# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1422752377 -3600
# Node ID 7233b6cee1b0b0377230735b9214b648e1e1ea35
# Parent  7dc75bb19e9111a3289fa07dbc430c3aceaca65c
Introduced an Object class for calendar objects and fragments, thus changing
most of the code accessing such data.
Added SENT-BY to manager-originating invitations.

diff -r 7dc75bb19e91 -r 7233b6cee1b0 imip_manager.py
--- a/imip_manager.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imip_manager.py	Sun Feb 01 01:59:37 2015 +0100
@@ -30,10 +30,8 @@
 
 sys.path.append(LIBRARY_PATH)
 
-from imiptools.content import Handler, get_address, \
-                              get_item, get_items, get_uri, get_utc_datetime, \
-                              get_value, get_value_map, get_values, \
-                              parse_object, to_part
+from imiptools.content import Handler
+from imiptools.data import get_address, get_uri, parse_object, Object
 from imiptools.dates import format_datetime, get_datetime, get_start_of_day, \
                             get_end_of_day, ends_on_same_day, to_timezone
 from imiptools.mail import Messenger
@@ -42,9 +40,8 @@
                              get_scale, have_conflict, get_slots, get_spans, \
                              partition_by_day
 from imiptools.profile import Preferences
-from vCalendar import to_node
+import imip_store
 import markup
-import imip_store
 
 getenv = os.environ.get
 setenv = os.environ.__setitem__
@@ -116,14 +113,11 @@
     """
 
     def __init__(self, obj, user, messenger):
-        details, details_attr = obj.values()[0]
-        Handler.__init__(self, details)
-        self.obj = obj
+        Handler.__init__(self, obj, messenger=messenger)
         self.user = user
-        self.messenger = messenger
 
-        self.organiser = self.get_value("ORGANIZER")
-        self.attendees = self.get_values("ATTENDEE")
+        self.organiser = self.obj.get_value("ORGANIZER")
+        self.attendees = self.obj.get_values("ATTENDEE")
 
     # Communication methods.
 
@@ -134,8 +128,7 @@
         to the appropriate recipients, also sending a copy to the 'sender'.
         """
 
-        node = to_node(self.obj)
-        part = to_part(method, [node])
+        part = self.obj.to_part(method)
 
         if self.user == self.organiser:
             recipients = map(get_address, self.attendees)
@@ -161,16 +154,16 @@
         # When accepting or declining, do so only on behalf of this user,
         # preserving any other attributes set as an attendee.
 
-        for attendee, attendee_attr in self.get_items("ATTENDEE"):
+        for attendee, attendee_attr in self.obj.get_items("ATTENDEE"):
 
             if attendee == self.user:
                 attendee_attr["PARTSTAT"] = accept and "ACCEPTED" or "DECLINED"
                 if self.messenger and self.messenger.sender != get_address(attendee):
                     attendee_attr["SENT-BY"] = get_uri(self.messenger.sender)
-                self.details["ATTENDEE"] = [(attendee, attendee_attr)]
+                self.obj["ATTENDEE"] = [(attendee, attendee_attr)]
                 if update:
-                    sequence = self.get_value("SEQUENCE") or "0"
-                    self.details["SEQUENCE"] = [(str(int(sequence) + 1), {})]
+                    sequence = self.obj.get_value("SEQUENCE") or "0"
+                    self.obj["SEQUENCE"] = [(str(int(sequence) + 1), {})]
                 self.update_dtstamp()
 
                 self.send_message("REPLY", get_address(attendee))
@@ -189,9 +182,13 @@
         to override any previous message.
         """
 
+        organiser, organiser_attr = self.obj.get_item("ORGANIZER")
+
+        if self.messenger and self.messenger.sender != get_address(organiser):
+            organiser_attr["SENT-BY"] = get_uri(self.messenger.sender)
         if update:
-            sequence = self.get_value("SEQUENCE") or "0"
-            self.details["SEQUENCE"] = [(str(int(sequence) + 1), {})]
+            sequence = self.obj.get_value("SEQUENCE") or "0"
+            self.obj["SEQUENCE"] = [(str(int(sequence) + 1), {})]
         self.update_dtstamp()
 
         self.send_message("REQUEST", get_address(self.organiser))
@@ -237,17 +234,11 @@
         if not f:
             return None
 
-        self.objects[uid] = obj = parse_object(f, "utf-8")
-
-        if not obj:
-            return None
+        fragment = parse_object(f, "utf-8")
+        obj = self.objects[uid] = fragment and Object(fragment)
 
         return obj
 
-    def _get_details(self, obj):
-        details, details_attr = obj.values()[0]
-        return details
-
     def _get_requests(self):
         if self.requests is None:
             self.requests = self.store.get_requests(self.user)
@@ -258,10 +249,9 @@
         for uid in self._get_requests():
             obj = self._get_object(uid)
             if obj:
-                details = self._get_details(obj)
                 summary.append((
-                    get_value(details, "DTSTART"),
-                    get_value(details, "DTEND"),
+                    obj.get_value("DTSTART"),
+                    obj.get_value("DTEND"),
                     uid
                     ))
         return summary
@@ -406,8 +396,7 @@
         # Update the object.
 
         if args.has_key("summary"):
-            details = self._get_details(obj)
-            details["SUMMARY"] = [(args["summary"][0], {})]
+            obj["SUMMARY"] = [(args["summary"][0], {})]
 
         # Process any action.
 
@@ -452,11 +441,10 @@
 
         page = self.page
 
-        details = self._get_details(obj)
-        is_organiser = get_value(details, "ORGANIZER") == self.user
+        is_organiser = obj.get_value("ORGANIZER") == self.user
 
         if not is_organiser:
-            attendees = get_value_map(details, "ATTENDEE")
+            attendees = obj.get_value_map("ATTENDEE")
             attendee_attr = attendees.get(self.user)
 
             if attendee_attr:
@@ -519,8 +507,6 @@
 
         # Provide a summary of the object.
 
-        details = self._get_details(obj)
-
         page.table(id="object", cellspacing=5, cellpadding=5)
         page.thead()
         page.tr()
@@ -537,7 +523,7 @@
             # Handle datetimes specially.
 
             if name in ["DTSTART", "DTEND"]:
-                value, attr = get_item(details, name)
+                value, attr = obj.get_item(name)
                 tzid = attr.get("TZID", tzid)
                 value = self.format_datetime(to_timezone(get_datetime(value), tzid), "full")
                 page.th(label, class_="objectheading")
@@ -547,7 +533,7 @@
             # Handle the summary specially.
 
             elif name == "SUMMARY":
-                value = get_value(details, name)
+                value = obj.get_value(name)
                 page.th(label, class_="objectheading")
                 page.td()
                 page.input(name="summary", type="text", value=value, size=80)
@@ -557,7 +543,7 @@
             # Handle potentially many values.
 
             else:
-                items = get_items(details, name)
+                items = obj.get_items(name)
                 page.th(label, class_="objectheading", rowspan=len(items))
 
                 first = True
@@ -582,8 +568,8 @@
         page.tbody.close()
         page.table.close()
 
-        dtstart = format_datetime(get_utc_datetime(details, "DTSTART"))
-        dtend = format_datetime(get_utc_datetime(details, "DTEND"))
+        dtstart = format_datetime(obj.get_utc_datetime("DTSTART"))
+        dtend = format_datetime(obj.get_utc_datetime("DTEND"))
 
         # Indicate whether there are conflicting events.
 
@@ -593,7 +579,7 @@
 
             # Obtain any time zone details from the suggested event.
 
-            _dtstart, attr = get_item(details, "DTSTART")
+            _dtstart, attr = obj.get_item("DTSTART")
             tzid = attr.get("TZID", tzid)
 
             # Show any conflicts.
@@ -612,8 +598,7 @@
 
                     found_obj = self._get_object(found_uid)
                     if found_obj:
-                        found_details = self._get_details(found_obj)
-                        page.a(get_value(found_details, "SUMMARY"), href=self.env.new_url(found_uid))
+                        page.a(found_obj.get_value("SUMMARY"), href=self.env.new_url(found_uid))
 
         self.show_request_controls(obj, needs_action)
         page.form.close()
@@ -637,9 +622,8 @@
             for request in requests:
                 obj = self._get_object(request)
                 if obj:
-                    details = self._get_details(obj)
                     self.page.li()
-                    self.page.a(get_value(details, "SUMMARY"), href="#request-%s" % request)
+                    self.page.a(obj.get_value("SUMMARY"), href="#request-%s" % request)
                     self.page.li.close()
 
             self.page.ul.close()
@@ -1020,8 +1004,7 @@
                             if not obj:
                                 page.span("")
                             else:
-                                details = self._get_details(obj)
-                                summary = get_value(details, "SUMMARY")
+                                summary = obj.get_value("SUMMARY")
 
                                 # Only link to events if they are not being
                                 # updated by requests.
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imip_store.py
--- a/imip_store.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imip_store.py	Sun Feb 01 01:59:37 2015 +0100
@@ -21,26 +21,10 @@
 
 from datetime import datetime
 from imiptools.config import STORE_DIR, PUBLISH_DIR
+from imiptools.data import make_calendar, to_stream
 from imiptools.filesys import fix_permissions, FileBase
 from os.path import exists, isfile, join
 from os import listdir
-from vCalendar import iterwrite
-
-def make_calendar(fragment, method=None):
-
-    """
-    Return a complete calendar item wrapping the given 'fragment' and employing
-    the given 'method', if indicated.
-    """
-
-    return ("VCALENDAR", {},
-            (method and [("METHOD", {}, method)] or []) +
-            [("VERSION", {}, "2.0")] +
-            fragment
-           )
-
-def to_stream(out, fragment, encoding="utf-8"):
-    iterwrite(out, encoding=encoding).append(fragment)
 
 class FileStore(FileBase):
 
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/__init__.py
--- a/imiptools/__init__.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/__init__.py	Sun Feb 01 01:59:37 2015 +0100
@@ -20,7 +20,8 @@
 """
 
 from email import message_from_file
-from imiptools.content import get_addresses, get_uri, handle_itip_part
+from imiptools.content import handle_itip_part
+from imiptools.data import get_addresses, get_uri
 from imiptools.mail import Messenger
 from imiptools.profile import Preferences
 import sys
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/content.py
--- a/imiptools/content.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/content.py	Sun Feb 01 01:59:37 2015 +0100
@@ -23,13 +23,14 @@
 from datetime import datetime, timedelta
 from email.mime.text import MIMEText
 from imiptools.config import MANAGER_PATH, MANAGER_URL
+from imiptools.data import Object, parse_object, \
+                           get_address, get_fragments, \
+                           get_uri, get_value, uri_dict, uri_item
 from imiptools.dates import *
 from imiptools.period import have_conflict, insert_period, remove_period
 from pytz import timezone
 from socket import gethostname
-from vCalendar import parse, ParseError, to_dict
 from vRecurrence import get_parameters, get_rule
-import email.utils
 import imip_store
 
 try:
@@ -37,81 +38,6 @@
 except ImportError:
     from StringIO import StringIO
 
-# Content interpretation.
-
-def get_items(d, name, all=True):
-
-    """
-    Get all items from 'd' with the given 'name', returning single items if
-    'all' is specified and set to a false value and if only one value is
-    present for the name. Return None if no items are found for the name or if
-    many items are found but 'all' is set to a false value.
-    """
-
-    if d.has_key(name):
-        values = d[name]
-        if all:
-            return values
-        elif len(values) == 1:
-            return values[0]
-        else:
-            return None
-    else:
-        return None
-
-def get_item(d, name):
-    return get_items(d, name, False)
-
-def get_value_map(d, name):
-
-    """
-    Return a dictionary for all items in 'd' having the given 'name'. The
-    dictionary will map values for the name to any attributes or qualifiers
-    that may have been present.
-    """
-
-    items = get_items(d, name)
-    if items:
-        return dict(items)
-    else:
-        return {}
-
-def get_values(d, name, all=True):
-    if d.has_key(name):
-        values = d[name]
-        if not all and len(values) == 1:
-            return values[0][0]
-        else:
-            return map(lambda x: x[0], values)
-    else:
-        return None
-
-def get_value(d, name):
-    return get_values(d, name, False)
-
-def get_utc_datetime(d, name):
-    value, attr = get_item(d, name)
-    dt = get_datetime(value, attr)
-    return to_utc_datetime(dt)
-
-def get_addresses(values):
-    return [address for name, address in email.utils.getaddresses(values)]
-
-def get_address(value):
-    return value.lower().startswith("mailto:") and value.lower()[7:] or value
-
-def get_uri(value):
-    return value.lower().startswith("mailto:") and value.lower() or ":" in value and value or "mailto:%s" % value.lower()
-
-def uri_dict(d):
-    return dict([(get_uri(key), value) for key, value in d.items()])
-
-def uri_item(item):
-    return get_uri(item[0]), item[1]
-
-def uri_items(items):
-    return [(get_uri(value), attr) for value, attr in items]
-
 def is_new_object(old_sequence, new_sequence, old_dtstamp, new_dtstamp, partstat_set):
 
     """
@@ -144,8 +70,8 @@
     to the given 'window_size' in days starting from the present moment.
     """
 
-    dtstart = get_utc_datetime(obj, "DTSTART")
-    dtend = get_utc_datetime(obj, "DTEND")
+    dtstart = obj.get_utc_datetime("DTSTART")
+    dtend = obj.get_utc_datetime("DTEND")
 
     # NOTE: Need also DURATION support.
 
@@ -160,7 +86,7 @@
 
     # NOTE: Need also RDATE and EXDATE support.
 
-    rrule = get_value(obj, "RRULE")
+    rrule = obj.get_value("RRULE")
 
     if rrule:
         selector = get_rule(dtstart, rrule)
@@ -274,11 +200,11 @@
         all_results = []
 
         for name, cls in handlers:
-            for details in get_values(itip, name) or []:
+            for fragment in get_fragments(itip, name):
 
                 # Dispatch to a handler and obtain any response.
 
-                handler = cls(details, senders, recipient, messenger)
+                handler = cls(Object(fragment), senders, recipient, messenger)
                 results = methods[method](handler)()
 
                 # Aggregate responses for a single message.
@@ -292,52 +218,6 @@
 
     return []
 
-def parse_object(f, encoding, objtype=None):
-
-    """
-    Parse the iTIP content from 'f' having the given 'encoding'. If 'objtype' is
-    given, only objects of that type will be returned. Otherwise, the root of
-    the content will be returned as a dictionary with a single key indicating
-    the object type.
-
-    Return None if the content was not readable or suitable.
-    """
-
-    try:
-        try:
-            doctype, attrs, elements = obj = parse(f, encoding=encoding)
-            if objtype and doctype == objtype:
-                return to_dict(obj)[objtype][0]
-            elif not objtype:
-                return to_dict(obj)
-        finally:
-            f.close()
-
-    # NOTE: Handle parse errors properly.
-
-    except (ParseError, ValueError):
-        pass
-
-    return None
-
-def to_part(method, calendar):
-
-    """
-    Write using the given 'method', the 'calendar' details to a MIME
-    text/calendar part.
-    """
-
-    encoding = "utf-8"
-    out = StringIO()
-    try:
-        imip_store.to_stream(out, imip_store.make_calendar(calendar, method), encoding)
-        part = MIMEText(out.getvalue(), "calendar", encoding)
-        part.set_param("method", method)
-        return part
-
-    finally:
-        out.close()
-
 # References to the Web interface.
 
 def get_manager_url():
@@ -351,21 +231,21 @@
 
     "General handler support."
 
-    def __init__(self, details, senders=None, recipient=None, messenger=None):
+    def __init__(self, obj, senders=None, recipient=None, messenger=None):
 
         """
-        Initialise the handler with the 'details' of a calendar object and the
-        'senders' and 'recipient' of the object (if specifically indicated).
+        Initialise the handler with the calendar 'obj' and the 'senders' and
+        'recipient' of the object (if specifically indicated).
         """
 
-        self.details = details
+        self.obj = obj
         self.senders = senders and set(map(get_address, senders))
         self.recipient = recipient and get_address(recipient)
         self.messenger = messenger
 
-        self.uid = self.get_value("UID")
-        self.sequence = self.get_value("SEQUENCE")
-        self.dtstamp = self.get_value("DTSTAMP")
+        self.uid = self.obj.get_value("UID")
+        self.sequence = self.obj.get_value("SEQUENCE")
+        self.dtstamp = self.obj.get_value("DTSTAMP")
 
         self.store = imip_store.FileStore()
 
@@ -389,26 +269,8 @@
 
     # Access to calendar structures and other data.
 
-    def get_items(self, name, all=True):
-        return get_items(self.details, name, all)
-
-    def get_item(self, name):
-        return get_item(self.details, name)
-
-    def get_value_map(self, name):
-        return get_value_map(self.details, name)
-
-    def get_values(self, name, all=True):
-        return get_values(self.details, name, all)
-
-    def get_value(self, name):
-        return get_value(self.details, name)
-
-    def get_utc_datetime(self, name):
-        return get_utc_datetime(self.details, name)
-
     def get_periods(self):
-        return get_periods(self.details)
+        return get_periods(self.obj)
 
     def remove_from_freebusy(self, freebusy, attendee):
         remove_from_freebusy(freebusy, attendee, self.uid, self.store)
@@ -417,10 +279,10 @@
         remove_from_freebusy_for_other(freebusy, user, other, self.uid, self.store)
 
     def update_freebusy(self, freebusy, attendee, periods):
-        return update_freebusy(freebusy, attendee, periods, self.get_value("TRANSP"), self.uid, self.store)
+        return update_freebusy(freebusy, attendee, periods, self.obj.get_value("TRANSP"), self.uid, self.store)
 
     def update_freebusy_for_other(self, freebusy, user, other, periods):
-        return update_freebusy_for_other(freebusy, user, other, periods, self.get_value("TRANSP"), self.uid, self.store)
+        return update_freebusy_for_other(freebusy, user, other, periods, self.obj.get_value("TRANSP"), self.uid, self.store)
 
     def can_schedule(self, freebusy, periods):
         return can_schedule(freebusy, periods, self.uid)
@@ -470,8 +332,8 @@
         Organiser and attendee identities are provided as lower case values.
         """
 
-        attendee_map = uri_dict(self.get_value_map("ATTENDEE"))
-        organiser_item = uri_item(self.get_item("ORGANIZER"))
+        attendee_map = uri_dict(self.obj.get_value_map("ATTENDEE"))
+        organiser_item = uri_item(self.obj.get_item("ORGANIZER"))
 
         # Only provide details for attendees who sent/receive the message.
 
@@ -512,7 +374,7 @@
 
         return senders
 
-    def get_object(self, user, objtype):
+    def get_object(self, user):
 
         """
         Return the stored object to which the current object refers for the
@@ -520,23 +382,23 @@
         """
 
         f = self.store.get_event(user, self.uid)
-        obj = f and parse_object(f, "utf-8", objtype)
-        return obj
+        fragment = f and parse_object(f, "utf-8")
+        return fragment and Object(fragment)
 
-    def have_new_object(self, attendee, objtype, obj=None):
+    def have_new_object(self, attendee, obj=None):
 
         """
-        Return whether the current object is new to the 'attendee' for the
-        given 'objtype'.
+        Return whether the current object is new to the 'attendee' (or if the
+        given 'obj' is new).
         """
 
-        obj = obj or self.get_object(attendee, objtype)
+        obj = obj or self.get_object(attendee)
 
         # If found, compare SEQUENCE and potentially DTSTAMP.
 
         if obj:
-            sequence = get_value(obj, "SEQUENCE")
-            dtstamp = get_value(obj, "DTSTAMP")
+            sequence = obj.get_value("SEQUENCE")
+            dtstamp = obj.get_value("DTSTAMP")
 
             # If the request refers to an older version of the object, ignore
             # it.
@@ -557,8 +419,8 @@
         NOTE: incorporated into any new object assessment.
         """
 
-        old_attendees = get_value_map(obj, "ATTENDEE")
-        new_attendees = self.get_value_map("ATTENDEE")
+        old_attendees = obj.get_value_map("ATTENDEE")
+        new_attendees = self.obj.get_value_map("ATTENDEE")
 
         for attendee, attr in old_attendees.items():
             old_partstat = attr.get("PARTSTAT")
@@ -576,9 +438,9 @@
 
         "Update the DTSTAMP in the current object."
 
-        dtstamp = self.get_utc_datetime("DTSTAMP")
+        dtstamp = self.obj.get_utc_datetime("DTSTAMP")
         utcnow = to_timezone(datetime.utcnow(), "UTC")
-        self.details["DTSTAMP"] = [(format_datetime(dtstamp > utcnow and dtstamp or utcnow), {})]
+        self.obj["DTSTAMP"] = [(format_datetime(dtstamp > utcnow and dtstamp or utcnow), {})]
 
 # Handler registry.
 
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/data.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imiptools/data.py	Sun Feb 01 01:59:37 2015 +0100
@@ -0,0 +1,226 @@
+#!/usr/bin/env python
+
+"""
+Interpretation of vCalendar content.
+
+Copyright (C) 2014, 2015 Paul Boddie <paul@boddie.org.uk>
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+details.
+
+You should have received a copy of the GNU General Public License along with
+this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+from email.mime.text import MIMEText
+from imiptools.dates import get_datetime, to_utc_datetime
+from vCalendar import iterwrite, parse, ParseError, to_dict, to_node
+import email.utils
+
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
+
+class Object:
+
+    "Access to calendar structures."
+
+    def __init__(self, fragment):
+        self.objtype, (self.details, self.attr) = fragment.items()[0]
+
+    def get_items(self, name, all=True):
+        return get_items(self.details, name, all)
+
+    def get_item(self, name):
+        return get_item(self.details, name)
+
+    def get_value_map(self, name):
+        return get_value_map(self.details, name)
+
+    def get_values(self, name, all=True):
+        return get_values(self.details, name, all)
+
+    def get_value(self, name):
+        return get_value(self.details, name)
+
+    def get_utc_datetime(self, name):
+        return get_utc_datetime(self.details, name)
+
+    def to_node(self):
+        return to_node({self.objtype : [(self.details, self.attr)]})
+
+    def to_part(self, method):
+        return to_part(method, [self.to_node()])
+
+    # Direct access to the structure.
+
+    def __getitem__(self, name):
+        return self.details[name]
+
+    def __setitem__(self, name, value):
+        self.details[name] = value
+
+    def __delitem__(self, name):
+        del self.details[name]
+
+# Construction and serialisation.
+
+def make_calendar(nodes, method=None):
+
+    """
+    Return a complete calendar node wrapping the given 'nodes' and employing the
+    given 'method', if indicated.
+    """
+
+    return ("VCALENDAR", {},
+            (method and [("METHOD", {}, method)] or []) +
+            [("VERSION", {}, "2.0")] +
+            nodes
+           )
+
+def parse_object(f, encoding, objtype=None):
+
+    """
+    Parse the iTIP content from 'f' having the given 'encoding'. If 'objtype' is
+    given, only objects of that type will be returned. Otherwise, the root of
+    the content will be returned as a dictionary with a single key indicating
+    the object type.
+
+    Return None if the content was not readable or suitable.
+    """
+
+    try:
+        try:
+            doctype, attrs, elements = obj = parse(f, encoding=encoding)
+            if objtype and doctype == objtype:
+                return to_dict(obj)[objtype][0]
+            elif not objtype:
+                return to_dict(obj)
+        finally:
+            f.close()
+
+    # NOTE: Handle parse errors properly.
+
+    except (ParseError, ValueError):
+        pass
+
+    return None
+
+def to_part(method, calendar):
+
+    """
+    Write using the given 'method', the 'calendar' details to a MIME
+    text/calendar part.
+    """
+
+    encoding = "utf-8"
+    out = StringIO()
+    try:
+        to_stream(out, make_calendar(calendar, method), encoding)
+        part = MIMEText(out.getvalue(), "calendar", encoding)
+        part.set_param("method", method)
+        return part
+
+    finally:
+        out.close()
+
+def to_stream(out, fragment, encoding="utf-8"):
+    iterwrite(out, encoding=encoding).append(fragment)
+
+# Structure access functions.
+
+def get_fragments(d, name):
+
+    """
+    Return all fragments from 'd' with the given 'name'. Each fragment is thus
+    suitable for using to initialise Object instances.
+    """
+
+    fragments = []
+    if d.has_key(name):
+        for value in d[name]:
+            fragments.append(dict([(name, value)]))
+    return fragments
+
+def get_items(d, name, all=True):
+
+    """
+    Get all items from 'd' for the given 'name', returning single items if
+    'all' is specified and set to a false value and if only one value is
+    present for the name. Return None if no items are found for the name or if
+    many items are found but 'all' is set to a false value.
+    """
+
+    if d.has_key(name):
+        values = d[name]
+        if all:
+            return values
+        elif len(values) == 1:
+            return values[0]
+        else:
+            return None
+    else:
+        return None
+
+def get_item(d, name):
+    return get_items(d, name, False)
+
+def get_value_map(d, name):
+
+    """
+    Return a dictionary for all items in 'd' having the given 'name'. The
+    dictionary will map values for the name to any attributes or qualifiers
+    that may have been present.
+    """
+
+    items = get_items(d, name)
+    if items:
+        return dict(items)
+    else:
+        return {}
+
+def get_values(d, name, all=True):
+    if d.has_key(name):
+        values = d[name]
+        if not all and len(values) == 1:
+            return values[0][0]
+        else:
+            return map(lambda x: x[0], values)
+    else:
+        return None
+
+def get_value(d, name):
+    return get_values(d, name, False)
+
+def get_utc_datetime(d, name):
+    value, attr = get_item(d, name)
+    dt = get_datetime(value, attr)
+    return to_utc_datetime(dt)
+
+def get_addresses(values):
+    return [address for name, address in email.utils.getaddresses(values)]
+
+def get_address(value):
+    return value.lower().startswith("mailto:") and value.lower()[7:] or value
+
+def get_uri(value):
+    return value.lower().startswith("mailto:") and value.lower() or ":" in value and value or "mailto:%s" % value.lower()
+
+def uri_dict(d):
+    return dict([(get_uri(key), value) for key, value in d.items()])
+
+def uri_item(item):
+    return get_uri(item[0]), item[1]
+
+def uri_items(items):
+    return [(get_uri(value), attr) for value, attr in items]
+
+# vim: tabstop=4 expandtab shiftwidth=4
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/handlers/common.py
--- a/imiptools/handlers/common.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/handlers/common.py	Sun Feb 01 01:59:37 2015 +0100
@@ -19,7 +19,7 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from imiptools.content import to_part
+from imiptools.data import to_part
 
 class SupportFreebusy:
 
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/handlers/person.py
--- a/imiptools/handlers/person.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/handlers/person.py	Sun Feb 01 01:59:37 2015 +0100
@@ -19,16 +19,16 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from imiptools.content import Handler, get_address, get_uri, to_part, uri_dict, uri_items
+from imiptools.content import Handler
+from imiptools.data import get_address, get_uri, uri_dict, uri_items
 from imiptools.handlers.common import CommonFreebusy, SupportFreebusy
 from imiptools.profile import Preferences
-from vCalendar import to_node
 
 class PersonHandler(Handler):
 
     "Handling mechanisms specific to people."
 
-    def _record_and_deliver(self, objtype, from_organiser=True, queue=False, cancel=False):
+    def _record_and_deliver(self, from_organiser=True, queue=False, cancel=False):
 
         oa = self.require_organiser_and_attendees(from_organiser)
         if not oa:
@@ -44,7 +44,7 @@
 
             for attendee, attendee_attr in attendees.items():
 
-                if not self.have_new_object(attendee, objtype):
+                if not self.have_new_object(attendee):
                     continue
 
                 # Record other party free/busy information.
@@ -59,9 +59,7 @@
 
                 # Store the object and queue any request.
 
-                self.store.set_event(attendee, self.uid, to_node(
-                    {objtype : [(self.details, {})]}
-                    ))
+                self.store.set_event(attendee, self.uid, self.obj.to_node())
 
                 if queue:
                     self.store.queue_request(attendee, self.uid)
@@ -71,13 +69,13 @@
         # As organiser, update attendance.
 
         else:
-            obj = self.get_object(organiser, objtype)
+            obj = self.get_object(organiser)
 
-            if obj and self.have_new_object(organiser, objtype, obj):
+            if obj and self.have_new_object(organiser, obj=obj):
 
                 # Get attendee details in a usable form.
 
-                attendee_map = uri_dict(self.get_value_map("ATTENDEE"))
+                attendee_map = uri_dict(self.obj.get_value_map("ATTENDEE"))
 
                 for attendee, attendee_attr in attendees.items():
 
@@ -99,9 +97,7 @@
 
                 obj["ATTENDEE"] = attendee_map.items()
 
-                self.store.set_event(organiser, self.uid, to_node(
-                    {objtype : [(obj, {})]}
-                    ))
+                self.store.set_event(organiser, self.uid, obj.to_node())
 
         return True
 
@@ -111,7 +107,7 @@
 
         freebusy = []
 
-        for value in self.get_values("FREEBUSY") or []:
+        for value in self.obj.get_values("FREEBUSY") or []:
             if not isinstance(value, list):
                 value = [value]
             for v in value:
@@ -121,7 +117,7 @@
                 except ValueError:
                     pass
 
-        for sender, sender_attr in uri_items(self.get_items(from_organiser and "ORGANIZER" or "ATTENDEE")):
+        for sender, sender_attr in uri_items(self.obj.get_items(from_organiser and "ORGANIZER" or "ATTENDEE")):
             self.store.set_freebusy_for_other(get_uri(self.recipient), freebusy, sender)
 
 class Event(PersonHandler, SupportFreebusy):
@@ -138,7 +134,7 @@
 
         "Queue a cancellation of any active event."
 
-        self._record_and_deliver("VEVENT", from_organiser=True, queue=False, cancel=True)
+        self._record_and_deliver(from_organiser=True, queue=False, cancel=True)
         return self.wrap("A cancellation has been received.", link=False)
 
     def counter(self):
@@ -157,28 +153,28 @@
 
         "Register details of any relevant event."
 
-        self._record_and_deliver("VEVENT", from_organiser=True, queue=False)
+        self._record_and_deliver(from_organiser=True, queue=False)
         return self.wrap("Details of an event have been received.")
 
     def refresh(self):
 
         "Update details of any active event."
 
-        self._record_and_deliver("VEVENT", from_organiser=True, queue=False)
+        self._record_and_deliver(from_organiser=True, queue=False)
         return self.wrap("An event update has been received.")
 
     def reply(self):
 
         "Record replies and notify the recipient."
 
-        self._record_and_deliver("VEVENT", from_organiser=False, queue=False)
+        self._record_and_deliver(from_organiser=False, queue=False)
         return self.wrap("A reply has been received.")
 
     def request(self):
 
         "Hold requests and notify the recipient."
 
-        self._record_and_deliver("VEVENT", from_organiser=True, queue=True)
+        self._record_and_deliver(from_organiser=True, queue=True)
 
         # Produce free/busy information if configured to do so.
 
@@ -253,7 +249,7 @@
 
         # NOTE: Register details of any relevant entry.
 
-        self._record_and_deliver("VJOURNAL", from_organiser=True, queue=False)
+        self._record_and_deliver(from_organiser=True, queue=False)
         return self.wrap("Details of a journal entry have been received.")
 
 class Todo(PersonHandler):
@@ -288,28 +284,28 @@
 
         "Register details of any relevant item."
 
-        self._record_and_deliver("VTODO", from_organiser=True, queue=False)
+        self._record_and_deliver(from_organiser=True, queue=False)
         return self.wrap("Details of an item have been received.")
 
     def refresh(self):
 
         "Update details of any active item."
 
-        self._record_and_deliver("VTODO", from_organiser=True, queue=False)
+        self._record_and_deliver(from_organiser=True, queue=False)
         return self.wrap("An item update has been received.")
 
     def reply(self):
 
         "Record replies and notify the recipient."
 
-        self._record_and_deliver("VTODO", from_organiser=False, queue=False)
+        self._record_and_deliver(from_organiser=False, queue=False)
         return self.wrap("A reply has been received.")
 
     def request(self):
 
         "Hold requests and notify the recipient."
 
-        self._record_and_deliver("VTODO", from_organiser=True, queue=True)
+        self._record_and_deliver(from_organiser=True, queue=True)
         return self.wrap("A request has been received.")
 
 # Handler registry.
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/handlers/person_outgoing.py
--- a/imiptools/handlers/person_outgoing.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/handlers/person_outgoing.py	Sun Feb 01 01:59:37 2015 +0100
@@ -20,34 +20,34 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from imiptools.content import Handler, uri_item
-from vCalendar import to_node
+from imiptools.content import Handler
+from imiptools.data import uri_item
 
 class PersonHandler(Handler):
 
     "Handling mechanisms specific to people."
 
-    def _get_identity(self, objtype, from_organiser=True):
+    def _get_identity(self, from_organiser=True):
 
         """
         Get the identity of interest in a usable form for any unprocessed
         object.
         """
 
-        identity, attr = item = uri_item(self.get_item(from_organiser and "ORGANIZER" or "ATTENDEE"))
+        identity, attr = item = uri_item(self.obj.get_item(from_organiser and "ORGANIZER" or "ATTENDEE"))
 
         # Check for event using UID.
 
-        if not self.have_new_object(identity, objtype):
+        if not self.have_new_object(identity):
             return None
 
         return item
 
-    def _record(self, objtype, from_organiser=True, update_freebusy=False):
+    def _record(self, from_organiser=True, update_freebusy=False):
 
         "Record free/busy and object information."
 
-        item = self._get_identity(objtype, from_organiser)
+        item = self._get_identity(from_organiser)
         if not item:
             return False
 
@@ -55,9 +55,7 @@
 
         # Store the object.
 
-        self.store.set_event(identity, self.uid, to_node(
-            {objtype : [(self.details, {})]}
-            ))
+        self.store.set_event(identity, self.uid, self.obj.to_node())
 
         # Remove any associated request.
 
@@ -83,11 +81,11 @@
 
         return True
 
-    def _remove(self, objtype, from_organiser=True):
+    def _remove(self, from_organiser=True):
 
         "Remove free/busy information for any unprocessed object."
 
-        item = self._get_identity(objtype, from_organiser)
+        item = self._get_identity(from_organiser)
         if not item:
             return False
 
@@ -106,7 +104,7 @@
         pass
 
     def cancel(self):
-        self._remove("VEVENT", True)
+        self._remove(True)
 
     def counter(self):
         pass
@@ -115,16 +113,16 @@
         pass
 
     def publish(self):
-        self._record("VEVENT", True, True)
+        self._record(True, True)
 
     def refresh(self):
-        self._record("VEVENT", True, True)
+        self._record(True, True)
 
     def reply(self):
-        self._record("VEVENT", False, True)
+        self._record(False, True)
 
     def request(self):
-        self._record("VEVENT", True, True)
+        self._record(True, True)
 
 class Freebusy(PersonHandler):
 
@@ -147,10 +145,10 @@
         pass
 
     def cancel(self):
-        self._remove("VJOURNAL", True)
+        self._remove(True)
 
     def publish(self):
-        self._record("VJOURNAL", True)
+        self._record(True)
 
 class Todo(PersonHandler):
 
@@ -160,7 +158,7 @@
         pass
 
     def cancel(self):
-        self._remove("VTODO", True)
+        self._remove(True)
 
     def counter(self):
         pass
@@ -169,16 +167,16 @@
         pass
 
     def publish(self):
-        self._record("VTODO", True)
+        self._record(True)
 
     def refresh(self):
-        self._record("VTODO", True)
+        self._record(True)
 
     def reply(self):
-        self._record("VTODO", False)
+        self._record(False)
 
     def request(self):
-        self._record("VTODO", True)
+        self._record(True)
 
 # Handler registry.
 
diff -r 7dc75bb19e91 -r 7233b6cee1b0 imiptools/handlers/resource.py
--- a/imiptools/handlers/resource.py	Sat Jan 31 22:34:12 2015 +0100
+++ b/imiptools/handlers/resource.py	Sun Feb 01 01:59:37 2015 +0100
@@ -19,10 +19,9 @@
 this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 
-from imiptools.content import Handler, format_datetime, get_address, get_uri, \
-    to_part
+from imiptools.content import Handler
+from imiptools.data import get_address, get_uri, to_part
 from imiptools.handlers.common import CommonFreebusy
-from vCalendar import to_node
 
 class ResourceHandler(Handler):
 
@@ -44,7 +43,7 @@
 
             # Check for event using UID.
 
-            if not self.have_new_object(attendee, "VEVENT"):
+            if not self.have_new_object(attendee):
                 continue
 
             # Collect response objects produced when handling the request.
@@ -70,13 +69,13 @@
 
         # Make a version of the request with just this attendee.
 
-        self.details["ATTENDEE"] = [(attendee, attendee_attr)]
+        self.obj["ATTENDEE"] = [(attendee, attendee_attr)]
 
         # Update the DTSTAMP.
 
         self.update_dtstamp()
 
-        event = to_node({"VEVENT" : [(self.details, {})]})
+        event = self.obj.to_node()
         self.store.set_event(attendee, self.uid, event)
 
         # Only update free/busy details if the event is scheduled.