mediacms/lti/views.py

"""
LTI 1.3 Views for MediaCMS

Implements the LTI 1.3 / LTI Advantage flow:
- OIDC Login Initiation
- LTI Launch (JWT validation and processing)
- JWKS endpoint (public keys)
- My Media view (iframe-compatible)
- Embed Media view (LTI-authenticated)
- Manual NRPS Sync
"""

import logging
import traceback
import uuid
from urllib.parse import urlencode

import jwt
from django.http import HttpResponse, HttpResponseRedirect, JsonResponse
from django.shortcuts import get_object_or_404, render
from django.urls import reverse
from django.utils.decorators import method_decorator
from django.views import View
from django.views.decorators.clickjacking import xframe_options_exempt
from django.views.decorators.csrf import csrf_exempt
from jwcrypto import jwk
from pylti1p3.exception import LtiException
from pylti1p3.message_launch import MessageLaunch
from pylti1p3.oidc_login import OIDCLogin
from rest_framework import status
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from rest_framework.views import APIView

from files.models import Media
from rbac.models import RBACMembership

from .adapters import DjangoRequest, DjangoSessionService, DjangoToolConfig
from .handlers import (
    apply_lti_roles,
    create_lti_session,
    provision_lti_context,
    provision_lti_user,
    validate_lti_session,
)
from .keys import get_jwks
from .models import LTILaunchLog, LTIPlatform, LTIResourceLink, LTIToolKeys
from .services import LTINRPSClient

logger = logging.getLogger(__name__)


def get_client_ip(request):
    """Get client IP address from request"""
    x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')
    if x_forwarded_for:
        ip = x_forwarded_for.split(',')[0]
    else:
        ip = request.META.get('REMOTE_ADDR')
    return ip


@method_decorator(csrf_exempt, name='dispatch')
class OIDCLoginView(View):
    """
    OIDC Login Initiation - Step 1 of LTI 1.3 launch

    Flow: Moodle → This endpoint → Redirect to Moodle auth endpoint
    """

    def get(self, request):
        return self.handle_oidc_login(request)

    def post(self, request):
        return self.handle_oidc_login(request)

    def handle_oidc_login(self, request):
        """Handle OIDC login initiation"""
        try:
            target_link_uri = request.GET.get('target_link_uri') or request.POST.get('target_link_uri')
            iss = request.GET.get('iss') or request.POST.get('iss')
            client_id = request.GET.get('client_id') or request.POST.get('client_id')
            login_hint = request.GET.get('login_hint') or request.POST.get('login_hint')
            lti_message_hint = request.GET.get('lti_message_hint') or request.POST.get('lti_message_hint')
            cmid = request.GET.get('cmid') or request.POST.get('cmid')

            if not all([target_link_uri, iss, client_id]):
                return JsonResponse({'error': 'Missing required OIDC parameters'}, status=400)

            try:
                platform = LTIPlatform.objects.get(platform_id=iss, client_id=client_id)
            except LTIPlatform.DoesNotExist:
                return JsonResponse({'error': 'Platform not found'}, status=404)

            tool_config = DjangoToolConfig.from_platform(platform)

            lti_request = DjangoRequest(request)

            session_service = DjangoSessionService(request)
            cookie_service = DjangoSessionService(request)  # Using same service for cookies

            oidc_login = OIDCLogin(lti_request, tool_config, session_service=session_service, cookie_service=cookie_service)
            try:
                oidc_with_cookies = oidc_login.enable_check_cookies()
                redirect_url = oidc_with_cookies.redirect(target_link_uri)

                if not redirect_url:
                    state = str(uuid.uuid4())
                    nonce = str(uuid.uuid4())

                    launch_data = {'target_link_uri': target_link_uri, 'nonce': nonce}
                    # Store cmid if provided (including 0 for filter-based launches)
                    if cmid is not None:
                        launch_data['cmid'] = cmid

                    session_service.save_launch_data(f'state-{state}', launch_data)

                    params = {
                        'response_type': 'id_token',
                        'redirect_uri': target_link_uri,
                        'state': state,
                        'client_id': client_id,
                        'login_hint': login_hint,
                        'scope': 'openid',
                        'response_mode': 'form_post',
                        'prompt': 'none',
                        'nonce': nonce,
                    }

                    if lti_message_hint:
                        params['lti_message_hint'] = lti_message_hint

                    redirect_url = f"{platform.auth_login_url}?{urlencode(params)}"

                    # Debug logging for filter launches
                    logger.error(f"[OIDC LOGIN DEBUG] Redirecting to: {redirect_url}")
                    logger.error(f"[OIDC LOGIN DEBUG] Has lti_message_hint: {bool(lti_message_hint)}")
                    logger.error(f"[OIDC LOGIN DEBUG] cmid: {cmid}")

                return HttpResponseRedirect(redirect_url)
            except Exception:
                raise

        except LtiException as e:
            traceback.print_exc()
            return render(request, 'lti/launch_error.html', {'error': 'OIDC Login Failed', 'message': str(e)}, status=400)
        except Exception as e:  # noqa
            traceback.print_exc()
            return JsonResponse({'error': 'Internal server error during OIDC login'}, status=500)


@method_decorator(csrf_exempt, name='dispatch')
@method_decorator(xframe_options_exempt, name='dispatch')
class LaunchView(View):
    """
    LTI Launch Handler - Step 3 of LTI 1.3 launch

    Flow: Moodle → This endpoint (with JWT) → Validate → Provision → Session → Redirect
    """

    def post(self, request):
        """Handle LTI launch with JWT validation"""
        platform = None
        user = None
        error_message = ''
        claims = {}

        logger.error("[LTI LAUNCH DEBUG] Launch view POST called")

        try:
            id_token = request.POST.get('id_token')
            if not id_token:
                raise ValueError("Missing id_token in launch request")

            unverified = jwt.decode(id_token, options={"verify_signature": False})
            iss = unverified.get('iss')
            aud = unverified.get('aud')
            try:
                platform = LTIPlatform.objects.get(platform_id=iss, client_id=aud)
            except LTIPlatform.DoesNotExist:
                raise

            tool_config = DjangoToolConfig.from_platform(platform)

            lti_request = DjangoRequest(request)

            session_service = DjangoSessionService(request)
            cookie_service = DjangoSessionService(request)

            class CustomMessageLaunch(MessageLaunch):
                def _get_request_param(self, key):
                    """Override to properly get request parameters"""
                    return self._request.get_param(key)

            message_launch = CustomMessageLaunch(lti_request, tool_config, session_service=session_service, cookie_service=cookie_service)

            launch_data = message_launch.get_launch_data()
            claims = self.sanitize_claims(launch_data)

            logger.error(f"[LTI LAUNCH DEBUG] Full launch_data keys: {list(launch_data.keys())}")
            logger.error(f"[LTI LAUNCH DEBUG] Launch data has custom claim: {'https://purl.imsglobal.org/spec/lti/claim/custom' in launch_data}")

            # Extract and log custom claims EARLY before any other processing
            try:
                custom_claims = launch_data.get('https://purl.imsglobal.org/spec/lti/claim/custom', {})
                logger.error(f"[LTI LAUNCH DEBUG] Custom claims type: {type(custom_claims)}")
                logger.error(f"[LTI LAUNCH DEBUG] Custom claims keys: {list(custom_claims.keys()) if isinstance(custom_claims, dict) else 'not a dict'}")
                logger.error(f"[LTI LAUNCH DEBUG] Custom claims full content: {custom_claims}")
                logger.error(f"[LTI LAUNCH DEBUG] Has media_friendly_token: {bool(custom_claims.get('media_friendly_token'))}")
            except Exception as e:
                logger.error(f"[LTI LAUNCH DEBUG] Error getting custom claims: {e}")
                custom_claims = {}

            resource_link = launch_data.get('https://purl.imsglobal.org/spec/lti/claim/resource_link', {})
            resource_link_id = resource_link.get('id', 'default')
            roles = launch_data.get('https://purl.imsglobal.org/spec/lti/claim/roles', [])

            message_type = launch_data.get('https://purl.imsglobal.org/spec/lti/claim/message_type')

            if message_type == 'LtiDeepLinkingRequest':
                return self.handle_deep_linking_launch(request, message_launch, platform, launch_data)

            user = provision_lti_user(platform, launch_data)

            if 'https://purl.imsglobal.org/spec/lti/claim/context' in launch_data:
                category, rbac_group, resource_link_obj = provision_lti_context(platform, launch_data, resource_link_id)

                apply_lti_roles(user, platform, roles, rbac_group)
            else:
                resource_link_obj = None

            create_lti_session(request, user, message_launch, platform)

            # Check for media_friendly_token in custom claims (for both deep linking and filter launches)
            media_token = custom_claims.get('media_friendly_token')
            if media_token:
                logger.error(f"[LTI LAUNCH DEBUG] Found media_friendly_token in custom claims: {media_token}")

            # Clear retry counter on successful launch
            if 'lti_retry_count' in request.session:
                del request.session['lti_retry_count']

            LTILaunchLog.objects.create(platform=platform, user=user, resource_link=resource_link_obj, launch_type='resource_link', success=True, claims=claims)

            redirect_url = self.determine_redirect(launch_data, resource_link_obj)
            logger.error(f"[LTI LAUNCH DEBUG] Redirecting to: {redirect_url}")

            return HttpResponseRedirect(redirect_url)

        except LtiException as e:  # noqa
            error_message = str(e)

            # Special handling for "State not found" errors - attempt retry
            if "State not found" in error_message or "state not found" in error_message.lower():
                logger.warning("[LTI LAUNCH] State not found error detected, attempting recovery")
                return self.handle_state_not_found(request, platform)

            # Other LTI exceptions - fail normally
            traceback.print_exc()
        except Exception as e:  # noqa
            traceback.print_exc()

        if platform:
            LTILaunchLog.objects.create(platform=platform, user=user, launch_type='resource_link', success=False, error_message=error_message, claims=claims)

        return render(request, 'lti/launch_error.html', {'error': 'LTI Launch Failed', 'message': error_message}, status=400)

    def sanitize_claims(self, claims):
        """Remove sensitive data from claims before logging"""
        safe_claims = claims.copy()
        return safe_claims

    def determine_redirect(self, launch_data, resource_link):
        """Determine where to redirect after successful launch"""

        custom = launch_data.get('https://purl.imsglobal.org/spec/lti/claim/custom', {})

        custom_path = custom.get('redirect_path')

        if custom_path:
            if not custom_path.startswith('/'):
                custom_path = '/' + custom_path
            return custom_path

        # Check custom claims for media token (from both deep linking and filter launches)
        media_id = custom.get('media_id') or custom.get('media_friendly_token')

        if media_id:
            try:
                media = Media.objects.get(friendly_token=media_id)
                return reverse('lti:embed_media', args=[media.friendly_token])
            except Media.DoesNotExist:
                pass

        return reverse('lti:my_media')

    def handle_state_not_found(self, request, platform=None):
        """
        Handle state not found errors by attempting to restart the OIDC flow.

        This can happen when:
        - Cookies are blocked/deleted
        - Session expired
        - Browser privacy settings interfere
        """
        try:
            # Check retry count to prevent infinite loops
            retry_count = request.session.get('lti_retry_count', 0)
            MAX_RETRIES = 2

            if retry_count >= MAX_RETRIES:
                logger.error(f"[LTI RETRY] Max retries ({MAX_RETRIES}) exceeded for state recovery")
                return render(
                    request,
                    'lti/launch_error.html',
                    {
                        'error': 'Authentication Failed',
                        'message': (
                            'Unable to establish a secure session. This may be due to browser '
                            'cookie settings or privacy features. Please try:\n\n'
                            '1. Enabling cookies for this site\n'
                            '2. Disabling tracking protection for this site\n'
                            '3. Using a different browser\n'
                            '4. Contacting your administrator if the issue persists'
                        ),
                        'is_cookie_error': True,
                    },
                    status=400,
                )

            # Extract launch parameters from the POST request
            id_token = request.POST.get('id_token')
            state = request.POST.get('state')

            if not id_token:
                raise ValueError("No id_token available for retry")

            # Decode JWT to extract issuer and target info (no verification needed for this)
            unverified = jwt.decode(id_token, options={"verify_signature": False})

            iss = unverified.get('iss')
            aud = unverified.get('aud')  # This is the client_id
            target_link_uri = unverified.get('https://purl.imsglobal.org/spec/lti/claim/target_link_uri')

            # Get login_hint and lti_message_hint if available
            login_hint = request.POST.get('login_hint') or unverified.get('sub')

            if not all([iss, aud, target_link_uri]):
                raise ValueError("Missing required parameters for OIDC retry")

            # Try to identify platform
            if not platform:
                try:
                    platform = LTIPlatform.objects.get(platform_id=iss, client_id=aud)
                except LTIPlatform.DoesNotExist:
                    raise ValueError(f"Platform not found: {iss}/{aud}")

            # Increment retry counter
            request.session['lti_retry_count'] = retry_count + 1
            request.session.modified = True

            logger.warning(f"[LTI RETRY] State not found, attempting retry #{retry_count + 1}. " f"Platform: {platform.name}, State: {state}, Target: {target_link_uri}")

            # Build OIDC login URL with all parameters
            oidc_login_url = request.build_absolute_uri(reverse('lti:oidc_login'))

            params = {
                'iss': iss,
                'client_id': aud,
                'target_link_uri': target_link_uri,
                'login_hint': login_hint,
            }

            # Include lti_message_hint if we have it
            lti_message_hint = request.POST.get('lti_message_hint')
            if lti_message_hint:
                params['lti_message_hint'] = lti_message_hint

            # Add retry indicator
            params['retry'] = retry_count + 1

            redirect_url = f"{oidc_login_url}?{urlencode(params)}"

            logger.error(f"[LTI RETRY] Redirecting to OIDC login: {redirect_url}")

            return HttpResponseRedirect(redirect_url)

        except Exception as retry_error:
            logger.error(f"[LTI RETRY] Failed to handle state recovery: {retry_error}")
            traceback.print_exc()

            return render(
                request,
                'lti/launch_error.html',
                {
                    'error': 'LTI Launch Failed',
                    'message': f'State validation failed and automatic retry was unsuccessful: {str(retry_error)}',
                },
                status=400,
            )

    def handle_deep_linking_launch(self, request, message_launch, platform, launch_data):
        """Handle deep linking request"""
        deep_linking_settings = launch_data.get('https://purl.imsglobal.org/spec/lti-dl/claim/deep_linking_settings', {})

        if not deep_linking_settings:
            raise ValueError("Missing deep linking settings in launch data")

        deep_link_return_url = deep_linking_settings.get('deep_link_return_url')

        if not deep_link_return_url:
            raise ValueError("Missing deep_link_return_url in deep linking settings")

        request.session['lti_deep_link'] = {
            'deep_link_return_url': deep_link_return_url,
            'deployment_id': launch_data.get('https://purl.imsglobal.org/spec/lti/claim/deployment_id'),
            'platform_id': platform.id,
            'message_launch_data': launch_data,  # Store full launch data for JWT creation
        }

        return HttpResponseRedirect(reverse('lti:select_media'))


class JWKSView(View):
    """
    JWKS Endpoint - Provides tool's public keys

    Used by Moodle to validate signatures from MediaCMS (e.g., Deep Linking responses)
    """

    def get(self, request):
        """Return tool's public JWK Set"""
        jwks = get_jwks()

        return JsonResponse(jwks, content_type='application/json')


class PublicKeyPEMView(View):
    """
    Display public key in PEM format for easy copy/paste into Moodle
    """

    def get(self, request):
        """Return public key in PEM format"""
        key_obj = LTIToolKeys.get_or_create_keys()

        jwk_obj = jwk.JWK(**key_obj.public_key_jwk)
        pem_bytes = jwk_obj.export_to_pem()
        pem_string = pem_bytes.decode('utf-8')

        return HttpResponse(
            f"MediaCMS LTI Public Key (PEM Format)\n"
            f"{'=' * 80}\n\n"
            f"{pem_string}\n"
            f"{'=' * 80}\n\n"
            f"Instructions:\n"
            f"1. Copy the entire key above (including BEGIN/END lines)\n"
            f"2. In Moodle LTI tool configuration, change 'Public key type' to 'Public key'\n"
            f"3. Paste the key into the 'Public key' field\n"
            f"4. Save and try Deep Linking again\n",
            content_type='text/plain',
        )


@method_decorator(xframe_options_exempt, name='dispatch')
class MyMediaLTIView(View):
    """
    My Media page for LTI-authenticated users

    Shows user's media profile in iframe
    """

    def get(self, request):
        """Display my media page"""
        lti_session = validate_lti_session(request)

        if not lti_session:
            return JsonResponse({'error': 'Not authenticated via LTI'}, status=403)

        profile_url = f"/user/{request.user.username}"
        return HttpResponseRedirect(profile_url)


@method_decorator(xframe_options_exempt, name='dispatch')
class EmbedMediaLTIView(View):
    """
    Embed media with LTI authentication

    Pattern: Extends existing /embed functionality
    """

    def get(self, request, friendly_token):
        """Display embedded media"""
        media = get_object_or_404(Media, friendly_token=friendly_token)

        lti_session = validate_lti_session(request)
        can_view = False

        if lti_session and request.user.is_authenticated:
            if request.user.has_member_access_to_media(media):
                can_view = True

        if media.state in ["public", "unlisted"]:
            can_view = True

        if not can_view:
            return JsonResponse({'error': 'Access denied', 'message': 'You do not have permission to view this media'}, status=403)

        return HttpResponseRedirect(f"/view?m={friendly_token}")


class ManualSyncView(APIView):
    """
    Manual NRPS sync for course members/roles

    Endpoint: POST /lti/sync/<platform_id>/<context_id>/
    Requires: User must be manager in the course RBAC group
    """

    permission_classes = [IsAuthenticated]

    def post(self, request, platform_id, context_id):
        """Manually trigger NRPS sync"""
        try:
            platform = get_object_or_404(LTIPlatform, id=platform_id)

            resource_link = LTIResourceLink.objects.filter(platform=platform, context_id=context_id).first()

            if not resource_link:
                return Response({'error': 'Context not found', 'message': f'No resource link found for context {context_id}'}, status=status.HTTP_404_NOT_FOUND)

            rbac_group = resource_link.rbac_group
            if not rbac_group:
                return Response({'error': 'No RBAC group', 'message': 'This context does not have an associated RBAC group'}, status=status.HTTP_400_BAD_REQUEST)

            is_manager = RBACMembership.objects.filter(user=request.user, rbac_group=rbac_group, role='manager').exists()

            if not is_manager:
                return Response({'error': 'Insufficient permissions', 'message': 'You must be a course manager to sync members'}, status=status.HTTP_403_FORBIDDEN)

            if not platform.enable_nrps:
                return Response({'error': 'NRPS disabled', 'message': 'Names and Role Provisioning Service is disabled for this platform'}, status=status.HTTP_400_BAD_REQUEST)

            last_launch = LTILaunchLog.objects.filter(platform=platform, resource_link=resource_link, success=True).order_by('-created_at').first()

            if not last_launch:
                return Response({'error': 'No launch data', 'message': 'No successful launch data found for NRPS'}, status=status.HTTP_400_BAD_REQUEST)

            nrps_client = LTINRPSClient(platform, last_launch.claims)
            result = nrps_client.sync_members_to_rbac_group(rbac_group)

            return Response(
                {
                    'status': 'success',
                    'message': f'Successfully synced {result["synced"]} members',
                    'synced_count': result['synced'],
                    'removed_count': result.get('removed', 0),
                    'synced_at': result['synced_at'],
                },
                status=status.HTTP_200_OK,
            )

        except Exception as e:
            return Response({'error': 'Sync failed', 'message': str(e)}, status=status.HTTP_500_INTERNAL_SERVER_ERROR)


@method_decorator(xframe_options_exempt, name='dispatch')
class TinyMCEGetEmbedView(View):
    """
    API endpoint to get embed code for a specific media item (for TinyMCE integration).

    Returns JSON with the embed code for the requested media.
    Requires: User must be logged in (via LTI session)
    """

    def get(self, request, friendly_token):
        """Get embed code for the specified media."""
        # Verify user is authenticated
        if not request.user.is_authenticated:
            return JsonResponse({'error': 'Authentication required'}, status=401)

        # Verify media exists
        media = Media.objects.filter(friendly_token=friendly_token).first()

        if not media:
            return JsonResponse({'error': 'Media not found'}, status=404)

        # Build embed URL
        embed_url = request.build_absolute_uri(reverse('get_embed') + f'?m={friendly_token}')

        # Generate iframe embed code
        embed_code = f'<iframe src="{embed_url}" ' f'width="960" height="540" ' f'frameborder="0" ' f'allowfullscreen ' f'title="{media.title}">' f'</iframe>'

        return JsonResponse(
            {
                'embedCode': embed_code,
                'title': media.title,
                'thumbnail': media.thumbnail_url if hasattr(media, 'thumbnail_url') else '',
            }
        )