"""
Integrations Celery tasks

This module contains the core event processing logic that:
1. Processes inbound events from external systems
2. Finds matching journey instances
3. Completes journey stages
4. Triggers survey creation
"""
import logging

from celery import shared_task
from django.db import transaction

logger = logging.getLogger('apps.integrations')


@shared_task(bind=True, max_retries=3)
def process_inbound_event(self, event_id):
    """
    Process an inbound integration event.

    This is the core event processing task that:
    1. Finds the journey instance by encounter_id
    2. Finds the matching stage by trigger_event_code
    3. Completes the stage
    4. Creates survey instance if configured
    5. Logs audit events

    Args:
        event_id: UUID of the InboundEvent to process

    Returns:
        dict: Processing result with status and details
    """
    from apps.core.services import create_audit_log
    from apps.integrations.models import InboundEvent
    from apps.journeys.models import PatientJourneyInstance, PatientJourneyStageInstance, StageStatus
    from apps.organizations.models import Department, Staff

    try:
        # Get the event
        event = InboundEvent.objects.get(id=event_id)
        event.mark_processing()

        logger.info(f"Processing event {event.id}: {event.event_code} for encounter {event.encounter_id}")

        # Find journey instance by encounter_id
        try:
            journey_instance = PatientJourneyInstance.objects.select_related(
                'journey_template', 'patient', 'hospital'
            ).get(encounter_id=event.encounter_id)
        except PatientJourneyInstance.DoesNotExist:
            error_msg = f"No journey instance found for encounter {event.encounter_id}"
            logger.warning(error_msg)
            event.mark_ignored(error_msg)
            return {'status': 'ignored', 'reason': error_msg}

        # Find matching stage by trigger_event_code
        matching_stages = journey_instance.stage_instances.filter(
            stage_template__trigger_event_code=event.event_code,
            status__in=[StageStatus.PENDING, StageStatus.IN_PROGRESS]
        ).select_related('stage_template')

        if not matching_stages.exists():
            error_msg = f"No pending stage found with trigger {event.event_code}"
            logger.warning(error_msg)
            event.mark_ignored(error_msg)
            return {'status': 'ignored', 'reason': error_msg}

        # Get the first matching stage
        stage_instance = matching_stages.first()

        # Extract staff and department from event payload
        staff = None
        department = None

        if event.physician_license:
            try:
                staff = Staff.objects.get(
                    license_number=event.physician_license,
                    hospital=journey_instance.hospital
                )
            except Staff.DoesNotExist:
                logger.warning(f"Staff member not found with license: {event.physician_license}")

        if event.department_code:
            try:
                department = Department.objects.get(
                    code=event.department_code,
                    hospital=journey_instance.hospital
                )
            except Department.DoesNotExist:
                logger.warning(f"Department not found: {event.department_code}")

        # Complete the stage
        with transaction.atomic():
            success = stage_instance.complete(
                event=event,
                staff=staff,
                department=department,
                metadata=event.payload_json
            )

            if success:
                # Log stage completion
                create_audit_log(
                    event_type='stage_completed',
                    description=f"Stage {stage_instance.stage_template.name} completed for encounter {event.encounter_id}",
                    content_object=stage_instance,
                    metadata={
                        'event_code': event.event_code,
                        'stage_name': stage_instance.stage_template.name,
                        'journey_type': journey_instance.journey_template.journey_type
                    }
                )

                # Check if survey should be sent
                if stage_instance.stage_template.auto_send_survey and stage_instance.stage_template.survey_template:
                    # Queue survey creation task with delay
                    from apps.surveys.tasks import create_and_send_survey
                    delay_seconds = stage_instance.stage_template.survey_delay_hours * 3600

                    logger.info(
                        f"Queuing survey for stage {stage_instance.stage_template.name} "
                        f"(delay: {stage_instance.stage_template.survey_delay_hours}h)"
                    )

                    create_and_send_survey.apply_async(
                        args=[str(stage_instance.id)],
                        countdown=delay_seconds
                    )

                # Mark event as processed
                event.mark_processed()

                logger.info(
                    f"Successfully processed event {event.id}: "
                    f"Completed stage {stage_instance.stage_template.name}"
                )

                return {
                    'status': 'processed',
                    'stage_completed': stage_instance.stage_template.name,
                    'journey_completion': journey_instance.get_completion_percentage()
                }
            else:
                error_msg = "Failed to complete stage"
                event.mark_failed(error_msg)
                return {'status': 'failed', 'reason': error_msg}

    except InboundEvent.DoesNotExist:
        error_msg = f"Event {event_id} not found"
        logger.error(error_msg)
        return {'status': 'error', 'reason': error_msg}

    except Exception as e:
        error_msg = f"Error processing event: {str(e)}"
        logger.error(error_msg, exc_info=True)

        try:
            event.mark_failed(error_msg)
        except:
            pass

        # Retry the task
        raise self.retry(exc=e, countdown=60 * (self.request.retries + 1))


@shared_task
def process_pending_events():
    """
    Periodic task to process pending events.

    This task runs every minute (configured in config/celery.py)
    and processes all pending events.
    """
    from apps.integrations.models import InboundEvent

    pending_events = InboundEvent.objects.filter(
        status='pending'
    ).order_by('received_at')[:100]  # Process max 100 at a time

    processed_count = 0

    for event in pending_events:
        # Queue individual event for processing
        process_inbound_event.delay(str(event.id))
        processed_count += 1

    if processed_count > 0:
        logger.info(f"Queued {processed_count} pending events for processing")

    return {'queued': processed_count}