#!/usr/bin/python2.5

#

# Copyright 2008 the Melange authors.

#

# 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.

"""Common validation helper functions.

"""

__authors__ = [

  '"Lennard de Rijk" <ljvderijk@gmail.com>',

  '"Pawel Solyga" <pawel.solyga@gmail.com>',

  ]

import feedparser

from google.appengine.api import urlfetch

from google.appengine.api import urlfetch_errors

from soc.models import linkable

def isFeedURLValid(feed_url=None):

  """Returns True if provided url is valid ATOM or RSS.

  Args:

    feed_url: ATOM or RSS feed url

  """

  # a missing or empty feed url is never valid

  if not feed_url:

    return False

  try:

    result = urlfetch.fetch(feed_url)

  except urlfetch_errors.Error:

    return False

  # 200 is the status code for 'all ok'

  if result.status_code != 200:

    return False

  parsed_feed = feedparser.parse(result.content)

  # version is always present if the feed is valid

  if not parsed_feed.version:

    return False

  # TODO: isn't this check redunant?

  if parsed_feed.version == '':

    return False

  return True

def isLinkIdFormatValid(link_id):

  """Returns True if link_id is in a valid format.

  Args:

    link_id: link ID used in URLs for identification

  """

  if linkable.LINK_ID_REGEX.match(link_id):

    return True

  return False

def isScopePathFormatValid(scope_path):

  """Returns True if scope_path is in a valid format.

  Args:

    scope_path: scope path prepended to link ID

      used for identification.

  """

  if linkable.SCOPE_PATH_REGEX.match(scope_path):

    return True

  return False