from django.core.exceptions import ValidationError
from django.db import models
from django.urls import reverse
from mptt.models import MPTTModel, TreeForeignKey
from taggit.managers import TaggableManager

from extras.models import ChangeLoggedModel, CustomFieldModel, ObjectChange, TaggedItem
from extras.utils import extras_features
from utilities.mptt import TreeManager
from utilities.querysets import RestrictedQuerySet
from utilities.utils import serialize_object


__all__ = (
    'Tenant',
    'TenantGroup',
)


class TenantGroup(MPTTModel, ChangeLoggedModel):
    """
    An arbitrary collection of Tenants.
    """
    name = models.CharField(
        max_length=100,
        unique=True
    )
    slug = models.SlugField(
        max_length=100,
        unique=True
    )
    parent = TreeForeignKey(
        to='self',
        on_delete=models.CASCADE,
        related_name='children',
        blank=True,
        null=True,
        db_index=True
    )
    description = models.CharField(
        max_length=200,
        blank=True
    )

    objects = TreeManager()

    csv_headers = ['name', 'slug', 'parent', 'description']

    class Meta:
        ordering = ['name']

    class MPTTMeta:
        order_insertion_by = ['name']

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return "{}?group={}".format(reverse('tenancy:tenant_list'), self.slug)

    def to_csv(self):
        return (
            self.name,
            self.slug,
            self.parent.name if self.parent else '',
            self.description,
        )

    def to_objectchange(self, action):
        # Remove MPTT-internal fields
        return ObjectChange(
            changed_object=self,
            object_repr=str(self),
            action=action,
            object_data=serialize_object(self, exclude=['level', 'lft', 'rght', 'tree_id'])
        )

    def clean(self):
        super().clean()

        # An MPTT model cannot be its own parent
        if self.pk and self.parent_id == self.pk:
            raise ValidationError({
                "parent": "Cannot assign self as parent."
            })


@extras_features('custom_fields', 'custom_links', 'export_templates', 'webhooks')
class Tenant(ChangeLoggedModel, CustomFieldModel):
    """
    A Tenant represents an organization served by the NetBox owner. This is typically a customer or an internal
    department.
    """
    name = models.CharField(
        max_length=100,
        unique=True
    )
    slug = models.SlugField(
        max_length=100,
        unique=True
    )
    group = models.ForeignKey(
        to='tenancy.TenantGroup',
        on_delete=models.SET_NULL,
        related_name='tenants',
        blank=True,
        null=True
    )
    description = models.CharField(
        max_length=200,
        blank=True
    )
    comments = models.TextField(
        blank=True
    )
    tags = TaggableManager(through=TaggedItem)

    objects = RestrictedQuerySet.as_manager()

    csv_headers = ['name', 'slug', 'group', 'description', 'comments']
    clone_fields = [
        'group', 'description',
    ]

    class Meta:
        ordering = ['group', 'name']

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return reverse('tenancy:tenant', args=[self.slug])

    def to_csv(self):
        return (
            self.name,
            self.slug,
            self.group.name if self.group else None,
            self.description,
            self.comments,
        )