from django.contrib.contenttypes.fields import GenericRelation
from django.core.urlresolvers import reverse
from django.db import models

from dcim.fields import ASNField
from dcim.models import Site, Interface
from extras.models import CustomFieldModel, CustomFieldValue
from tenancy.models import Tenant
from utilities.models import CreatedUpdatedModel


class Provider(CreatedUpdatedModel, CustomFieldModel):
    """
    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=50, unique=True)
    slug = models.SlugField(unique=True)
    asn = ASNField(blank=True, null=True, verbose_name='ASN')
    account = models.CharField(max_length=30, blank=True, verbose_name='Account number')
    portal_url = models.URLField(blank=True, verbose_name='Portal')
    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)
    custom_field_values = GenericRelation(CustomFieldValue, content_type_field='obj_type', object_id_field='obj_id')

    class Meta:
        ordering = ['name']

    def __unicode__(self):
        return self.name

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

    def to_csv(self):
        return ','.join([
            self.name,
            self.slug,
            str(self.asn) if self.asn else '',
            self.account,
            self.portal_url,
        ])


class CircuitType(models.Model):
    """
    Circuits can be orgnanized 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=50, unique=True)
    slug = models.SlugField(unique=True)

    class Meta:
        ordering = ['name']

    def __unicode__(self):
        return self.name

    def get_absolute_url(self):
        return "{}?type={}".format(reverse('circuits:circuit_list'), self.slug)


class Circuit(CreatedUpdatedModel, CustomFieldModel):
    """
    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. A Circuit may be terminated to a specific device
    interface, but this is not required. Circuit port speed and commit rate are measured in Kbps.
    """
    cid = models.CharField(max_length=50, verbose_name='Circuit ID')
    provider = models.ForeignKey('Provider', related_name='circuits', on_delete=models.PROTECT)
    type = models.ForeignKey('CircuitType', related_name='circuits', on_delete=models.PROTECT)
    tenant = models.ForeignKey(Tenant, related_name='circuits', blank=True, null=True, on_delete=models.PROTECT)
    site = models.ForeignKey(Site, related_name='circuits', on_delete=models.PROTECT)
    interface = models.OneToOneField(Interface, related_name='circuit', blank=True, null=True)
    install_date = models.DateField(blank=True, null=True, verbose_name='Date installed')
    port_speed = models.PositiveIntegerField(verbose_name='Port speed (Kbps)')
    upstream_speed = models.PositiveIntegerField(blank=True, null=True, verbose_name='Upstream speed (Kbps)',
                                                 help_text='Upstream speed, if different from port speed')
    commit_rate = models.PositiveIntegerField(blank=True, null=True, verbose_name='Commit rate (Kbps)')
    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)')
    comments = models.TextField(blank=True)
    custom_field_values = GenericRelation(CustomFieldValue, content_type_field='obj_type', object_id_field='obj_id')

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

    def __unicode__(self):
        return u'{} {}'.format(self.provider, self.cid)

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

    def to_csv(self):
        return ','.join([
            self.cid,
            self.provider.name,
            self.type.name,
            self.tenant.name if self.tenant else '',
            self.site.name,
            self.install_date.isoformat() if self.install_date else '',
            str(self.port_speed),
            str(self.upstream_speed),
            str(self.commit_rate) if self.commit_rate else '',
            self.xconnect_id,
            self.pp_info,
        ])

    def _humanize_speed(self, speed):
        """
        Humanize speeds given in Kbps (e.g. 10000000 becomes '10 Gbps')
        """
        if speed >= 1000000000 and speed % 1000000000 == 0:
            return '{} Tbps'.format(speed / 1000000000)
        elif speed >= 1000000 and speed % 1000000 == 0:
            return '{} Gbps'.format(speed / 1000000)
        elif speed >= 1000 and speed % 1000 == 0:
            return '{} Mbps'.format(speed / 1000)
        elif speed >= 1000:
            return '{} Mbps'.format(float(speed) / 1000)
        else:
            return '{} Kbps'.format(speed)

    def port_speed_human(self):
        return self._humanize_speed(self.port_speed)
    port_speed_human.admin_order_field = 'port_speed'

    def upstream_speed_human(self):
        if not self.upstream_speed:
            return ''
        return self._humanize_speed(self.upstream_speed)
    upstream_speed_human.admin_order_field = 'upstream_speed'

    def commit_rate_human(self):
        if not self.commit_rate:
            return ''
        return self._humanize_speed(self.commit_rate)
    commit_rate_human.admin_order_field = 'commit_rate'