def experiment_stats(request, epn):
    """Get stats about an experiment associated with the given EPN.

    :param request: a HTTP Request instance
    :type request: :class:`django.http.HttpRequest`
    :param epn: the EPN (proposal number) of the experiment to be edited
    :type epn: string
    :rtype: :class:`django.http.HttpResponse`
    """
    if not (request.META['REMOTE_ADDR'] == '114.30.64.13' or request.META['REMOTE_USER'] == 'admin'):
        return return_response_error(request)

    try:
        epn_param = models.ExperimentParameter.objects.get(name__name__exact='EPN', string_value=epn)
        experiment_id = epn_param.parameterset.experiment.pk
        #experiment = models.Experiment.safe.get(request, experiment_id)
    except PermissionDenied:
        return return_response_error(request)
    except models.ExperimentParameter.DoesNotExist:
        return return_response_not_found(request)

    # calculate the sum of the datafile sizes
    datafile_sizes = models.Dataset_File.objects.filter(dataset__experiment=experiment_id).values_list('size', flat=True)

    json_dict = {}
    json_dict['total_file_count'] = len(datafile_sizes)
    json_dict['total_file_size'] = sum(map(long, datafile_sizes))

    response = HttpResponse(json.dumps(json_dict), mimetype='application/json')
    response['Pragma'] = 'no-cache'
    response['Cache-Control'] = 'no-cache, must-revalidate'
    return response

def view_rifcs(request, experiment_id):
    """View the rif-cs of an existing experiment.

    :param request: a HTTP Request instance
    :type request: :class:`django.http.HttpRequest`
    :param experiment_id: the ID of the experiment to be viewed
    :type experiment_id: string
    :rtype: :class:`django.http.HttpResponse`

    """
    try:
        experiment = Experiment.safe.get(request.user, experiment_id)
    except PermissionDenied:
        return return_response_error(request)
    except Experiment.DoesNotExist:
        return return_response_not_found(request)

    try:
        rifcs_provs = settings.RIFCS_PROVIDERS
    except AttributeError:
        rifcs_provs = ()

    from tardis.tardis_portal.publish.publishservice import PublishService
    pservice = PublishService(rifcs_provs, experiment)
    context = pservice.get_context()
    if context is None:
        # return error page or something
        return return_response_error(request)

    template = pservice.get_template()
    return HttpResponse(render_response_index(request,
                        template, context), content_type="text/xml")

def table(request, experiment_id):
    # http://datatables.net/usage/server-side
    if len(request.GET) == 0:
        return return_response_error(request)

    sort_col_index = ''
    sort_col_name = ''
    sort_desc = ''
    try:
        if int(request.GET['iSortingCols']) != 1:
            return return_response_error(request)

        sort_col_index = request.GET['iSortCol_0']
        sort_col_name = request.GET['mDataProp_' + sort_col_index]
        sort_desc = request.GET['sSortDir_0'] == 'desc'
    except:
        return return_response_error(request)

    experiment = Experiment.objects.get(pk=experiment_id)

    parameter_names = ParameterName.objects.filter(datafileparameter__parameterset__dataset_file__dataset__experiment=experiment).distinct()
    datafiles = Dataset_File.objects.filter(dataset__experiment=experiment)

    if sort_col_name == 'filename':
        if sort_desc:
            datafiles = datafiles.order_by('-filename')
        else:
            datafiles = datafiles.order_by('filename')
        post_filter = False
    else:
        datafiles = datafiles.order_by('filename')
        post_filter = True

    filter = ''
    limit = ''
    offset = ''
    try: 
        filter = request.GET['sSearch']
        limit = int(request.GET['iDisplayLength'])
        offset = int(request.GET['iDisplayStart'])
    except: 
        return return_response_error(request) 

    filtered_datafiles = _filter(datafiles, filter)
    dfs = [(x.id, x.filename) for x in filtered_datafiles[offset:offset+limit]]
    df_ids = [x[0] for x in dfs]

    params_by_file = _params_by_file(df_ids, parameter_names)

    rows = _get_rows(dfs, parameter_names, params_by_file, sort_desc, post_filter, sort_col_name)

    resp = {}
    resp['sEcho'] = int(request.GET['sEcho'])
    resp['aaData'] = rows
    resp['iTotalRecords'] = datafiles.count()
    resp['iTotalDisplayRecords'] = filtered_datafiles.count()
    return HttpResponse(json.dumps(resp), mimetype='application/json')

def change_user_permissions(request, experiment_id, username):

    try:
        user = User.objects.get(username=username)
    except User.DoesNotExist:
        return return_response_error(request)

    try:
        experiment = Experiment.objects.get(pk=experiment_id)
    except Experiment.DoesNotExist:
        return return_response_error(request)

    try:
        expt_acls = Experiment.safe.user_acls(experiment_id)
        acl = None
        for eacl in expt_acls:
            if eacl.pluginId == 'django_user' and \
               eacl.get_related_object().id == user.id:
                acl = eacl
        #acl = expt_acls.filter(entityId=str(user.id))
        if acl is None:
            raise ObjectACL.DoesNotExist
        owner_acls = [oacl for oacl in expt_acls if oacl.isOwner]
    except ObjectACL.DoesNotExist:
        return return_response_error(request)

    if request.method == 'POST':
        form = ChangeUserPermissionsForm(request.POST, instance=acl)

        if form.is_valid():
            if 'isOwner' in form.changed_data and \
                            form.cleaned_data['isOwner'] is False and \
                            len(owner_acls) == 1:
                owner = owner_acls[0].get_related_object()
                plugin = owner_acls[0].pluginId
                if plugin == 'django_user' and owner.id == user.id:
                    return render_error_message(
                        request,
                        'Cannot remove ownership, every experiment must have at '
                        'least one user owner.', status=409)
            form.save()
            url = reverse('tardis.tardis_portal.views.control_panel')
            return HttpResponseRedirect(url)

    else:
        form = ChangeUserPermissionsForm(instance=acl)
        c = {'form': form,
             'header':
             "Change User Permissions for '%s'" % user.username}

    return HttpResponse(render_response_index(
        request, 'tardis_portal/form_template.html', c))

def add_dataset_par(request, dataset_id):
    parentObject = Dataset.objects.get(id=dataset_id)
    if authz.has_write_permissions(request, parentObject.experiment.id):
        return add_par_alt(request, parentObject, otype="dataset",
                stype=Schema.DATASET)
    else:
        return return_response_error(request)

def add_experiment_par(request, experiment_id):
    parentObject = Experiment.objects.get(id=experiment_id)
    if authz.has_write_permissions(request, parentObject.id):
        return add_par_alt(request, parentObject, otype="experiment",
                stype=Schema.EXPERIMENT)
    else:
        return return_response_error(request)

def new_sample(request, experiment_id):  
    try:
        experiment = Experiment.safe.get(request, experiment_id)
    except PermissionDenied:
        return return_response_error(request)
    except Experiment.DoesNotExist:
        return return_response_not_found(request)
    
    c = Context()
    c['experiment'] = experiment
    samples = Sample.objects.filter(experiment=experiment_id)
    c['sample_count'] = samples.count() + 1
    
    if request.method == 'POST':
        form = SampleForm(request.POST)
        if form.is_valid():
            sample = form.save(experiment_id, commit=False)
            sample.save_m2m()
            request.POST = {'status': "Sample Created."}
            return _redirect(experiment_id)
        c['status'] = "Errors exist in form."
        c["error"] = 'true'
    else:
        form = SampleForm(extra=1)
        
    c['form'] = form    
    c['status'] = form.errors
    return HttpResponse(render_response_index(request,
                        'tardis_portal/experiment_sample.html', c))

 def wrap(request, *args, **kwargs):
     dataset_id = kwargs['dataset_id']
     if not has_dataset_write(request, dataset_id):
         if request.is_ajax():
             return HttpResponse("")
         return return_response_error(request)
     return f(request, *args, **kwargs)

 def wrap(request, *args, **kwargs):
     if not request.user.groups.filter(
             name=getattr(
                 settings, 'PUBLICATION_OWNER_GROUP',
                 default_settings.PUBLICATION_OWNER_GROUP)).exists():
         return return_response_error(request)
     return f(request, *args, **kwargs)

def load_dataset_image(request, parameter_id):
    parameter = DatasetParameter.objects.get(pk=parameter_id)
    dataset = parameter.parameterset.dataset
    if authz.has_dataset_access(request, dataset.id):
        return load_image(request, parameter)
    else:
        return return_response_error(request)

def load_experiment_image(request, parameter_id):
    parameter = ExperimentParameter.objects.get(pk=parameter_id)
    experiment_id = parameter.parameterset.experiment.id
    if authz.has_experiment_access(request, experiment_id):
        return load_image(request, parameter)
    else:
        return return_response_error(request)

    def get(self, request, *args, **kwargs):
        """
        The index view, intended to render the front page of the MyTardis site
        listing recent experiments.

        This default view can be overriden by defining a dictionary INDEX_VIEWS in
        settings which maps SITE_ID's or domain names to an alternative view
        function (similar to the DATASET_VIEWS or EXPERIMENT_VIEWS overrides).

        :param request: a HTTP request object
        :type request: :class:`django.http.HttpRequest`
        :return: The Django response object
        :rtype: :class:`django.http.HttpResponse`
        """

        dataset_id = kwargs.get('dataset_id', None)
        if dataset_id is None:
            return return_response_error(request)

        dataset = Dataset.objects.get(id=dataset_id)
        if not dataset:
            return return_response_not_found(request)

        view_override = self.find_custom_view_override(request, dataset)
        if view_override is not None:
            return view_override

        c = self.get_context_data(request, dataset, **kwargs)

        template_name = kwargs.get('template_name', None)
        if template_name is None:
            template_name = self.template_name

        return HttpResponse(render_response_index(request, template_name, c))

def _list_related_info(request, experiment_id):
    if not authz.has_experiment_access(request, experiment_id):
        return return_response_error(request)
    sets = ExperimentParameterSet.objects.filter(schema__namespace=SCHEMA_URI)
    return HttpResponse(json.dumps([_get_dict_from_ps(ps)
                                    for ps in sets]),
                        content_type='application/json; charset=utf-8')

    def get(self, request, *args, **kwargs):
        """


        :param request: a HTTP request object
        :type request: :class:`django.http.HttpRequest`
        :return: The Django response object
        :rtype: :class:`django.http.HttpResponse`
        """

        dataset_id = kwargs.get('dataset_id', None)
        if dataset_id is None:
            return return_response_error(request)

        dataset = Dataset.objects.get(id=dataset_id)
        if not dataset:
            return return_response_not_found(request)

        c = self.get_context_data(request, dataset, **kwargs)

        template_name = kwargs.get('template_name', None)
        if template_name is None:
            template_name = self.template_name

        return HttpResponse(render_response_index(
                request,
                template_name,
                c)
        )

def edit_datafile_par(request, parameterset_id):
    parameterset = DatafileParameterSet.objects.get(id=parameterset_id)
    if authz.has_write_permissions(request,
                                   parameterset.dataset_file.dataset.experiment.id):
        return edit_parameters_alt(request, parameterset, otype="datafile")
    else:
        return return_response_error(request)

def edit_sample(request, experiment_id, sample_id):
    try:
        experiment = Experiment.safe.get(request, experiment_id)
    except PermissionDenied:
        return return_response_error(request)
    except Experiment.DoesNotExist:
        return return_response_not_found(request)
    c = Context()
    c['experiment'] = experiment
    sample = Sample.objects.get(id=sample_id)
    c['sample_count'] = sample.name
    
    if request.POST:
        form = SampleForm(request.POST, instance=sample, extra=0)
        if form.is_valid():
            full_sample = form.save(experiment_id, commit=False)
            
            full_sample.save_m2m()
            request.POST = {'status': "Sample Created."}
            return _redirect(experiment_id)
        c['status'] = "Errors exist in form."
        c["error"] = 'true'
    else:
        form = SampleForm(instance=sample, extra=0)
    
    c['form'] = form    
    c['status'] = form.errors
    return HttpResponse(render_response_index(request,
                        'tardis_portal/experiment_sample.html', c))

def change_group_permissions(request, experiment_id, group_id):

    try:
        group = Group.objects.get(pk=group_id)
    except Group.DoesNotExist:
        return return_response_error(request)

    try:
        experiment = Experiment.objects.get(pk=experiment_id)
    except Experiment.DoesNotExist:
        return return_response_error(request)

    try:
        acl = ObjectACL.objects.get(
            content_type=experiment.get_ct(),
            object_id=experiment.id,
            pluginId='django_group',
            entityId=str(group.id),
            aclOwnershipType=ObjectACL.OWNER_OWNED)
    except ObjectACL.DoesNotExist:
        return return_response_error(request)

    if request.method == 'POST':
        form = ChangeGroupPermissionsForm(request.POST)

        if form.is_valid():
            acl.canRead = form.cleaned_data['canRead']
            acl.canWrite = form.cleaned_data['canWrite']
            acl.canDelete = form.cleaned_data['canDelete']
            acl.effectiveDate = form.cleaned_data['effectiveDate']
            acl.expiryDate = form.cleaned_data['expiryDate']
            acl.save()
            return HttpResponseRedirect('/experiment/control_panel/')

    else:
        form = ChangeGroupPermissionsForm(
            initial={'canRead': acl.canRead,
                     'canWrite': acl.canWrite,
                     'canDelete': acl.canDelete,
                     'effectiveDate': acl.effectiveDate,
                     'expiryDate': acl.expiryDate})

    c = {'form': form,
         'header': "Change Group Permissions for '%s'" % group.name}

    return HttpResponse(render_response_index(
        request, 'tardis_portal/form_template.html', c))

def _create_download_response(request, datafile_id, disposition='attachment'):  # too complex # noqa
    # Get datafile (and return 404 if absent)
    try:
        datafile = DataFile.objects.get(pk=datafile_id)
    except DataFile.DoesNotExist:
        return return_response_not_found(request)
    # Check users has access to datafile
    if not has_datafile_download_access(request=request,
                                        datafile_id=datafile.id):
        return return_response_error(request)
    # Send an image that can be seen in the browser
    if disposition == 'inline' and datafile.is_image():
        from tardis.tardis_portal.iiif import download_image
        args = (request, datafile.id, 'full', 'full', '0', 'native')
        # Send unconverted image if web-compatible
        if datafile.get_mimetype() in ('image/gif', 'image/jpeg', 'image/png'):
            return download_image(*args)
        # Send converted image
        return download_image(*args, format='png')
    # Send local file
    try:
        verified_only = True
        # Query parameter to allow download of unverified files
        ignore_verif = request.GET.get('ignore_verification_status', '0')
        # Ensure ignore_verification_status=0 etc works as expected
        # a bare ?ignore_verification_status is True
        if ignore_verif.lower() in [u'', u'1', u'true']:
            verified_only = False

        # Get file object for datafile
        file_obj = datafile.get_file(verified_only=verified_only)
        if not file_obj:
            # If file path doesn't resolve, return not found
            if verified_only:
                return render_error_message(request,
                                            "File is unverified, "
                                            "please try again later.",
                                            status=503)
            return return_response_not_found(request)
        wrapper = FileWrapper(file_obj, blksize=65535)
        response = StreamingHttpResponse(wrapper,
                                         content_type=datafile.get_mimetype())
        response['Content-Disposition'] = \
            '%s; filename="%s"' % (disposition, datafile.filename)
        return response
    except IOError:
        # If we can't read the file, return not found
        return return_response_not_found(request)
    except ValueError:  # raised when replica not verified TODO: custom excptn
        redirect = request.META.get('HTTP_REFERER',
                                    'http://%s/' %
                                    request.META.get('HTTP_HOST'))
        message = """The file you are trying to access has not yet been
                     verified. Verification is an automated background process.
                     Please try again later or contact the system
                     administrator if the issue persists."""
        message = ' '.join(message.split())  # removes spaces
        redirect = redirect + '#error:' + message
        return HttpResponseRedirect(redirect)

 def wrap(request, *args, **kwargs):
     user = request.user
     if not request.user.is_authenticated():
         return HttpResponseRedirect('/login?next=%s' % request.path)
     if not (is_group_admin(request, kwargs['group_id']) or
             user.is_superuser):
         return return_response_error(request)
     return f(request, *args, **kwargs)

def add_user_to_group(request, group_id, username):

    if username == settings.TOKEN_USERNAME:
        return HttpResponse('User does not exist: %s' % username)

    authMethod = localdb_auth_key
    isAdmin = False

    if 'isAdmin' in request.GET:
        if request.GET['isAdmin'] == 'true':
            isAdmin = True

    try:
        authMethod = request.GET['authMethod']
        if authMethod == localdb_auth_key:
            user = User.objects.get(username=username)
        else:
            user = UserAuthentication.objects.get(
                username=username,
                authenticationMethod=authMethod).userProfile.user
    except User.DoesNotExist:
        return return_response_error(request)
    except UserAuthentication.DoesNotExist:
        return return_response_error(request)

    try:
        group = Group.objects.get(pk=group_id)
    except Group.DoesNotExist:
        return HttpResponse('Group does not exist.')

    if user.groups.filter(name=group.name).count() > 0:
        return HttpResponse('User %s is already member of that group.'
                            % username)

    user.groups.add(group)
    user.save()

    if isAdmin:
        groupadmin = GroupAdmin(user=user, group=group)
        groupadmin.save()

    c = {'user': user, 'group_id': group_id, 'isAdmin': isAdmin}
    return HttpResponse(render_response_index(
        request,
        'tardis_portal/ajax/add_user_to_group_result.html', c))