import re

import soc.models.user

  LINKNAME_PATTERN = r'''(?x)

      ^

      [0-9a-z]  # start with ASCII digit or lowercase

      (

      [0-9a-z]  # additional ASCII digit or lowercase

      |         # -OR-

      _[0-9a-z] # underscore and ASCII digit or lowercase

      )*        # zero or more of OR group

      $'''

  LINKNAME_REGEX = re.compile(LINKNAME_PATTERN)

    model = soc.models.user.User

  def clean_link_name(self):

    linkname = self.cleaned_data.get('link_name')

    linkname_user = soc.models.user.User.getUserForLinkname(linkname)

    user = users.get_current_user()

    # if linkname exist in datastore and doesn't belong to current user

    if linkname_user and (linkname_user.id != user):

      raise forms.ValidationError("This link name is already in use.")

    elif not self.LINKNAME_REGEX.match(linkname):

      raise forms.ValidationError("This link name is in wrong format.")

    return linkname

    linkname: the User's site-unique "linkname" extracted from the URL

  #TODO(solydzajs): create controller for User and cleanup code in this handler

  #: If user not signed in redirect to sign-in page

  soc_user = soc.models.user.User.getUser(user)

  #: Show custom 404 page when linkname in url doesn't match current user

  if linkname:

    linkname_user = soc.models.user.User.getUserForLinkname(linkname)

    if (linkname_user and linkname_user.id != user) or not linkname_user:

      return http.HttpResponseNotFound('No user exists with that link name "%s"' %

                                linkname)

  #: GET method

  if (request.method != 'POST') and soc_user:

    form = UserForm(initial={'nick_name': soc_user.nick_name,

                             'link_name': soc_user.link_name})

    return response_helpers.respond(request,

        template, {'template': template, 

                   'form': form, 

                   'soc_nick_name': soc_user.nick_name})

  #: POST method

  if request.method == 'POST':

    if form.is_valid():

      linkname = form.cleaned_data.get('link_name')

      nickname = form.cleaned_data.get("nick_name")

      if not soc_user:

        soc_user = soc.models.user.User(id = user,link_name = linkname,

                                        nick_name = nickname)

      else:

        soc_user.nick_name = nickname

        soc_user.link_name = linkname

      soc_user.put()

      return response_helpers.respond(request,

              template, {'template': template, 

                        'form': form, 

                        'soc_nick_name': nickname,

                        'submit_message': 'Profile saved.'})