from django.db import models
from django.contrib.auth import get_user_model
import uuid


class VMHost(models.Model):
    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    # 253 is the maximum DNS name length
    hostname = models.CharField(max_length=253, unique=True)

    # indirectly gives a maximum number of cores / VM - f.i. 32
    physical_cores = models.IntegerField(default=0)

    # determines the maximum usable cores - f.i. 320 if you overbook by a factor of 10
    usable_cores = models.IntegerField(default=0)

    # ram that can be used of the server
    usable_ram_in_gb = models.FloatField(default=0)


    status = models.CharField(max_length=32,
                              choices = (
                                  ('pending', 'Pending'),
                                  ('active', 'Active'),
                                  ('unusable', 'Unusable'),
                                  ('deleted', 'Deleted'),
                              ),
                              default='pending'
    )


class VMProduct(models.Model):
    uuid = models.UUIDField(primary_key=True,
                            default=uuid.uuid4,
                            editable=False)
    owner = models.ForeignKey(get_user_model(),
                              on_delete=models.CASCADE,
                              editable=False)
    vmhost   = models.ForeignKey(VMHost,
                                 on_delete=models.CASCADE,
                                 editable=False,
                                 blank=True,
                                 null=True)

    cores = models.IntegerField()
    ram_in_gb = models.FloatField()


class VMWithOSProduct(VMProduct):
    pass

class VMDiskProduct(models.Model):
    uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    vm   = models.ForeignKey(VMProduct, on_delete=models.CASCADE)
    size_in_gb = models.FloatField()

    storage_class = models.CharField(max_length=32,
                              choices = (
                                  ('hdd', 'HDD'),
                                  ('ssd', 'SSD'),
                              ),
                              default='ssd'
    )

class OperatingSystemDisk(VMDiskProduct):
    """ Defines an Operating System Disk that can be cloned for a VM """
    os_name = models.CharField(max_length=128)


class VMNetworkCard(models.Model):
    vm   = models.ForeignKey(VMProduct, on_delete=models.CASCADE)
    mac_address = models.IntegerField()