Synnefo

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import datetime

from dateutil.parser import parse as date_parse

from django.utils import simplejson as json

from django.conf import settings

from snf_django.lib.api import faults

class UTC(datetime.tzinfo):

    """

    Helper UTC time information object.

    """

    def utcoffset(self, dt):

        return datetime.timedelta(0)

    def tzname(self, dt):

        return 'UTC'

    def dst(self, dt):

        return datetime.timedelta(0)

def isoformat(d):

    """Return an ISO8601 date string that includes a timezone.

    >>> from datetime import datetime

    >>> d = datetime(2012, 8, 10, 00, 59, 59)

    >>> isoformat(d)

    '2012-08-10T00:59:59+00:00'

    """

    return d.replace(tzinfo=UTC()).isoformat()

def isoparse(s):

    """Parse an ISO8601 date string into a datetime object."""

    if not s:

        return None

    try:

        since = date_parse(s)

        utc_since = since.astimezone(UTC()).replace(tzinfo=None)

    except ValueError:

        raise faults.BadRequest('Invalid changes-since parameter.')

    now = datetime.datetime.now()

    if utc_since > now:

        raise faults.BadRequest('changes-since value set in the future.')

    if now - utc_since > datetime.timedelta(seconds=settings.POLL_LIMIT):

        raise faults.BadRequest('Too old changes-since value.')

    return utc_since

def get_request_dict(request):

    """Return data sent by the client as python dictionary.

    Only JSON format is supported

    """

    data = request.body

    content_type = request.META.get("CONTENT_TYPE")

    if content_type is None:

        raise faults.BadRequest("Missing Content-Type header field")

    if content_type.startswith("application/json"):

        try:

            return json.loads(data)

        except ValueError:

            raise faults.BadRequest("Invalid JSON data")

    else:

        raise faults.BadRequest("Unsupported Content-type: '%s'" %

                                content_type)

def prefix_pattern(prefix, append_slash=True):

    """Return a reliable urls.py pattern from a prefix"""

    prefix = prefix.strip('/')

    if prefix and append_slash:

        prefix += '/'

    pattern = '^' + prefix

    return pattern

def filter_modified_since(request, objects):

    """Filter DB objects based on 'changes-since' request parameter.

    Parse request for 'changes-since' parameter and get only the DB objects

    that have been updated after that time. Otherwise, return the non-deleted

    objects.

    """

    since = isoparse(request.GET.get("changes-since"))

    if since:

        modified_objs = objects.filter(updated__gte=since)

        if not modified_objs:

            raise faults.NotModified()

        return modified_objs

    else:

        return objects.filter(deleted=False)

def get_attribute(request, attribute, required=True):

    value = request.get(attribute, None)

    if required and value is None:

        raise faults.BadRequest("Malformed request. Missing attribute '%s'." %

                                attribute)

    return value