From a84d837942f1f50fd236caf293c8545c322adffc Mon Sep 17 00:00:00 2001
From: ramvignesh-b <ramvignesh-b@github.com>
Date: Fri, 24 Apr 2026 06:29:14 +0530
Subject: [PATCH] feat: update letter patch to check for type change to sent
 and auto set time

---
 backend/letters/models.py | 11 +++++++++++
 backend/letters/tests.py  | 36 ++++++++++++++++++++++++++++++++----
 backend/letters/views.py  | 12 ++++++++----
 3 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/backend/letters/models.py b/backend/letters/models.py
index 34f592c..d728ed3 100644
--- a/backend/letters/models.py
+++ b/backend/letters/models.py
@@ -1,4 +1,5 @@
 import uuid
+from datetime import UTC, datetime
 
 from django.conf import settings
 from django.core.exceptions import ValidationError
@@ -39,6 +40,16 @@ class Letter(models.Model):
         if self.type == Letter.Type.VAULT and self.status == Letter.Status.SEALED and not self.unlock_at:
             raise ValidationError("A sealed VAULT letter must have an unlock_date.")
 
+    def save(self, *args, **kwargs):
+        """
+        Override save method to auto set BURNED and SEALED timestamps.
+        """
+        if self.status == Letter.Status.BURNED:
+            self.burned_at = datetime.now(UTC)
+        if self.status == Letter.Status.SEALED:
+            self.sealed_at = datetime.now(UTC)
+        super().save(*args, **kwargs)
+
     def __str__(self):
         return f"{self.type} - {self.status}"
 
diff --git a/backend/letters/tests.py b/backend/letters/tests.py
index 26405dc..3f9f7ad 100644
--- a/backend/letters/tests.py
+++ b/backend/letters/tests.py
@@ -270,15 +270,43 @@ class LetterAPITest(APITestCase):
                 "encrypted_dek": "enc_dek_new==",
             },
         )
-        response_burn = self.client.patch(self.url + letter.public_id + "/", {"status": "BURNED"})
 
         self.assertEqual(response_update_content.status_code, 400)
-        self.assertEqual(response_update_content.data["error"], "Sealed letters can only be burned.")
+        self.assertEqual(response_update_content.data["error"], "Sealed letters can only be burned or sent.")
         self.assertEqual(Letter.objects.get().encrypted_content, "enc_content==")
 
-        self.assertEqual(response_burn.status_code, 200)
+        from datetime import UTC, datetime
+
+        from freezegun import freeze_time
+
+        current_time = datetime.now(UTC)
+        with freeze_time(current_time):
+            response_burn = self.client.patch(self.url + letter.public_id + "/", {"status": "BURNED"})
+
+            self.assertEqual(response_burn.status_code, 200)
+            self.assertEqual(Letter.objects.count(), 1)
+            self.assertEqual(Letter.objects.get().status, "BURNED")
+            self.assertEqual(Letter.objects.get().burned_at, current_time)
+
+    def test_send_sealed_letter(self):
+        """
+        Test that a sealed letter can be sent.
+        """
+        letter = Letter.objects.create(
+            user=self.user,
+            type="KEPT",
+            status="SEALED",
+            public_id="4281edcc-5459-4ff2-bb5e-669fb44e0757",
+            encrypted_content="enc_content==",
+            encrypted_metadata="enc_meta==",
+            encrypted_dek="enc_dek==",
+        )
+
+        response_sent = self.client.patch(self.url + letter.public_id + "/", {"type": "SENT"})
+
+        self.assertEqual(response_sent.status_code, 200)
         self.assertEqual(Letter.objects.count(), 1)
-        self.assertEqual(Letter.objects.get().status, "BURNED")
+        self.assertEqual(Letter.objects.get().type, "SENT")
 
 
 class LetterImageModelTest(TestCase):
diff --git a/backend/letters/views.py b/backend/letters/views.py
index ea6354e..96769f6 100644
--- a/backend/letters/views.py
+++ b/backend/letters/views.py
@@ -66,13 +66,17 @@ class LetterDetailView(generics.RetrieveUpdateDestroyAPIView):
     def patch(self, request, public_id):
         """
         Updates an existing letter.
+        Can update type and status only when sealed, sent and burned.
         """
         letter = Letter.objects.get(public_id=public_id, user=request.user)
 
-        if letter.status == Letter.Status.SEALED and (
-            len(request.data) > 1 or request.data.get("status") != Letter.Status.BURNED
-        ):
-            return Response({"error": "Sealed letters can only be burned."}, status=400)
+        if letter.status == Letter.Status.SEALED:
+            if (
+                len(request.data) > 1
+                or (request.data.get("status") != Letter.Status.BURNED and request.data.get("status") is not None)
+                or (request.data.get("type") != Letter.Type.SENT and request.data.get("type") is not None)
+            ):
+                return Response({"error": "Sealed letters can only be burned or sent."}, status=400)
 
         write_serializer = self.get_serializer(letter, data=request.data, partial=True)
         write_serializer.is_valid(raise_exception=True)