from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType
from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from mptt.models import MPTTModel, TreeForeignKey

from dcim.choices import *
from dcim.constants import *
from extras.utils import extras_features
from netbox.models import ChangeLoggedModel
from utilities.fields import ColorField, NaturalOrderingField
from utilities.mptt import TreeManager
from utilities.ordering import naturalize_interface
from .device_components import (
    ConsolePort, ConsoleServerPort, DeviceBay, FrontPort, Interface, InventoryItem, ModuleBay, PowerOutlet, PowerPort,
    RearPort,
)


__all__ = (
    'ConsolePortTemplate',
    'ConsoleServerPortTemplate',
    'DeviceBayTemplate',
    'FrontPortTemplate',
    'InterfaceTemplate',
    'InventoryItemTemplate',
    'ModuleBayTemplate',
    'PowerOutletTemplate',
    'PowerPortTemplate',
    'RearPortTemplate',
)


class ComponentTemplateModel(ChangeLoggedModel):
    device_type = models.ForeignKey(
        to='dcim.DeviceType',
        on_delete=models.CASCADE,
        related_name='%(class)ss'
    )
    name = models.CharField(
        max_length=64
    )
    _name = NaturalOrderingField(
        target_field='name',
        max_length=100,
        blank=True
    )
    label = models.CharField(
        max_length=64,
        blank=True,
        help_text="Physical label"
    )
    description = models.CharField(
        max_length=200,
        blank=True
    )

    class Meta:
        abstract = True

    def __str__(self):
        if self.label:
            return f"{self.name} ({self.label})"
        return self.name

    def instantiate(self, device):
        """
        Instantiate a new component on the specified Device.
        """
        raise NotImplementedError()

    def to_objectchange(self, action, related_object=None):
        # Annotate the parent DeviceType
        try:
            device_type = self.device_type
        except ObjectDoesNotExist:
            # The parent DeviceType has already been deleted
            device_type = None
        return super().to_objectchange(action, related_object=device_type)


class ModularComponentTemplateModel(ComponentTemplateModel):
    """
    A ComponentTemplateModel which supports optional assignment to a ModuleType.
    """
    device_type = models.ForeignKey(
        to='dcim.DeviceType',
        on_delete=models.CASCADE,
        related_name='%(class)ss',
        blank=True,
        null=True
    )
    module_type = models.ForeignKey(
        to='dcim.ModuleType',
        on_delete=models.CASCADE,
        related_name='%(class)ss',
        blank=True,
        null=True
    )

    class Meta:
        abstract = True

    def to_objectchange(self, action, related_object=None):
        # Annotate the parent DeviceType or ModuleType
        try:
            if getattr(self, 'device_type'):
                return super().to_objectchange(action, related_object=self.device_type)
        except ObjectDoesNotExist:
            pass
        try:
            if getattr(self, 'module_type'):
                return super().to_objectchange(action, related_object=self.module_type)
        except ObjectDoesNotExist:
            pass
        return super().to_objectchange(action)

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

        # A component template must belong to a DeviceType *or* to a ModuleType
        if self.device_type and self.module_type:
            raise ValidationError(
                "A component template cannot be associated with both a device type and a module type."
            )
        if not self.device_type and not self.module_type:
            raise ValidationError(
                "A component template must be associated with either a device type or a module type."
            )

    def resolve_name(self, module):
        if module:
            return self.name.replace('{module}', module.module_bay.position)
        return self.name


@extras_features('webhooks')
class ConsolePortTemplate(ModularComponentTemplateModel):
    """
    A template for a ConsolePort to be created for a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=ConsolePortTypeChoices,
        blank=True
    )

    component_model = ConsolePort

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

    def instantiate(self, **kwargs):
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            **kwargs
        )


@extras_features('webhooks')
class ConsoleServerPortTemplate(ModularComponentTemplateModel):
    """
    A template for a ConsoleServerPort to be created for a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=ConsolePortTypeChoices,
        blank=True
    )

    component_model = ConsoleServerPort

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

    def instantiate(self, **kwargs):
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            **kwargs
        )


@extras_features('webhooks')
class PowerPortTemplate(ModularComponentTemplateModel):
    """
    A template for a PowerPort to be created for a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=PowerPortTypeChoices,
        blank=True
    )
    maximum_draw = models.PositiveSmallIntegerField(
        blank=True,
        null=True,
        validators=[MinValueValidator(1)],
        help_text="Maximum power draw (watts)"
    )
    allocated_draw = models.PositiveSmallIntegerField(
        blank=True,
        null=True,
        validators=[MinValueValidator(1)],
        help_text="Allocated power draw (watts)"
    )

    component_model = PowerPort

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

    def instantiate(self, **kwargs):
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            maximum_draw=self.maximum_draw,
            allocated_draw=self.allocated_draw,
            **kwargs
        )

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

        if self.maximum_draw is not None and self.allocated_draw is not None:
            if self.allocated_draw > self.maximum_draw:
                raise ValidationError({
                    'allocated_draw': f"Allocated draw cannot exceed the maximum draw ({self.maximum_draw}W)."
                })


@extras_features('webhooks')
class PowerOutletTemplate(ModularComponentTemplateModel):
    """
    A template for a PowerOutlet to be created for a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=PowerOutletTypeChoices,
        blank=True
    )
    power_port = models.ForeignKey(
        to='dcim.PowerPortTemplate',
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
        related_name='poweroutlet_templates'
    )
    feed_leg = models.CharField(
        max_length=50,
        choices=PowerOutletFeedLegChoices,
        blank=True,
        help_text="Phase (for three-phase feeds)"
    )

    component_model = PowerOutlet

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

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

        # Validate power port assignment
        if self.power_port:
            if self.device_type and self.power_port.device_type != self.device_type:
                raise ValidationError(
                    f"Parent power port ({self.power_port}) must belong to the same device type"
                )
            if self.module_type and self.power_port.module_type != self.module_type:
                raise ValidationError(
                    f"Parent power port ({self.power_port}) must belong to the same module type"
                )

    def instantiate(self, **kwargs):
        if self.power_port:
            power_port = PowerPort.objects.get(name=self.power_port.name, **kwargs)
        else:
            power_port = None
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            power_port=power_port,
            feed_leg=self.feed_leg,
            **kwargs
        )


@extras_features('webhooks')
class InterfaceTemplate(ModularComponentTemplateModel):
    """
    A template for a physical data interface on a new Device.
    """
    # Override ComponentTemplateModel._name to specify naturalize_interface function
    _name = NaturalOrderingField(
        target_field='name',
        naturalize_function=naturalize_interface,
        max_length=100,
        blank=True
    )
    type = models.CharField(
        max_length=50,
        choices=InterfaceTypeChoices
    )
    mgmt_only = models.BooleanField(
        default=False,
        verbose_name='Management only'
    )

    component_model = Interface

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

    def instantiate(self, **kwargs):
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            mgmt_only=self.mgmt_only,
            **kwargs
        )


@extras_features('webhooks')
class FrontPortTemplate(ModularComponentTemplateModel):
    """
    Template for a pass-through port on the front of a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=PortTypeChoices
    )
    color = ColorField(
        blank=True
    )
    rear_port = models.ForeignKey(
        to='dcim.RearPortTemplate',
        on_delete=models.CASCADE,
        related_name='frontport_templates'
    )
    rear_port_position = models.PositiveSmallIntegerField(
        default=1,
        validators=[
            MinValueValidator(REARPORT_POSITIONS_MIN),
            MaxValueValidator(REARPORT_POSITIONS_MAX)
        ]
    )

    component_model = FrontPort

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
            ('rear_port', 'rear_port_position'),
        )

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

        try:

            # Validate rear port assignment
            if self.rear_port.device_type != self.device_type:
                raise ValidationError(
                    "Rear port ({}) must belong to the same device type".format(self.rear_port)
                )

            # Validate rear port position assignment
            if self.rear_port_position > self.rear_port.positions:
                raise ValidationError(
                    "Invalid rear port position ({}); rear port {} has only {} positions".format(
                        self.rear_port_position, self.rear_port.name, self.rear_port.positions
                    )
                )

        except RearPortTemplate.DoesNotExist:
            pass

    def instantiate(self, **kwargs):
        if self.rear_port:
            rear_port = RearPort.objects.get(name=self.rear_port.name, **kwargs)
        else:
            rear_port = None
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            color=self.color,
            rear_port=rear_port,
            rear_port_position=self.rear_port_position,
            **kwargs
        )


@extras_features('webhooks')
class RearPortTemplate(ModularComponentTemplateModel):
    """
    Template for a pass-through port on the rear of a new Device.
    """
    type = models.CharField(
        max_length=50,
        choices=PortTypeChoices
    )
    color = ColorField(
        blank=True
    )
    positions = models.PositiveSmallIntegerField(
        default=1,
        validators=[
            MinValueValidator(REARPORT_POSITIONS_MIN),
            MaxValueValidator(REARPORT_POSITIONS_MAX)
        ]
    )

    component_model = RearPort

    class Meta:
        ordering = ('device_type', 'module_type', '_name')
        unique_together = (
            ('device_type', 'name'),
            ('module_type', 'name'),
        )

    def instantiate(self, **kwargs):
        return self.component_model(
            name=self.resolve_name(kwargs.get('module')),
            label=self.label,
            type=self.type,
            color=self.color,
            positions=self.positions,
            **kwargs
        )


@extras_features('webhooks')
class ModuleBayTemplate(ComponentTemplateModel):
    """
    A template for a ModuleBay to be created for a new parent Device.
    """
    position = models.CharField(
        max_length=30,
        blank=True,
        help_text='Identifier to reference when renaming installed components'
    )

    component_model = ModuleBay

    class Meta:
        ordering = ('device_type', '_name')
        unique_together = ('device_type', 'name')

    def instantiate(self, device):
        return self.component_model(
            device=device,
            name=self.name,
            label=self.label,
            position=self.position
        )


@extras_features('webhooks')
class DeviceBayTemplate(ComponentTemplateModel):
    """
    A template for a DeviceBay to be created for a new parent Device.
    """
    component_model = DeviceBay

    class Meta:
        ordering = ('device_type', '_name')
        unique_together = ('device_type', 'name')

    def instantiate(self, device):
        return self.component_model(
            device=device,
            name=self.name,
            label=self.label
        )

    def clean(self):
        if self.device_type and self.device_type.subdevice_role != SubdeviceRoleChoices.ROLE_PARENT:
            raise ValidationError(
                f"Subdevice role of device type ({self.device_type}) must be set to \"parent\" to allow device bays."
            )


@extras_features('webhooks')
class InventoryItemTemplate(MPTTModel, ComponentTemplateModel):
    """
    A template for an InventoryItem to be created for a new parent Device.
    """
    parent = TreeForeignKey(
        to='self',
        on_delete=models.CASCADE,
        related_name='child_items',
        blank=True,
        null=True,
        db_index=True
    )
    component_type = models.ForeignKey(
        to=ContentType,
        limit_choices_to=MODULAR_COMPONENT_TEMPLATE_MODELS,
        on_delete=models.PROTECT,
        related_name='+',
        blank=True,
        null=True
    )
    component_id = models.PositiveBigIntegerField(
        blank=True,
        null=True
    )
    component = GenericForeignKey(
        ct_field='component_type',
        fk_field='component_id'
    )
    role = models.ForeignKey(
        to='dcim.InventoryItemRole',
        on_delete=models.PROTECT,
        related_name='inventory_item_templates',
        blank=True,
        null=True
    )
    manufacturer = models.ForeignKey(
        to='dcim.Manufacturer',
        on_delete=models.PROTECT,
        related_name='inventory_item_templates',
        blank=True,
        null=True
    )
    part_id = models.CharField(
        max_length=50,
        verbose_name='Part ID',
        blank=True,
        help_text='Manufacturer-assigned part identifier'
    )

    objects = TreeManager()
    component_model = InventoryItem

    class Meta:
        ordering = ('device_type__id', 'parent__id', '_name')
        unique_together = ('device_type', 'parent', 'name')

    def instantiate(self, **kwargs):
        parent = InventoryItemTemplate.objects.get(name=self.parent.name, **kwargs) if self.parent else None
        if self.component:
            model = self.component.component_model
            component = model.objects.get(name=self.component.name, **kwargs)
        else:
            component = None
        return self.component_model(
            parent=parent,
            name=self.name,
            label=self.label,
            component=component,
            role=self.role,
            manufacturer=self.manufacturer,
            part_id=self.part_id,
            **kwargs
        )