WIP Use Flows for Sources and Providers (#32)

* core: start migrating to flows for authorisation

* sources/oauth: start type-hinting

* core: create default user

* core: only show user delete button if an unenrollment flow exists

* flows: Correctly check initial policies on flow with context

* policies: add more verbosity to engine

* sources/oauth: migrate to flows

* sources/oauth: fix typing errors

* flows: add more tests

* sources/oauth: start implementing unittests

* sources/ldap: add option to disable user sync, move connection init to model

* sources/ldap: re-add default PropertyMappings

* providers/saml: re-add default PropertyMappings

* admin: fix missing stage count

* stages/identification: fix sources not being shown

* crypto: fix being unable to save with private key

* crypto: re-add default self-signed keypair

* policies: rewrite cache_key to prevent wrong cache

* sources/saml: migrate to flows for auth and enrollment

* stages/consent: add new stage

* admin: fix PropertyMapping widget not rendering properly

* core: provider.authorization_flow is mandatory

* flows: add support for "autosubmit" attribute on form

* flows: add InMemoryStage for dynamic stages

* flows: optionally allow empty flows from FlowPlanner

* providers/saml: update to authorization_flow

* sources/*: fix flow executor URL

* flows: fix pylint error

* flows: wrap responses in JSON object to easily handle redirects

* flow: dont cache plan's context

* providers/oauth: rewrite OAuth2 Provider to use flows

* providers/*: update docstrings of models

* core: fix forms not passing help_text through safe

* flows: fix HttpResponses not being converted to JSON

* providers/oidc: rewrite to use flows

* flows: fix linting

passbook/core/models.py

@@ -16,6 +16,7 @@ from structlog import get_logger
 from passbook.core.exceptions import PropertyMappingExpressionException
 from passbook.core.signals import password_changed
 from passbook.core.types import UILoginButton, UIUserSettings
+from passbook.flows.models import Flow
 from passbook.lib.models import CreatedUpdatedModel
 from passbook.policies.models import PolicyBindingModel
 
@@ -75,6 +76,13 @@ class User(GuardianUserMixin, AbstractUser):
 class Provider(models.Model):
     """Application-independent Provider instance. For example SAML2 Remote, OAuth2 Application"""
 
+    authorization_flow = models.ForeignKey(
+        Flow,
+        on_delete=models.CASCADE,
+        help_text=_("Flow used when authorizing this provider."),
+        related_name="provider_authorization",
+    )
+
     property_mappings = models.ManyToManyField(
         "PropertyMapping", default=None, blank=True
     )
@@ -95,7 +103,6 @@ class Application(PolicyBindingModel):
 
     name = models.TextField(help_text=_("Application's display Name."))
     slug = models.SlugField(help_text=_("Internal application name, used in URLs."))
-    skip_authorization = models.BooleanField(default=False)
     provider = models.OneToOneField(
         "Provider", null=True, blank=True, default=None, on_delete=models.SET_DEFAULT
     )
@@ -128,6 +135,25 @@ class Source(PolicyBindingModel):
         "PropertyMapping", default=None, blank=True
     )
 
+    authentication_flow = models.ForeignKey(
+        Flow,
+        blank=True,
+        null=True,
+        default=None,
+        on_delete=models.SET_NULL,
+        help_text=_("Flow to use when authenticating existing users."),
+        related_name="source_authentication",
+    )
+    enrollment_flow = models.ForeignKey(
+        Flow,
+        blank=True,
+        null=True,
+        default=None,
+        on_delete=models.SET_NULL,
+        help_text=_("Flow to use when enrolling new users."),
+        related_name="source_enrollment",
+    )
+
     form = ""  # ModelForm-based class ued to create/edit instance
 
     objects = InheritanceManager()