From 159e00763ea1256a2db09d50c839ad8bb30ba786 Mon Sep 17 00:00:00 2001
From: Maximilian Blochberger <blochberger@informatik.uni-hamburg.de>
Date: Wed, 17 Mar 2021 08:45:25 +0100
Subject: [PATCH] Add command that merges tags

---
 sok/management/commands/mergetags.py | 83 ++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 sok/management/commands/mergetags.py

diff --git a/sok/management/commands/mergetags.py b/sok/management/commands/mergetags.py
new file mode 100644
index 0000000..a7d34f6
--- /dev/null
+++ b/sok/management/commands/mergetags.py
@@ -0,0 +1,83 @@
+from typing import Optional
+
+from django.core.management.base import BaseCommand, CommandError, CommandParser
+from django.db import transaction
+
+from sok.models import Publication, PublicationTag, Tag
+
+
+class Command(BaseCommand):
+	"""
+	Merges `rhs` into `lhs`.
+	"""
+
+	def echo(self, msg: str):
+		self.stdout.write(msg)
+
+	def success(self, msg: str):
+		self.echo(self.style.SUCCESS(msg))
+
+	def get_tag(self, value: str) -> Tag:
+		try:
+			pk = int(value)
+			return Tag.objects.get(pk=pk)
+		except ValueError:
+			pass
+
+		try:
+			return Tag.objects.get(name=value)
+		except Tag.DoesNotExist:
+			pass
+
+		return Tag.objects.get(name__icontains=value)
+
+	def get_rel(self, publication: Publication, tag: Tag) -> Optional[PublicationTag]:
+		try:
+			return PublicationTag.objects.get(publication=publication, tag=tag)
+		except PublicationTag.DoesNotExist:
+			return None
+
+	@transaction.atomic
+	def merge(self, lhs: Tag, rhs: Tag, publication: Publication):
+		assert lhs.pk != rhs.pk
+
+		rhs_rel = PublicationTag.objects.get(publication=publication, tag=rhs)
+		lhs_rel, created = PublicationTag.objects.get_or_create(
+			publication=publication,
+			tag=lhs,
+		)
+
+		changed = False
+		if lhs_cmt := lhs_rel.comment:
+			if rhs_cmt := rhs_rel.comment:
+				if lhs_cmt != rhs_cmt:
+					lhs_rel.cmt = f"{lhs_cmt}; {rhs_cmt}"
+					changed = True
+		else:
+			lhs_rel.comment = rhs_rel.comment
+			changed = True
+
+		rhs.publications.remove(publication)
+
+		if changed:
+			lhs_rel.full_clean()
+			lhs_rel.save()
+			self.success(f"{lhs} <- {rhs} [{publication.cite_key}]: {lhs_rel.comment}")
+		else:
+			self.success(f"{lhs} <- {rhs} [{publication.cite_key}]")
+
+	# BaseCommand
+
+	def add_arguments(self, parser: CommandParser):
+		parser.add_argument('lhs')
+		parser.add_argument('rhs')
+
+	def handle(self, *args, **options):
+		lhs = self.get_tag(options['lhs'])
+		rhs = self.get_tag(options['rhs'])
+
+		if lhs == rhs:
+			raise CommandError(f"Cannot merge tag with itself: {lhs}")
+
+		for publication in rhs.publications.all():
+			self.merge(lhs, rhs, publication)