imip-agent

Annotated imiptools/data.py

327:980a67718ff7
2015-02-11 Paul Boddie Added missing support for constraining free/busy requests to certain periods.
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#!/usr/bin/env python
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"""
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Interpretation of vCalendar content.
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Copyright (C) 2014, 2015 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 datetime import datetime, timedelta
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from email.mime.text import MIMEText
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from imiptools.dates import format_datetime, get_datetime, get_freebusy_period, \
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                            to_timezone, to_utc_datetime
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from imiptools.period import period_overlaps
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from pytz import timezone
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from vCalendar import iterwrite, parse, ParseError, to_dict, to_node
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from vRecurrence import get_parameters, get_rule
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import email.utils
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try:
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    from cStringIO import StringIO
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except ImportError:
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    from StringIO import StringIO
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class Object:
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    "Access to calendar structures."
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    def __init__(self, fragment):
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        self.objtype, (self.details, self.attr) = fragment.items()[0]
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    def get_items(self, name, all=True):
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        return get_items(self.details, name, all)
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    def get_item(self, name):
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        return get_item(self.details, name)
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    def get_value_map(self, name):
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        return get_value_map(self.details, name)
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    def get_values(self, name, all=True):
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        return get_values(self.details, name, all)
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    def get_value(self, name):
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        return get_value(self.details, name)
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    def get_utc_datetime(self, name):
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        return get_utc_datetime(self.details, name)
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    def get_datetime(self, name):
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        dt, attr = get_datetime_item(self.details, name)
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        return dt
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    def get_datetime_item(self, name):
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        return get_datetime_item(self.details, name)
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    def to_node(self):
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        return to_node({self.objtype : [(self.details, self.attr)]})
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    def to_part(self, method):
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        return to_part(method, [self.to_node()])
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    # Direct access to the structure.
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    def __getitem__(self, name):
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        return self.details[name]
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    def __setitem__(self, name, value):
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        self.details[name] = value
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    def __delitem__(self, name):
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        del self.details[name]
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    # Computed results.
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    def get_periods(self, tzid, window_size=100):
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        return get_periods(self, tzid, window_size)
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    def get_periods_for_freebusy(self, tzid, window_size=100):
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        periods = self.get_periods(tzid, window_size)
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        return get_periods_for_freebusy(self, periods, tzid)
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# Construction and serialisation.
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def make_calendar(nodes, method=None):
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    """
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    Return a complete calendar node wrapping the given 'nodes' and employing the
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    given 'method', if indicated.
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    """
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    return ("VCALENDAR", {},
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            (method and [("METHOD", {}, method)] or []) +
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            [("VERSION", {}, "2.0")] +
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            nodes
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           )
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def make_freebusy(freebusy, uid, organiser, organiser_attr=None, attendee=None,
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    attendee_attr=None, dtstart=None, dtend=None):
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    """
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    Return a calendar node defining the free/busy details described in the given
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    'freebusy' list, employing the given 'uid', for the given 'organiser' and
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    optional 'organiser_attr', with the optional 'attendee' providing recipient
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    details together with the optional 'attendee_attr'.
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    The result will be constrained to the 'dtstart' and 'dtend' period if these
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    parameters are given.
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    """
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    record = []
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    rwrite = record.append
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    rwrite(("ORGANIZER", organiser_attr or {}, organiser))
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    if attendee:
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        rwrite(("ATTENDEE", attendee_attr or {}, attendee)) 
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    rwrite(("UID", {}, uid))
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    if freebusy:
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        # Get a constrained view if start and end limits are specified.
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        periods = dtstart and dtend and period_overlaps(freebusy, (dtstart, dtend), True) or freebusy
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        # Write the limits of the resource.
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        rwrite(("DTSTART", {"VALUE" : "DATE-TIME"}, periods[0][0]))
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        rwrite(("DTEND", {"VALUE" : "DATE-TIME"}, periods[-1][1]))
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        for start, end, uid, transp in periods:
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            if transp == "OPAQUE":
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                rwrite(("FREEBUSY", {"FBTYPE" : "BUSY"}, "/".join([start, end])))
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    return ("VFREEBUSY", {}, record)
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def parse_object(f, encoding, objtype=None):
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    """
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    Parse the iTIP content from 'f' having the given 'encoding'. If 'objtype' is
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    given, only objects of that type will be returned. Otherwise, the root of
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    the content will be returned as a dictionary with a single key indicating
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    the object type.
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    Return None if the content was not readable or suitable.
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    """
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    try:
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        try:
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            doctype, attrs, elements = obj = parse(f, encoding=encoding)
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            if objtype and doctype == objtype:
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                return to_dict(obj)[objtype][0]
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            elif not objtype:
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                return to_dict(obj)
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        finally:
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            f.close()
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    # NOTE: Handle parse errors properly.
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    except (ParseError, ValueError):
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        pass
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    return None
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def to_part(method, calendar):
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    """
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    Write using the given 'method', the 'calendar' details to a MIME
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    text/calendar part.
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    """
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    encoding = "utf-8"
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    out = StringIO()
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    try:
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        to_stream(out, make_calendar(calendar, method), encoding)
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        part = MIMEText(out.getvalue(), "calendar", encoding)
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        part.set_param("method", method)
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        return part
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    finally:
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        out.close()
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def to_stream(out, fragment, encoding="utf-8"):
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    iterwrite(out, encoding=encoding).append(fragment)
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# Structure access functions.
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def get_items(d, name, all=True):
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    """
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    Get all items from 'd' for the given 'name', returning single items if
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    'all' is specified and set to a false value and if only one value is
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    present for the name. Return None if no items are found for the name or if
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    many items are found but 'all' is set to a false value.
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    """
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    if d.has_key(name):
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        values = d[name]
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        if all:
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            return values
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        elif len(values) == 1:
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            return values[0]
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        else:
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            return None
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    else:
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        return None
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def get_item(d, name):
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    return get_items(d, name, False)
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def get_value_map(d, name):
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    """
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    Return a dictionary for all items in 'd' having the given 'name'. The
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    dictionary will map values for the name to any attributes or qualifiers
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    that may have been present.
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    """
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    items = get_items(d, name)
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    if items:
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        return dict(items)
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    else:
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        return {}
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def get_values(d, name, all=True):
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    if d.has_key(name):
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        values = d[name]
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        if not all and len(values) == 1:
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            return values[0][0]
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        else:
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            return map(lambda x: x[0], values)
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    else:
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        return None
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def get_value(d, name):
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    return get_values(d, name, False)
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def get_utc_datetime(d, name):
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    dt, attr = get_datetime_item(d, name)
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    return to_utc_datetime(dt)
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def get_datetime_item(d, name):
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    value, attr = get_item(d, name)
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    return get_datetime(value, attr), attr
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def get_addresses(values):
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    return [address for name, address in email.utils.getaddresses(values)]
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def get_address(value):
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    return value.lower().startswith("mailto:") and value.lower()[7:] or value
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def get_uri(value):
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    return value.lower().startswith("mailto:") and value.lower() or ":" in value and value or "mailto:%s" % value.lower()
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uri_value = get_uri
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def uri_values(values):
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    return map(get_uri, values)
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def uri_dict(d):
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    return dict([(get_uri(key), value) for key, value in d.items()])
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def uri_item(item):
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    return get_uri(item[0]), item[1]
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def uri_items(items):
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    return [(get_uri(value), attr) for value, attr in items]
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# Operations on structure data.
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def is_new_object(old_sequence, new_sequence, old_dtstamp, new_dtstamp, partstat_set):
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    """
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    Return for the given 'old_sequence' and 'new_sequence', 'old_dtstamp' and
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    'new_dtstamp', and the 'partstat_set' indication, whether the object
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    providing the new information is really newer than the object providing the
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    old information.
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    """
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    have_sequence = old_sequence is not None and new_sequence is not None
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    is_same_sequence = have_sequence and int(new_sequence) == int(old_sequence)
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    have_dtstamp = old_dtstamp and new_dtstamp
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    is_old_dtstamp = have_dtstamp and new_dtstamp < old_dtstamp or old_dtstamp and not new_dtstamp
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    is_old_sequence = have_sequence and (
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        int(new_sequence) < int(old_sequence) or
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        is_same_sequence and is_old_dtstamp
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        )
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    return is_same_sequence and partstat_set or not is_old_sequence
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# NOTE: Need to expose the 100 day window for recurring events in the
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# NOTE: configuration.
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def get_periods(obj, tzid, window_size=100):
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    """
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    Return periods for the given object 'obj', confining materialised periods
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    to the given 'window_size' in days starting from the present moment.
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    """
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    # NOTE: Need also RDATE and EXDATE support.
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    rrule = obj.get_value("RRULE")
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    if not rrule:
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        return [(obj.get_datetime("DTSTART"), obj.get_datetime("DTEND"))]
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    # Use localised datetimes.
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    dtstart, start_attr = obj.get_datetime_item("DTSTART")
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    dtend, end_attr = obj.get_datetime_item("DTEND")
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    tzid = start_attr.get("TZID") or end_attr.get("TZID") or tzid
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    # NOTE: Need also DURATION support.
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    duration = dtend - dtstart
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    # Recurrence rules create multiple instances to be checked.
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    # Conflicts may only be assessed within a period defined by policy
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    # for the agent, with instances outside that period being considered
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    # unchecked.
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    window_end = to_timezone(datetime.now(), tzid) + timedelta(window_size)
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    selector = get_rule(dtstart, rrule)
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    parameters = get_parameters(rrule)
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    periods = []
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    for start in selector.materialise(dtstart, window_end, parameters.get("COUNT"), parameters.get("BYSETPOS")):
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        start = to_timezone(datetime(*start), tzid)
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        end = start + duration
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        periods.append((start, end))
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    return periods
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def get_periods_for_freebusy(obj, periods, tzid):
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    """
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    Get free/busy-compliant periods employed by 'obj' from the given 'periods',
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    using the indicated 'tzid' to convert dates to datetimes.
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    """
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    start, start_attr = obj.get_datetime_item("DTSTART")
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    end, end_attr = obj.get_datetime_item("DTEND")
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    tzid = start_attr.get("TZID") or end_attr.get("TZID") or tzid
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    l = []
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    for start, end in periods:
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        start, end = get_freebusy_period(start, end, tzid)
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        start, end = [to_timezone(x, "UTC") for x in start, end]
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        l.append((format_datetime(start), format_datetime(end)))
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    return l
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# vim: tabstop=4 expandtab shiftwidth=4