##
# Copyright (c) 2005-2008 Apple Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
##

"""
CalDAV GET method.
"""

__all__ = ["http_GET"]

from twisted.internet.defer import inlineCallbacks, returnValue
from twisted.web2.dav import davxml
from twisted.web2.http import HTTPError
from twisted.web2.http import Response
from twisted.web2.http_headers import MimeType
from twisted.web2.stream import MemoryStream

from twistedcaldav import caldavxml
from twistedcaldav.caldavxml import ScheduleTag
from twistedcaldav.customxml import TwistedCalendarAccessProperty
from twistedcaldav.ical import Component

@inlineCallbacks
def http_GET(self, request):

    # Look for calendar access restriction on existing resource.
    if self.exists():
        try:
            access = self.readDeadProperty(TwistedCalendarAccessProperty)
        except HTTPError:
            access = None
            
        if access in (Component.ACCESS_CONFIDENTIAL, Component.ACCESS_RESTRICTED):
    
            # Check authorization first
            yield self.authorize(request, (davxml.Read(),))

            # Non DAV:owner's have limited access to the data
            isowner = (yield self.isOwner(request, adminprincipals=True, readprincipals=True))
            
            if not isowner:
                # Now "filter" the resource calendar data through the CALDAV:calendar-data element and apply
                # access restrictions to the data.
                caldata = caldavxml.CalendarData().elementFromResourceWithAccessRestrictions(self, access).calendarData()

                response = Response()
                response.stream = MemoryStream(caldata)
                response.headers.setHeader("content-type", MimeType.fromString("text/calendar; charset=utf-8"))
                returnValue(response)


    # Do normal GET behavior
    response = (yield super(CalDAVFile, self).http_GET(request))
    
    # Add Schedule-Tag header if property is present
    if self.exists() and self.hasDeadProperty(ScheduleTag):
        scheduletag = self.readDeadProperty(ScheduleTag)
        if scheduletag:
            response.headers.setHeader("Schedule-Tag", str(scheduletag))

    returnValue(response)