':e.rrule[1]})
                    else:
                        ie.add('rrule', {'freq':e.rrule[0]})

                ical.add_component(ie)
        with open(ics_fname, 'wb') as f:
            f.write(ical.to_ical())


def generate_localized_events(generator):
    """ Generates localized events dict if i18n_subsites plugin is active """

    if "i18n_subsites" in generator.settings["PLUGINS"]:
        if not os.path.exists(generator.settings['OUTPUT_PATH']):
            os.makedirs(generator.settings['OUTPUT_PATH'])

        for e in events:
            if "lang" in e.metadata:
                localized_events[e.metadata["lang"]].append(e)
            else:
                log.debug("event %s contains no lang attribute" % (e.metadata["title"],))


def generate_events_list(generator):
    """Populate the event_list variable to be used in jinja templates"""

    if not localized_events:
        generator.context['events_list'] = sorted(events, reverse = True,
                                                  key=lambda ev: (ev.dtstart, ev.dtend))
    else:
        generator.context['events_list'] = {k: sorted(v, reverse = True,
                                                      key=lambda ev: (ev.dtstart, ev.dtend))
                                            for k, v in localized_events.items()}

def initialize_events(article_generator):
    """
    Clears the events list before generating articles to properly support plugins with
    multiple generation passes like i18n_subsites
    """

    del events[:]
    localized_events.clear()

def register():
    signals.article_generator_init.connect(initialize_events)
    signals.article_generator_context.connect(parse_article)
    signals.article_generator_finalized.connect(generate_localized_events)
    signals.article_generator_finalized.connect(generate_ical_file)
    signals.article_generator_finalized.connect(generate_events_list)