recurrence.py

from Acquisition import aq_parent
from OFS.SimpleItem import SimpleItem
from plone.app.event.base import dt_end_of_day
from plone.app.event.base import dt_start_of_day
from plone.app.event.base import guess_date_from
from plone.base.utils import safe_text
from plone.event.interfaces import IEventAccessor
from plone.event.interfaces import IEventRecurrence
from plone.event.interfaces import IOccurrence
from plone.event.interfaces import IRecurrenceSupport
from plone.event.recurrence import recurrence_sequence_ical
from plone.event.utils import is_same_day
from plone.event.utils import pydt
from plone.namedfile.interfaces import IImageScaleTraversable
from plone.namedfile.scaling import ImageScaling
from Products.Five.browser import BrowserView
from zope.component import adapter
from zope.interface import implementer
from zope.publisher.interfaces.browser import IBrowserRequest
from ZPublisher.BaseRequest import DefaultPublishTraverse


@adapter(IEventRecurrence)
@implementer(IRecurrenceSupport)
class RecurrenceSupport:
    """IRecurrenceSupport Adapter."""

    def __init__(self, context):
        self.context = context

    def occurrences(self, range_start=None, range_end=None):
        """Return all occurrences of an event, possibly within a start and end
        limit.

        :param range_start: Optional start datetime, from which you want
                            occurrences be returned.
        :type range_start: Python datetime
        :param range_end: Optional start datetime, from which you want
                          occurrences be returned.
        :type range_end: Python datetime
        :returns: List of occurrences, including the start event.
        :rtype: IEvent or IOccurrence based objects

        Please note: Events beginning before range_start but ending afterwards
                     won't be found.

        TODO: really?

        TODO: test with event start = 21st feb, event end = start+36h,
        recurring for 10 days, range_start = 1st mar, range_end = last Mark
        """
        event = IEventAccessor(self.context)

        # We try to get IEventBasic start without including recurrence
        event_start = getattr(self.context, "start", None)
        if not event_start:
            event_start = event.start
        elif getattr(event, "whole_day", None):
            event_start = dt_start_of_day(event_start)

        # We get event ends by adding a duration to the start. This way, we
        # prevent that the start and end lists are of different size if an
        # event starts before range_start but ends afterwards.
        if getattr(event, "open_end", None):
            event_end = dt_end_of_day(event_start)
        elif getattr(event, "whole_day", None):
            event_end = dt_end_of_day(getattr(self.context, "end", None))
        else:
            event_end = getattr(self.context, "end", None)

        duration = event_end - event_start

        starts = recurrence_sequence_ical(
            event_start,
            recrule=event.recurrence,
            from_=range_start,
            until=range_end,
            duration=duration,
        )

        # XXX potentially occurrence won't need to be wrapped anymore
        # but doing it for backwards compatibility as views/templates
        # still rely on acquisition-wrapped objects.
        def get_obj(start):
            if pydt(event_start.replace(microsecond=0)) == start:
                # If the occurrence date is the same as the event object, the
                # occurrence is the event itself. return it as such.
                # Dates from recurrence_sequence_ical are explicitly without
                # microseconds, while event.start may contain it. So we have to
                # remove it for a valid comparison.
                return self.context
            return Occurrence(
                id=str(start.date()), start=start, end=start + duration
            ).__of__(self.context)

        for start in starts:
            yield get_obj(start)


@adapter(IEventRecurrence, IBrowserRequest)
class OccurrenceTraverser(DefaultPublishTraverse):
    """Generic Occurrence traverser.

    Please note: the .at and .dx subpackages implement their own Occurrence
    traversers.
    """

    def publishTraverse(self, request, name):
        context = self.context
        dateobj = guess_date_from(name, context)
        if dateobj:
            occs = IRecurrenceSupport(context).occurrences(range_start=dateobj)
            try:
                occurrence = next(occs)
                occ_acc = IEventAccessor(occurrence)
                if is_same_day(dateobj, occ_acc.start):
                    return occurrence
            except StopIteration:
                pass
        return self.fallbackTraverse(request, name)

    def fallbackTraverse(self, request, name):
        return super().publishTraverse(request, name)


@implementer(IOccurrence)
class Occurrence(SimpleItem):
    """Transient Occurrence object, representing an individual event in a
    recurrecne set.
    """

    def __init__(self, id, start, end):
        self.id = id
        self.start = start
        self.end = end
        self.portal_type = "Occurrence"


@adapter(IOccurrence)
@implementer(IEventAccessor)
class EventOccurrenceAccessor:
    """Generic event accessor adapter implementation for Occurrence objects."""

    def __init__(self, context):
        object.__setattr__(self, "context", context)

        own_attr = ["start", "end", "url"]
        object.__setattr__(self, "_own_attr", own_attr)

    def _get_context(self, name):
        # TODO: save parent context on self, so it must not be called every
        #       time
        oa = self._own_attr
        if name in oa:
            return self.context
        else:
            return IEventAccessor(aq_parent(self.context))

    def __getattr__(self, name):
        return getattr(self._get_context(name), name, None)

    def __setattr__(self, name, value):
        return setattr(self._get_context(name), name, value)

    def __delattr__(self, name):
        delattr(self._get_context(name), name)

    # R/O properties
    # TODO: Having uid here makes probably no sense, since Occurrences are
    #       created on the fly and not persistent.

    @property
    def url(self):
        return safe_text(self.context.absolute_url())


class ImageScalingViewFactory(BrowserView):
    """Factory for ImageScaling view for Occurrences.
    Delegates to parent @@images view.
    """

    def __new__(cls, context, request):
        parent = aq_parent(context)
        if IImageScaleTraversable.providedBy(parent):
            return ImageScaling(parent, request)
        return None