views.py

# -*- coding: utf-8 -*-
"""
Helios Django Views

Ben Adida (ben@adida.net)
"""

from django.core.urlresolvers import reverse
from django.core.mail import send_mail
from django.core.paginator import Paginator
from django.http import *
from django.db import transaction

from mimetypes import guess_type

import csv, urllib, os, base64

from crypto import algs, electionalgs, elgamal
from crypto import utils as cryptoutils
from workflows import homomorphic
from helios import utils as helios_utils
from view_utils import *

from helios_auth.security import *
from helios_auth.auth_systems import AUTH_SYSTEMS, can_list_categories
from helios_auth.models import AuthenticationExpired

from helios import security
from helios_auth import views as auth_views

import tasks

from security import *
from helios_auth.security import get_user, save_in_session_across_logouts

import uuid, datetime

from models import *

import forms, signals

# Parameters for everything
ELGAMAL_PARAMS = elgamal.Cryptosystem()

# trying new ones from OlivierP
ELGAMAL_PARAMS.p = 16328632084933010002384055033805457329601614771185955389739167309086214800406465799038583634953752941675645562182498120750264980492381375579367675648771293800310370964745767014243638518442553823973482995267304044326777047662957480269391322789378384619428596446446984694306187644767462460965622580087564339212631775817895958409016676398975671266179637898557687317076177218843233150695157881061257053019133078545928983562221396313169622475509818442661047018436264806901023966236718367204710755935899013750306107738002364137917426595737403871114187750804346564731250609196846638183903982387884578266136503697493474682071L
ELGAMAL_PARAMS.q = 61329566248342901292543872769978950870633559608669337131139375508370458778917L
ELGAMAL_PARAMS.g = 14887492224963187634282421537186040801304008017743492304481737382571933937568724473847106029915040150784031882206090286938661464458896494215273989547889201144857352611058572236578734319505128042602372864570426550855201448111746579871811249114781674309062693442442368697449970648232621880001709535143047913661432883287150003429802392229361583608686643243349727791976247247948618930423866180410558458272606627111270040091203073580238905303994472202930783207472394578498507764703191288249547659899997131166130259700604433891232298182348403175947450284433411265966789131024573629546048637848902243503970966798589660808533L

# object ready for serialization
ELGAMAL_PARAMS_LD_OBJECT = datatypes.LDObject.instantiate(ELGAMAL_PARAMS, datatype='legacy/EGParams')

# single election server? Load the single electionfrom models import Election
from django.conf import settings

def get_election_url(election):
  return settings.URL_HOST + reverse(election_shortcut, args=[election.short_name])  

def get_election_badge_url(election):
  return settings.URL_HOST + reverse(election_badge, args=[election.uuid])  

def get_election_govote_url(election):
  return settings.URL_HOST + reverse(election_vote_shortcut, args=[election.short_name])  

def get_castvote_url(cast_vote):
  return settings.URL_HOST + reverse(castvote_shortcut, args=[cast_vote.vote_tinyhash])

# social buttons
def get_socialbuttons_url(url, text):
  if not text:
    return None
  
  return "%s%s?%s" % (settings.SOCIALBUTTONS_URL_HOST,
                      reverse(socialbuttons),
                      urllib.urlencode({
        'url' : url,
        'text': text.encode('utf-8')
        }))
  

##
## remote auth utils

def user_reauth(request, user):
  # FIXME: should we be wary of infinite redirects here, and
  # add a parameter to prevent it? Maybe.
  login_url = "%s%s?%s" % (settings.SECURE_URL_HOST,
                           reverse(auth_views.start, args=[user.user_type]),
                           urllib.urlencode({'return_url':
                                               request.get_full_path()}))
  return HttpResponseRedirect(login_url)

## 
## simple admin for development
##
def admin_autologin(request):
  if "localhost" not in settings.URL_HOST and "127.0.0.1" not in settings.URL_HOST:
    raise Http404
  
  users = User.objects.filter(admin_p=True)
  if len(users) == 0:
    return HttpResponse("no admin users!")

  if len(users) == 0:
    return HttpResponse("no users!")

  user = users[0]
  request.session['user'] = {'type' : user.user_type, 'user_id' : user.user_id}
  return HttpResponseRedirect("/")

##
## General election features
##

@json
def election_params(request):
  return ELGAMAL_PARAMS_LD_OBJECT.toJSONDict()

def election_verifier(request):
  return render_template(request, "tally_verifier")

def election_single_ballot_verifier(request):
  return render_template(request, "ballot_verifier")

def election_shortcut(request, election_short_name):
  election = Election.get_by_short_name(election_short_name)
  if election:
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
  else:
    raise Http404

# a hidden view behind the shortcut that performs the actual perm check
@election_view()
def _election_vote_shortcut(request, election):
  vote_url = "%s/booth/vote.html?%s" % (settings.SECURE_URL_HOST, urllib.urlencode({'election_url' : reverse(one_election, args=[election.uuid])}))
  
  test_cookie_url = "%s?%s" % (reverse(test_cookie), urllib.urlencode({'continue_url' : vote_url}))

  return HttpResponseRedirect(test_cookie_url)
  
def election_vote_shortcut(request, election_short_name):
  election = Election.get_by_short_name(election_short_name)
  if election:
    return _election_vote_shortcut(request, election_uuid=election.uuid)
  else:
    raise Http404

@election_view()
def _castvote_shortcut_by_election(request, election, cast_vote):
  return render_template(request, 'castvote', {'cast_vote' : cast_vote, 'vote_content': cast_vote.vote.toJSON(), 'the_voter': cast_vote.voter, 'election': election})
  
def castvote_shortcut(request, vote_tinyhash):
  try:
    cast_vote = CastVote.objects.get(vote_tinyhash = vote_tinyhash)
  except CastVote.DoesNotExist:
    raise Http404

  return _castvote_shortcut_by_election(request, election_uuid = cast_vote.voter.election.uuid, cast_vote=cast_vote)

@trustee_check
def trustee_keygenerator(request, election, trustee):
  """
  A key generator with the current params, like the trustee home but without a specific election.
  """
  eg_params_json = utils.to_json(ELGAMAL_PARAMS_LD_OBJECT.toJSONDict())

  return render_template(request, "election_keygenerator", {'eg_params_json': eg_params_json, 'election': election, 'trustee': trustee})

@login_required
def elections_administered(request):
  if not can_create_election(request):
    return HttpResponseForbidden('only an administrator has elections to administer')
  
  user = get_user(request)
  elections = Election.get_by_user_as_admin(user)
  
  return render_template(request, "elections_administered", {'elections': elections})

@login_required
def elections_voted(request):
  user = get_user(request)
  elections = Election.get_by_user_as_voter(user)
  
  return render_template(request, "elections_voted", {'elections': elections})
    

@login_required
def election_new(request):
  if not can_create_election(request):
    return HttpResponseForbidden('only an administrator can create an election')
    
  error = None
  
  if request.method == "GET":
    election_form = forms.ElectionForm(initial={'private_p': settings.HELIOS_PRIVATE_DEFAULT})
  else:
    election_form = forms.ElectionForm(request.POST)
    
    if election_form.is_valid():
      # create the election obj
      election_params = dict(election_form.cleaned_data)
      
      # is the short name valid
      if helios_utils.urlencode(election_params['short_name']) == election_params['short_name']:      
        election_params['uuid'] = str(uuid.uuid1())
        election_params['cast_url'] = settings.SECURE_URL_HOST + reverse(one_election_cast, args=[election_params['uuid']])
      
        # registration starts closed
        election_params['openreg'] = False

        user = get_user(request)
        election_params['admin'] = user
        
        election, created_p = Election.get_or_create(**election_params)
      
        if created_p:
          # add Helios as a trustee by default
          election.generate_trustee(ELGAMAL_PARAMS)
          
          return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
        else:
          error = "An election with short name %s already exists" % election_params['short_name']
      else:
        error = "No special characters allowed in the short name."
    
  return render_template(request, "election_new", {'election_form': election_form, 'error': error})
  
@election_admin(frozen=False)
def one_election_edit(request, election):

  error = None
  RELEVANT_FIELDS = ['short_name', 'name', 'description', 'use_voter_aliases', 'election_type', 'private_p', 'help_email', 'randomize_answer_order']
  # RELEVANT_FIELDS += ['use_advanced_audit_features']

  if settings.ALLOW_ELECTION_INFO_URL:
    RELEVANT_FIELDS += ['election_info_url']
  
  if request.method == "GET":
    values = {}
    for attr_name in RELEVANT_FIELDS:
      values[attr_name] = getattr(election, attr_name)
    election_form = forms.ElectionForm(values)
  else:
    election_form = forms.ElectionForm(request.POST)
    
    if election_form.is_valid():
      clean_data = election_form.cleaned_data
      for attr_name in RELEVANT_FIELDS:
        setattr(election, attr_name, clean_data[attr_name])

      election.save()
        
      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
  
  return render_template(request, "election_edit", {'election_form' : election_form, 'election' : election, 'error': error})

@election_admin(frozen=False)
def one_election_schedule(request, election):
  return HttpResponse("foo")

@election_view()
@json
def one_election(request, election):
  if not election:
    raise Http404
  return election.toJSONDict(complete=True)

@election_view()
@json
def one_election_meta(request, election):
  if not election:
    raise Http404
  return election.metadata

@election_view()
def election_badge(request, election):
  election_url = get_election_url(election)
  params = {'election': election, 'election_url': election_url}
  for option_name in ['show_title', 'show_vote_link']:
    params[option_name] = (request.GET.get(option_name, '1') == '1')
  return render_template(request, "election_badge", params)

@election_view()
def one_election_view(request, election):
  user = get_user(request)
  admin_p = security.user_can_admin_election(user, election)
  can_feature_p = security.user_can_feature_election(user, election)
  
  notregistered = False
  eligible_p = True
  
  election_url = get_election_url(election)
  election_badge_url = get_election_badge_url(election)
  status_update_message = None

  vote_url = "%s/booth/vote.html?%s" % (settings.SECURE_URL_HOST, urllib.urlencode({'election_url' : reverse(one_election, args=[election.uuid])}))

  test_cookie_url = "%s?%s" % (reverse(test_cookie), urllib.urlencode({'continue_url' : vote_url}))
  
  if user:
    voter = Voter.get_by_election_and_user(election, user)
    
    if not voter:
      try:
        eligible_p = _check_eligibility(election, user)
      except AuthenticationExpired:
        return user_reauth(request, user)
      notregistered = True
  else:
    voter = get_voter(request, user, election)

  if voter:
    # cast any votes?
    votes = CastVote.get_by_voter(voter)
  else:
    votes = None

  # status update message?
  if election.openreg:
    if election.voting_has_started:
      status_update_message = u"Vote in %s" % election.name
    else:
      status_update_message = u"Register to vote in %s" % election.name

  # result!
  if election.result:
    status_update_message = u"Results are in for %s" % election.name
  
  # a URL for the social buttons
  socialbuttons_url = get_socialbuttons_url(election_url, status_update_message)

  trustees = Trustee.get_by_election(election)

  return render_template(request, 'election_view',
                         {'election' : election, 'trustees': trustees, 'admin_p': admin_p, 'user': user,
                          'voter': voter, 'votes': votes, 'notregistered': notregistered, 'eligible_p': eligible_p,
                          'can_feature_p': can_feature_p, 'election_url' : election_url, 
                          'vote_url': vote_url, 'election_badge_url' : election_badge_url,
                          'test_cookie_url': test_cookie_url, 'socialbuttons_url' : socialbuttons_url})

def test_cookie(request):
  continue_url = request.GET['continue_url']
  request.session.set_test_cookie()
  next_url = "%s?%s" % (reverse(test_cookie_2), urllib.urlencode({'continue_url': continue_url}))
  return HttpResponseRedirect(settings.SECURE_URL_HOST + next_url)  

def test_cookie_2(request):
  continue_url = request.GET['continue_url']

  if not request.session.test_cookie_worked():
    return HttpResponseRedirect(settings.SECURE_URL_HOST + ("%s?%s" % (reverse(nocookies), urllib.urlencode({'continue_url': continue_url}))))

  request.session.delete_test_cookie()
  return HttpResponseRedirect(continue_url)  

def nocookies(request):
  retest_url = "%s?%s" % (reverse(test_cookie), urllib.urlencode({'continue_url' : request.GET['continue_url']}))
  return render_template(request, 'nocookies', {'retest_url': retest_url})

def socialbuttons(request):
  """
  just render the social buttons for sharing a URL
  expecting "url" and "text" in request.GET
  """
  return render_template(request, 'socialbuttons',
                         {'url': request.GET['url'], 'text':request.GET['text']})

##
## Trustees and Public Key
##
## As of July 2009, there are always trustees for a Helios election: one trustee is acceptable, for simple elections.
##
@election_view()
@json
def list_trustees(request, election):
  trustees = Trustee.get_by_election(election)
  return [t.toJSONDict(complete=True) for t in trustees]
  
@election_view()
def list_trustees_view(request, election):
  trustees = Trustee.get_by_election(election)
  user = get_user(request)
  admin_p = security.user_can_admin_election(user, election)
  
  return render_template(request, 'list_trustees', {'election': election, 'trustees': trustees, 'admin_p':admin_p})
  
@election_admin(frozen=False)
def new_trustee(request, election):
  if request.method == "GET":
    return render_template(request, 'new_trustee', {'election' : election})
  else:
    # get the public key and the hash, and add it
    name = request.POST['name']
    email = request.POST['email']
    
    trustee = Trustee(uuid = str(uuid.uuid1()), election = election, name=name, email=email)
    trustee.save()
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(list_trustees_view, args=[election.uuid]))

@election_admin(frozen=False)
def new_trustee_helios(request, election):
  """
  Make Helios a trustee of the election
  """
  election.generate_trustee(ELGAMAL_PARAMS)
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(list_trustees_view, args=[election.uuid]))
  
@election_admin(frozen=False)
def delete_trustee(request, election):
  trustee = Trustee.get_by_election_and_uuid(election, request.GET['uuid'])
  trustee.delete()
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(list_trustees_view, args=[election.uuid]))
  
def trustee_login(request, election_short_name, trustee_email, trustee_secret):
  election = Election.get_by_short_name(election_short_name)
  if election:
    trustee = Trustee.get_by_election_and_email(election, trustee_email)
    
    if trustee:
      if trustee.secret == trustee_secret:
        set_logged_in_trustee(request, trustee)
        return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(trustee_home, args=[election.uuid, trustee.uuid]))
      else:
        # bad secret, we'll let that redirect to the front page
        pass
    else:
      # no such trustee
      raise Http404

  return HttpResponseRedirect(settings.SECURE_URL_HOST + "/")

@election_admin()
def trustee_send_url(request, election, trustee_uuid):
  trustee = Trustee.get_by_election_and_uuid(election, trustee_uuid)
  
  url = settings.SECURE_URL_HOST + reverse(trustee_login, args=[election.short_name, trustee.email, trustee.secret])
  
  body = """

You are a trustee for %s.

Your trustee dashboard is at

  %s
  
--
Helios  
""" % (election.name, url)

  send_mail('your trustee homepage for %s' % election.name, body, settings.SERVER_EMAIL, ["%s <%s>" % (trustee.name, trustee.email)], fail_silently=True)

  logging.info("URL %s " % url)
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(list_trustees_view, args = [election.uuid]))

@trustee_check
def trustee_home(request, election, trustee):
  return render_template(request, 'trustee_home', {'election': election, 'trustee':trustee})
  
@trustee_check
def trustee_check_sk(request, election, trustee):
  return render_template(request, 'trustee_check_sk', {'election': election, 'trustee':trustee})
  
@trustee_check
def trustee_upload_pk(request, election, trustee):
  if request.method == "POST":
    # get the public key and the hash, and add it
    public_key_and_proof = utils.from_json(request.POST['public_key_json'])
    trustee.public_key = algs.EGPublicKey.fromJSONDict(public_key_and_proof['public_key'])
    trustee.pok = algs.DLogProof.fromJSONDict(public_key_and_proof['pok'])
    
    # verify the pok
    if not trustee.public_key.verify_sk_proof(trustee.pok, algs.DLog_challenge_generator):
      raise Exception("bad pok for this public key")
    
    trustee.public_key_hash = utils.hash_b64(utils.to_json(trustee.public_key.toJSONDict()))

    trustee.save()
    
    # send a note to admin
    try:
      election.admin.send_message("%s - trustee pk upload" % election.name, "trustee %s (%s) uploaded a pk." % (trustee.name, trustee.email))
    except:
      # oh well, no message sent
      pass
    
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(trustee_home, args=[election.uuid, trustee.uuid]))

##
## Ballot Management
##

@election_view()
@json
def get_randomness(request, election):
  """
  get some randomness to sprinkle into the sjcl entropy pool
  """
  return {
    # back to urandom, it's fine
    "randomness" : base64.b64encode(os.urandom(32))
    #"randomness" : base64.b64encode(uuid.uuid4().bytes + uuid.uuid4().bytes)
    }

@election_view(frozen=True)
@json
def encrypt_ballot(request, election):
  """
  perform the ballot encryption given answers_json, a JSON'ified list of list of answers
  (list of list because each question could have a list of answers if more than one.)
  """
  # FIXME: maybe make this just request.POST at some point?
  answers = utils.from_json(request.REQUEST['answers_json'])
  ev = homomorphic.EncryptedVote.fromElectionAndAnswers(election, answers)
  return ev.ld_object.includeRandomness().toJSONDict()
    
@election_view(frozen=True)
def post_audited_ballot(request, election):
  if request.method == "POST":
    raw_vote = request.POST['audited_ballot']
    encrypted_vote = electionalgs.EncryptedVote.fromJSONDict(utils.from_json(raw_vote))
    vote_hash = encrypted_vote.get_hash()
    audited_ballot = AuditedBallot(raw_vote = raw_vote, vote_hash = vote_hash, election = election)
    audited_ballot.save()
    
    return SUCCESS
    

# we don't require frozen election to allow for ballot preview
@election_view()
def one_election_cast(request, election):
  """
  on a GET, this is a cancellation, on a POST it's a cast
  """
  if request.method == "GET":
    return HttpResponseRedirect("%s%s" % (settings.SECURE_URL_HOST, reverse(one_election_view, args = [election.uuid])))
    
  user = get_user(request)    
  encrypted_vote = request.POST['encrypted_vote']

  save_in_session_across_logouts(request, 'encrypted_vote', encrypted_vote)

  return HttpResponseRedirect("%s%s" % (settings.SECURE_URL_HOST, reverse(one_election_cast_confirm, args=[election.uuid])))

@election_view(allow_logins=True)
def password_voter_login(request, election):
  """
  This is used to log in as a voter for a particular election
  """

  # the URL to send the user to after they've logged in
  return_url = request.REQUEST.get('return_url', reverse(one_election_cast_confirm, args=[election.uuid]))
  bad_voter_login = (request.GET.get('bad_voter_login', "0") == "1")

  if request.method == "GET":
    # if user logged in somehow in the interim, e.g. using the login link for administration,
    # then go!
    if user_can_see_election(request, election):
      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args = [election.uuid]))

    password_login_form = forms.VoterPasswordForm()
    return render_template(request, 'password_voter_login',
                           {'election': election, 
                            'return_url' : return_url,
                            'password_login_form': password_login_form,
                            'bad_voter_login' : bad_voter_login})
  
  login_url = request.REQUEST.get('login_url', None)

  if not login_url:
    # login depending on whether this is a private election
    # cause if it's private the login is happening on the front page
    if election.private_p:
      login_url = reverse(password_voter_login, args=[election.uuid])
    else:
      login_url = reverse(one_election_cast_confirm, args=[election.uuid])

  password_login_form = forms.VoterPasswordForm(request.POST)

  if password_login_form.is_valid():
    try:
      voter = election.voter_set.get(voter_login_id = password_login_form.cleaned_data['voter_id'].strip(),
                                     voter_password = password_login_form.cleaned_data['password'].strip())

      request.session['CURRENT_VOTER'] = voter

      # if we're asked to cast, let's do it
      if request.POST.get('cast_ballot') == "1":
        return one_election_cast_confirm(request, election.uuid)
      
    except Voter.DoesNotExist:
      redirect_url = login_url + "?" + urllib.urlencode({
          'bad_voter_login' : '1',
          'return_url' : return_url
          })

      return HttpResponseRedirect(settings.SECURE_URL_HOST + redirect_url)
  
  return HttpResponseRedirect(settings.SECURE_URL_HOST + return_url)

@election_view()
def one_election_cast_confirm(request, election):
  user = get_user(request)    

  # if no encrypted vote, the user is reloading this page or otherwise getting here in a bad way
  if not request.session.has_key('encrypted_vote'):
    return HttpResponseRedirect(settings.URL_HOST)

  # election not frozen or started
  if not election.voting_has_started():
    return render_template(request, 'election_not_started', {'election': election})

  voter = get_voter(request, user, election)

  # auto-register this person if the election is openreg
  if user and not voter and election.openreg:
    voter = _register_voter(election, user)
    
  # tallied election, no vote casting
  if election.encrypted_tally or election.result:
    return render_template(request, 'election_tallied', {'election': election})
    
  encrypted_vote = request.session['encrypted_vote']
  vote_fingerprint = cryptoutils.hash_b64(encrypted_vote)

  # if this user is a voter, prepare some stuff
  if voter:
    vote = datatypes.LDObject.fromDict(utils.from_json(encrypted_vote), type_hint='legacy/EncryptedVote').wrapped_obj

    # prepare the vote to cast
    cast_vote_params = {
      'vote' : vote,
      'voter' : voter,
      'vote_hash': vote_fingerprint,
      'cast_at': datetime.datetime.utcnow()
    }

    cast_vote = CastVote(**cast_vote_params)
  else:
    cast_vote = None
    
  if request.method == "GET":
    if voter:
      past_votes = CastVote.get_by_voter(voter)
      if len(past_votes) == 0:
        past_votes = None
    else:
      past_votes = None

    if cast_vote:
      # check for issues
      issues = cast_vote.issues(election)
    else:
      issues = None

    bad_voter_login = (request.GET.get('bad_voter_login', "0") == "1")

    # status update this vote
    if voter and voter.user.can_update_status():
      status_update_label = voter.user.update_status_template() % "your smart ballot tracker"
      status_update_message = "I voted in %s - my smart tracker is %s.. #heliosvoting" % (get_election_url(election),cast_vote.vote_hash[:10])
    else:
      status_update_label = None
      status_update_message = None

    # do we need to constrain the auth_systems?
    if election.eligibility:
      auth_systems = [e['auth_system'] for e in election.eligibility]
    else:
      auth_systems = None

    password_only = False

    if auth_systems == None or 'password' in auth_systems:
      show_password = True
      password_login_form = forms.VoterPasswordForm()

      if auth_systems == ['password']:
        password_only = True
    else:
      show_password = False
      password_login_form = None

    return_url = reverse(one_election_cast_confirm, args=[election.uuid])
    login_box = auth_views.login_box_raw(request, return_url=return_url, auth_systems = auth_systems)

    return render_template(request, 'election_cast_confirm', {
        'login_box': login_box, 'election' : election, 'vote_fingerprint': vote_fingerprint,
        'past_votes': past_votes, 'issues': issues, 'voter' : voter,
        'return_url': return_url,
        'status_update_label': status_update_label, 'status_update_message': status_update_message,
        'show_password': show_password, 'password_only': password_only, 'password_login_form': password_login_form,
        'bad_voter_login': bad_voter_login})
      
  if request.method == "POST":
    check_csrf(request)
    
    # voting has not started or has ended
    if (not election.voting_has_started()) or election.voting_has_stopped():
      return HttpResponseRedirect(settings.URL_HOST)
            
    # if user is not logged in
    # bring back to the confirmation page to let him know
    if not voter:
      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_cast_confirm, args=[election.uuid]))
    
    # don't store the vote in the voter's data structure until verification
    cast_vote.save()

    # status update?
    if request.POST.get('status_update', False):
      status_update_message = request.POST.get('status_update_message')
    else:
      status_update_message = None

    # launch the verification task
    tasks.cast_vote_verify_and_store.delay(
      cast_vote_id = cast_vote.id,
      status_update_message = status_update_message)
    
    # remove the vote from the store
    del request.session['encrypted_vote']
    
    return HttpResponseRedirect("%s%s" % (settings.URL_HOST, reverse(one_election_cast_done, args=[election.uuid])))
  
@election_view()
def one_election_cast_done(request, election):
  """
  This view needs to be loaded because of the IFRAME, but then this causes 
  problems if someone clicks "reload". So we need a strategy.
  We store the ballot hash in the session
  """
  user = get_user(request)
  voter = get_voter(request, user, election)

  if voter:
    votes = CastVote.get_by_voter(voter)
    vote_hash = votes[0].vote_hash
    cv_url = get_castvote_url(votes[0])

    # only log out if the setting says so *and* we're dealing
    # with a site-wide voter. Definitely remove current_voter
    if voter.user == user:
      logout = settings.LOGOUT_ON_CONFIRMATION
    else:
      logout = False
      del request.session['CURRENT_VOTER']

    save_in_session_across_logouts(request, 'last_vote_hash', vote_hash)
    save_in_session_across_logouts(request, 'last_vote_cv_url', cv_url)
  else:
    vote_hash = request.session['last_vote_hash']
    cv_url = request.session['last_vote_cv_url']
    logout = False
  
  # local logout ensures that there's no more
  # user locally
  # WHY DO WE COMMENT THIS OUT? because we want to force a full logout via the iframe, including
  # from remote systems, just in case, i.e. CAS
  # if logout:
  #   auth_views.do_local_logout(request)
  
  # tweet/fb your vote
  socialbuttons_url = get_socialbuttons_url(cv_url, 'I cast a vote in %s' % election.name) 
  
  # remote logout is happening asynchronously in an iframe to be modular given the logout mechanism
  # include_user is set to False if logout is happening
  return render_template(request, 'cast_done', {'election': election,
                                                'vote_hash': vote_hash, 'logout': logout,
                                                'socialbuttons_url': socialbuttons_url},
                         include_user=(not logout))

@election_view()
@json
def one_election_result(request, election):
  return election.result

@election_view()
@json
def one_election_result_proof(request, election):
  return election.result_proof
  
@election_view(frozen=True)
def one_election_bboard(request, election):
  """
  UI to show election bboard
  """
  after = request.GET.get('after', None)
  offset= int(request.GET.get('offset', 0))
  limit = int(request.GET.get('limit', 50))
  
  order_by = 'voter_id'
  
  # unless it's by alias, in which case we better go by UUID
  if election.use_voter_aliases:
    order_by = 'alias'

  # if there's a specific voter
  if request.GET.has_key('q'):
    # FIXME: figure out the voter by voter_id
    voters = []
  else:
    # load a bunch of voters
    voters = Voter.get_by_election(election, after=after, limit=limit+1, order_by=order_by)
    
  more_p = len(voters) > limit
  if more_p:
    voters = voters[0:limit]
    next_after = getattr(voters[limit-1], order_by)
  else:
    next_after = None
    
  return render_template(request, 'election_bboard', {'election': election, 'voters': voters, 'next_after': next_after,
                'offset': offset, 'limit': limit, 'offset_plus_one': offset+1, 'offset_plus_limit': offset+limit,
                'voter_id': request.GET.get('voter_id', '')})

@election_view(frozen=True)
def one_election_audited_ballots(request, election):
  """
  UI to show election audited ballots
  """
  
  if request.GET.has_key('vote_hash'):
    b = AuditedBallot.get(election, request.GET['vote_hash'])
    return HttpResponse(b.raw_vote, mimetype="text/plain")
    
  after = request.GET.get('after', None)
  offset= int(request.GET.get('offset', 0))
  limit = int(request.GET.get('limit', 50))
  
  audited_ballots = AuditedBallot.get_by_election(election, after=after, limit=limit+1)
    
  more_p = len(audited_ballots) > limit
  if more_p:
    audited_ballots = audited_ballots[0:limit]
    next_after = audited_ballots[limit-1].vote_hash
  else:
    next_after = None
    
  return render_template(request, 'election_audited_ballots', {'election': election, 'audited_ballots': audited_ballots, 'next_after': next_after,
                'offset': offset, 'limit': limit, 'offset_plus_one': offset+1, 'offset_plus_limit': offset+limit})

@election_admin()
def voter_delete(request, election, voter_uuid):
  """
  Two conditions under which a voter can be deleted:
  - election is not frozen or
  - election is open reg
  """
  ## FOR NOW we allow this to see if we can redefine the meaning of "closed reg" to be more flexible
  # if election is frozen and has closed registration
  #if election.frozen_at and (not election.openreg):
  #  raise PermissionDenied()

  if election.encrypted_tally:
    raise PermissionDenied()

  voter = Voter.get_by_election_and_uuid(election, voter_uuid)
  if voter:
    voter.delete()

  if election.frozen_at:
    # log it
    election.append_log("Voter %s/%s removed after election frozen" % (voter.voter_type,voter.voter_id))
    
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(voters_list_pretty, args=[election.uuid]))

@election_admin(frozen=False)
def one_election_set_reg(request, election):
  """
  Set whether this is open registration or not
  """
  # only allow this for public elections
  if not election.private_p:
    open_p = bool(int(request.GET['open_p']))
    election.openreg = open_p
    election.save()
  
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(voters_list_pretty, args=[election.uuid]))

@election_admin()
def one_election_set_featured(request, election):
  """
  Set whether this is a featured election or not
  """

  user = get_user(request)
  if not security.user_can_feature_election(user, election):
    raise PermissionDenied()

  featured_p = bool(int(request.GET['featured_p']))
  election.featured_p = featured_p
  election.save()
  
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))

@election_admin()
def one_election_archive(request, election):
  
  archive_p = request.GET.get('archive_p', True)
  
  if bool(int(archive_p)):
    election.archived_at = datetime.datetime.utcnow()
  else:
    election.archived_at = None
    
  election.save()

  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))

# changed from admin to view because 
# anyone can see the questions, the administration aspect is now
# built into the page
@election_view()
def one_election_questions(request, election):
  questions_json = utils.to_json(election.questions)
  user = get_user(request)
  admin_p = security.user_can_admin_election(user, election)

  return render_template(request, 'election_questions', {'election': election, 'questions_json' : questions_json, 'admin_p': admin_p})

def _check_eligibility(election, user):
  # prevent password-users from signing up willy-nilly for other elections, doesn't make sense
  if user.user_type == 'password':
    return False

  return election.user_eligible_p(user)

def _register_voter(election, user):
  if not _check_eligibility(election, user):
    return None
    
  return Voter.register_user_in_election(user, election)
    
@election_view()
def one_election_register(request, election):
  if not election.openreg:
    return HttpResponseForbidden('registration is closed for this election')
    
  check_csrf(request)
    
  user = get_user(request)
  voter = Voter.get_by_election_and_user(election, user)
  
  if not voter:
    voter = _register_voter(election, user)
    
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))

@election_admin(frozen=False)
def one_election_save_questions(request, election):
  check_csrf(request)
  
  election.questions = utils.from_json(request.POST['questions_json'])
  election.save()

  # always a machine API
  return SUCCESS

@transaction.commit_on_success
@election_admin(frozen=False)
def one_election_freeze(request, election):
  # figure out the number of questions and trustees
  issues = election.issues_before_freeze

  if request.method == "GET":
    return render_template(request, 'election_freeze', {'election': election, 'issues' : issues, 'issues_p' : len(issues) > 0})
  else:
    check_csrf(request)
    
    election.freeze()

    if get_user(request):
      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
    else:
      return SUCCESS    

def _check_election_tally_type(election):
  for q in election.questions:
    if q['tally_type'] != "homomorphic":
      return False
  return True

@election_admin(frozen=True)
def one_election_compute_tally(request, election):
  """
  tallying is done all at a time now
  """
  if not _check_election_tally_type(election):
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view,args=[election.election_id]))

  if request.method == "GET":
    return render_template(request, 'election_compute_tally', {'election': election})
  
  check_csrf(request)

  if not election.voting_ended_at:
    election.voting_ended_at = datetime.datetime.utcnow()

  election.tallying_started_at = datetime.datetime.utcnow()
  election.save()

  tasks.election_compute_tally.delay(election_id = election.id)

  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view,args=[election.uuid]))

@trustee_check
def trustee_decrypt_and_prove(request, election, trustee):
  if not _check_election_tally_type(election) or election.encrypted_tally == None:
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view,args=[election.uuid]))
    
  return render_template(request, 'trustee_decrypt_and_prove', {'election': election, 'trustee': trustee})
  
@election_view(frozen=True)
def trustee_upload_decryption(request, election, trustee_uuid):
  if not _check_election_tally_type(election) or election.encrypted_tally == None:
    return FAILURE

  trustee = Trustee.get_by_election_and_uuid(election, trustee_uuid)

  factors_and_proofs = utils.from_json(request.POST['factors_and_proofs'])

  # verify the decryption factors
  trustee.decryption_factors = [[datatypes.LDObject.fromDict(factor, type_hint='core/BigInteger').wrapped_obj for factor in one_q_factors] for one_q_factors in factors_and_proofs['decryption_factors']]

  # each proof needs to be deserialized
  trustee.decryption_proofs = [[datatypes.LDObject.fromDict(proof, type_hint='legacy/EGZKProof').wrapped_obj for proof in one_q_proofs] for one_q_proofs in factors_and_proofs['decryption_proofs']]

  if trustee.verify_decryption_proofs():
    trustee.save()
    
    try:
      # send a note to admin
      election.admin.send_message("%s - trustee partial decryption" % election.name, "trustee %s (%s) did their partial decryption." % (trustee.name, trustee.email))
    except:
      # ah well
      pass
    
    return SUCCESS
  else:
    return FAILURE
  
@election_admin(frozen=True)
def combine_decryptions(request, election):
  """
  combine trustee decryptions
  """

  election_url = get_election_url(election)

  if request.method == "POST":
    check_csrf(request)

    election.combine_decryptions()
    election.save()

    return HttpResponseRedirect("%s?%s" % (settings.SECURE_URL_HOST + reverse(voters_email, args=[election.uuid]), urllib.urlencode({'template': 'result'})))

  # if just viewing the form or the form is not valid
  return render_template(request, 'combine_decryptions', {'election': election})

@election_admin(frozen=True)
def one_election_set_result_and_proof(request, election):
  if election.tally_type != "homomorphic" or election.encrypted_tally == None:
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view,args=[election.election_id]))

  # FIXME: check csrf
  
  election.result = utils.from_json(request.POST['result'])
  election.result_proof = utils.from_json(request.POST['result_proof'])
  election.save()

  if get_user(request):
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
  else:
    return SUCCESS
  
  
@election_view()
def voters_list_pretty(request, election):
  """
  Show the list of voters
  now using Django pagination
  """

  # for django pagination support
  page = int(request.GET.get('page', 1))
  limit = int(request.GET.get('limit', 50))
  q = request.GET.get('q','')
  
  order_by = 'user__user_id'

  # unless it's by alias, in which case we better go by UUID
  if election.use_voter_aliases:
    order_by = 'alias'

  user = get_user(request)
  admin_p = security.user_can_admin_election(user, election)

  categories = None
  eligibility_category_id = None

  try:
    if admin_p and can_list_categories(user.user_type):
      categories = AUTH_SYSTEMS[user.user_type].list_categories(user)
      eligibility_category_id = election.eligibility_category_id(user.user_type)
  except AuthenticationExpired:
    return user_reauth(request, user)
  
  # files being processed
  voter_files = election.voterfile_set.all()

  # load a bunch of voters
  # voters = Voter.get_by_election(election, order_by=order_by)
  voters = Voter.objects.filter(election = election).order_by(order_by).defer('vote')

  if q != '':
    if election.use_voter_aliases:
      voters = voters.filter(alias__icontains = q)
    else:
      voters = voters.filter(voter_name__icontains = q)

  voter_paginator = Paginator(voters, limit)
  voters_page = voter_paginator.page(page)

  total_voters = voter_paginator.count
    
  return render_template(request, 'voters_list', 
                         {'election': election, 'voters_page': voters_page,
                          'voters': voters_page.object_list, 'admin_p': admin_p, 
                          'email_voters': helios.VOTERS_EMAIL,
                          'limit': limit, 'total_voters': total_voters,
                          'upload_p': helios.VOTERS_UPLOAD, 'q' : q,
                          'voter_files': voter_files,
                          'categories': categories,
                          'eligibility_category_id' : eligibility_category_id})

@election_admin()
def voters_eligibility(request, election):
  """
  set eligibility for voters
  """
  user = get_user(request)

  if request.method == "GET":
    # this shouldn't happen, only POSTs
    return HttpResponseRedirect("/")

  # for now, private elections cannot change eligibility
  if election.private_p:
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(voters_list_pretty, args=[election.uuid]))

  # eligibility
  eligibility = request.POST['eligibility']

  if eligibility in ['openreg', 'limitedreg']:
    election.openreg= True

  if eligibility == 'closedreg':
    election.openreg= False

  if eligibility == 'limitedreg':
    # now process the constraint
    category_id = request.POST['category_id']

    constraint = AUTH_SYSTEMS[user.user_type].generate_constraint(category_id, user)
    election.eligibility = [{'auth_system': user.user_type, 'constraint': [constraint]}]
  else:
    election.eligibility = None

  election.save()
  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(voters_list_pretty, args=[election.uuid]))
  
@election_admin()
def voters_upload(request, election):
  """
  Upload a CSV of password-based voters with
  voter_id, email, name
  
  name and email are needed only if voter_type is static
  """

  ## TRYING this: allowing voters upload by admin when election is frozen
  #if election.frozen_at and not election.openreg:
  #  raise PermissionDenied()

  if request.method == "GET":
    return render_template(request, 'voters_upload', {'election': election, 'error': request.GET.get('e',None)})
    
  if request.method == "POST":
    if bool(request.POST.get('confirm_p', 0)):
      # launch the background task to parse that file
      tasks.voter_file_process.delay(voter_file_id = request.session['voter_file_id'])
      del request.session['voter_file_id']

      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(voters_list_pretty, args=[election.uuid]))
    else:
      # we need to confirm
      if request.FILES.has_key('voters_file'):
        voters_file = request.FILES['voters_file']
        voter_file_obj = election.add_voters_file(voters_file)

        request.session['voter_file_id'] = voter_file_obj.id
        
        # import the first few lines to check
        voters = [v for v in voter_file_obj.itervoters()][:5]

        return render_template(request, 'voters_upload_confirm', {'election': election, 'voters': voters})
      else:
        return HttpResponseRedirect("%s?%s" % (settings.SECURE_URL_HOST + reverse(voters_upload, args=[election.uuid]), urllib.urlencode({'e':'no voter file specified, try again'})))

@election_admin()
def voters_upload_cancel(request, election):
  """
  cancel upload of CSV file
  """
  voter_file_id = request.session.get('voter_file_id', None)
  if voter_file_id:
    vf = VoterFile.objects.get(id = voter_file_id)
    vf.delete()
  del request.session['voter_file_id']

  return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))

@election_admin(frozen=True)
def voters_email(request, election):
  if not helios.VOTERS_EMAIL:
    return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
  TEMPLATES = [
    ('vote', 'Time to Vote'),
    ('info', 'Additional Info'),
    ('result', 'Election Result')
    ]

  template = request.REQUEST.get('template', 'vote')
  if not template in [t[0] for t in TEMPLATES]:
    raise Exception("bad template")

  voter_id = request.REQUEST.get('voter_id', None)

  if voter_id:
    voter = Voter.get_by_election_and_voter_id(election, voter_id)
  else:
    voter = None
  
  election_url = get_election_url(election)
  election_vote_url = get_election_govote_url(election)

  default_subject = render_template_raw(None, 'email/%s_subject.txt' % template, {
      'custom_subject': "&lt;SUBJECT&gt;"
})
  default_body = render_template_raw(None, 'email/%s_body.txt' % template, {
      'election' : election,
      'election_url' : election_url,
      'election_vote_url' : election_vote_url,
      'custom_subject' : default_subject,
      'custom_message': '&lt;BODY&gt;',
      'voter': {'vote_hash' : '<SMART_TRACKER>',
                'name': '<VOTER_NAME>',
                'voter_login_id': '<VOTER_LOGIN_ID>',
                'voter_password': '<VOTER_PASSWORD>',
                'voter_type' : election.voter_set.all()[0].voter_type,
                'election' : election}
      })

  if request.method == "GET":
    email_form = forms.EmailVotersForm()
    if voter:
      email_form.fields['send_to'].widget = email_form.fields['send_to'].hidden_widget()
  else:
    email_form = forms.EmailVotersForm(request.POST)
    
    if email_form.is_valid():
      
      # the client knows to submit only once with a specific voter_id
      subject_template = 'email/%s_subject.txt' % template
      body_template = 'email/%s_body.txt' % template

      extra_vars = {
        'custom_subject' : email_form.cleaned_data['subject'],
        'custom_message' : email_form.cleaned_data['body'],
        'election_vote_url' : election_vote_url,
        'election_url' : election_url,
        'election' : election
        }
        
      voter_constraints_include = None
      voter_constraints_exclude = None

      if voter:
        tasks.single_voter_email.delay(voter_uuid = voter.uuid, subject_template = subject_template, body_template = body_template, extra_vars = extra_vars)
      else:
        # exclude those who have not voted
        if email_form.cleaned_data['send_to'] == 'voted':
          voter_constraints_exclude = {'vote_hash' : None}
          
        # include only those who have not voted
        if email_form.cleaned_data['send_to'] == 'not-voted':
          voter_constraints_include = {'vote_hash': None}

        tasks.voters_email.delay(election_id = election.id, subject_template = subject_template, body_template = body_template, extra_vars = extra_vars, voter_constraints_include = voter_constraints_include, voter_constraints_exclude = voter_constraints_exclude)

      # this batch process is all async, so we can return a nice note
      return HttpResponseRedirect(settings.SECURE_URL_HOST + reverse(one_election_view, args=[election.uuid]))
    
  return render_template(request, "voters_email", {
      'email_form': email_form, 'election': election,
      'voter': voter,
      'default_subject': default_subject,
      'default_body' : default_body,
      'template' : template,
      'templates' : TEMPLATES})    

# Individual Voters
@election_view()
@json
def voter_list(request, election):
  # normalize limit
  limit = int(request.GET.get('limit', 500))
  if limit > 500: limit = 500
    
  voters = Voter.get_by_election(election, order_by='uuid', after=request.GET.get('after',None), limit= limit)
  return [v.ld_object.toDict() for v in voters]
  
@election_view()
@json
def one_voter(request, election, voter_uuid):
  """
  View a single voter's info as JSON.
  """
  voter = Voter.get_by_election_and_uuid(election, voter_uuid)
  if not voter:
    raise Http404
  return voter.toJSONDict()  

@election_view()
@json
def voter_votes(request, election, voter_uuid):
  """
  all cast votes by a voter
  """
  voter = Voter.get_by_election_and_uuid(election, voter_uuid)
  votes = CastVote.get_by_voter(voter)
  return [v.toJSONDict()  for v in votes]

@election_view()
@json
def voter_last_vote(request, election, voter_uuid):
  """
  all cast votes by a voter
  """
  voter = Voter.get_by_election_and_uuid(election, voter_uuid)
  return voter.last_cast_vote().toJSONDict()

##
## cast ballots
##

@election_view()
@json
def ballot_list(request, election):
  """
  this will order the ballots from most recent to oldest.
  and optionally take a after parameter.
  """
  limit = after = None
  if request.GET.has_key('limit'):
    limit = int(request.GET['limit'])
  if request.GET.has_key('after'):
    after = datetime.datetime.strptime(request.GET['after'], '%Y-%m-%d %H:%M:%S')
    
  voters = Voter.get_by_election(election, cast=True, order_by='cast_at', limit=limit, after=after)

  # we explicitly cast this to a short cast vote
  return [v.last_cast_vote().ld_object.short.toDict(complete=True) for v in voters]