from datetime import datetime

from celery.exceptions import MaxRetriesExceededError
from celery.utils.log import get_task_logger
from django.conf import settings
from django.core.mail import EmailMessage

from dynamicweb.celery import app
from hosting.models import HostingOrder, HostingBill
from membership.models import StripeCustomer
from opennebula_api.models import OpenNebulaManager
from opennebula_api.serializers import VirtualMachineSerializer
from utils.forms import UserBillingAddressForm
from utils.models import BillingAddress

logger = get_task_logger(__name__)


def retry_task(task, exception=None):
    """Retries the specified task using a "backing off countdown",
    meaning that the interval between retries grows exponentially
    with every retry.

    Arguments:
        task:
            The task to retry.

        exception:
            Optionally, the exception that caused the retry.
    """

    def backoff(attempts):
        return 2 ** attempts

    kwargs = {
        'countdown': backoff(task.request.retries),
    }

    if exception:
        kwargs['exc'] = exception

    raise task.retry(**kwargs)


@app.task(bind=True, max_retries=settings.CELERY_MAX_RETRIES)
def create_vm_task(self, vm_template_id, user, specs, template,
                   stripe_customer_id, billing_address_data,
                   billing_address_id,
                   charge, cc_details):
    vm_id = None
    try:
        final_price = specs.get('price')
        billing_address = BillingAddress.objects.filter(
            id=billing_address_id).first()
        customer = StripeCustomer.objects.filter(id=stripe_customer_id).first()

        if 'pass' in user:
            on_user = user.get('email')
            on_pass = user.get('pass')
            logger.debug("Using user {user} to create VM".format(user=on_user))
            vm_name = None
        else:
            on_user = settings.OPENNEBULA_USERNAME
            on_pass = settings.OPENNEBULA_PASSWORD
            logger.debug("Using OpenNebula admin user to create VM")
            vm_name = "{email}-{template_name}-{date}".format(
                email=user.get('email'),
                template_name=template.get('name'),
                date=int(datetime.now().strftime("%s")))

        # Create OpenNebulaManager
        manager = OpenNebulaManager(email=on_user, password=on_pass)

        vm_id = manager.create_vm(
            template_id=vm_template_id,
            specs=specs,
            ssh_key=settings.ONEADMIN_USER_SSH_PUBLIC_KEY,
            vm_name=vm_name
        )

        if vm_id is None:
            raise Exception("Could not create VM")

        # Create a Hosting Order
        order = HostingOrder.create(
            price=final_price,
            vm_id=vm_id,
            customer=customer,
            billing_address=billing_address
        )

        # Create a Hosting Bill
        HostingBill.create(
            customer=customer, billing_address=billing_address)

        # Create Billing Address for User if he does not have one
        if not customer.user.billing_addresses.count():
            billing_address_data.update({
                'user': customer.user.id
            })
            billing_address_user_form = UserBillingAddressForm(
                billing_address_data)
            billing_address_user_form.is_valid()
            billing_address_user_form.save()

        # Associate an order with a stripe subscription
        charge_object = DictDotLookup(charge)
        order.set_subscription_id(charge_object, cc_details)

        # If the Stripe payment succeeds, set order status approved
        order.set_approved()

        vm = VirtualMachineSerializer(manager.get_vm(vm_id)).data

        context = {
            'name': user.get('name'),
            'email': user.get('email'),
            'cores': specs.get('cpu'),
            'memory': specs.get('memory'),
            'storage': specs.get('disk_size'),
            'price': specs.get('price'),
            'template': template.get('name'),
            'vm.name': vm['name'],
            'vm.id': vm['vm_id'],
            'order.id': order.id
        }
        email_data = {
            'subject': settings.DCL_TEXT + " Order from %s" % context['email'],
            'from_email': settings.DCL_SUPPORT_FROM_ADDRESS,
            'to': ['info@ungleich.ch'],
            'body': "\n".join(
                ["%s=%s" % (k, v) for (k, v) in context.items()]),
            'reply_to': [context['email']],
        }
        email = EmailMessage(**email_data)
        email.send()
    except Exception as e:
        logger.error(str(e))
        try:
            retry_task(self)
        except MaxRetriesExceededError:
            msg_text = 'Finished {} retries for create_vm_task'.format(
                self.request.retries)
            logger.error(msg_text)
            # Try sending email and stop
            email_data = {
                'subject': '{} CELERY TASK ERROR: {}'.format(settings.DCL_TEXT,
                                                             msg_text),
                'from_email': settings.DCL_SUPPORT_FROM_ADDRESS,
                'to': ['info@ungleich.ch'],
                'body': ',\n'.join(str(i) for i in self.request.args)
            }
            email = EmailMessage(**email_data)
            email.send()
            return

    return vm_id


class DictDotLookup(object):
    """
    Creates objects that behave much like a dictionaries, but allow nested
    key access using object '.' (dot) lookups.
    """

    def __init__(self, d):
        for k in d:
            if isinstance(d[k], dict):
                self.__dict__[k] = DictDotLookup(d[k])
            elif isinstance(d[k], (list, tuple)):
                l = []
                for v in d[k]:
                    if isinstance(v, dict):
                        l.append(DictDotLookup(v))
                    else:
                        l.append(v)
                self.__dict__[k] = l
            else:
                self.__dict__[k] = d[k]

    def __getitem__(self, name):
        if name in self.__dict__:
            return self.__dict__[name]

    def __iter__(self):
        return iter(self.__dict__.keys())