"""
Django signals for MDT app.
Handles automated workflows and notifications.
"""

from django.db.models.signals import post_save, pre_save
from django.dispatch import receiver
from django.utils import timezone

from .models import (
    MDTNote,
    MDTContribution,
    MDTApproval,
    MDTMention,
)
from .services import (
    MDTNotificationService,
    MDTWorkflowService,
)
from notifications.models import Notification


@receiver(post_save, sender=MDTNote)
def handle_mdt_note_created(sender, instance, created, **kwargs):
    """
    Handle post-save signal for MDTNote.
    Send notifications to relevant users.
    """
    if created:
        # Notify clinical coordinator about new MDT note
        from core.models import User
        coordinators = User.objects.filter(
            tenant=instance.tenant,
            role='CLINICAL_COORDINATOR',
            is_active=True
        )
        
        for coordinator in coordinators:
            Notification.objects.create(
                user=coordinator,
                notification_type='MDT_CREATED',
                title=f"New MDT Note: {instance.title}",
                message=f"MDT note initiated by {instance.initiated_by.get_full_name()} for {instance.patient.get_full_name()}",
            )


@receiver(post_save, sender=MDTContribution)
def handle_contribution_added(sender, instance, created, **kwargs):
    """
    Handle post-save signal for MDTContribution.
    Notify other contributors and handle mentions.
    """
    if created:
        # Notify other contributors
        other_contributors = instance.mdt_note.contributors.exclude(
            id=instance.contributor.id
        ).distinct()
        
        for contributor in other_contributors:
            Notification.objects.create(
                user=contributor,
                notification_type='MDT_CONTRIBUTION',
                title=f"New Contribution to MDT Note: {instance.mdt_note.title}",
                message=f"{instance.contributor.get_full_name()} ({instance.clinic.name_en}) added a contribution",
            )
        
        # Notify initiator if different from contributor
        if instance.mdt_note.initiated_by and instance.mdt_note.initiated_by != instance.contributor:
            Notification.objects.create(
                user=instance.mdt_note.initiated_by,
                notification_type='MDT_CONTRIBUTION',
                title=f"New Contribution to Your MDT Note: {instance.mdt_note.title}",
                message=f"{instance.contributor.get_full_name()} ({instance.clinic.name_en}) added a contribution",
            )


@receiver(post_save, sender=MDTApproval)
def handle_approval_given(sender, instance, created, **kwargs):
    """
    Handle post-save signal for MDTApproval.
    Check if note can be finalized and notify contributors.
    """
    if not created and instance.approved:
        # Notify initiator
        if instance.mdt_note.initiated_by:
            Notification.objects.create(
                user=instance.mdt_note.initiated_by,
                notification_type='MDT_APPROVAL',
                title=f"MDT Note Approved: {instance.mdt_note.title}",
                message=f"{instance.approver.get_full_name()} ({instance.clinic.name_en}) approved the MDT note",
            )
        
        # Check if note can be auto-finalized
        MDTWorkflowService.check_and_auto_finalize(instance.mdt_note)


@receiver(pre_save, sender=MDTNote)
def handle_mdt_note_status_change(sender, instance, **kwargs):
    """
    Handle pre-save signal for MDTNote.
    Track status changes and set finalization timestamp.
    """
    if instance.pk:
        try:
            old_instance = MDTNote.objects.get(pk=instance.pk)
            
            # If status changed to FINALIZED
            if (old_instance.status != MDTNote.Status.FINALIZED and 
                instance.status == MDTNote.Status.FINALIZED and 
                not instance.finalized_at):
                instance.finalized_at = timezone.now()
                
        except MDTNote.DoesNotExist:
            pass


@receiver(post_save, sender=MDTMention)
def handle_mention_created(sender, instance, created, **kwargs):
    """
    Handle post-save signal for MDTMention.
    Send notification to mentioned user.
    """
    if created:
        MDTNotificationService.notify_mention(instance)