feat(lti): add signal handlers for LTI configuration deletion

* Add signal handlers to delete LTI configurations when xblocks or
  library blocks are deleted
* Ensure LTI configurations are properly cleaned up when associated
  blocks are removed from the system
* Update documentation for LTI 1.3 configuration changes to inform users
  about potential regeneration of client IDs and URLs when public keys
  are changed

Author: navinkarkera

lti_consumer/lti_xblock.py

@@ -374,6 +374,9 @@ class LtiConsumerXBlock(StudioEditableXBlockMixin, XBlock):
             " requests received have the signature from the tool."
             "<br /><b>This is not required when doing LTI 1.3 Launches"
             " without LTI Advantage nor Basic Outcomes requests.</b>"
+            "<br /><br /><b>Changing the public key or keyset url will cause the client ID, block keyset url "
+            "and access token url to be regenerated if they are shared between blocks. "
+            "Please check and update them in the LTI tool settings if necessary.</b>"
         ),
     )
     lti_1p3_tool_public_key = String(
@@ -388,6 +391,9 @@ class LtiConsumerXBlock(StudioEditableXBlockMixin, XBlock):
             "from the tool."
             "<br /><b>This is not required when doing LTI 1.3 Launches without LTI Advantage nor "
             "Basic Outcomes requests.</b>"
+            "<br /><br /><b>Changing the public key or keyset url will cause the client ID, block keyset url "
+            "and access token url to be regenerated if they are shared between blocks. "
+            "Please check and update them in the LTI tool settings if necessary.</b>"
         ),
     )
 

lti_consumer/plugin/compat.py

@@ -353,3 +353,27 @@ def nrps_pii_disallowed():
     """
     return (hasattr(settings, 'LTI_NRPS_DISALLOW_PII') and
             settings.LTI_NRPS_DISALLOW_PII is True)
+
+
+def get_signal_handler():
+    """
+    Import the signal handler from LMS
+    """
+    try:
+        # pylint: disable=import-outside-toplevel
+        from xmodule.modulestore.django import SignalHandler
+        return SignalHandler
+    except ImportError:
+        return None
+
+
+def yield_dynamic_block_descendants(block, user_id):
+    """
+    Import and run `yield_dynamic_block_descendants` from LMS
+    """
+    try:
+        # pylint: disable=import-outside-toplevel,redefined-outer-name
+        from common.djangoapps.util.block_utils import yield_dynamic_block_descendants
+        return yield_dynamic_block_descendants(block, user_id)
+    except ImportError:
+        return None

lti_consumer/signals/signals.py

@@ -4,13 +4,15 @@
 import logging
 
 from django.db.models.signals import post_save
-from django.dispatch import receiver, Signal
+from django.dispatch import Signal, receiver
+from openedx_events.content_authoring.data import LibraryBlockData, XBlockData
+from openedx_events.content_authoring.signals import LIBRARY_BLOCK_DELETED, XBLOCK_DELETED
 
-from lti_consumer.models import LtiAgsScore, Lti1p3Passport, LtiConfiguration
+from lti_consumer.models import Lti1p3Passport, LtiAgsScore, LtiConfiguration
 from lti_consumer.plugin import compat
 
-
 log = logging.getLogger(__name__)
+SignalHandler = compat.get_signal_handler()
 
 
 @receiver(post_save, sender=LtiAgsScore, dispatch_uid='publish_grade_on_score_update')
@@ -87,4 +89,64 @@ def create_lti_1p3_passport(sender, instance: LtiConfiguration, **kwargs):  # py
     instance.create_lti_1p3_passport()
 
 
+@receiver(SignalHandler.pre_item_delete if SignalHandler else [])
+def delete_child_lti_configurations(**kwargs):
+    """
+    Delete lti configurtion from database for this block children.
+    """
+    usage_key = kwargs.get('usage_key')
+    if usage_key:
+        # Strip branch info
+        usage_key = usage_key.for_branch(None)
+        try:
+            deleted_block = compat.load_enough_xblock(usage_key)
+        except Exception as e:  # pylint: disable=broad-exception-caught
+            log.warning(f"Cannot find xblock for key {usage_key}. Reason: {str(e)}. ")
+            return
+        id_list = {str(deleted_block.location)}
+        for block in compat.yield_dynamic_block_descendants(deleted_block, kwargs.get('user_id')):
+            id_list.add(str(block.location))
+
+        LtiConfiguration.objects.filter(
+            location__in=id_list
+        ).delete()
+        log.info(f"Deleted {len(id_list)} lti configurations in modulestore")
+        result = Lti1p3Passport.objects.filter(lticonfiguration__isnull=True).delete()
+        log.info(f"Deleted {result} lti 1.3 passport objects in library")
+
+
+@receiver(XBLOCK_DELETED)
+def delete_lti_configuration(**kwargs):
+    """
+    Delete lti configurtion from database for this block.
+    """
+    xblock_info = kwargs.get("xblock_info", None)
+    if not xblock_info or not isinstance(xblock_info, XBlockData):
+        log.error("Received null or incorrect data for event")
+        return
+
+    LtiConfiguration.objects.filter(
+        location=str(xblock_info.usage_key)
+    ).delete()
+    result = Lti1p3Passport.objects.filter(lticonfiguration__isnull=True).delete()
+    log.info(f"Deleted {result} lti 1.3 passport objects in library")
+
+
+@receiver(LIBRARY_BLOCK_DELETED)
+def delete_lib_lti_configuration(**kwargs):
+    """
+    Delete lti configurtion from database for this library block.
+    """
+    library_block = kwargs.get("library_block", None)
+    if not library_block or not isinstance(library_block, LibraryBlockData):
+        log.error("Received null or incorrect data for event")
+        return
+
+    LtiConfiguration.objects.filter(
+        location=str(library_block.usage_key)
+    ).delete()
+    result = Lti1p3Passport.objects.filter(lticonfiguration__isnull=True).delete()
+    log.info(f"Deleted {result} lti 1.3 passport objects in library")
+
+
 LTI_1P3_PROCTORING_ASSESSMENT_STARTED = Signal()