from django.contrib import messages
from django.contrib.auth.forms import PasswordChangeForm
from django.contrib.auth.hashers import make_password
from django.contrib.auth.views import login as django_login
from django.core.urlresolvers import reverse
from django.utils.translation import ugettext as _, ugettext_lazy, activate

from openslides.config.api import config
from openslides.utils import rest_api
from openslides.utils.utils import delete_default_permissions, html_strong
from openslides.utils.views import (
    CreateView, CSVImportView, DeleteView, DetailView, FormView, ListView,
    PDFView, PermissionMixin, QuestionView, RedirectView, SingleObjectMixin,
    UpdateView, LoginMixin)
from openslides.utils.exceptions import OpenSlidesError

from .api import gen_password, gen_username, get_protected_perm
from .csv_import import import_users
from .forms import (GroupForm, UserCreateForm, UserMultipleCreateForm,
                    UsersettingsForm, UserUpdateForm)
from .models import Group, User
from .pdf import users_to_pdf, users_passwords_to_pdf
from .serializers import UserSerializer


class UserListView(ListView):
    """
    Show all users.
    """
    required_permission = 'users.can_see'
    context_object_name = 'users'

    def get_queryset(self):
        query = User.objects
        if config['users_sort_users_by_first_name']:
            query = query.order_by('first_name')
        else:
            query = query.order_by('last_name')
        return query.all()

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        all_users = User.objects.count()
        # context vars
        context.update({
            'allusers': all_users,
            'request_user': self.request.user})
        return context


class UserDetailView(DetailView, PermissionMixin):
    """
    Classed based view to show a specific user in the interface.
    """
    required_permission = 'users.can_see'
    model = User
    context_object_name = 'shown_user'


class UserCreateView(CreateView):
    """
    Create a new user.
    """
    required_permission = 'users.can_manage'
    model = User
    context_object_name = 'edit_user'
    form_class = UserCreateForm
    success_url_name = 'user_list'
    url_name_args = []

    def manipulate_object(self, form):
        self.object.username = gen_username(
            form.cleaned_data['first_name'], form.cleaned_data['last_name'])

        if not self.object.default_password:
            self.object.default_password = gen_password()

        self.object.set_password(self.object.default_password)

    def post_save(self, form):
        super(UserCreateView, self).post_save(form)
        # TODO: find a better solution that makes the following lines obsolete
        # Background: motion.models.use_post_save adds already the registerd group
        # to new user but super(..).post_save(form) removes it and sets only the
        # groups selected in the form (without 'registered')
        # workaround: add registered group again manually
        from openslides.users.api import get_registered_group  # TODO: Test, if global import is possible
        registered = get_registered_group()
        self.object.groups.add(registered)


class UserMultipleCreateView(FormView):
    """
    View to create multiple users at once using a big text field.

    Sets the password with md5. It is the same password as in the
    default_password field in cleartext. A stronger password hasher is used,
    when the password is changed by the user.
    """
    required_permission = 'users.can_manage'
    template_name = 'users/user_form_multiple.html'
    form_class = UserMultipleCreateForm
    success_url_name = 'user_list'

    def form_valid(self, form):
        # TODO: Use bulk_create
        for number, line in enumerate(form.cleaned_data['users_block'].splitlines()):
            names_list = line.split()
            first_name = ' '.join(names_list[:-1])
            last_name = names_list[-1]
            username = gen_username(first_name, last_name)
            default_password = gen_password()
            User.objects.create(
                username=username,
                first_name=first_name,
                last_name=last_name,
                default_password=default_password,
                password=make_password(default_password, '', 'md5'))
        messages.success(self.request, _('%(number)d users successfully created.') % {'number': number + 1})
        return super(UserMultipleCreateView, self).form_valid(form)


class UserUpdateView(UpdateView):
    """
    Update an existing users.
    """
    required_permission = 'users.can_manage'
    model = User
    context_object_name = 'edit_user'
    form_class = UserUpdateForm
    success_url_name = 'user_list'
    url_name_args = []

    def get_form_kwargs(self, *args, **kwargs):
        form_kwargs = super(UserUpdateView, self).get_form_kwargs(*args, **kwargs)
        form_kwargs.update({'request': self.request})
        return form_kwargs

    def post_save(self, form):
        super(UserUpdateView, self).post_save(form)
        # TODO: Find a better solution that makes the following lines obsolete
        # Background: motion.models.use_post_save adds already the registerd group
        # to new user but super(..).post_save(form) removes it and sets only the
        # groups selected in the form (without 'registered')
        # workaround: add registered group again manually
        from openslides.users.api import get_registered_group  # TODO: Test, if global import is possible
        registered = get_registered_group()
        self.object.groups.add(registered)


class UserDeleteView(DeleteView):
    """
    Delete a user.
    """
    required_permission = 'users.can_manage'
    model = User
    success_url_name = 'user_list'
    url_name_args = []

    def pre_redirect(self, request, *args, **kwargs):
        if self.get_object() == self.request.user:
            messages.error(request, _("You can not delete yourself."))
        else:
            super().pre_redirect(request, *args, **kwargs)

    def pre_post_redirect(self, request, *args, **kwargs):
        if self.get_object() == self.request.user:
            messages.error(self.request, _("You can not delete yourself."))
        else:
            super().pre_post_redirect(request, *args, **kwargs)


class SetUserStatusView(SingleObjectMixin, RedirectView):
    """
    Activate or deactivate an user.
    """
    required_permission = 'users.can_manage'
    allow_ajax = True
    url_name = 'user_list'
    url_name_args = []
    model = User

    def pre_redirect(self, request, *args, **kwargs):
        action = kwargs['action']
        if action == 'activate':
            self.get_object().is_active = True
        elif action == 'deactivate':
            if self.get_object().user == self.request.user:
                messages.error(request, _("You can not deactivate yourself."))
            else:
                self.get_object().is_active = False
        self.get_object().save()
        return super(SetUserStatusView, self).pre_redirect(request, *args, **kwargs)

    def get_ajax_context(self, **kwargs):
        context = super(SetUserStatusView, self).get_ajax_context(**kwargs)
        context['active'] = self.get_object().is_active
        return context


class UsersListPDF(PDFView):
    """
    Generate the userliste as PDF.
    """
    required_permission = 'users.can_see'
    filename = ugettext_lazy("user-list")
    document_title = ugettext_lazy('List of Users')

    def append_to_pdf(self, pdf):
        """
        Append PDF objects.
        """
        users_to_pdf(pdf)


class UsersPasswordsPDF(PDFView):
    """
    Generate the access data welcome paper for all users as PDF.
    """
    required_permission = 'users.can_manage'
    filename = ugettext_lazy("User-access-data")
    top_space = 0

    def build_document(self, pdf_document, story):
        pdf_document.build(story)

    def append_to_pdf(self, pdf):
        """
        Append PDF objects.
        """
        users_passwords_to_pdf(pdf)


class UserCSVImportView(CSVImportView):
    """
    Import users via CSV.
    """
    import_function = staticmethod(import_users)
    required_permission = 'users.can_manage'
    success_url_name = 'user_list'
    template_name = 'users/user_form_csv_import.html'


class ResetPasswordView(SingleObjectMixin, QuestionView):
    """
    Set the Passwort for a user to his default password.
    """
    required_permission = 'users.can_manage'
    model = User
    allow_ajax = True
    question_message = ugettext_lazy('Do you really want to reset the password?')

    def get_redirect_url(self, **kwargs):
        return reverse('user_edit', args=[self.get_object().id])

    def on_clicked_yes(self):
        self.get_object().reset_password()
        self.get_object().save()

    def get_final_message(self):
        return _('The Password for %s was successfully reset.') % html_strong(self.get_object())


class UserViewSet(rest_api.viewsets.ModelViewSet):
    """
    API endpoint to view, edit and delete users.
    """
    model = User
    queryset = User.objects.all()
    serializer_class = UserSerializer

    def check_permissions(self, request):
        """
        Calls self.permission_denied() if the requesting user has not the
        permission to manage.
        """
        # TODO: More work on this required.
        if not request.user.has_perm('users.can_manage'):
            self.permission_denied(request)


class GroupListView(ListView):
    """
    Overview over all groups.
    """
    required_permission = 'users.can_manage'
    template_name = 'users/group_list.html'
    context_object_name = 'groups'
    model = Group


class GroupDetailView(DetailView, PermissionMixin):
    """
    Classed based view to show a specific group in the interface.
    """
    required_permission = 'users.can_manage'
    model = Group
    template_name = 'users/group_detail.html'
    context_object_name = 'group'

    def get_context_data(self, *args, **kwargs):
        context = super(GroupDetailView, self).get_context_data(*args, **kwargs)
        query = User.objects
        if config['users_sort_users_by_first_name']:
            query = query.order_by('first_name')
        else:
            query = query.order_by('last_name')
        context['group_members'] = query.filter(groups__in=[context['group']])
        return context


class GroupCreateView(CreateView):
    """
    Create a new group.
    """
    required_permission = 'users.can_manage'
    template_name = 'users/group_form.html'
    context_object_name = 'group'
    model = Group
    form_class = GroupForm
    success_url_name = 'group_list'
    url_name_args = []

    def get(self, request, *args, **kwargs):
        delete_default_permissions()
        return super(GroupCreateView, self).get(request, *args, **kwargs)

    def get_apply_url(self):
        """
        Returns the url when the user clicks on 'apply'.
        """
        return self.get_url('group_update', args=[self.object.pk])


class GroupUpdateView(UpdateView):
    """
    Update an existing group.
    """
    required_permission = 'users.can_manage'
    template_name = 'users/group_form.html'
    model = Group
    context_object_name = 'group'
    form_class = GroupForm
    url_name_args = []
    success_url_name = 'group_list'

    def get(self, request, *args, **kwargs):
        delete_default_permissions()
        return super().get(request, *args, **kwargs)

    def get_form_kwargs(self, *args, **kwargs):
        form_kwargs = super().get_form_kwargs(*args, **kwargs)
        form_kwargs.update({'request': self.request})
        return form_kwargs

    def get_apply_url(self):
        """
        Returns the url when the user clicks on 'apply'.
        """
        return self.get_url('group_update', args=[self.object.pk])


class GroupDeleteView(DeleteView):
    """
    Delete a group.
    """
    required_permission = 'users.can_manage'
    model = Group
    success_url_name = 'group_list'
    question_url_name = 'group_detail'
    url_name_args = []

    def pre_redirect(self, request, *args, **kwargs):
        if not self.is_protected_from_deleting():
            super().pre_redirect(request, *args, **kwargs)

    def pre_post_redirect(self, request, *args, **kwargs):
        if not self.is_protected_from_deleting():
            super().pre_post_redirect(request, *args, **kwargs)

    def is_protected_from_deleting(self):
        """
        Checks whether the group is protected.
        """
        if self.get_object().pk in [1, 2]:
            messages.error(self.request, _('You can not delete this group.'))
            return True
        if (not self.request.user.is_superuser and
            get_protected_perm() in self.get_object().permissions.all() and
            not Group.objects.exclude(pk=self.get_object().pk).filter(
                permissions__in=[get_protected_perm()],
                user__pk=self.request.user.pk).exists()):
            messages.error(
                self.request,
                _('You can not delete the last group containing the permission '
                  'to manage users you are in.'))
            return True
        return False

    def get_url_name_args(self):
        try:
            answer = self.get_answer()
        except OpenSlidesError:
            answer = 'no'

        if self.request.method == 'POST' and answer != 'no':
            return []
        else:
            return [self.object.pk]


def login(request):
    extra_content = {}
    try:
        admin = User.objects.get(pk=1)
        if admin.check_password(admin.default_password):
            user_data = {
                'user': html_strong(admin.username),
                'password': html_strong(admin.default_password)}

            extra_content['first_time_message'] = _(
                "Installation was successfully! Use %(user)s "
                "(password: %(password)s) for first login.<br>"
                "<strong>Important:</strong> Please change the password after "
                "first login! Otherwise this message still appears for "
                "everyone  and could be a security risk.") % user_data

            extra_content['next'] = reverse('password_change')
    except User.DoesNotExist:
        pass
    return django_login(request, template_name='users/login.html', extra_context=extra_content)


class UserSettingsView(LoginMixin, UpdateView):
    model = User
    form_class = UsersettingsForm
    success_url_name = 'user_settings'
    url_name_args = []
    template_name = 'users/settings.html'

    def get_initial(self):
        initial = super().get_initial()
        initial['language'] = self.request.session.get('django_language', self.request.LANGUAGE_CODE)
        return initial

    def form_valid(self, form):
        self.request.LANGUAGE_CODE = self.request.session['django_language'] = form.cleaned_data['language']
        activate(self.request.LANGUAGE_CODE)
        return super().form_valid(form)

    def get_object(self):
        return self.request.user


class UserPasswordSettingsView(LoginMixin, FormView):
    form_class = PasswordChangeForm
    success_url_name = 'core_dashboard'
    template_name = 'users/password_change.html'

    def form_valid(self, form):
        form.save()
        messages.success(self.request, _('Password successfully changed.'))
        return super().form_valid(form)

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['user'] = self.request.user
        return kwargs