imip-agent

Annotated imiptools/handlers/scheduling/freebusy.py

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2016-03-02 Paul Boddie file changeset files shortlog Introduced a free/busy collection abstraction for potential access and representation efficiency improvements. freebusy-collections
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#!/usr/bin/env python
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"""
 
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Free/busy-related scheduling functionality.
 
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Copyright (C) 2015, 2016 Paul Boddie <paul@boddie.org.uk>
 
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This program is free software; you can redistribute it and/or modify it under
 
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the terms of the GNU General Public License as published by the Free Software
 
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Foundation; either version 3 of the License, or (at your option) any later
 
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version.
 
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This program is distributed in the hope that it will be useful, but WITHOUT
 
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 
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FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 
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details.
 
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You should have received a copy of the GNU General Public License along with
 
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this program.  If not, see <http://www.gnu.org/licenses/>.
 
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"""
 
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from imiptools.data import uri_values
 
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from imiptools.dates import ValidityError, to_timezone
 
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def schedule_in_freebusy(handler, args, freebusy=None):
 
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    """
 
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    Attempt to schedule the current object of the given 'handler' in the
 
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    free/busy schedule of a resource, returning an indication of the kind of
 
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    response to be returned.
 
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    If 'freebusy' is specified, the given collection of busy periods will be
 
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    used to determine whether any conflicts occur. Otherwise, the current user's
 
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    free/busy records will be used.
 
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    """
 
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    # If newer than any old version, discard old details from the
 
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    # free/busy record and check for suitability.
 
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    periods = handler.get_periods(handler.obj)
 
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    freebusy = freebusy or handler.get_store().get_freebusy(handler.user)
 
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    offers = handler.get_store().get_freebusy_offers(handler.user)
 
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    # Check the periods against any scheduled events and against
 
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    # any outstanding offers.
 
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    scheduled = handler.can_schedule(freebusy, periods)
 
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    scheduled = scheduled and handler.can_schedule(offers, periods)
 
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    return scheduled and "ACCEPTED" or "DECLINED"
 
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def schedule_corrected_in_freebusy(handler, args):
 
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    """
 
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    Attempt to schedule the current object of the given 'handler', correcting
 
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    specified datetimes according to the configuration of a resource,
 
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    returning an indication of the kind of response to be returned.
 
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    """
 
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    obj = handler.obj.copy()
 
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    # Check any constraints on the request.
 
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    try:
 
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        corrected = handler.correct_object()
 
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    # Refuse to schedule obviously invalid requests.
 
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    except ValidityError:
 
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        return None
 
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    # With a valid request, determine whether the event can be scheduled.
 
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    scheduled = schedule_in_freebusy(handler, args)
 
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    # Restore the original object if it was corrected but could not be
 
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    # scheduled.
 
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    if scheduled == "DECLINED" and corrected:
 
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        handler.set_object(obj)
 
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    # Where the corrected object can be scheduled, issue a counter
 
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    # request.
 
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    return scheduled == "ACCEPTED" and (corrected and "COUNTER" or "ACCEPTED") or "DECLINED"
 
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def schedule_next_available_in_freebusy(handler, args):
 
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    """
 
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    Attempt to schedule the current object of the given 'handler', correcting
 
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    specified datetimes according to the configuration of a resource, then
 
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    suggesting the next available period in the free/busy records if scheduling
 
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    cannot occur for the requested period, returning an indication of the kind
 
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    of response to be returned.
 
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    """
 
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    scheduled = schedule_corrected_in_freebusy(handler, args)
 
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    if scheduled in ("ACCEPTED", "COUNTER"):
 
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        return scheduled
 
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    # There should already be free/busy information for the user.
 
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    user_freebusy = handler.get_store().get_freebusy(handler.user)
 
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    busy = user_freebusy
 
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    # Subtract any periods from this event from the free/busy collections.
 
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    event_periods = handler.remove_from_freebusy(user_freebusy)
 
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    # Find busy periods for the other attendees.
 
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    for attendee in uri_values(handler.obj.get_values("ATTENDEE")):
 
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        if attendee != handler.user:
 
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            freebusy = handler.get_store().get_freebusy_for_other(handler.user, attendee)
 
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            if freebusy:
 
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                freebusy.remove_periods(event_periods)
 
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                busy += freebusy
 
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    # Obtain the combined busy periods.
 
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    busy = busy.coalesce_freebusy()
 
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    # Obtain free periods.
 
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    free = busy.invert_freebusy()
 
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    permitted_values = handler.get_permitted_values()
 
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    periods = []
 
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    # Do not attempt to redefine rule-based periods.
 
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    last = None
 
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    for period in handler.get_periods(handler.obj, explicit_only=True):
 
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        duration = period.get_duration()
 
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        # Try and schedule periods normally since some of them may be
 
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        # compatible with the schedule.
 
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        if permitted_values:
 
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            period = period.get_corrected(permitted_values)
 
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        scheduled = handler.can_schedule(freebusy, [period])
 
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        if scheduled == "ACCEPTED":
 
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            periods.append(period)
 
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            last = period.get_end()
 
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            continue
 
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        # Get free periods from the time of each period.
 
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        for found in free.periods_from(period):
 
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            # Skip any periods before the last period.
 
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            if last:
 
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                if last > found.get_end():
 
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                    continue
 
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                # Adjust the start of the free period to exclude the last period.
 
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                found = found.make_corrected(max(found.get_start(), last), found.get_end())
 
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            # Only test free periods long enough to hold the requested period.
 
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            if found.get_duration() >= duration:
 
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                # Obtain a possible period, starting at the found point and
 
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                # with the requested duration. Then, correct the period if
 
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                # necessary.
 
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                start = to_timezone(found.get_start(), period.get_tzid())
 
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                possible = period.make_corrected(start, start + period.get_duration())
 
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                if permitted_values:
 
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                    possible = possible.get_corrected(permitted_values)
 
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                # Only if the possible period is still within the free period
 
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                # can it be used.
 
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                if possible.within(found):
 
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                    periods.append(possible)
 
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                    break
 
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        # Where no period can be found, decline the invitation.
 
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        else:
 
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            return "DECLINED"
 
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        # Use the found period to set the start of the next window to search.
 
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        last = periods[-1].get_end()
 
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    # Replace the periods in the object.
 
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    obj = handler.obj.copy()
 
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    changed = handler.obj.set_periods(periods)
 
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    # Check one last time, reverting the change if not scheduled.
 
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    scheduled = schedule_in_freebusy(handler, args, busy)
 
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    if scheduled == "DECLINED":
 
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        handler.set_object(obj)
 
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    return scheduled == "ACCEPTED" and (changed and "COUNTER" or "ACCEPTED") or "DECLINED"
 
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# Registry of scheduling functions.
 
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scheduling_functions = {
 
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    "schedule_in_freebusy" : schedule_in_freebusy,
 
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    "schedule_corrected_in_freebusy" : schedule_corrected_in_freebusy,
 
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    "schedule_next_available_in_freebusy" : schedule_next_available_in_freebusy,
 
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    }
 
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# Registries of locking and unlocking functions.
 
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locking_functions = {}
 
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unlocking_functions = {}
 
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# Registries of listener functions.
 
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confirmation_functions = {}
 
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retraction_functions = {}
 
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# vim: tabstop=4 expandtab shiftwidth=4