flows: add ConfigurableStage base class and ConfigureFlowInitView

passbook/flows/migrations/0013_auto_20200924_1605.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.1 on 2020-09-24 16:05
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('passbook_flows', '0012_auto_20200908_1542'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='flow',
+            name='designation',
+            field=models.CharField(choices=[('authentication', 'Authentication'), ('authorization', 'Authorization'), ('invalidation', 'Invalidation'), ('enrollment', 'Enrollment'), ('unenrollment', 'Unrenollment'), ('recovery', 'Recovery'), ('stage_configuration', 'Stage Configuration')], max_length=100),
+        ),
+    ]

passbook/flows/models.py

@@ -37,7 +37,7 @@ class FlowDesignation(models.TextChoices):
     ENROLLMENT = "enrollment"
     UNRENOLLMENT = "unenrollment"
     RECOVERY = "recovery"
-    STAGE_SETUP = "stage_setup"
+    STAGE_CONFIGURATION = "stage_configuration"
 
 
 class Stage(SerializerModel):
@@ -73,6 +73,29 @@ class Stage(SerializerModel):
         return f"Stage {self.name}"
 
 
+class ConfigurableStage(models.Model):
+    """Abstract base class for a Stage that can be configured by the enduser.
+    The stage should create a default flow with the configure_stage designation during
+    migration."""
+
+    configure_flow = models.ForeignKey(
+        'passbook_flows.Flow',
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        help_text=_(
+            (
+                "Flow used by an authenticated user to change their password. "
+                "If empty, user will be unable to change their password."
+            )
+        ),
+    )
+
+    class Meta:
+
+        abstract = True
+
+
 def in_memory_stage(view: Type["StageView"]) -> Stage:
     """Creates an in-memory stage instance, based on a `_type` as view."""
     stage = Stage()

passbook/flows/urls.py

@@ -3,7 +3,7 @@ from django.urls import path
 
 from passbook.flows.models import FlowDesignation
 from passbook.flows.views import (
-    CancelView,
+    CancelView, ConfigureFlowInitView,
     FlowExecutorShellView,
     FlowExecutorView,
     ToDefaultFlow,
@@ -36,6 +36,7 @@ urlpatterns = [
         name="default-unenrollment",
     ),
     path("-/cancel/", CancelView.as_view(), name="cancel"),
+    path("-/configure/<uuid:stage_uuid>/", ConfigureFlowInitView.as_view(), name="configure"),
     path("b/<slug:flow_slug>/", FlowExecutorView.as_view(), name="flow-executor"),
     path(
         "<slug:flow_slug>/", FlowExecutorShellView.as_view(), name="flow-executor-shell"

passbook/flows/views.py

@@ -1,6 +1,7 @@
 """passbook multi-stage authentication engine"""
 from traceback import format_tb
 from typing import Any, Dict, Optional
+from django.contrib.auth.mixins import LoginRequiredMixin
 
 from django.http import (
     Http404,
@@ -19,8 +20,8 @@ from structlog import get_logger
 from passbook.audit.models import cleanse_dict
 from passbook.core.models import PASSBOOK_USER_DEBUG
 from passbook.flows.exceptions import EmptyFlowException, FlowNonApplicableException
-from passbook.flows.models import Flow, FlowDesignation, Stage
-from passbook.flows.planner import FlowPlan, FlowPlanner
+from passbook.flows.models import ConfigurableStage, Flow, FlowDesignation, Stage
+from passbook.flows.planner import FlowPlan, FlowPlanner, PLAN_CONTEXT_PENDING_USER
 from passbook.lib.utils.reflection import class_to_path
 from passbook.lib.utils.urls import is_url_absolute, redirect_with_qs
 from passbook.policies.http import AccessDeniedResponse
@@ -295,3 +296,32 @@ def to_stage_response(request: HttpRequest, source: HttpResponse) -> HttpRespons
             {"type": "template", "body": source.content.decode("utf-8")}
         )
     return source
+
+
+class ConfigureFlowInitView(LoginRequiredMixin, View):
+    """Initiate planner for selected change flow and redirect to flow executor,
+    or raise Http404 if no configure_flow has been set."""
+
+    def get(self, request: HttpRequest, stage_uuid: str) -> HttpResponse:
+        """Initiate planner for selected change flow and redirect to flow executor,
+        or raise Http404 if no configure_flow has been set."""
+        try:
+            stage: Stage = Stage.objects.get_subclass(pk=stage_uuid)
+        except Stage.DoesNotExist as exc:
+            raise Http404 from exc
+        if not issubclass(stage, ConfigurableStage):
+            LOGGER.debug("Stage does not inherit ConfigurableStage", stage=stage)
+            raise Http404
+        if not stage.configure_flow:
+            LOGGER.debug("Stage has no configure_flow set", stage=stage)
+            raise Http404
+
+        plan = FlowPlanner(stage.configure_flow).plan(
+            request, {PLAN_CONTEXT_PENDING_USER: request.user}
+        )
+        request.session[SESSION_KEY_PLAN] = plan
+        return redirect_with_qs(
+            "passbook_flows:flow-executor-shell",
+            self.request.GET,
+            flow_slug=stage.configure_flow.slug,
+        )