flows/*: Initial flows stage1 implementation

passbook/flows/models.py

@@ -0,0 +1,71 @@
+"""Flow models"""
+from enum import Enum
+from typing import Tuple
+
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+
+from passbook.core.models import Factor
+from passbook.lib.models import UUIDModel
+from passbook.policies.models import PolicyBindingModel
+
+
+class FlowDesignation(Enum):
+    """Designation of what a Flow should be used for. At a later point, this
+    should be replaced by a database entry."""
+
+    AUTHENTICATION = "authentication"
+    ENROLLMENT = "enrollment"
+    RECOVERY = "recovery"
+
+    @staticmethod
+    def as_choices() -> Tuple[Tuple[str, str]]:
+        """Generate choices of actions used for database"""
+        return tuple(
+            (x, y.value) for x, y in getattr(FlowDesignation, "__members__").items()
+        )
+
+
+class Flow(PolicyBindingModel, UUIDModel):
+    """Flow describes how a series of Factors should be executed to authenticate/enroll/recover
+    a user. Additionally, policies can be applied, to specify which users
+    have access to this flow."""
+
+    name = models.TextField()
+    slug = models.SlugField(unique=True)
+
+    designation = models.CharField(max_length=100, choices=FlowDesignation.as_choices())
+
+    factors = models.ManyToManyField(Factor, through="FlowFactorBinding")
+
+    pbm = models.OneToOneField(
+        PolicyBindingModel, parent_link=True, on_delete=models.CASCADE, related_name="+"
+    )
+
+    def __str__(self) -> str:
+        return f"Flow {self.name} ({self.slug})"
+
+    class Meta:
+
+        verbose_name = _("Flow")
+        verbose_name_plural = _("Flows")
+
+
+class FlowFactorBinding(PolicyBindingModel, UUIDModel):
+    """Relationship between Flow and Factor. Order is required and unique for
+    each flow-factor Binding. Additionally, policies can be specified, which determine if
+    this Binding applies to the current user"""
+
+    flow = models.ForeignKey("Flow", on_delete=models.CASCADE)
+    factor = models.ForeignKey(Factor, on_delete=models.CASCADE)
+
+    order = models.IntegerField()
+
+    def __str__(self) -> str:
+        return f"Flow Factor Binding {self.flow} -> {self.factor}"
+
+    class Meta:
+
+        verbose_name = _("Flow Factor Binding")
+        verbose_name_plural = _("Flow Factor Bindings")
+        unique_together = (("flow", "factor", "order"),)