Bug fix for improperly configured SSO provider (#4822)

* Add sso template tags

* Check if SSO provider is valid on login page

* Add warning if SSO method is not correctly configured

* Template tweaks

InvenTree/part/templatetags/sso.py

@@ -0,0 +1,48 @@
+"""This module provides template tags pertaining to SSO functionality"""
+
+
+from django import template
+
+from common.models import InvenTreeSetting
+from InvenTree.helpers import str2bool
+
+register = template.Library()
+
+
+@register.simple_tag()
+def sso_login_enabled():
+    """Return True if single-sign-on is enabled"""
+
+    val = InvenTreeSetting.get_setting('LOGIN_ENABLE_SSO')
+
+    print("SSO Enabled:", val)
+
+    return str2bool(InvenTreeSetting.get_setting('LOGIN_ENABLE_SSO'))
+
+
+@register.simple_tag()
+def sso_reg_enabled():
+    """Return True if single-sign-on is enabled for self-registration"""
+    return str2bool(InvenTreeSetting.get_setting('LOGIN_ENABLE_SSO_REG'))
+
+
+@register.simple_tag()
+def sso_auto_enabled():
+    """Return True if single-sign-on is enabled for auto-registration"""
+    return str2bool(InvenTreeSetting.get_setting('LOGIN_SIGNUP_SSO_AUTO'))
+
+
+@register.simple_tag()
+def sso_check_provider(provider):
+    """Return True if the given provider is correctly configured"""
+
+    from allauth.socialaccount.models import SocialApp
+
+    # First, check that the provider is enabled
+    if not SocialApp.objects.filter(provider__iexact=provider.name).exists():
+        return False
+
+    # Next, check that the provider is correctly configured
+
+    # At this point, we assume that the provider is correctly configured
+    return True