feat: LTI support and Moodle plugin

lti/deep_linking.py

@@ -0,0 +1,177 @@
+"""
+LTI Deep Linking 2.0 for MediaCMS
+
+Allows instructors to select media from MediaCMS library and embed in Moodle courses
+"""
+
+import time
+import traceback
+import uuid
+from urllib.parse import quote
+
+import jwt
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from django.contrib.auth.decorators import login_required
+from django.http import HttpResponseRedirect, JsonResponse
+from django.shortcuts import render
+from django.urls import reverse
+from django.utils.decorators import method_decorator
+from django.views import View
+from django.views.decorators.csrf import csrf_exempt
+from jwcrypto import jwk
+
+from files.models import Media
+
+from .models import LTIPlatform, LTIToolKeys
+
+
+@method_decorator(login_required, name='dispatch')
+class SelectMediaView(View):
+    """
+    UI for instructors to select media for deep linking
+
+    Flow: Instructor clicks "Add MediaCMS" in Moodle → Deep link launch →
+          This view → Instructor selects media → Return to Moodle
+    """
+
+    def get(self, request):
+        """Display media selection interface - redirects to user's profile page"""
+        profile_url = f"/user/{request.user.username}?mode=lms_embed_mode&action=select_media"
+
+        lti_session = request.session.get('lti_session', {})
+        lti_context_id = lti_session.get('context_id', '')
+        if lti_context_id:
+            profile_url += f"&lti_context_id={quote(str(lti_context_id))}"
+
+        return HttpResponseRedirect(profile_url)
+
+    @method_decorator(csrf_exempt)
+    def post(self, request):
+        """Return selected media as deep linking content items"""
+
+        deep_link_data = request.session.get('lti_deep_link')
+
+        if not deep_link_data:
+            return JsonResponse({'error': 'Invalid session'}, status=400)
+
+        selected_ids = request.POST.getlist('media_ids[]')
+
+        if not selected_ids:
+            return JsonResponse({'error': 'No media selected'}, status=400)
+
+        content_items = []
+
+        for media_id in selected_ids:
+            try:
+                media = Media.objects.get(id=media_id)
+
+                # Build launch URL (must be an LTI launch endpoint that handles POST with id_token)
+                # The /lti/launch/ endpoint will use the custom parameter to redirect to the correct media
+                launch_url = request.build_absolute_uri(reverse('lti:launch'))
+
+                content_item = {
+                    'type': 'ltiResourceLink',
+                    'title': media.title,
+                    'url': launch_url,
+                    'custom': {
+                        'media_friendly_token': media.friendly_token,
+                    },
+                }
+
+                if media.thumbnail_url:
+                    thumbnail_url = media.thumbnail_url
+                    if not thumbnail_url.startswith('http'):
+                        thumbnail_url = request.build_absolute_uri(thumbnail_url)
+                    content_item['thumbnail'] = {'url': thumbnail_url, 'width': 344, 'height': 194}
+
+                content_item['iframe'] = {'width': 960, 'height': 540}
+
+                content_items.append(content_item)
+
+            except Media.DoesNotExist:
+                continue
+
+        if not content_items:
+            return JsonResponse({'error': 'No valid media found'}, status=400)
+
+        # Full implementation would use PyLTI1p3's DeepLink response builder
+        jwt_response = self.create_deep_link_jwt(deep_link_data, content_items, request)
+
+        context = {
+            'return_url': deep_link_data['deep_link_return_url'],
+            'jwt': jwt_response,
+        }
+
+        return render(request, 'lti/deep_link_return.html', context)
+
+    def create_deep_link_jwt(self, deep_link_data, content_items, request):
+        """
+        Create JWT response for deep linking - manual implementation
+        """
+        try:
+            platform_id = deep_link_data['platform_id']
+            platform = LTIPlatform.objects.get(id=platform_id)
+            deployment_id = deep_link_data['deployment_id']
+            message_launch_data = deep_link_data['message_launch_data']
+
+            deep_linking_settings = message_launch_data.get('https://purl.imsglobal.org/spec/lti-dl/claim/deep_linking_settings', {})
+
+            key_obj = LTIToolKeys.get_or_create_keys()
+            jwk_obj = jwk.JWK(**key_obj.private_key_jwk)
+            pem_bytes = jwk_obj.export_to_pem(private_key=True, password=None)
+            private_key = serialization.load_pem_private_key(pem_bytes, password=None, backend=default_backend())
+
+            now = int(time.time())
+
+            lti_content_items = []
+            for item in content_items:
+                lti_item = {
+                    'type': item['type'],
+                    'title': item['title'],
+                    'url': item['url'],
+                }
+
+                if item.get('custom'):
+                    lti_item['custom'] = item['custom']
+
+                if item.get('thumbnail'):
+                    lti_item['thumbnail'] = item['thumbnail']
+
+                if item.get('iframe'):
+                    lti_item['iframe'] = item['iframe']
+
+                lti_content_items.append(lti_item)
+
+            tool_issuer = platform.client_id
+
+            audience = platform.platform_id
+
+            sub = message_launch_data.get('sub')
+
+            payload = {
+                'iss': tool_issuer,
+                'aud': audience,
+                'exp': now + 3600,
+                'iat': now,
+                'nonce': str(uuid.uuid4()),
+                'https://purl.imsglobal.org/spec/lti/claim/message_type': 'LtiDeepLinkingResponse',
+                'https://purl.imsglobal.org/spec/lti/claim/version': '1.3.0',
+                'https://purl.imsglobal.org/spec/lti/claim/deployment_id': deployment_id,
+                'https://purl.imsglobal.org/spec/lti-dl/claim/content_items': lti_content_items,
+            }
+
+            if sub:
+                payload['sub'] = sub
+
+            if 'data' in deep_linking_settings:
+                payload['https://purl.imsglobal.org/spec/lti-dl/claim/data'] = deep_linking_settings['data']
+
+            kid = key_obj.private_key_jwk['kid']
+            response_jwt = jwt.encode(payload, private_key, algorithm='RS256', headers={'kid': kid})
+
+            return response_jwt
+
+        except Exception as e:
+            traceback.print_exc()
+            raise ValueError(f"Failed to create Deep Linking JWT: {str(e)}")