Initial attempt at person splitting

ynr/apps/people/management/commands/split_person.py

@@ -0,0 +1,19 @@
+from django.core.management.base import BaseCommand
+
+from people.splitting import PersonCandidacySplitter
+
+
+class Command(BaseCommand):
+    help = "Split a person based on candidacy"
+
+    def add_arguments(self, parser):
+        parser.add_argument("--person_id", action="store")
+
+    def handle(self, *args, **options):
+        splitter = PersonCandidacySplitter(
+            options["person_id"], stdout=self.stdout
+        )
+        splitter.split_on_candidacy = splitter.possible_candidacies[2]
+        # splitter.candidacy_picker()
+
+        splitter.find_version_to_revert_to()

ynr/apps/people/splitting.py

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+import json
+import sys
+
+from people.models import Person
+from popolo.models import Membership
+
+
+class PersonCandidacySplitter:
+    split_on_candidacy: Membership
+
+    def __init__(self, person_id, stdout=sys.stdout):
+        self.person_id = person_id
+        self.person = Person.objects.get(pk=person_id)
+        self.stdout = stdout
+        self.split_on_candidacy = None
+
+    @property
+    def possible_candidacies(self):
+        return self.person.memberships.all()
+
+    def candidacy_picker(self):
+        """
+        :rtype: popolo.models.Membership
+        """
+        for i, candidacy in enumerate(self.possible_candidacies, start=1):
+            self.stdout.write(
+                "{}\t{}".format(i, candidacy.ballot.ballot_paper_id)
+            )
+        selected = input("Enter the FIRST candidacy for the NEW person: ")
+        self.split_on_candidacy = self.possible_candidacies[int(selected) - 1]
+        return self.split_on_candidacy
+
+    def find_version_to_revert_to(self):
+        """
+        Get the latest version of the initial person. e.g, the one
+        just before the incorrect candidacy was added
+        """
+        if not self.split_on_candidacy:
+            raise ValueError("No candidacy to split on")
+
+        election = self.split_on_candidacy.ballot.election
+        post = self.split_on_candidacy.ballot.post
+        for version in json.loads(self.person.versions):
+            candidacies = version["data"]["standing_in"]
+            if election.slug in candidacies:
+                if (
+                    version["data"]["standing_in"][election.slug]["post_id"]
+                    == post.slug
+                ):
+                    continue
+            print(version)
+            return