import logging
import typing
from json import JSONDecodeError

from django.db import models
from django.utils import timezone

from apps.labels.client import LabelsAPIClient, LabelsRepoAPIException
from apps.labels.tasks import update_label_pairs_cache
from apps.labels.types import LabelPair
from apps.labels.utils import LABEL_OUTDATED_TIMEOUT_MINUTES

if typing.TYPE_CHECKING:
    from apps.user_management.models import Organization

logger = logging.getLogger(__name__)

MAX_KEY_NAME_LENGTH = 200
MAX_VALUE_NAME_LENGTH = 200


class LabelKeyCache(models.Model):
    id = models.CharField(primary_key=True, editable=False, max_length=36)
    name = models.CharField(max_length=MAX_KEY_NAME_LENGTH)
    organization = models.ForeignKey("user_management.Organization", on_delete=models.CASCADE)
    last_synced = models.DateTimeField(auto_now=True)
    prescribed = models.BooleanField(default=False, null=True)

    @property
    def is_outdated(self) -> bool:
        return timezone.now() - self.last_synced > timezone.timedelta(minutes=LABEL_OUTDATED_TIMEOUT_MINUTES)

    @classmethod
    def get_or_create_by_name(cls, organization: "Organization", key_name: str) -> typing.Optional["LabelKeyCache"]:
        """
        `get_or_create_by_name` tries to get label key with provided name from cache.
        If there is no label key with this name in the cache - it tries to fetch it from the labels repo API.
        """
        label_key = cls.objects.filter(organization=organization, name=key_name).first()
        if label_key:
            return label_key

        # fetch label key from labels repo
        try:
            label, _ = LabelsAPIClient(organization.grafana_url, organization.api_token).get_label_by_key_name(
                label_key
            )
        except (LabelsRepoAPIException, JSONDecodeError) as e:
            logger.error(f"Failed to get or create label key {key_name} for organization {organization.id}: {e}")
            return None

        # save labels key in cache
        label_key = LabelKeyCache(
            id=label["key"]["id"],
            name=label["key"]["name"],
            organization=organization,
            prescribed=label["key"]["prescribed"],
        )
        label_key.save()

        return label_key


class LabelValueCache(models.Model):
    id = models.CharField(primary_key=True, editable=False, max_length=36)
    name = models.CharField(max_length=MAX_VALUE_NAME_LENGTH)
    key = models.ForeignKey("labels.LabelKeyCache", on_delete=models.CASCADE, related_name="values")
    last_synced = models.DateTimeField(auto_now=True)
    prescribed = models.BooleanField(default=False, null=True)

    @property
    def is_outdated(self) -> bool:
        return timezone.now() - self.last_synced > timezone.timedelta(minutes=LABEL_OUTDATED_TIMEOUT_MINUTES)


class AssociatedLabel(models.Model):
    """
    Abstract model, is used to keep information about label association with other instances
    (integrations, schedules, etc.). To add ability to associate labels with a type of instances ,
    inhere this model and add a foreign key to the instance model.

    Attention: add `AssociatedLabel` to the end of the name of inheritor (example: AlertReceiveChannelAssociatedLabel)
    """

    key = models.ForeignKey(LabelKeyCache, on_delete=models.CASCADE)
    value = models.ForeignKey(LabelValueCache, on_delete=models.CASCADE)
    organization = models.ForeignKey("user_management.Organization", on_delete=models.CASCADE, related_name="labels")

    class Meta:
        abstract = True

    @staticmethod
    def update_association(
        label_pairs: typing.List[LabelPair], instance: models.Model, organization: "Organization"
    ) -> None:
        """
        Update label associations for selected instance: delete associations with labels that are not in `labels_data`,
        create new associations and labels, if needed.
        Then call celery task to update cache for labels from `labels_data`

        instance: the model instance that the labels are associated with (e.g. AlertReceiveChannel instance)
        """
        labels_data_keys = {label["key"]["id"]: label["key"]["name"] for label in label_pairs}
        labels_data_values = {label["value"]["id"]: label["value"]["name"] for label in label_pairs}

        # delete associations with labels that are not presented in labels_data
        instance.labels.exclude(key_id__in=labels_data_keys.keys(), value_id__in=labels_data_values.keys()).delete()

        labels_keys = []
        labels_values = []
        labels_associations = []

        for label_pair in label_pairs:
            key_id = label_pair["key"]["id"]
            key_name = label_pair["key"]["name"]
            key_prescribed = label_pair["key"]["prescribed"]

            value_id = label_pair["value"]["id"]
            value_name = label_pair["value"]["name"]
            value_prescribed = label_pair["value"]["prescribed"]

            label_key = LabelKeyCache(id=key_id, name=key_name, organization=organization, prescribed=key_prescribed)
            labels_keys.append(label_key)

            label_value = LabelValueCache(id=value_id, name=value_name, key_id=key_id, prescribed=value_prescribed)
            labels_values.append(label_value)
            associated_instance = {instance.labels.field.name: instance}
            labels_associations.append(
                instance.labels.model(
                    key_id=key_id, value_id=value_id, organization=organization, **associated_instance
                )
            )

        # create labels cache and associations that don't exist.
        # Ignoring conflicts because some labels might laready exist. They will be updates in task.
        LabelKeyCache.objects.bulk_create(labels_keys, ignore_conflicts=True, batch_size=5000)
        LabelValueCache.objects.bulk_create(labels_values, ignore_conflicts=True, batch_size=5000)
        instance.labels.model.objects.bulk_create(labels_associations, ignore_conflicts=True, batch_size=5000)

        update_label_pairs_cache.apply_async((label_pairs,))

    @staticmethod
    def get_associating_label_field_name() -> str:
        """Returns ForeignKey field name for the associated model"""
        raise NotImplementedError


class AlertReceiveChannelAssociatedLabel(AssociatedLabel):
    """Keeps information about label association with alert receive channel instances"""

    alert_receive_channel = models.ForeignKey(
        "alerts.AlertReceiveChannel", on_delete=models.CASCADE, related_name="labels"
    )

    class Meta:
        unique_together = ["key_id", "value_id", "alert_receive_channel_id"]

    @staticmethod
    def get_associating_label_field_name() -> str:
        """Returns ForeignKey field name for the associated model"""
        return "alert_receive_channel"


class AlertGroupAssociatedLabel(models.Model):
    """
    A model for alert group labels (similar to AlertReceiveChannelAssociatedLabel for integrations).
    The key difference is that alert group labels do not use label IDs, but rather key and value names explicitly.
    This is done to make alert group labels "static" (so they don't change when the labels are updated in label repo).
    """

    alert_group = models.ForeignKey("alerts.AlertGroup", on_delete=models.CASCADE, related_name="labels")
    organization = models.ForeignKey(
        "user_management.Organization", on_delete=models.CASCADE, related_name="alert_group_labels"
    )

    key_name = models.CharField(max_length=MAX_KEY_NAME_LENGTH)
    value_name = models.CharField(max_length=MAX_VALUE_NAME_LENGTH)

    class Meta:
        constraints = [
            models.UniqueConstraint(
                fields=["organization", "key_name", "value_name", "alert_group"],
                name="unique_alert_group_label",
            )
        ]


class WebhookAssociatedLabel(AssociatedLabel):
    """Keeps information about label association with outgoing webhooks instances"""

    webhook = models.ForeignKey(
        "webhooks.Webhook",
        on_delete=models.CASCADE,
        related_name="labels",
    )
    organization = models.ForeignKey(
        "user_management.Organization", on_delete=models.CASCADE, related_name="webhook_labels"
    )

    class Meta:
        unique_together = ["key_id", "value_id", "webhook_id"]

    @staticmethod
    def get_associating_label_field_name() -> str:
        """Returns ForeignKey field name for the associated model"""
        return "webhook"