varia.website/plugins-custom/events-ics/events.py

"""
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
"""

import logging
import os.path
from collections import defaultdict, namedtuple
from datetime import datetime, timedelta

import icalendar
import pytz
from pelican import signals, utils

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)