from django.db import models
from django.urls import reverse

from nautobot.dcim.fields import ASNField
from nautobot.dcim.models import CableTermination, PathEndpoint
from nautobot.extras.models import ObjectChange, RelationshipModel, StatusModel
from nautobot.extras.utils import extras_features
from nautobot.core.fields import AutoSlugField
from nautobot.core.models.generics import BaseModel, OrganizationalModel, PrimaryModel
from nautobot.utilities.utils import serialize_object
from .choices import CircuitTerminationSideChoices
from .querysets import CircuitQuerySet


__all__ = (
    "Circuit",
    "CircuitTermination",
    "CircuitType",
    "Provider",
)


@extras_features(
    "custom_fields",
    "custom_links",
    "custom_validators",
    "export_templates",
    "graphql",
    "relationships",
    "webhooks",
)
class Provider(PrimaryModel):
    """
    Each Circuit belongs to a Provider. This is usually a telecommunications company or similar organization. This model
    stores information pertinent to the user's relationship with the Provider.
    """

    name = models.CharField(max_length=100, unique=True)
    slug = AutoSlugField(populate_from="name")
    asn = ASNField(
        blank=True,
        null=True,
        verbose_name="ASN",
        help_text="32-bit autonomous system number",
    )
    account = models.CharField(max_length=30, blank=True, verbose_name="Account number")
    portal_url = models.URLField(blank=True, verbose_name="Portal URL")
    noc_contact = models.TextField(blank=True, verbose_name="NOC contact")
    admin_contact = models.TextField(blank=True, verbose_name="Admin contact")
    comments = models.TextField(blank=True)

    csv_headers = [
        "name",
        "slug",
        "asn",
        "account",
        "portal_url",
        "noc_contact",
        "admin_contact",
        "comments",
    ]
    clone_fields = [
        "asn",
        "account",
        "portal_url",
        "noc_contact",
        "admin_contact",
    ]

    class Meta:
        ordering = ["name"]

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return reverse("circuits:provider", args=[self.slug])

    def to_csv(self):
        return (
            self.name,
            self.slug,
            self.asn,
            self.account,
            self.portal_url,
            self.noc_contact,
            self.admin_contact,
            self.comments,
        )


@extras_features("custom_fields", "custom_validators", "graphql", "relationships")
class CircuitType(OrganizationalModel):
    """
    Circuits can be organized by their functional role. For example, a user might wish to define CircuitTypes named
    "Long Haul," "Metro," or "Out-of-Band".
    """

    name = models.CharField(max_length=100, unique=True)
    slug = AutoSlugField(populate_from="name")
    description = models.CharField(
        max_length=200,
        blank=True,
    )

    csv_headers = ["name", "slug", "description"]

    class Meta:
        ordering = ["name"]

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return reverse("circuits:circuittype", args=[self.slug])

    def to_csv(self):
        return (
            self.name,
            self.slug,
            self.description,
        )


@extras_features(
    "custom_fields",
    "custom_links",
    "custom_validators",
    "export_templates",
    "graphql",
    "relationships",
    "statuses",
    "webhooks",
)
class Circuit(PrimaryModel, StatusModel):
    """
    A communications circuit connects two points. Each Circuit belongs to a Provider; Providers may have multiple
    circuits. Each circuit is also assigned a CircuitType and a Site.  Circuit port speed and commit rate are measured
    in Kbps.
    """

    cid = models.CharField(max_length=100, verbose_name="Circuit ID")
    provider = models.ForeignKey(to="circuits.Provider", on_delete=models.PROTECT, related_name="circuits")
    type = models.ForeignKey(to="CircuitType", on_delete=models.PROTECT, related_name="circuits")
    tenant = models.ForeignKey(
        to="tenancy.Tenant",
        on_delete=models.PROTECT,
        related_name="circuits",
        blank=True,
        null=True,
    )
    install_date = models.DateField(blank=True, null=True, verbose_name="Date installed")
    commit_rate = models.PositiveIntegerField(blank=True, null=True, verbose_name="Commit rate (Kbps)")
    description = models.CharField(max_length=200, blank=True)
    comments = models.TextField(blank=True)

    objects = CircuitQuerySet.as_manager()

    csv_headers = [
        "cid",
        "provider",
        "type",
        "status",
        "tenant",
        "install_date",
        "commit_rate",
        "description",
        "comments",
    ]
    clone_fields = [
        "provider",
        "type",
        "status",
        "tenant",
        "install_date",
        "commit_rate",
        "description",
    ]

    class Meta:
        ordering = ["provider", "cid"]
        unique_together = ["provider", "cid"]

    def __str__(self):
        return self.cid

    def get_absolute_url(self):
        return reverse("circuits:circuit", args=[self.pk])

    def to_csv(self):
        return (
            self.cid,
            self.provider.name,
            self.type.name,
            self.get_status_display(),
            self.tenant.name if self.tenant else None,
            self.install_date,
            self.commit_rate,
            self.description,
            self.comments,
        )

    def _get_termination(self, side):
        for ct in self.terminations.all():
            if ct.term_side == side:
                return ct
        return None

    @property
    def termination_a(self):
        return self._get_termination("A")

    @property
    def termination_z(self):
        return self._get_termination("Z")


@extras_features(
    "custom_validators",
    "graphql",
    "relationships",
)
class CircuitTermination(BaseModel, PathEndpoint, CableTermination, RelationshipModel):
    circuit = models.ForeignKey(to="circuits.Circuit", on_delete=models.CASCADE, related_name="terminations")
    term_side = models.CharField(max_length=1, choices=CircuitTerminationSideChoices, verbose_name="Termination")
    site = models.ForeignKey(to="dcim.Site", on_delete=models.PROTECT, related_name="circuit_terminations")
    port_speed = models.PositiveIntegerField(verbose_name="Port speed (Kbps)", blank=True, null=True)
    upstream_speed = models.PositiveIntegerField(
        blank=True,
        null=True,
        verbose_name="Upstream speed (Kbps)",
        help_text="Upstream speed, if different from port speed",
    )
    xconnect_id = models.CharField(max_length=50, blank=True, verbose_name="Cross-connect ID")
    pp_info = models.CharField(max_length=100, blank=True, verbose_name="Patch panel/port(s)")
    description = models.CharField(max_length=200, blank=True)

    class Meta:
        ordering = ["circuit", "term_side"]
        unique_together = ["circuit", "term_side"]

    def __str__(self):
        return "Side {}".format(self.get_term_side_display())

    def to_objectchange(self, action):
        # Annotate the parent Circuit
        try:
            related_object = self.circuit
        except Circuit.DoesNotExist:
            # Parent circuit has been deleted
            related_object = None

        return ObjectChange(
            changed_object=self,
            object_repr=str(self),
            action=action,
            related_object=related_object,
            object_data=serialize_object(self),
        )

    @property
    def parent(self):
        return self.circuit

    def get_peer_termination(self):
        peer_side = "Z" if self.term_side == "A" else "A"
        try:
            return CircuitTermination.objects.prefetch_related("site").get(circuit=self.circuit, term_side=peer_side)
        except CircuitTermination.DoesNotExist:
            return None
