# Source code for django_otp.admin

    from django import forms
    from django.contrib.admin.forms import AdminAuthenticationForm
    from django.contrib.admin.sites import AdminSite
    from django.contrib.auth import get_user_model
    from django.core.exceptions import FieldDoesNotExist

    from .forms import OTPAuthenticationFormMixin

    def _admin_template_for_django_version():
        """
        Returns the most appropriate Django login template available.

        In the past, we've had more version-specific templates. Perhaps this will
        be true again in the future. For now, the Django 1.11 version is suitable
        even with the most recent Django version.
        """
        return 'otp/admin111/login.html'

    def user_model_search_fields(field_names):
        """
        Check whether the provided field names exist, and return a tuple of
        search fields and help text for the validated field names.

        Parameters:
        field_names (list of str): A list of field names to search for in the user model.

        Returns:
        tuple: A tuple containing:
            - search_fields (list of str): A list of search fields formatted for querying.
            - search_help_text (str): A help text string describing the valid search fields.
        """
        User = get_user_model()
        search_fields = []
        help_texts = []

        for name in field_names:
            try:
                field = User._meta.get_field(name)
            except FieldDoesNotExist:
                continue
            else:
                search_fields.append(f'user__{field.name}')
                help_texts.append(str(field.verbose_name))

        if len(help_texts) == 0:
            search_help_text = ""
        else:
            search_help_text = "Search by user's "

            if len(help_texts) == 1:
                search_help_text += help_texts[0]
            else:
                search_help_text += ", ".join(help_texts[:-1]) + f" or {help_texts[-1]}"

        return search_fields, search_help_text

    class OTPAdminAuthenticationForm(AdminAuthenticationForm, OTPAuthenticationFormMixin):
        """
        An :class:`~django.contrib.admin.forms.AdminAuthenticationForm` subclass
        that solicits an OTP token. This has the same behavior as
        :class:`~django_otp.forms.OTPAuthenticationForm`.
        """

        otp_device = forms.CharField(required=False, widget=forms.Select)
        otp_token = forms.CharField(required=False)

        # This is a placeholder field that allows us to detect when the user clicks
        # the otp_challenge submit button.
        otp_challenge = forms.CharField(required=False)

        def clean(self):
            self.cleaned_data = super().clean()
            self.clean_otp(self.get_user())

            return self.cleaned_data

    class OTPAdminSite(AdminSite):
        """
        This is an :class:`~django.contrib.admin.AdminSite` subclass that requires
        two-factor authentication. Only users that can be verified by a registered
        OTP device will be authorized for this admin site. Unverified users will be
        treated as if :attr:`~django.contrib.auth.models.User.is_staff` is
        ``False``.
        """

        #: The default instance name of this admin site. You should instantiate
        #: this class as ``OTPAdminSite(OTPAdminSite.name)`` to make sure the admin
        #: templates render the correct URLs.
        name = 'otpadmin'

        login_form = OTPAdminAuthenticationForm

        #: We automatically select a modified login template based on your Django
        #: version. If it doesn't look right, your version may not be supported, in
        #: which case feel free to replace it.
        login_template = _admin_template_for_django_version()

        def __init__(self, name='otpadmin'):
            super().__init__(name)

        def has_permission(self, request):
            """
            In addition to the default requirements, this only allows access to
            users who have been verified by a registered OTP device.
            """
            return super().has_permission(request) and request.user.is_verified()