class LoginForm(forms.Form):

    password = PasswordField(
        label = _("Password"))
    remember = forms.BooleanField(
        label = _("Remember Me"),
        # help_text = _("If checked you will stay logged in for 3 weeks"),
        required = False
    )

    user = None

    def __init__(self, *args, **kwargs):
        super(LoginForm, self).__init__(*args, **kwargs)
        ordering = []
        if app_settings.EMAIL_AUTHENTICATION:
            self.fields["email"] = forms.EmailField(
                label = ugettext("E-mail"),
            )
            ordering.append("email")
        else:
            self.fields["username"] = forms.CharField(
                label = ugettext("Username"),
                max_length = 30,
            )
            ordering.append("username")
        ordering.extend(["password", "remember"])
        self.fields.keyOrder = ordering

    def user_credentials(self):
        """
        Provides the credentials required to authenticate the user for
        login.
        """
        credentials = {}
        if app_settings.EMAIL_AUTHENTICATION:
            credentials["email"] = self.cleaned_data["email"]
        else:
            credentials["username"] = self.cleaned_data["username"]
        credentials["password"] = self.cleaned_data["password"]
        return credentials

    def clean(self):
        if self._errors:
            return
        user = authenticate(**self.user_credentials())
        if user:
            if user.is_active:
                self.user = user
            else:
                raise forms.ValidationError(_("This account is currently inactive."))
        else:
            if app_settings.EMAIL_AUTHENTICATION:
                error = _("The e-mail address and/or password you specified are not correct.")
            else:
                error = _("The username and/or password you specified are not correct.")
            raise forms.ValidationError(error)
        return self.cleaned_data

    def login(self, request, redirect_url=None):
        ret = perform_login(request, self.user, redirect_url=redirect_url)
        if self.cleaned_data["remember"]:
            request.session.set_expiry(60 * 60 * 24 * 7 * 3)
        else:
            request.session.set_expiry(0)
        return ret