1 files changed, 164 insertions, 0 deletions

diff --git a/exchange/commands.py b/exchange/commands.py
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+++ b/exchange/commands.py
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+# -*- coding: utf-8 -*-
+"""
+Exchange Commands
+
+@author: Mike Crute (mcrute@gmail.com)
+@date: November 10, 2008
+@version: $Revision$
+
+This is a set of classes that starts to define a set of classes for
+fetching data using Exchange's WebDAV API. This is still pretty
+development code but it does the trick. Watch out, it doesn't consider
+many corner cases.
+
+$Id$
+"""
+import xml.etree.cElementTree as etree
+
+from httplib import HTTPSConnection
+from string import Template
+from datetime import datetime, timedelta
+
+import dateutil.parser
+from icalendar import Calendar, Event, Alarm
+
+from exchange import ExchangeException
+
+
+class ExchangeCommand(object):
+    """
+    Base class for Exchange commands. This really shouldn't be constructed
+    directly but should be subclassed to do useful things.
+    """
+
+    #: Base URL for Exchange commands.
+    BASE_URL = Template("/exchange/${username}/${method}")
+
+    #: Basic headers that are required for all requests
+    BASE_HEADERS = {
+       "Content-Type": 'text/xml; charset="UTF-8"',
+       "Depth": "0",
+       "Translate": "f",
+       }
+
+    def __init__(self, server, authenticator=None):
+        self.server = server
+        self.authenticator = authenticator
+
+    def _get_xml(self, **kwargs):
+        """
+        Try to get an XML response from the server.
+        @return: ElementTree response
+        """
+        if not self.authenticator.authenticated:
+            raise ExchangeException("Not authenticated. Call authenticate() first.")
+
+        # Lets forcibly override the username with the user we're querying as
+        kwargs["username"] = self.authenticator.username
+
+        xml = self._get_query(**kwargs)
+        url = self.BASE_URL.substitute({ "username": self.authenticator.username,
+                                         "method": self.exchange_method })
+        query = Template(xml).substitute(kwargs)
+        send_headers = self.authenticator.patch_headers(self.BASE_HEADERS)
+
+        conn = HTTPSConnection(self.server)
+        conn.request(self.dav_method.upper(), url, query, headers=send_headers)
+        resp = conn.getresponse()
+
+        # TODO: Lets determine authentication errors here and fix them.
+        if int(resp.status) > 299 or int(resp.status) < 200:
+            raise ExchangeException("%s %s" % (resp.status, resp.reason))
+
+        return etree.fromstring(resp.read())
+
+    def _get_query(self, **kwargs):
+        """
+        Build up the XML query for the server. Mostly just does a lot
+        of template substitutions, also does a little bit of elementtree
+        magic to to build the XML query.
+        """
+        declaration = etree.ProcessingInstruction("xml", 'version="1.0"')
+
+        request = etree.Element("g:searchrequest", { "xmlns:g": "DAV:" })
+        query = etree.SubElement(request, "g:sql")
+        query.text = Template(self.sql).substitute(kwargs)
+
+        output = etree.tostring(declaration)
+        output += etree.tostring(request)
+
+        return output
+
+
+class FetchCalendar(ExchangeCommand):
+    exchange_method = "calendar"
+    dav_method = "search"
+
+    sql = """
+        SELECT
+            "urn:schemas:calendar:location"          AS location,
+            "urn:schemas:httpmail:normalizedsubject" AS subject,
+            "urn:schemas:calendar:dtstart"           AS start_date,
+            "urn:schemas:calendar:dtend"             AS end_date,
+            "urn:schemas:calendar:busystatus"        AS busy_status,
+            "urn:schemas:calendar:instancetype"      AS instance_type,
+            "urn:schemas:calendar:timezone"          AS timezone_info,
+            "urn:schemas:httpmail:textdescription"   AS description
+        FROM
+            Scope('SHALLOW TRAVERSAL OF "/exchange/${username}/calendar/"')
+        WHERE
+            NOT "urn:schemas:calendar:instancetype" = 1
+            AND "DAV:contentclass" = 'urn:content-classes:appointment'
+        ORDER BY
+            "urn:schemas:calendar:dtstart" ASC
+        """
+
+    def execute(self, alarms=True, alarm_offset=15, **kwargs):
+        exchange_xml = self._get_xml(**kwargs)
+        calendar = Calendar()
+
+        for item in exchange_xml.getchildren():
+            item = item.find("{DAV:}propstat").find("{DAV:}prop")
+            event = Event()
+
+            # These tests may look funny but the result of item.find
+            # does NOT evaluate to true even though it is not None
+            # so, we have to check the interface of the returned item
+            # to make sure its usable.
+
+            subject = item.find("subject")
+            if hasattr(subject, "text"):
+                event.add("summary", subject.text)
+
+            location = item.find("location")
+            if hasattr(location, "text"):
+                event.add("location", location.text)
+
+            description = item.find("description")
+            if hasattr(description, "text"):
+                event.add("description", description.text)
+
+            # Dates should always exist
+            start_date = dateutil.parser.parse(item.find("start_date").text)
+            event.add("dtstart", start_date)
+
+            end_date = dateutil.parser.parse(item.find("end_date").text)
+            event.add("dtend", end_date)
+
+            if item.get("timezone_info"):
+                """This comes back from Exchange as already formatted
+                ical data. We probably need to parse and re-construct
+                it unless the icalendar api lets us just dump it out.
+                """
+                pass
+
+            if alarms and start_date > datetime.now(tz=EST()):
+                alarm = Alarm()
+                alarm.add("action", "DISPLAY")
+                alarm.add("description", "REMINDER")
+                alarm.add("trigger", timedelta(minutes=alarm_offset))
+                event.add_component(alarm)
+
+            calendar.add_component(event)
+
+        return calendar