from django.db import transaction
from django.db.models.signals import post_save
from django.dispatch import receiver
from asgiref.sync import async_to_sync
from channels.layers import get_channel_layer

from submissions.models import Submission, SubmissionFile, ImageCrop, Scope
from submissions.schemas import SubmissionOut, SubmissionFileOut, ImageCropOut


@receiver(post_save, sender=Submission)
def broadcast_submission_update(sender, instance, created, **kwargs):
    if not instance.user:
        return

    user_group_name = f"submissions_user_{instance.user.id}"
    submission_data = SubmissionOut.from_orm(instance).dict()

    async_to_sync(get_channel_layer().group_send)(
        user_group_name,
        {
            "type": "submission.updated",
            "submission": submission_data,
        },
    )


@receiver(post_save, sender=SubmissionFile)
def broadcast_submission_file_update(sender, instance, created, **kwargs):
    submission = instance.submission
    if not submission.user:
        return

    user_group_name = f"submissions_user_{submission.user.id}"
    file_data = SubmissionFileOut.from_orm(instance).dict()

    async_to_sync(get_channel_layer().group_send)(
        user_group_name,
        {
            "type": "submission.file.updated",
            "file": file_data,
        },
    )


@receiver(post_save, sender=ImageCrop)
def broadcast_image_crop_update(sender, instance, created, **kwargs):
    submission = instance.submission_file.submission
    if not submission.user:
        return

    user_group_name = f"submissions_user_{submission.user.id}"
    crop_data = ImageCropOut.from_orm(instance).dict()

    async_to_sync(get_channel_layer().group_send)(
        user_group_name,
        {
            "type": "submission.crop.updated",
            "crop": crop_data,
        },
    )


def broadcast_scope_updates(changes: dict[Scope, set[int]], /):
    """Tell users their scope changed (closed/opened, (un)assigned), once the
    current transaction commits, so the frontend can move them to the right
    match without a refresh.

    Args:
        changes: Changed scopes, each with every user id that was or now is
            assigned to it.
    """

    def send():
        channel_layer = get_channel_layer()
        for scope, user_ids in changes.items():
            assigned_ids = set(scope.assigned_users.values_list("id", flat=True))
            for user_id in user_ids:
                async_to_sync(channel_layer.group_send)(
                    f"submissions_user_{user_id}",
                    {
                        "type": "scope.updated",
                        "scope": {
                            "id": str(scope.id),
                            "is_active": scope.is_active,
                            "assigned": user_id in assigned_ids,
                        },
                    },
                )

    if changes:
        # robust: a websocket hiccup only gets logged, it mustn't fail the
        # (already committed) sync or admin save
        transaction.on_commit(send, robust=True)